ALBERT

Beschreibung: In this work, porous Ni-625 superalloys were produced by use of a water soluble pore forming agent prior to sintering. Carbamide particles were used as the space-holder materials. After mixing and compaction, the space-holder particles were extracted using warm water leaching over a range of temperatures. The porous green parts were subsequently thermally debinding to remove the paraffin wax under a pure Argon atmosphere, and subsequently sintered at high vacuum. The effects of volume fraction of space-holder particles on density, porosity, and elastic modulus were investigated. Microstructures were captured using optical and scanning electron microscopy. Pore size was quantified using image analysis software integral to the scanning electron microscopy. In addition, compression tests were conducted on the sintered samples.

Beschreibung: The hot deformation behavior of solution and aging FGH96 superalloy were investigated in the deformation temperature range of 1000-1175 °C and strain rate range of 0.001-5.0/s on a Gleeble-1500 thermo-mechanical simulator. The results show that the true stress-strain curves are typical of the occurrence of dynamic recrystallization (DRX). The value of the activation energy and materials constants of A and n was obtained through the hyperbolic sine function between the peak stress and Zener-Hollomon parameter. Optical microscopy observations of the grains showed that Zener-Hollomon parameter affected the DRX grain size obviously. In addition, the constitutive equations and DRX kinetics model were also built. The processing maps with the strain of 0.3 and 0.6 were obtained on the basis of dynamic materials model. The results predicted that there existed instability regions at around 1050 °C when the strain rate exceeds 0.01/s.

Beschreibung: In this paper, the results of fatigue behavior on friction stir welded joints of aluminum alloy EN AW 6082-T6 are reported. In particular, the study presents the influence of the geometry of a welding tool on fatigue strengths and tensile strengths. The test joints were prepared as single side welded and double side welded by FSW. The welding was performed at various linear welding speeds (224, 560, and 900 mm/min) and one rotational speed of 710 rev./min using three different tool shapes. The results of macro examination and tensile test led to the selection of a single set of tool movement parameters at which the test joints for fatigue test were made. Samples were tested in two states of surface condition, i.e., “as-welded” and with mechanically removed marks left by rotating and moving tool during FSW process. Studies have shown that fatigue behavior of FSW joints depends on the tool shape used in the welding process as well as the surface condition of welded joints and manner of joint production.

Beschreibung: Porous Fe-Al intermetallics with different nominal compositions (from Fe-8 wt.% Al to Fe-50 wt.% Al) were fabricated by Fe and Al elemental powders through reaction synthesis. The effects of the Al content on the pore structure properties, and the comparison of pore structure stabilities at high-temperatures among the porous Fe-Al intermetallics and porous Ti, Ni, 316L stainless steel samples, were systematically studied. Results showed that the open porosity, maximum pore size, and permeability vary with the Al content. Porous Fe-(25-30 wt.%) Al intermetallics show good shape controllability and excellent pore structure stability at 1073 K in air, which suggests that these porous Fe-Al intermetallics could be used for filtration at high temperatures.

Beschreibung: VO 2 thin films were deposited on soda lime glass substrates with ZnO, TiO 2 , SnO 2 , and CeO 2 thin films applied as buffer layers between the VO 2 films and the substrates in order to investigate the effect of buffer layer on the formation and the thermochromic properties of VO 2 film. Buffer layers with thicknesses over 50 nm were found to affect the formation of VO 2 film, which was confirmed by XRD spectra. By using ZnO, TiO 2 , and SnO 2 buffer layers, monoclinic VO 2 (VO 2 (M)) film was successfully fabricated on soda lime glass at 370 °C. On the contrary, films of VO 2 (B), which is known to have no phase transition near room temperature, were formed rather than VO 2 (M) when the film was deposited on CeO 2 buffer layer at the same film deposition temperature. The excellent thermochromic properties of the films deposited on ZnO, TiO 2 , and SnO 2 buffer layers were confirmed from the temperature dependence of electrical resistivity from room temperature to 80 °C. Especially, due to the tendency of ZnO thin film to grow with a high degree of preferred orientation on soda lime glass at low temperature, the VO 2 film deposited on ZnO buffer layer exhibits the best thermochromic properties compared to those on other buffer layer materials used in this study. These results suggest that deposition of VO 2 films on soda lime glass at low temperature with excellent thermochromic properties can be achieved by considering the buffer layer material having structural similarity with VO 2 . Moreover, the degree of crystallization of buffer layer is also related with that of VO 2 film, and thus ZnO can be one of the most effective buffer layer materials.

Beschreibung: Fe-Cr 3 C 2 hard coatings with varying Cr 3 C 2 content were produced on 35CrMo steel substrates by laser cladding. The experimental results showed that the coatings were uniform, continuous, and free of cracks. High adhesions between all produced coatings and their corresponding substrates were obtained due to the metallurgical interfaces between them. The microstructures of the coatings were mainly composed of austenitic dendrites and M 7 C 3 . The microhardness gradually increased from the bottom to the top of the coating, and increased with elevation of Cr 3 C 2 content. The Fe-Cr 3 C 2 coatings improved the sliding wear resistance of the 35CrMo steel substrates obviously, and the dominant wear mechanism was spalling fatigue, with plowed grooves on the worn surfaces.

Beschreibung: PVA-TiO 2 nanocomposite polymer electrolytes (PEs) were produced with different amounts of TiO 2 (0, 5, 10, 15, and 20 wt.%) using the electrospinning process. Morphological studies of PVA-TiO 2 nanofibers were accomplished with SEM. PVA-TiO 2 membranes exhibited a high porosity of 79-91%. The impedance results showed that incorporation of TiO 2 into the nanofiber membrane improved its ionic conductivity from 0.7 × 10 −5 to 2.5 × 10 −5  S/cm at room temperature. Nanofiber PEs showed very good reversibility and electrochemical stability up to 4.7 V. Diffusion coefficient of Li ion into PVA-TiO 2 nanocomposite PEs was estimated by using a complex numerical model of partial differential equation for evaluation of ion transmission. Diffusion coefficient of PVA-TiO 2 PEs containing different amounts of TiO 2 (0, 5, 10, 15, and 20 wt.%) increased with increasing the nanoparticles content.

Beschreibung: Synthesis of nanostructure titania powders and in situ crystallization of anatase coating layer on sintered alumina granules by solvothermal method were investigated. In coating process, addition of polyvinyl alcohol (PVA) as binder to solvothermal solution was also studied. Microstructure analyses of powders showed that crystallization and growth of nanostructure anatase phase in a thin gel layer were enhanced with temperature increase. The titania nanopowders synthesized at 120 °C and 8 h represented photodegradation of methyl orange solution as model wastewater up to maximum 94% yield in slurry photoreactor. However, in coating process, with increasing temperature to 220 °C and coating time to 24 h, adhesion and photocatalytic properties of the coated layer were improved. Furthermore, PVA binder addition led to formation of more uniform layer with less attrition loss in the reactor.

Beschreibung: Microstructure evolution after solutionizing and ageing treatment of cast AZ80 Mg alloy were investigated using optical and scanning electron microscopy. Effect of these treatments on grain size, β-Mg 17 Al 12 intermetallic phase, mechanical behavior, and flow asymmetry were investigated. The initial continuous network of β-phase found to be reduced after solutionizing. The dissolution of β-phase and simultaneous grain growth are found to be interrelated. Mechanical properties including yield strength, maximum strength (ultimate compressive strength), and maximum strain attainable in compressive found almost twice than the corresponding values obtained in tension. The asymmetry in compressive and tensile properties is found to decrease with grain size at certain solutionizing duration. Particular heat treatment found to offer best combination of tensile compressive flow properties in AZ80 Mg alloy. Aging under certain conditions found to minimize the strength asymmetry.

Beschreibung: In the present study, A-TIG welding was carried out on grade 91 steel plates of size 220 × 110 × 10 mm using the in-house developed activated flux to produce butt-joints. The room-temperature impact toughness of the A-TIG as-welded joint was low due to the presence of untempered martensite matrix despite the low microinclusion density caused by activated flux and also low δ-ferrite (〈0.5 %) content. Toughness after postweld heat treatment (PWHT) at 760 °C-2 h was 20 J as against the required value of 47 J as per the specification EN: 1557:1997. However, there was a significant improvement in impact toughness after PWHT at 760 °C for 3 h. The improvement in toughness was attributed to softening of martensite matrix caused by precipitation of carbides due to tempering reactions. The precipitates are of type M 23 C 6 , and they are observed at grain boundary as well as within the grains. The A-TIG-processed grade 91 steel weld joint was found to meet the toughness requirements after PWHT at 760 °C-3 h. Observations of fracture surfaces using SEM revealed that the as-welded joint failed by brittle fracture, whereas post-weld heat-treated weld joints failed by decohesive rupture mode.

Beschreibung: Cu-7Cr-0.07Ag alloys were prepared by casting and directional solidification, from which deformation-processed in situ composites were prepared by thermo-mechanical processing. The microstructure, mechanical properties, and electrical properties were investigated using optical microscopy, scanning electronic microscopy, tensile testing, and a micro-ohmmeter. The second-phase Cr grains of the directional solidification Cu-7Cr-0.07Ag in situ composite were parallel to the drawing direction and were finer, which led to a higher tensile strength and a better combination of properties.

Beschreibung: In this paper, two different heat treatment processes of a 9% Ni steel for large liquefied natural gas storage tanks were performed in an industrial heating furnace. The former was a special heat treatment process consisting of quenching and intercritical quenching and tempering (Q-IQ-T). The latter was a heat treatment process only consisting of quenching and tempering. Mechanical properties were measured by tensile testing and charpy impact testing, and the microstructure was analyzed by optical microscopy, transmission electron microscopy, and x-ray diffraction. The results showed that outstanding mechanical properties were obtained from the Q-IQ-T process in comparison with the Q-T process, and a cryogenic toughness with charpy impact energy value of 201 J was achieved at 77 K. Microstructure analysis revealed that samples of the Q-IQ-T process had about 9.8% of austenite in needle-like martensite, while samples of the Q-T process only had about 0.9% of austenite retained in tempered martensite.

Beschreibung: Stress corrosion cracking studies of aluminum alloys AA2219, AA8090, and AA5456 in heat-treated and non heat-treated condition were carried out using electrochemical noise technique with various applied stresses. Electrochemical noise time series data (corrosion potential vs. time) was obtained for the stressed tensile specimens in 3.5% NaCl aqueous solution at room temperature (27 °C). The values of drop in corrosion potential, total corrosion potential, mean corrosion potential, and hydrogen overpotential were evaluated from corrosion potential versus time series data. The electrochemical noise time series data was further analyzed with rescaled range ( R / S ) analysis proposed by Hurst to obtain the Hurst exponent. According to the results, higher values of the Hurst exponents with increased applied stresses showed more susceptibility to stress corrosion cracking as confirmed in case of alloy AA 2219 and AA8090.

Beschreibung: Ti 5 Si 3 was fabricated by self-propagating high-temperature synthesis (SHS), mechanical-activated SHS (MASHS), and mechanical alloying with the aim of investigating the effect of milling energy on final product. For MASHS process, Ti and Si as starting materials were milled by high energy ball milling, with ball-to-powder weight ratio (BPR) of 10:1, for different times (1, 3, and 6 h), then pressed to form pellets. Green compacts were placed in a tube furnace preheated to three different temperatures of 1000, 900, and 800 °C with argon atmosphere for the synthesis. The milled and synthesized powders were characterized by means of XRD and SEM. The results showed that Ti 5 Si 3 was not formed during milling up to 3 h, after that a trace of Ti 5 Si 3 peaks can be detected from XRD pattern. The increase in milling time prior the combustion reaction caused a decrease in the crystallite size of the final product and ignition temperature of the reactant. The average crystallite sizes of Ti 5 Si 3 after activation of 1, 3, and 6 h were calculated 87, 55, and 48 nm, respectively. Higher milling energy in BPR 15:1, led to the full reaction and formation of nanostructured Ti 5 Si 3 in milling media by mechanical alloying method, even after 1 h. The crystallite sizes of Ti 5 Si 3 after milling of powders from 1, 3, and 6 h, were calculated 70, 26, and 14 nm, respectively. For the SHS process Ti and Si were mixed in the methanol. The combustion reactions were carried out in the tubular furnace and reactor. SEM results showed that Products were formed via MASHS process have more uniformity of microstructure compared to those synthesized via SHS process.

Beschreibung: In this paper, we present results of electrode durability testing and electrode design in a pulsed electrohydraulic discharge environment. Pulsed electrohydraulic forming (EHF) is an electrodynamic process based upon high-voltage discharge of capacitors between two electrodes positioned in a fluid-filled chamber. EHF enables a more uniform distribution of strains, widens the formability window, and reduces elastic springback in the final part when compared to traditional sheet metal stamping. This extended formability allows the fabrication of panels of alternative high strength alloys that are otherwise difficult to make conventionally. It was found that, of the materials tested, steel electrodes not only survived the stresses encountered in the EHF chamber but also had lower erosion rates compared to molybdenum. Erosion rates were found to be constant for low carbon steel at 3.7 mm 3 /discharge, and they were high enough that the initial tip geometry was rapidly worn away and a more geometrically and thus electrically stable tip geometry had to be selected. Entrained air in the system had little influence on erosion rates but numerical modeling suggests that the erosion process takes place during the very initial stages of the pulse. Lastly, it was determined that the electrodes discussed in this paper can survive 2000 pulses.

Beschreibung: With the aim to produce a coating having good corrosion and wear resistance alongside hardness but lesser friction coefficient, Ni-P-PTFE-Al 2 O 3 (NiPPA) dispersion coating was developed. This was achieved by introducing nanosized polytetrafluoroethylene (PTFE) and alumina (Al 2 O 3 ) in the Ni-P matrix deposited on mild steel substrate. The coating was characterized using scanning electron microscopy, energy dispersive analysis of x-ray, and x-ray diffractrometry. Microhardness and wear resistance of the coating was measured using Vicker’s hardness tester and Pin-on-Disc method, respectively. The corrosion behavior was measured using electrochemical polarization and immersion tests with and without exposure in 3.5% NaCl solution. It is observed that codeposition of Al 2 O 3 and PTFE particles with Ni-P coating results in comparatively smooth surface with nodular grains. The NiPPA coating was observed to have moderate hardness between electroless Ni-P-PTFE and Ni-P-Al 2 O 3 coating and good wear resistance with lubricating effect. Addition of both PTFE and Al 2 O 3 is observed to enhance corrosion resistance of the Ni-P coating. However, improvement in corrosion resistance is more due to addition of Al 2 O 3 than PTFE. Continuous exposure for 10-20 days in corrosive solution is found to deteriorate corrosion protection properties of the coating.

Beschreibung: A dimensional deformation measurement system (XJTUDIC/VS) based on digital image correlation was employed to measure the deformation and strain field of Cu/Al clad metals made using the explosive welding technique. An extensometer with a gage length of 50 mm was used during the Q235 tensile test to verify the strain measurement accuracy of the system. The results demonstrate that the accuracy of the XJTUDIC/VS system is ≥0.5%, which is very close to that of the extensometer. The anisotropy of Cu/Al clad metals under uniaxial tension after 0, 1.5, 2.5, and 4.5% prestrain was investigated. With an increase in strain, the true stress-strain curve varied at different directions in the same prestrains. The strain hardening rate, r value (changes from 0.1 to 0.9), and n value (changes from 0.25 to 0.35) all strongly depended on loading directions and prestrains. The linear relations between longitudinal strain and transverse strain were also influenced by tensile directions and prestrains. Cu/Al clad metals generally presented strong anisotropy.

Beschreibung: High cycle fatigue tests of a cast Al-12Si-CuNiMg alloy are carried out under different stress amplitudes at room temperature. The scanning and transmission electron microscopy observations are used to examine the fracture surfaces and dislocation structures of the tested material, respectively. The results show that the fatigue damage originates from the microstructural defects, and the fracture surface morphology is typical quasi-cleavage fracture. With the increasing strain amplitude, the material fatigue life obviously decreases; however, the dislocation density increases significantly, which leads to the formation of the dislocation walls and cells. Under the cycle loading, the eutectic Si phase and the secondary particles undergo fracture. The pinning effect of the precipitates on the dislocations becomes obvious, indicating that the Al-12Si-CuNiMg alloy has the cyclic hardening characteristic.

Beschreibung: The current study aimed to investigate the effect of fluidized sand bed (FB) quenching on the mechanical performance of B319.2 aluminum cast alloys. Traditional water and conventional hot air (CF) quenching media were used to establish a relevant comparison with FB quenching. Quality charts were generated using two models of quality indices to support the selection of material conditions on the basis of the proposed quality indices. The use of an FB for the direct quenching-aging treatment of B319.2 casting alloys yields greater UTS and YS values compared to conventional furnace quenched alloys. The strength values of T6 tempered B319 alloys are greater when quenched in water compared with those quenched in an FB or CF. For the same aging conditions (170°C/4h), the fluidized bed quenched-aged 319 alloys show nearly the same or better strength values than those quenched in water and then aged in a CF or an FB. Based on the quality charts developed for alloys subjected to different quenching media, higher quality index values are obtained by conventional furnace quenched-aged T6-tempered B319 alloys. The modification factor has the most significant effect on the quality results of the alloys investigated, for all heat treatment cycles, as compared to other metallurgical parameters. The results of alloys subjected to multi-temperature aging cycles reveal that the optimum strength properties of B319.2 alloys, however, is obtained by applying multi-temperature aging cycles such as, for example, 240 °C/2 h followed by 170 °C/8 h, rather than T6 aging treatments. The regression models indicate that the mean quality values of B319 alloys are highly quench sensitive due to the formation of a larger percent of clusters in Al-Si-Cu-Mg alloys. These clusters act as heterogeneous nucleation sites for precipitation and enhance the aging process.

Beschreibung: The effects of Ti addition on phase transformation, precipitation behavior, and microhardness response of Cu40Zn brass were investigated at elevated heat treatment (HT) temperatures using the powder metallurgy method. The volume fraction of the α phase increased with the elevated temperatures, which showed an equal value as that of the β phase at 400 °C, and reached a maximum value of 55.9% at 500 °C. The solid solubility of Ti in Cu40Zn brass matrix decreased as the HT temperature increased. Supersaturated Ti showed high chemical potential for precipitates' reaction in Cu40Zn brass. Lower HT temperature retained higher Ti solid solubility and fine precipitates. The precipitates presented in form of Cu 2 TiZn intermetallic compound, distributing uniformly in brass matrix which suppressed the phase and grain growth. After HT at elevated temperature, the precipitates coalesced, grew coarser, and segregated at the primary particle boundaries. The microhardness of the BS40-1.0Ti compact was primarily not only dependent on the solid solubility of Ti, but also dependent on the phase volume fraction of the α and β phases.

Beschreibung: Nihard Grade-4, a nickel-bearing cast iron widely used in slurry pumps and hydrodynamic components, is evaluated for its erosive wear response under mining conditions using a statistical approach. Experiments were conducted by varying the factors namely velocity, slurry concentration, angle of impingement, and pH in three levels, using L9 orthogonal array. Analysis of variance was used to rank the factors influencing erosive wear. The results indicate that velocity is the most influencing factor followed by the angle of impingement, slurry concentration, and pH. Interaction effects of velocity, slurry concentration, angle of impingement, and pH on erosion rate have been discussed. Wear morphology was also studied using SEM characterization technique. At lower angle (30°) of impingement, the erosion of material is by micro fracture and shallow ploughing with the plastic deformation of the ductile austenitic matrix. At the normal angle (90°) of impingement, the material loss from the surface is found because of deep indentation, forming protruded lips which are removed by means of repeated impact of the erodent.

Beschreibung: MAR-M247 is a nickel-based superalloy that contains 3 wt.% Ta (weight percent of tantalum). Considering the chemical similarity between tantalum and niobium (Nb) and the lower cost of Nb, a modified MAR-M247 superalloy was produced with total replacement of Ta by Nb in this work. The samples were previously solutioned at 1260°C for 8 h and then aged at different times (between 5 and 80 h) and temperatures (between 780 and 980°C). The microstructures of the aged samples were characterized with a scanning electron microscope (SEM and FEG-SEM, both with EDS). Simulations of the MC carbide and γ′ fraction and the Ta and Nb content in both MC carbide and γ′ phase were performed with Thermo-Calc software (TT_Ni8 database) and simulations of the γ′ growth rate and γ′ mean diameter were performed with JMatPro software. MC carbide with high Hf content was observed in all the aged samples, in agreement with thermodynamic simulation results. The equilibrium γ′ fraction decreases from 67 mol.% at 780°C to 52 mol.% at 980°C. Good agreement between the calculated and experimentally determined γ′ particle size was also found. The growth rate of γ′ at 980°C is about 8 times higher than that at 780°C and 3 times higher than that at 880°C. The hardness values do not change considerably after aging at 780 and 880°C. However, these values decrease significantly after aging at 980°C.

Beschreibung: Bulk texture measurement of multi-axial forged body center cubic interstitial free steel performed in this study using x-ray and neutron diffraction indicated the presence of a strong {101}〈111〉 single texture component. Viscoplastic self-consistent simulations could successfully predict the formation of this texture component by incorporating the complicated strain path followed during this process and assuming the activity of {101}〈111〉 slip system. In addition, a first-order estimate of mechanical properties in terms of highly anisotropic yield locus and Lankford parameter was also obtained from the simulations.

Beschreibung: The inhibition effect of cefoperazone (CP) on the corrosion behavior of carbon steel in 0.5 M HCl solution was studied using potentiodynamic polarization, electrochemical impedance spectroscopy, and electrochemical frequency modulation techniques along with scanning electron microscopy (SEM). Results showed that the inhibition efficiency increases with increasing inhibitor concentration and decreases with increasing the temperature. The results indicated that the inhibitive action of CP can be attributed to its adsorption. The results show that CP possesses excellent inhibiting effect for the corrosion of carbon steel and the inhibitor acts as mixed-type inhibitor. The adsorption process is spontaneous and follows Langmuir adsorption isotherm model. The surface adsorption of the inhibitor molecules decreases the double-layer capacitance and increases the polarization resistance. SEM results indicate the formation of an adsorbed protective film on the metal surface. The results obtained from the different techniques were in good agreement which prove the validity of these tools in the measurements of the tested inhibitor.

Beschreibung: Formability of magnesium alloys at room temperature or slightly elevated temperatures is low, and exhibiting poor resistance to strain localization and failure. However, it is possible to improve the formability of AZ31 magnesium alloy sheet at high strain rate such as by electromagnetic forming (or magnetic pulse forming). In this study, experimental investigation of uniaxial tension of AZ31 sheet by magnetic pulse forming at room temperature was presented. The approximate rectangular flat spiral coil was employed to carry out the experiments. The specimens used in the tension test by magnetic pulse forming were same as the quasi-static uniaxial test. The samples were placed close to the outside of coil where an approximately homogenous magnetic field distribution prevailed. The experimental results indicate that the total elongation of AZ31 sheet improves about 37% compared with the quasi-static case. Non-uniform deformation occurs in the specimen. The maximum strain takes place on the area C , where is plotted on the specimen. The major and minor principal strains at most increase by approximately 112 and 96% under 5.12 kJ energy. The experimental results obtained in this study provide the fundamentals for the investigation of high speed forming of AZ31 magnesium alloy sheets.

Beschreibung: ZrO 2 was brazed to Ti-6Al-4V using a Zr 55 Cu 30 Al 10 Ni 5 (at.%) amorphous filler in a high vacuum at 1173-1273 K. The influences of brazing temperature, holding time, and cooling rate on the microstructure and shear strength of the joints were investigated. The interfacial microstructures can be characterized as ZrO 2 /ZrO 2− x  + TiO/(Zr,Ti) 2 (Cu,Ni)/(Zr,Ti) 2 (Cu,Ni,Al)/acicular Widmanstäten structure/Ti-6Al-4V. With the increase in the brazing temperature, both the thickness of the ZrO 2− x  + TiO layer and the content of the (Zr,Ti) 2 (Cu,Ni) phase decreased. However, the acicular Widmanstäten structure gradually increased. With the increase in the holding time, the (Zr,Ti) 2 (Cu,Ni) phase decreased, and the thickness of the (Zr,Ti) 2 (Cu,Ni) + (Zr,Ti) 2 (Cu,Ni,Al) layer decreased. In addition, cracks formed adjacent to the ZrO 2 side under rapid cooling. The microstructures produced under various fabrication parameters directly influence the shear strength of the joints. When ZrO 2 and Ti-6Al-4V couples were brazed at 1173 K for 10 min and then cooled at a rate of 5 K/min, the maximum shear strength of 95 MPa was obtained.

Beschreibung: Mechanical alloying (MA) and the field-activated and pressure-assisted in situ synthesis (FAPAS) were combined to prepare the ultra-hard and super-abrasive AlMgB 14 with the characteristics of fast heating-up, high efficiency, and low energy cost. Such preparations using the elemental constituents, such as Al, Mg, and B, were performed at a vacuum annealed temperature of 1500 °C under a pressure of 60 MPa. The resultant ceramics were characterized by SEM, EDS, and XRD. It was shown that the samples contained uniform AlMgB 14 , and the maximum hardness on the sample surface may reach 32.5 GPa. Furthermore, a second experiment was performed, in which MgH 2 was used as one of the starting materials instead of elemental Mg, but this approach did not produce AlMgB 14 .

Beschreibung: The influences of Y and Y-rich mischmetal (Ym) additions on microstructural and compressive properties of as-cast Al-13Mg-0.8Mn alloy prepared by vacuum suction casting were investigated in this study. The average secondary dendrite arm spacing (SDAS) was decreased when adding Y and Ym additions. Moreover, the Al 2 Y and Al 2 Ym phases formed during the solidification were mainly distributed along the grain boundary. The mechanical results reveal that both Y and Ym additions are effective in increasing the compressive strength and hardness. The values of yield compressive strength, ultimate compressive strength, and Brinell hardness of the as-cast Al-13Mg-0.8Mn-0.8Y alloy are 357 MPa, 510 MPa, and 138, respectively. The improved mechanical properties are mainly attributed to fine SDAS and precipitation strengthening. A typical cleavage fracture mode is observed on the compressive fracture surfaces of the alloys.

Beschreibung: Finding the geometry and properties of a ceramic tile after its firing using simulations, is relevant because several defects can occur and the tile can be rejected if the conditions of the firing are inadequate for the geometry and materials of the tile. Previous works present limitations because they do not use a model characteristic of ceramics at high temperatures and they oversimplify the simulations. As a response to such shortcomings, this article presents a simulation with a three-dimensional Norton’s model, which is characteristic of ceramics at high temperatures. The results of our simulated experiments show advantages with respect to the identification of the mechanisms that contribute to the final shape of the body. Our work is able to divide the history of temperatures in stages where the evolution of the thermal, elastic, and creep deformations is simplified and meaningful. That is achieved because our work found that curvature is the most descriptive parameter of the simulation. Future work is to be realized in the creation of a model that takes into account that the shrinkage is dependent on the history of temperatures.

Beschreibung: Microstructure, mechanical properties, and wear resistance of B-bearing high-speed steel (HSS) roll material containing 0.90-1.00% C, 1.3-1.5% B, 0.8-1.5% W, 0.8-1.5% Mo, 4.6-5.0% Cr, 1.0-1.2% V, and 0.15-0.20% Ti were studied by means of the optical microscopy (OM), the scanning electron microscopy (SEM), x-ray diffraction (XRD), hardness, impact toughness, and pin-on-disk abrasion tests. The results showed that as-cast structure of B-bearing HSS consisted of α-Fe-, M 23 (B,C) 6 -, M 3 (B 0.7 C 0.3 )-, and M 2 (B,C)-type borocarbides, a small quantity of retained austenite, and a small amount of TiC. The hardness and impact toughness values of as-cast B-bearing HSS reached 65-67 HRC and 80-85 kJ/cm 2 , respectively. There were many M 23 (B,C) 6 -precipitated phases in the matrix after tempering, and then, with increasing temperature, the amount of precipitated phases increased considerably. Hardness of B-bearing HSS gradually decreased with the increasing tempering temperature, and the change of tempering temperature had no obvious effect on impact toughness. B-bearing HSS tempered at 500 °C has excellent wear resistance, which can be attributed to the effect of boron.

Beschreibung: The objective of this work is to model the thermal expansion coefficients of various Ni-based superalloys used in gas turbine components. The thermal expansion coefficient is described as a function of temperature, chemical composition including Ni, Cr, Co, Mo, W, Ta, Nb, Al, Ti, B, Zr, and C contents as well as heat treatment including solutionizing and aging. Experimental values are well described and their relative changes well correlated by the model. Because gas turbine engine components operate under severe loading conditions and at high and varying temperatures, the prediction of their thermal expansion coefficient is crucial. The model developed in this work can be useful for design optimizations for minimizing thermo-mechanical stresses between the base alloys and potential protective coatings or adjacent components. It can substantially contribute to improve the performance and service life of gas turbine components.

Beschreibung: An investigation was carried out to examine the influence of structural and mechanical properties on wear behavior of austempered ductile iron (ADI). Ductile iron (DI) samples were austenitized at 900 °C for 60 min and subsequently austempered for 60 min at three temperatures: 270, 330, and 380 °C. Microstructures of the as-cast DI and ADIs were characterized using optical and scanning microscopy, respectively. The structural parameters, volume fraction of austenite, carbon content of austenite, and ferrite particle size were determined using x-ray diffraction technique. Mechanical properties including Vicker’s hardness, 0.2% proof strength, ultimate tensile strength, ductility, and strain hardening coefficient were determined. Wear tests were carried out under dry sliding conditions using pin-on-disk machine with a linear speed of 2.4 m/s. Normal load and sliding distance were 45 N and 1.7 × 10 4  m, respectively. ADI developed at higher austempering temperature has large amounts of austenite, which contribute toward improvement in the wear resistance through stress-induced martensitic transformation, and strain hardening of austenite. Wear rate was found to depend on 0.2% proof strength, ductility, austenite content, and its carbon content. Study of worn surfaces and nature of wear debris revealed that the fine ausferrite structure in ADIs undergoes oxidational wear, but the coarse ausferrite structure undergoes adhesion, delamination, and mild abrasion too.

Beschreibung: This paper proposes a new level of understanding of two-point incremental forming (TPIF) with partial die by means of a combined theoretical and experimental investigation. The theoretical developments include an innovative extension of the analytical model for rotational symmetric single point incremental forming (SPIF), originally developed by the authors, to address the influence of the major operating parameters of TPIF and to successfully explain the differences in formability between SPIF and TPIF. The experimental work comprised the mechanical characterization of the material and the determination of its formability limits at necking and fracture by means of circle grid analysis and benchmark incremental sheet forming tests. Results show the adequacy of the proposed analytical model to handle the deformation mechanics of SPIF and TPIF with partial die and demonstrate that neck formation is suppressed in TPIF, so that traditional forming limit curves are inapplicable to describe failure and must be replaced by fracture forming limits derived from ductile damage mechanics. The overall geometric accuracy of sheet metal parts produced by TPIF with partial die is found to be better than that of parts fabricated by SPIF due to smaller elastic recovery upon unloading.

Beschreibung: The long-term durability of ceramics coated glass with high performance should be appropriately evaluated prior to their applications. Fatigue properties of such materials should be clarified to ensure the long-term durability. In this work, a borosilicate glass was coated with single- and two-layered ceramic thin films by a sputtering method. Fatigue tests of coated glass were conducted under bending mode, and fatigue properties of coated glass were investigated. It was revealed that the fatigue life of glass coated with two-layered film became longer compared with those of glass substrate and glass coated single-layered film. Hardness as surface characteristics of coated films, and bending strength as bulk property of coated glass were correlated with the average fatigue life, though no good correlation was found between them. Fatigue resistance strength was proposed as another strength parameter. It was found that the average fatigue life was adequately expressed by a power function of fatigue resistance strength.

Beschreibung: In this paper, the influence of the cooling rate and cooling media after a standard solution heat treatment on the size and distribution of the gamma prime phase (γ′) in the nickel-based super alloy INCONEL 738 in over-aged conditions is described. The volume fraction of the gamma prime depends on the chemical composition of the alloy, the solution treatment temperature and the cooling rate; in over-aged alloys (i.e., with more than 25,000 h of service) the volume fraction of γ′ is about 78.8%. However, it has been demonstrated that in order to maintain excellent creep strength a volume fraction of at least 60% or lower is required. In this work the volume fraction was optimized between 40 and 55% by means of a standard solution heat treatment at 1120 °C using different cooling gases. A γ′ volume fraction of 54.8% was obtained by using argon as the cooling medium at a cooling rate of 87 °C/min, producing a precipitate of partial distribution of primary and secondary γ′. Better results were obtained in a nitrogen atmosphere at a cooling rate of 287 °C/min, leading to a volume fraction of 40% and obtaining a total re-precipitation of primary and secondary γ′.

Beschreibung: In this study, we have characterized the microstructure, resistivity, and dynamic deformation behavior of Cu/Ru/SiO 2 and Cu/SiO 2 samples under scratch loading conditions. Cu/Ru/SiO 2 samples showed higher elastic recovery and hardness when compared to the Cu/SiO 2 samples. In the case of Cu/Ru/SiO 2 samples, Ru acts as a glue layer between the Cu and the SiO 2 substrate providing both strength and toughness against dynamic loading. Hence, the critical load for delamination is higher for Cu/Ru/SiO 2 samples compared to Cu/SiO 2 samples. Our results show that Cu/Ru/SiO 2 thin films present significant potential to be used in Cu metallization.

Beschreibung: The inhibition effect of mild steel (MS) corrosion in 1 M HCl was studied by the addition of indole alkaloids (crude) isolated from Alstonia angustifolia var. latifolia ( A. latifolia ) leaves at 303 K. Potentiodynamic polarization, impedance spectroscopy, scanning electron microscopy (SEM), and Fourier transform infrared (FTIR) analyses were used for this study. Results show that the isolated alkaloid extract of A. latifolia is a good inhibitor and exhibited maximum inhibition efficiency (above 80%) at concentrations between 3 and 5 mg/L. Polarization measurements indicated that the inhibitor does not alter the mechanism of either anodic or cathodic reactions and acted as mixed-type inhibitor. The inhibition efficiencies of both electrochemical techniques are found to be in good agreement and adsorption of inhibitor follows Langmuir isotherm. Adsorption of inhibitor over metal surface was well supported by the SEM studies, while FTIR studies evidenced the presence of indole alkaloids as green inhibitor that reduces the rate of corrosion.

Beschreibung: The coating formation in a kinetic spray process mainly depends on the impact of inflight particles at a high velocity. The plastic deformation at the impact interface would disrupt the native oxide scale on the particle and the substrate to generate the intimate contact of the atomic structures. Accordingly, it poses a challenge in producing ceramic coating during kinetic spray because of the lack of plasticity of ceramic powders at room temperature. In this study, we proposed to prepare ZrO 2 ceramic coatings using partially amorphized powder with nanometer size in the kinetic spray process. To prepare the powder for the use of the kinetic spray, the amorphization and grain refinement of ZrO 2 powder in mechanical ball milling were studied. The results showed that the amorphization and grain refinement were improved because of the formation of solid solution when the CeO 2 agent was added. Subsequently, a nearly spherical powder was achieved via spray drying using the milled powders. The plasticity of the milled powders was tested in the kinetic spray process using Nitrogen as process gas. A dense ZrO 2 -CeO 2 coating with a thickness of 50 μm was formed, whereas spraying milled ZrO 2 powder can only lead to an inhomogeneous dispersion of the destructible particles on the surface of the substrate.

Beschreibung: Laser surface alloying (LSA), with Wallex-50 and Tribaloy-700 powders, and laser transformation hardening (LTH) reduced the silt erosion rate in 16Cr-5Ni steel. Slurry erosion wear tests were conducted on 16Cr-5Ni steel, LSA-modified steel, and LT-hardened steel at different angles of impingement and velocities at a constant size of silica particles. The LSA-modified steel and LT-hardened steel showed improved wear resistance by about 1.5-3 times as compared to substrate 16Cr-5Ni steel for all angles of impingement. This improvement in hardness and erosion resistance was due to the incorporation of carbides and hard complex phases after LSA and LTH.

Beschreibung: In this study, an artificial neural network (ANN) was employed to predict the contact fatigue life of alloy cast steel rolls (ACSRs) as a function of alloy composition, heat treatment parameters, and contact stress by utilizing the back-propagation algorithm. The ANN was trained and tested using experimental data and a very good performance of the neural network was achieved. The well-trained neural network was then adopted to predict the contact fatigue life of chromium alloyed cast steel rolls with different alloy compositions and heat treatment processes. The prediction results showed that the maximum value of contact fatigue life was obtained with quenching at 960 °C, tempering at 520 °C, and under the contact stress of 2355 MPa. The optimal alloy composition was C-0.54, Si-0.66, Mn-0.67, Cr-4.74, Mo-0.46, V-0.13, Ni-0.34, and Fe-balance (wt.%). Some explanations of the predicted results from the metallurgical viewpoints are given. A convenient and powerful method of optimizing alloy composition and heat treatment parameters of ACSRs has been developed.

Beschreibung: The hot deformation behavior of AMS 5708 nickel-based superalloy was investigated by means of hot compression tests and a processing map in the temperature range of 950-1200 °C and a strain rate range of 0.01-1 s −1 was constructed. The true stress-true strain curves showed that the maximum flow stress decreases with the increase of temperature and decrease of strain rate. The developed processing map based on experimental data, showed variations of efficiency of power dissipation relating to temperature and strain rate at constant strain. Interpretation of the processing map showed one stable domain, in which dynamic recrystallization was the dominant microstructural phenomenon, and one instability domain with flow localization. The results of interpretation of flow stress curves and processing map were verified by the microstructure observations. There are two optimum conditions for hot working of this alloy with efficiency peak of 0.36: the first is at 1150 °C for a strain rate of 1 s −1 that produces a fine grained microstructure. The second is at 1200 °C for a strain rate of 0.01 s −1 that produces a coarse grained microstructure.

Beschreibung: Setaria verticillata leaf extract (SVLE) as corrosion inhibitor in 1M H 2 SO 4 was investigated by weight loss techniques and electrochemical techniques at 308-328 K. Inhibition efficiency of SVLE was found to increase with increasing concentration but decreased with temperature. Polarization measurements revealed that SVLE acted as mixed-type inhibitor. Impedance diagrams showed that increasing of SVLE concentration increased charge transfer resistance and decreased double layer capacitance. The adsorption of SVLE on the mild surface obeyed the Langmuir adsorption isotherm. Protective film formation against corrosion was confirmed by SEM and FTIR.

Beschreibung: Nickel-iron-based alloy 718 was thermally exposed in peak-aged condition at 550 and 650 °C, from 5 to 100 h, with and without salt coatings and was tested in tension at room temperature and elevated temperatures. Standard tensile specimens were coated with three different salts (in wt.%): NaCl(100), Na 2 SO 4  + NaCl (75/25), and Na 2 SO 4  + NaCl + V 2 O 5 (90/5/5). Exposure of salt-coated specimens at 550 and 650 °C revealed formation of scales and corrosion pits. Tensile deformation resulted in cracking of the surface oxide/corrosion scale. The uncoated specimens showed formation of oxide scales on the surface, without any cracking whereas the salt-coated specimens showed surface cracking and pitting at some places. However, tensile properties were not degraded due to salt coatings.

Beschreibung:    The effect of NaOH content of electrolyte on the properties of ceramic coatings, produced in silicate solution, was studied. Morphology, chemical analysis, phase composition, and cross-section of the ceramic coatings were investigated by SEM, EDS, XRD, and OM, respectively. The corrosion resistance and corrosion mechanism were also studied using potentiodynamic polarization and electrochemical impedance spectroscopy in a 3.5% NaCl solution. To study the surface roughness, a brightness SEM image analysis method was used. Results suggested that increasing the NaOH concentration of sediment production size causes thickness and coating roughness to decrease. The lowest corrosion rate belonged to the twofold layer coating produced in 10 g/L of NaOH. Other samples, with higher concentrations of NaOH, had reduced porosity, and thus an increase in the corrosion resistance was observed. These coatings mainly consisted of α/γ-Al 2 O 3 and amorphous silica. Content Type Journal Article Pages 1-8 DOI 10.1007/s11665-012-0151-1 Authors D. Salehi Doolabi, Department of Materials Science and Engineering, Faculty of Engineering, Shahid Bahonar University of Kerman, P.O. Box 76175-133, Islamic Republic Blvd., Kerman, Iran M. Ehteshamzadeh, Department of Materials Science and Engineering, Faculty of Engineering, Shahid Bahonar University of Kerman, P.O. Box 76175-133, Islamic Republic Blvd., Kerman, Iran S. M. M. Mirhosseini, Faculty of Materials Science and Engineering, Sharif University of Technology, Tehran, Iran Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung:    In this study, the electric resistance spot welding process was applied to zinc-coated steel sheets used in automotive industry. Spot welding parameters namely, electrode form, electrode material, and electrode force were stayed constant, and welding current and welding time have been changed to detect the optimum welding parameters for maximum joint strength. Using 4, 5, 6, 7, and 8 kA welding currents and 5, 10, 15, 20, and 25 cycles welding times 1.0-1.0 mm sheets were spot welded to prepare samples. These spot-welded joints were then exposed to uniaxial tensile test, and tensile-shear and tensile-peel forces prior to breaking were determined. In addition, microstructures were detected by SEM and micro-hardness was measured from different regions of resistance spot-welded samples and recommendations showing the optimum welding parameters were given to users. Content Type Journal Article Pages 1-8 DOI 10.1007/s11665-012-0189-0 Authors Ugur Ozsarac, Department of Metallurgical and Materials Engineering, Technology Faculty, Sakarya University, Sakarya, Turkey Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung:    Strain aging and hardening behaviors of a 304 stainless steel containing deformation-induced martensite were investigated by examining mechanical properties and microstructural evolution for different aging temperature and time. Introduced age hardening mechanisms of a cold rolled 304 stainless steel were the additional formation of α′-martensite, hardening of α′-martensite, and hardening of deformed austenite. The increased amount of α′-martensite at an aging temperature of 450 °C confirmed the additional formation of α′-martensite as a hardening mechanism in a cold rolled 304 stainless steel. Additionally, the increased hardness in both α′-martensite and austenite phases with aging temperature proved that hardening of both α′-martensite and austenite phases would be effective as hardening mechanisms in cold rolled and aged 304 stainless steels. The results suggested that among hardening mechanisms, hardening of an α′-martensite phase, including the diffusion of interstitial solute carbon atoms to dislocations and the precipitation of fine carbide particles would become a major hardening mechanism during aging of cold rolled 304 stainless steels. Content Type Journal Article Pages 1-6 DOI 10.1007/s11665-012-0186-3 Authors S. W. Jeong, School of Advanced Material Engineering, Kookmin University, 861-1 Jeongneung-Dong, Songbuk-Ku, Seoul, 136-702 Republic of Korea U. G. Kang, School of Advanced Material Engineering, Kookmin University, 861-1 Jeongneung-Dong, Songbuk-Ku, Seoul, 136-702 Republic of Korea J. Y. Choi, Stainless Steel Research Group, POSCO Technical Research Laboratories, POSCO, P.O. Box 36, Pohang, 790-785 Republic of Korea W. J. Nam, School of Advanced Material Engineering, Kookmin University, 861-1 Jeongneung-Dong, Songbuk-Ku, Seoul, 136-702 Republic of Korea Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung:    This study investigates the microstructure, electrical, corrosion, and mechanical properties of plate-shaped aluminum-copper couple produced using the explosive welding method. Mechanical tests, including hardness, tensile, tensile-shear, and impact test, concluded that the Al-Cu bimetal had an acceptable joint resistance. In this study, local intermetallic regions formed on the interface of the joint of the aluminum-copper bimetal, produced using the explosive welding technique. However, the formed intermetallic regions had no significant effect on the mechanical properties of the joint, except for increasing its hardness. According to electrical conductivity tests, the Al-Cu bimetal had an average electrical conductivity in comparison to the electrical conductivity of aluminum and copper, which were the original materials forming the joint. According to the results of electro-chemical corrosion test, during which galvanic corrosion formed, the Al side of the Al-Cu bimetal was more anodic due to its high electronegativity; as a result, it was exposed to more corrosion in comparison to the copper side. Content Type Journal Article Pages 1-5 DOI 10.1007/s11665-012-0203-6 Authors Mustafa Acarer, Technical Education Faculty, Karabuk University, 78100 Karabuk, Turkey Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung:    Ti and its alloys are widely used in manufacturing orthopedic implants as prostheses for joint replacement because of their high corrosion resistance and excellent biocompatibility. However, they lack in bone-bonding ability and leads to higher rate of osteolysis and subsequent loosening of implants. In order to enhance the bone-bonding ability of these alloys, various surface-modification techniques are generally employed. The present investigation is mainly concerned with the surface modification of Cp-Ti and Ti-5Al-2Nb-1Ta alloy using a mixture of alkali and hydrogen peroxide followed by subsequent heat treatment to produce a porous gel layer with anatase structure, which enhances osseointegration. The morphological behavior was examined by x-ray diffractometer (XRD), atomic force microscopy (AFM), and scanning electron microscopy (SEM) coupled with energy dispersive x-ray analysis (EDX). The in vitro characterization of all the specimens was evaluated by immersing the specimens in simulated body fluid solution to assess the apatite formation over the metal surface. The apatite formation was confirmed by XRD, SEM-EDX, and Fourier transform infrared spectroscopy (FT-IR). Further, the electrochemical corrosion behaviors of both the untreated and treated specimens were evaluated using potentiodynamic polarization and electrochemical impedance spectroscopy. The results revealed that the surface-modified and heat-treated specimens exhibited higher corrosion resistance and excellent biocompatibility when compared to the chemical and untreated specimens. Content Type Journal Article Pages 1-11 DOI 10.1007/s11665-012-0143-1 Authors Y. Sasikumar, Department of Chemistry, Anna University, Chennai, 600 025 India N. Rajendran, Department of Chemistry, Anna University, Chennai, 600 025 India Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung:    This study investigates the mechanical properties of Al-7Si-0.3Mg (A356) alloy affected by the spinning deformation processing (SDP). The cast structure of the A356 alloy becomes elongated with increasing reduction in thickness. This leads to reduction of casting defects, and refines and distributes the eutectic silicon phase throughout the Al-matrix. The hardness tends to reach a steady value due to the uniformity of the microstructure with the reduction in thickness. The SDP leads to a re-arrangement in the eutectic region, which forces the propagation of cracks through the ductile α-Al phase. The tensile strength and elongation increases accordingly. The improvement on tensile strength and elongation produces the best quality index for A356 alloy. Content Type Journal Article Pages 1-6 DOI 10.1007/s11665-011-0089-8 Authors Yin-Chun Cheng, Department of Mechanical Engineering, National Central University, No. 300, Jhongda Rd., Jhongli City, Taoyuan County 32001, Taiwan, ROC Chih-Kuang Lin, Department of Mechanical Engineering, National Central University, No. 300, Jhongda Rd., Jhongli City, Taoyuan County 32001, Taiwan, ROC An-Hung Tan, Department of Mechanical Engineering Ching-Yun University, No. 229, Jianxing Rd., Zhongli City, Taoyuan County 32097, Taiwan, ROC Shih-Yuan Hsu, Department of Mechanical Engineering, National Central University, No. 300, Jhongda Rd., Jhongli City, Taoyuan County 32001, Taiwan, ROC Sheng-Long Lee, Department of Mechanical Engineering, National Central University, No. 300, Jhongda Rd., Jhongli City, Taoyuan County 32001, Taiwan, ROC Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung:    Alumina ceramic foams have been infiltrated with an Al-10 Mg alloy, by a capillarity-driven process, to create interpenetrating composites. Infiltration maps are presented for three different foam types which depict the temperature and time required for successful infiltration. The Young’s modulus of “fully” infiltrated composites containing approximately 18, 25, and 36 vol.% ceramic were measured and found to be 96, 110, and 124 GPa, respectively. Porosimetry of the foams revealed a significant fraction of closed porosity within the cell walls, the quantity of which increases with foam density, which accounts for the lower density and stiffness values that were measured, compared with those predicted by a simple model. Content Type Journal Article Pages 1-7 DOI 10.1007/s11665-012-0147-x Authors R. Gil, Facultad de Ingeniería, Universidad de Los Andes, Mérida, Venezuela A. R. Kennedy, Manufacturing Research Group, Faculty of Engineering, University of Nottingham, Nottingham, NG7 2RD UK Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung:    A combination of the transverse tensile test and the unilaterally coupled finite element method was used to evaluate the interfacial normal bond strength and stress distribution of titanium matrix composites (TMCs). In addition, in order to identify the interface shear failure mode of TMCs under transverse loading, both the push-out test and the finite element method have been developed to characterize the interfacial shear strength of TMCs, which is the interfacial shear failure criterion. This article studies the results of the experiments, which suggested that the interfacial normal bond and shear strength of SiC f /Ti-6Al-4V were 300 and 350 MPa, respectively, and the interface failure mode of TMCs under the transverse tensile test was radial failure rather than shear failure. Moreover, the effect of residual stress on the radial stress is also discussed in detail in this article. Content Type Journal Article Pages 1-5 DOI 10.1007/s11665-011-0094-y Authors Xu Yanfang, College of Mechanical and Electrical Engineering, North University of China, Taiyuan, 030051 People’s Republic of China Su Tiexiong, College of Mechanical and Electrical Engineering, North University of China, Taiyuan, 030051 People’s Republic of China Yuan Meini, College of Mechanical and Electrical Engineering, North University of China, Taiyuan, 030051 People’s Republic of China Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung:    In the present work, cladding of hardfacing WC10Co2Ni powder on austenitic stainless steel has been developed through a novel processing technique. The clads were developed using microwave hybrid heating. The clad of average thickness ~2 mm has been developed through the exposure of microwave radiation at frequency 2.45 GHz and power 900 W for the duration of 360 s. The developed clads were characterized using field emission scanning electron microscope, X-ray elemental analysis, X-ray diffraction, and measurement of Vicker’s microhardness. The microstructure study of the clad showed good metallurgical bonding with substrate and revealed that clads are free from any visible interface cracking. Clads were formed with partial dilution of a thin layer of the substrate. The cermet microstructure mainly consists of relatively soft metallic matrix phase and uniformly distributed hard carbide phase with skeleton-like structure. The developed clads exhibit an average microhardness of 1064 ± 99 Hv. The porosity of developed clad has been significantly less at approximately 0.89%. Content Type Journal Article Pages 1-8 DOI 10.1007/s11665-012-0142-2 Authors Dheeraj Gupta, Department of Mechanical and Industrial Engineering, Indian Institute of Technology Roorkee, Roorkee, 247667 India Apurbba Kumar Sharma, Department of Mechanical and Industrial Engineering, Indian Institute of Technology Roorkee, Roorkee, 247667 India Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung:    The purpose of this test was to evaluate the effects of calcium magnesium acetate (CMA) and sodium chloride (NaCl)—two common substances used to de-ice roadways—on the corrosion and fatigue behavior of annealed AISI 4140 steel. When CMA-corroded, NaCl-corroded, and as-machined samples were tested using R  = 0.1, and f  = 20 Hz, it was found that, within the scope of this study, samples corroded in both 3.5% CMA solution and 3.5% NaCl solution exhibited a lower fatigue strength than samples tested in the as-machined, uncorroded condition. For the short lives tested in this study, the difference in the effects of CMA and NaCl is minimal. However, at longer lives it is suspected, based on the trends, that the CMA solution would be less detrimental to the fatigue life. Content Type Journal Article Pages 1-5 DOI 10.1007/s11665-012-0167-6 Authors William P. Dean, Department of Mechanical and Aerospace Engineering, University of Alabama in Huntsville, Huntsville, AL 35899, USA Brittain J. Sanford, Department of Mechanical and Aerospace Engineering, University of Alabama in Huntsville, Huntsville, AL 35899, USA Matthew R. Wright, Department of Mechanical and Aerospace Engineering, University of Alabama in Huntsville, Huntsville, AL 35899, USA Jeffrey L. Evans, Department of Mechanical and Aerospace Engineering, University of Alabama in Huntsville, Huntsville, AL 35899, USA Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung:    In the present investigation, the correlation of composition-processing-property for TC11 titanium alloy was established using principal component analysis (PCA) and artificial neural network (ANN) based on the experimental datasets obtained from the forging experiments. During the PCA step, the feature vector is extracted by calculating the eigenvalue of correlation coefficient matrix for training dataset, and the dimension of input variables is reduced from 11 to 6 features. Thus, PCA offers an efficient method to characterize the data with a high degree of dimensionality reduction. During the ANN step, the principal components were chosen as the input parameters and the mechanical properties as the output parameters, including the ultimate tensile strength ( \upsigma \text b ), yield strength ( \upsigma 0.2 ), elongation ( \updelta ), and reduction of area (φ). The training of ANN model was conducted using back-propagation learning algorithm. The results clearly present ideal agreement between the predicted value of PCA-ANN model and experimental value, indicating that the established model is a powerful tool to construct the correlation of composition-processing-property for TC11 titanium alloy. More importantly, the integrated method of PCA and ANN is also able to be utilized as the mechanical property prediction for the other alloys. Content Type Journal Article Pages 1-7 DOI 10.1007/s11665-012-0162-y Authors Yu Sun, State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an, 710072 People’s Republic of China Weidong Zeng, State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an, 710072 People’s Republic of China Yongqing Zhao, Northwest Institute for Nonferrous Metal Research, Xi’an, 710016 People’s Republic of China Yitao Shao, State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an, 710072 People’s Republic of China Yigang Zhou, State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an, 710072 People’s Republic of China Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung:    The forming limit diagram (FLD) is a useful method for characterizing the formability of sheet metals. In this article, different numerical models were used to investigate the FLD of tailor-welded blank (TWB). TWBs were CO 2 laser-welded samples of interstitial-free (IF) steel sheets with difference in thickness. The results of the numerical models were compared with the experimental FLD as well as with the empirical model proposed by the North American Deep Drawing Research Group. The emphasis of this investigation is to determine the performance of these different approaches in predicting the FLD. These numerical models for FLD are: second derivative of thinning (SDT), effective strain rate (ESR), major strain rate (MSR), thickness strain rate (TSR), and thickness gradient (TG). Results of this research show necking will be happened, when the value of MSR, TSR, ESR criteria is maximum, TG ≤ 0.78 and SDT criterion has the first peak in forming process time. The value of dome height of TWB samples at failure was predicted based on the numerical models for samples with different widths. These numerical predictions were compared with the experimental results. The SDT model indicates a better agreement with experimental results in prediction of both the FLD and the limit dome height (LDH) in comparison to the other numerical models. Both numerical and experimental results show that minimum of LDH is happened in plane strain condition. Content Type Journal Article Pages 1-9 DOI 10.1007/s11665-012-0156-9 Authors Rasoul Safdarian Korouyeh, Tarbiat Modares University, Jalal Ale Ahmad Highway, P.O. Box 14115-143, Tehran, Iran Hassan Moslemi Naeini, Tarbiat Modares University, Jalal Ale Ahmad Highway, P.O. Box 14115-143, Tehran, Iran Gholamhosein Liaghat, Tarbiat Modares University, Jalal Ale Ahmad Highway, P.O. Box 14115-143, Tehran, Iran Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung:    This article describes attempts to characterize by standardized tests of tile materials used in the construction area the performance-based properties of foamed glass samples with novel glass coatings. New glass coated foam glass (Foamglas ® ) insulating tiles have been tested by several standard tests (UNI Iso, ASTM) to define their suitability for energy saving buildings: impact tests, thermal shock resistance, wear resistance, water absorption, frost resistance, resistance to stains. Except for impact tests, glass coated foam glass (Foamglas ® ) satisfied all the requirements above, resulting to be thermal shock resistant, according to Uni Iso 10545-9 (Al spheres); effective to reduce the pristine Foamglas ® surface water absorption, according to Uni En 1609:1999 and 12087:1999; frost resistant, according to Uni Iso 10545-12 and class 5 towards olive oil, according to Uni Iso 10545-14. Wear tests and hot water corrosion behavior tests have been done on the proposed coating and on a commercial soda-lime glass: the glass coated foam glass resulted to be suitable where corrosion and wear resistance are not a concern. Content Type Journal Article Pages 1-9 DOI 10.1007/s11665-012-0164-9 Authors Andrea Ventrella, Materials Science and Chemical Engineering Department, Politecnico di Torino, Corso Duca Degli Abruzzi 24, 10129 Torino, Italy Federico Smeacetto, Materials Science and Chemical Engineering Department, Politecnico di Torino, Corso Duca Degli Abruzzi 24, 10129 Torino, Italy Milena Salvo, Materials Science and Chemical Engineering Department, Politecnico di Torino, Corso Duca Degli Abruzzi 24, 10129 Torino, Italy Monica Ferraris, Materials Science and Chemical Engineering Department, Politecnico di Torino, Corso Duca Degli Abruzzi 24, 10129 Torino, Italy Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung:    In order to produce shape memory rings for constrained-recovery pipe couplings, from Fe-14 Mn-6 Si-9 Cr-5 Ni (mass%) powders, the main technological steps were (i) mechanical alloying, (ii) sintering, (iii) hot rolling, (iv) hot-shape setting, and (v) thermomechanical training. The article generally describes, within its experimental-procedure section, the last four technological steps of this process the primary purpose of which has been to accurately control both chemical composition and the grain size of shape memory rings. Details of the results obtained in the first technological step, on raw powders employed both in an initial commercial state and in a mixture state of commercial and mechanically alloyed (MA) powders, which were subjected to several heating-cooling cycles have been reported and discussed. By means of differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and X-ray diffraction (XRD), the thermal behaviors of the two sample powders have been analyzed. The effects of the heating-cooling cycles, on raw commercial powders and on 50% MA powders, respectively, were argued from the point of view of specific temperatures and heat variations, of elemental diffusion after thermal cycling and of crystallographic parameters, determined by DSC, SEM, and XRD, respectively. Content Type Journal Article Pages 1-10 DOI 10.1007/s11665-012-0168-5 Authors B. Pricop, Faculty of Materials Science and Engineering, The “Gheorghe Asachi” Technical University from Iaşi, Bd. D. Mangeron 61A, 700050 Iasi, Romania U. Söyler, Particulate Materials Laboratory, Metallurgical and Materials Engineering Department, Istanbul Technical University, 34469 Maslak, Istanbul, Turkey N. M. Lohan, Faculty of Materials Science and Engineering, The “Gheorghe Asachi” Technical University from Iaşi, Bd. D. Mangeron 61A, 700050 Iasi, Romania B. Özkal, Particulate Materials Laboratory, Metallurgical and Materials Engineering Department, Istanbul Technical University, 34469 Maslak, Istanbul, Turkey L. G. Bujoreanu, Faculty of Materials Science and Engineering, The “Gheorghe Asachi” Technical University from Iaşi, Bd. D. Mangeron 61A, 700050 Iasi, Romania D. Chicet, Faculty of Mechanical Engineering, The “Gheorghe Asachi” Technical University from Iaşi, Bd. D. Mangeron 61-63, 700050 Iasi, Romania C. Munteanu, Faculty of Mechanical Engineering, The “Gheorghe Asachi” Technical University from Iaşi, Bd. D. Mangeron 61-63, 700050 Iasi, Romania Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung:    Laser cladding of tungsten carbide (WC) on stainless steels 13Cr-4Ni and AISI 304 substrates has been performed using high power diode laser. The cladded stainless steels were characterized for microstructural changes, hardness, solid particle erosion resistance and corrosion behavior. Resistance of the clad to solid particle erosion was evaluated using alumina particles according to ASTM G76 and corrosion behavior was studied by employing the anodic polarization and open circuit potential measurement in 3.5% NaCl solution and tap water. The hardness of laser cladded AISI 304 and 13Cr-4Ni stainless steel was increased up to 815 and 725Hv 100 g , respectively. The erosion resistance of the modified surface was improved significantly such that the erosion rate of cladded AISI 304 (at 114 W/mm 2 ) was observed ~0.74 mg/cm 2 /h as compared to ~1.16 and 0.97 mg/cm 2 /h for untreated AISI 304 and 13Cr-4Ni, respectively. Laser cladding of both the stainless steels, however, reduced the corrosion resistance in both NaCl and tap water. Content Type Journal Article Pages 1-9 DOI 10.1007/s11665-012-0170-y Authors Raghuvir Singh, CSIR-National Metallurgical Laboratory, Jamshedpur, 831007 India Mukesh Kumar, CSIR-National Metallurgical Laboratory, Jamshedpur, 831007 India Deepak Kumar, CSIR-National Metallurgical Laboratory, Jamshedpur, 831007 India Suman K. Mishra, CSIR-National Metallurgical Laboratory, Jamshedpur, 831007 India Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung:    Copper-graphite composite is an important tribological material used in electrical sliding contact applications like electrical brushes in motors and generators. The electrical sliding contact experiences multiple stresses such as mechanical pressure and temperature. Traditional life tests under normal operating condition would be a time-consuming process due to the longer expected life of the composite. Accelerated wear testing was carried out to evaluate the life characteristics of the composite. This work focuses on evaluation of tribological performance of microwave-sintered copper-graphite composite using accelerated wear testing methodology using high temperature pin-on-disc tribometer. Microstructural studies of worn out surfaces were carried out using SEM with EDAX. Reliability and analysis on life characteristics were performed on the time-to-failure data using temperature-nonthermal-accelerated life-stress model. The obtained times-to-failure data from the accelerated wear testing was extrapolated to normal usage condition. Temperature and pressure are significantly affecting the wear performance. Self-lubricating action of graphite and improvement in wear resistance is helpful in extending the life of copper graphite composite. The life of the composite obtained through testing at mean and 99% reliability are 18,725 and 16,950 h, respectively. Content Type Journal Article Pages 1-9 DOI 10.1007/s11665-012-0161-z Authors K. Rajkumar, Department of Mechanical Engineering, Indian Institute of Technology-Delhi, New Delhi, 110016 India S. Aravindan, Department of Mechanical Engineering, Indian Institute of Technology-Delhi, New Delhi, 110016 India M. S. Kulkarni, Department of Mechanical Engineering, Indian Institute of Technology-Delhi, New Delhi, 110016 India Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung:    Cobalt-based alloys of the Stellite family are used as hardfacing for sealing surfaces of valves operating in desalination and power plants because of their excellent low friction and anti-galling properties in high-load sliding contact under the prevailing conditions. However, insufficient control of pressure and temperature during operation can degrade the integrity of the hardfaced material thus leading to its premature failure. This article presents a failure investigation carried out on the disk of a main stop gate valve that was used in a desalination plant. The disk was manufactured from X20 as a substrate material and a cobalt-based alloy for hardfacing. The cobalt-based hardfacing suffered from many surface and subsurface cracks that degraded its integrity. It was concluded that high-pressure steam flowing against the disk had tilted it and, thus, disturbed the alignment between the surfaces of the disk and the seat, leading to wear and large frictional heat that resulted in the degradation of the microstructure of the hardfacing layer and formation of the observed cracks. Content Type Journal Article Pages 1-7 DOI 10.1007/s11665-012-0413-y Authors A. Almazrouee, Manufacturing Engineering Technology Department, College of Technological Studies, PAAET, P.O. Box 42325, 70654 Shuwaikh, Kuwait S. Al-Faheed, Power Plant, Ministry of Electricity and Water, Kuwait City, Kuwait H. M. Shalaby, Kuwait Institute for Scientific Research, P.O. Box 24885, 13109 Safat, Kuwait Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung:    In this work, a high-energy planetary mill was used to modify the chemical stability of indium-bearing zinc ferrite (indium-bearing ZnFe 2 O 4 , IBZF) and improve indium and zinc leachabilities. The microstructures, morphologies, and leaching characteristics of IBZF samples milled under different milling conditions were investigated by particle size analysis, Brunauer-Emmett-Teller specific surface area analysis, x-ray diffraction, scanning electron microscopy, Fourier transform infrared spectra, Mössbauer spectrometry, and leaching experiments. The results show that the planetary ball milling has obvious effects on the microstructure and leaching characteristic of IBZF. Increasing the rotation speed and milling time cause the increase in the specific surface area, structure defects, and the breakage of the crystalline network, which result in a significant increase of indium and zinc extractions. In particular, the changes of crystal lattice structure induced by planetary ball milling play a key role in improving indium and zinc leachabilities from IBZF. The planetary ball milling also results in the redistribution of Zn 2+ and Fe 3+ in IBZF. Content Type Journal Article Pages 1-8 DOI 10.1007/s11665-012-0352-7 Authors J. H. Yao, School of Chemistry and Chemical Engineering, Guangxi University, Nanning, 530004 People’s Republic of China X. H. Li, School of Chemistry and Chemical Engineering, Guangxi University, Nanning, 530004 People’s Republic of China L. P. Pan, School of Chemistry and Chemical Engineering, Guangxi University, Nanning, 530004 People’s Republic of China J. M. Mo, School of Chemistry and Chemical Engineering, Guangxi University, Nanning, 530004 People’s Republic of China Z. P. Wen, School of Chemistry and Chemical Engineering, Guangxi University, Nanning, 530004 People’s Republic of China Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung:    This paper discusses the application of rapid solidification by the melt-spinning method for the preparation of thin NiTi-based ribbons. Generally, the application of rapid solidification via melt-spinning can change the microstructure, improving the ductility and shape memory characteristics and lead to small-dimensioned samples. Several thousand thermal cycles were performed on the trained ribbons using bending deformation procedure, continuously observing the changes in the shape memory and transformation behaviors. These changes are due to the appearance of an intermediate phase which was stabilized probably by the accumulation of defects introduced by thermomechanical training. The influence of training and thermal cycling on characteristics of ribbons was studied by x-ray diffraction and transmission electron microscopy and differential scanning calorimetry. The results displayed that bending training methods were useful in developing a two-way shape memory effect (TWSME). All samples show a shape memory effect immediately after processing without further heat treatment. The addition of copper in NiTi alloys was effective to narrow the transformation hysteresis. The W addition has improved the stability of the TWSME and mechanical properties. The TWSME of ribbons and its stability are well suited for important applications such as microsensors and microactuators. Content Type Journal Article Pages 1-10 DOI 10.1007/s11665-012-0379-9 Authors K. Mehrabi, Department of Physical Metallurgy and Materials Testing, University of Leoben, Leoben, Austria M. Bruncko, Department of Physical Metallurgy and Materials Testing, University of Leoben, Leoben, Austria A. C. Kneissl, Department of Physical Metallurgy and Materials Testing, University of Leoben, Leoben, Austria Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung:    Superelastic NiTi shape memory alloy (SMA) has high recoverable strain and outstanding damping capacity, and has been used as a damping material for many applications. When subjected to displacement-controlled cyclic deformation, the material exhibits distinctive temperature and stress oscillations due to the release of latent heat and hysteresis heat and the heat transfer with the ambient. In this paper, we establish a model to predict the temperature variation of NiTi SMA wire specimen under the cyclic phase transition by lumped heat transfer analysis. Closed-form solution on the evolution of the temperature is obtained. It is shown that, for all the test frequencies, steady-state cyclic thermal response of the specimen can be reached after a certain number of loading cycles in a transient stage, exhibiting a kind of “thermal shake down.” In the steady state, the temperature profile oscillates around a mean temperature plateau. We show that the temperature oscillation is mainly due to the release/absorption of latent heat during cyclic phase transition, while the mean temperature rise of the specimen is caused by the accumulation of the hysteretic heat of the phase transition. The model predictions agree well with the experimental results. Content Type Journal Article Pages 1-4 DOI 10.1007/s11665-012-0395-9 Authors Hao Yin, Department of Mechanical Engineering, The Hong Kong University of Science and Technology, Hong Kong, China Qingping Sun, Department of Mechanical Engineering, The Hong Kong University of Science and Technology, Hong Kong, China Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung:    The spray-deposited SiCp/Al-20Si-3Cu functionally graded material (FGM) can meet the structure design requirements of brake disk. The effects of rotational speed and load on the wear and friction behaviors of the SiCp/Al-20Si-3Cu FGM sliding against the resin matrix friction material were investigated. For comparison, the wear and friction behaviors of a commercially used cast iron (HT250) brake rotor were also studied. The results indicate that the friction coefficient of the SiCp/Al-20Si-3Cu FGM decreases constantly with the increase of load or rotational speed and is affected by the gradient distribution of SiC particles. The wear rate of the SiCp/Al-20Si-3Cu FGM firstly increases, then decreases and finally increases again with increasing load or speed, and is about 1/10 of that of HT250. Based on observations and analyses on the morphology and substructure of the worn surface, the mechanical mixing layer acts as a protective coating and lubricant, and its thickness reduces with the SiC content increasing. Furthermore, it is proposed that the dominant wear mechanism of SiCp/Al-20Si-3Cu FGM changes from the abrasive wear to the oxidative wear and further to the delamination wear with increasing load or speed. Content Type Journal Article Pages 1-10 DOI 10.1007/s11665-012-0409-7 Authors B. Su, College of Materials Science and Engineering, Hunan University, Changsha, 410082 Hunan, People’s Republic of China H. G. Yan, College of Materials Science and Engineering, Hunan University, Changsha, 410082 Hunan, People’s Republic of China J. H. Chen, College of Materials Science and Engineering, Hunan University, Changsha, 410082 Hunan, People’s Republic of China P. L. Zeng, College of Materials Science and Engineering, Hunan University, Changsha, 410082 Hunan, People’s Republic of China G. Chen, College of Materials Science and Engineering, Hunan University, Changsha, 410082 Hunan, People’s Republic of China C. C. Chen, College of Materials Science and Engineering, Hunan University, Changsha, 410082 Hunan, People’s Republic of China Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung:    This research aims to explore magnetomechanical effect as a nondestructive method to monitor the failure process of steel structural elements subjected to compressive loadings. Experiments on steel tubular joints were carried out to study the relationship between the applied load and the magnetomechanical field. Results show that the mechanical response and the magnetomechanical response demonstrate similar behavior to the applied load in the whole loading progress. At the critical load of buckling, the load-magnetic field curve has a bifurcation point corresponding to the traditional bifurcation of load-displacement curve. This research demonstrates that the stress-induced magnetic filed can be utilized as an important indicator of impending failure in steel structural elements. Content Type Journal Article Pages 1-4 DOI 10.1007/s11665-012-0410-1 Authors Sheng Bao, Institute of Structural Engineering, Zhejiang University, Hangzhou, 310058 Zhejiang, People’s Republic of China Fan Xu, Institute of Structural Engineering, Zhejiang University, Hangzhou, 310058 Zhejiang, People’s Republic of China Jiyang Wang, Institute of Structural Engineering, Zhejiang University, Hangzhou, 310058 Zhejiang, People’s Republic of China Hangfei Lou, Institute of Structural Engineering, Zhejiang University, Hangzhou, 310058 Zhejiang, People’s Republic of China Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung: Strain-Controlled Low-Cycle Fatigue Properties of Extruded 6061-T6 Aluminum Alloy Content Type Journal Article Pages 1-3 DOI 10.1007/s11665-012-0411-0 Authors A. T. Brammer, Department of Mechanical Engineering, The University of Alabama, Tuscaloosa, AL 35487, USA J. B. Jordon, Department of Mechanical Engineering, The University of Alabama, Tuscaloosa, AL 35487, USA P. G. Allison, Engineering Research and Development Center, Army Corp of Engineers, Vicksburg, MS 39180, USA M. E. Barkey, Department of Aerospace Engineering and Mechanics, The University of Alabama, Tuscaloosa, AL 35487, USA Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung:    In this article, a fatigue damage parameter is proposed to assess the multiaxial fatigue lives of ductile metals based on the critical plane concept: Fatigue crack initiation is controlled by the maximum shear strain, and the other important effect in the fatigue damage process is the normal strain and stress. This fatigue damage parameter introduces a stress-correlated factor, which describes the degree of the non-proportional cyclic hardening. Besides, a three-parameter multiaxial fatigue criterion is used to correlate the fatigue lifetime of metallic materials with the proposed damage parameter. Under the uniaxial loading, this three-parameter model reduces to the recently developed Zhang’s model for predicting the uniaxial fatigue crack initiation life. The accuracy and reliability of this three-parameter model are checked against the experimental data found in literature through testing six different ductile metals under various strain paths with zero/non-zero mean stress. Content Type Journal Article Pages 1-9 DOI 10.1007/s11665-012-0197-0 Authors Jia Liu, The Science Institute, Air Force Engineering University, East Chang Le Road, Xi’an, 710051 China Jing Li, The Science Institute, Air Force Engineering University, East Chang Le Road, Xi’an, 710051 China Zhong-ping Zhang, The Science Institute, Air Force Engineering University, East Chang Le Road, Xi’an, 710051 China Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung:    This article reports about the tests carried to investigate microbial-induced corrosion on stainless steels due to sulfate-reducing bacteria sp. Desulfotomaculum nigrificans in different host media. Stainless steel 304L, 316L, and 2205 were selected for the test. Modified Baar’s media (BM), sodium chloride solution, and artificial sea water (SW) were used as test solutions in anaerobic conditions. Electrochemical polarization and immersion test were performed to estimate the extent of corrosion rate and pitting on stainless steels. SEM/EDS were used to study the details inside/outside pits formed on the corroded samples. Biofilm formed on corroded coupons was analyzed for its components by UV/Visible spectroscopy. Corrosion attack on the test samples was observed maximum in case of exposure to SW followed by NaCl solution, both having sulfide and chloride whereas stainless steel exposed to BM, having sulfide, showed minimum attack. Tendency of extracellular polymeric substances to bind metal ions is observed to be responsible for governing the extent of corrosion attack. Content Type Journal Article Pages 1-9 DOI 10.1007/s11665-012-0384-z Authors Suman Lata, Materials Science Group, Department of Paper Technology, IIT, Roorkee, Saharanpur Campus, Saharanpur, 247001 India Chhaya Sharma, Materials Science Group, Department of Paper Technology, IIT, Roorkee, Saharanpur Campus, Saharanpur, 247001 India Ajay K. Singh, Materials Science Group, Department of Paper Technology, IIT, Roorkee, Saharanpur Campus, Saharanpur, 247001 India Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung:    Inclusions content is important for the mechanical behavior and performances of NiTi-based products particularly in fatigue-rated devices. Higher inclusions content has been correlated to reductions in transformation temperatures and strain recovery under mechanical or thermo-mechanical cycling. Moreover, most fatigue fractures show inclusions at the initiation site. However, there is a general lack of information on the nature and characteristics of such inclusions, especially those typically recognized as intermetallics oxides. In this study, the common scanning electron microscopy technique has been used to investigate the chemistry and morphology of inclusions in commercial standard VIM/VAR binary NiTi alloys. The defined experimental procedure, results, and their significance will be presented and discussed. Content Type Journal Article Pages 1-6 DOI 10.1007/s11665-012-0366-1 Authors A. Coda, SAES Getters S.p.A, Lainate, MI, Italy S. Zilio, SAES Getters S.p.A, Lainate, MI, Italy D. Norwich, Memry Corporation, Bethel, CT, USA F. Sczerzenie, SAES Smart Materials, New Hartford, NY, USA Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung:    The aim of this work was to form NiTi and TiNiCo body temperature activated and superelastic staples for clinical joining of mandible and face bone fractures. The alloys were obtained by VIM technique. Hot and cold processing was applied to obtain wires of required diameters. The martensitic transformation was studied by DSC, XRD, and TEM. The shape memory effects were measured by a bend and free recovery ASTM F2082-06 test. The superelasticity was recorded in the tension stress-strain and by the three-point bending cycles in an instrument equipped with a Hottinger force transducer and LVDT. Excellent superelastic behavior of TiNiCo wires was obtained after cold working and annealing at 400-500 °C. The body temperature activated shape memory staples were applied for fixation of mandibular condyle fractures. In experiments on the skull models, fixation of the facial fractures by using shape memory and superelastic staples were compared. The superelastic staples were used in osteosynthesis of zygomatico-maxillo-orbital fractures. Content Type Journal Article Pages 1-7 DOI 10.1007/s11665-012-0372-3 Authors Z. Lekston, Institute of Materials Science, University of Silesia, Katowice, Poland D. Stróż, Institute of Materials Science, University of Silesia, Katowice, Poland M. Jędrusik-Pawłowska, Department of Skull and Maxillofacial Surgery, Silesian Medical University, Katowice, Poland Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung:    An investigation was carried out to examine the influence of structural and mechanical properties on wear behavior of austempered ductile iron (ADI). Ductile iron (DI) samples were austenitized at 900 °C for 60 min and subsequently austempered for 60 min at three temperatures: 270, 330, and 380 °C. Microstructures of the as-cast DI and ADIs were characterized using optical and scanning microscopy, respectively. The structural parameters, volume fraction of austenite, carbon content of austenite, and ferrite particle size were determined using x-ray diffraction technique. Mechanical properties including Vicker’s hardness, 0.2% proof strength, ultimate tensile strength, ductility, and strain hardening coefficient were determined. Wear tests were carried out under dry sliding conditions using pin-on-disk machine with a linear speed of 2.4 m/s. Normal load and sliding distance were 45 N and 1.7 × 10 4  m, respectively. ADI developed at higher austempering temperature has large amounts of austenite, which contribute toward improvement in the wear resistance through stress-induced martensitic transformation, and strain hardening of austenite. Wear rate was found to depend on 0.2% proof strength, ductility, austenite content, and its carbon content. Study of worn surfaces and nature of wear debris revealed that the fine ausferrite structure in ADIs undergoes oxidational wear, but the coarse ausferrite structure undergoes adhesion, delamination, and mild abrasion too. Content Type Journal Article Pages 1-7 DOI 10.1007/s11665-012-0380-3 Authors Uma Batra, Department of Materials & Metallurgical Engineering, PEC University of Technology, Chandigarh, India Nimish Batra, Mechanical Engineering Department, Thapar University, Patiala, 147004 Punjab, India J. D. Sharma, Department of Materials & Metallurgical Engineering, PEC University of Technology, Chandigarh, India Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung:    Finding the geometry and properties of a ceramic tile after its firing using simulations, is relevant because several defects can occur and the tile can be rejected if the conditions of the firing are inadequate for the geometry and materials of the tile. Previous works present limitations because they do not use a model characteristic of ceramics at high temperatures and they oversimplify the simulations. As a response to such shortcomings, this article presents a simulation with a three-dimensional Norton’s model, which is characteristic of ceramics at high temperatures. The results of our simulated experiments show advantages with respect to the identification of the mechanisms that contribute to the final shape of the body. Our work is able to divide the history of temperatures in stages where the evolution of the thermal, elastic, and creep deformations is simplified and meaningful. That is achieved because our work found that curvature is the most descriptive parameter of the simulation. Future work is to be realized in the creation of a model that takes into account that the shrinkage is dependent on the history of temperatures. Content Type Journal Article Pages 1-7 DOI 10.1007/s11665-012-0354-5 Authors Guillermo Peris-Fajarnés, Centro de Investigación en Tecnologías Gráficas, Universidad Politécnica de Valencia, Valencia, Spain Beatriz Defez, Centro de Investigación en Tecnologías Gráficas, Universidad Politécnica de Valencia, Valencia, Spain Ricardo Serrano, CAD CAM CAE Laboratory, Universidad EAFIT, Medellín, Colombia Oscar E. Ruiz, CAD CAM CAE Laboratory, Universidad EAFIT, Medellín, Colombia Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung:    Ultrafine β-silicon carbide (β-SiC) powders were successfully synthesized by carbothermal-reduction reaction (CRR) of sepiolite. Sepiolite of Turkish deposits as a silica (SiO 2 ) precursor and carbon black as a reducing agent were mixed with constant C/SiO 2 molar ratio of 4. Mixed powders were subjected to CRR at temperatures of 1450, 1500, and 1550 °C for 1 h in an atmosphere-controlled tube furnace under argon flow of 5 cm 3 /min. The precursor and resultant powder products were characterized by XRD, SEM, and EDX. Phase transformation was observed in powder products after CRR as a function of the reaction temperature. The results show that the cotton-like nature of sepiolite makes it an effective mineral precursor for synthesis of SiC powders, and that SiC transformation was optimized at 1550 °C with a particle size of approximately 200 nm. Content Type Journal Article Pages 1-6 DOI 10.1007/s11665-012-0300-6 Authors Cengiz Bağci, Department of Machine and Metal Technologies, Vocational High School of Akdağmadeni, Bozok University, 66300 Yozgat, Turkey Halil Arik, Department of Metallurgy and Materials Engineering, Faculty of Technology, Gazi University, 06500 Ankara, Turkey Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung:    Ni-free Ti-based shape memory alloys (SMAs) are increasingly recognized as promising functional materials for medical applications. The mechanical properties of these metastable Ti-based SMAs are sensitive to aging and thermomechanical treatment. Effects of severe plastic deformation (SPD)-equal channel angular pressing (ECAP) and aging on superelastic behavior of Ni-free Ti-based SMAs, Ti-9.8Mo-3.9Nb-2V-3.1Al wt.% (TMNVA) and Ti-25at.%Nb, have been investigated. The results show that the yielding strength of TMNVA alloy increases sharply with the number of ECAP processes—to greater than 1,400 MPa after two passes ECAP—but elongation of TMNVA alloy decreases severely and the plasticity is lost completely after two passes ECAP. Both ECAP process and flash annealing treatment have weak contribution to the superelastic recoverable strains of Ti-Mo-based alloy. For Ti-25at.%Nb alloy, after one pass ECAP process at 400 °C, the yielding stress increases obviously, and the recovery strain increases a little. With the further increase in the number of ECAP processes, the yielding stress and the recovery strain change little. Aging treatment at low temperature after ECAP process is in favor of superelasticity of Ti-25at.%Nb alloy. An almost completely recoverable strain of 1.5% is obtained in Ti-25at.%Nb alloy after two passes ECAP and aging at 300 °C for 1 h. The mechanisms of the effects of SPD and aging are also discussed. Content Type Journal Article Pages 1-7 DOI 10.1007/s11665-012-0391-0 Authors Jie Song, State Key Laboratory of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240 China Xiaoning Zhang, State Key Laboratory of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240 China Chaoying Xie, State Key Laboratory of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240 China Liming Wang, Jiangsu Fasten Company Limited, Jiangying, Jiangshu, China M. H. Wu, Advanced Materials Technology, Edwards Life Sciences LLC, Irvine, CA, USA Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung:    Medical device fractures during gamma and electron beam (eBeam) sterilization have been reported. Two common factors in these device fractures were a constraining force and the presence of fluorinated ethylene propylene (FEP). This study investigated the effects of eBeam sterilization on constrained light-oxide nitinol wires in FEP. The goal was to recreate these fractures and determine their root cause. Superelastic nitinol wires were placed inside FEP tubes and constrained with nominal outer fiber strains of 10, 15, and 20%. These samples were then subjected to a range of eBeam sterilization doses up to 400 kGy and compared with unconstrained wires also subjected to sterilization. Fractures were observed at doses of 〉100 kGy. Analysis of the fracture surfaces indicated that the samples failed due to irradiation-assisted stress-corrosion cracking (IASCC). This same effect was also observed to occur with PTFE at 400 kGy. These results suggest that nitinol is susceptible to IASCC when in the presence of a constraining stress, fluorinated polymers, and irradiation. Content Type Journal Article Pages 1-5 DOI 10.1007/s11665-012-0396-8 Authors Stuart A. Smith, Metallurgical Solutions, Redwood City, CA, USA Brock Gause, Nutek Corporation, Hayward, CA, USA David Plumley, Fort Wayne Metals, Fort Wayne, IN, USA Masao J. Drexel, Confirmd LLC, Redwood City, CA, USA Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung:    Currently, with the increasing demand of high production output, much attention is paid to the research and development of multi-hole extrusion die. However, owing to the complexity of multi-hole porthole extrusion technology, it has not been applied widely in practice for the production of aluminum profiles, especially for porthole die with an odd number of die orifices. The purpose of this study is to design a three-hole porthole die for producing an aluminum tube and to optimize the location of die orifices based on computer-aided design and engineering. First, three-hole extrusion dies for different locations of die orifices are designed. Then, extrusion processes with different multi-hole porthole dies are simulated by means of HyperXtrude. Through numerical simulation, metal flow, temperature distribution, welding pressure, extrusion load, and die stress, etc. could be obtained, and the effects of the location of die orifices on extrusion process are investigated. With the increasing distance between die orifice and extrusion center (described as eccentricity ratio), metal flow becomes nonhomogeneous, and twisting or bending deformation of profile occurs, but the welding pressure rises, which improves the welding quality of profiles. However, the required extrusion force, billet and die temperature, die displacement, and stress induce no significant changes. In comparison with the extrusion force during single-hole porthole extrusion, there is 18.5% decrease of extrusion force during three-hole porthole extrusion. Finally, design rules for this kind of multi-hole extrusion dies are summarized. Content Type Journal Article Pages 1-10 DOI 10.1007/s11665-012-0405-y Authors Cunsheng Zhang, Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials (Ministry of Education), Shandong University, Jinan, 250061 Shandong, People’s Republic of China Guoqun Zhao, Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials (Ministry of Education), Shandong University, Jinan, 250061 Shandong, People’s Republic of China Hao Chen, Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials (Ministry of Education), Shandong University, Jinan, 250061 Shandong, People’s Republic of China Yanjin Guan, Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials (Ministry of Education), Shandong University, Jinan, 250061 Shandong, People’s Republic of China Haijin Cai, Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials (Ministry of Education), Shandong University, Jinan, 250061 Shandong, People’s Republic of China Baojie Gao, CSR Qingdao Sifang Co., Ltd, Qingdao, 266111 Shandong, People’s Republic of China Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung:    Metallic tie-rods are currently used in many historical buildings for absorbing the out-of-plane horizontal forces of arches, vaults and roof trusses, despite they exhibit several limitations under service and seismic conditions. In this paper, a post-tensioned system based on the superelastic properties of Ni-Ti shape memory alloys is proposed for improving the structural performances of traditional metallic tie-rods. First, the thermal behavior under service conditions is investigated based on the results of numerical and experimental studies. Subsequently, the seismic performances under strong earthquakes are verified trough a number of shaking table tests on a 1:4-scale timber roof truss model. The outcomes of these studies fully confirm the achievement of the design objectives of the proposed prototype device. Content Type Journal Article Pages 1-10 DOI 10.1007/s11665-012-0414-x Authors Donatello Cardone, University of Basilicata, Viale dell’Ateneo Lucano 10, Potenza, Italy Salvatore Sofia, University of Basilicata, Viale dell’Ateneo Lucano 10, Potenza, Italy Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung:    High performance friction systems, e.g., dry clutches and brakes, require a good wear resistance and a friction coefficient that is nearly independent from sliding velocity and environmental conditions. Organic-based friction materials have reached their limitations regarding higher power densities. Engineering ceramics such as alumina (Al 2 O 3 ) or silicon carbide (SiC) offer a great potential since remarkably higher thermal and mechanical loading is possible. However, the tribological performance of these monolithic ceramics is still insufficient. The aim of the present study was to assess the potential of a laser-assisted surface modification process in order to improve the tribological performance with regard to the application in dry friction systems. Therefore, commercially available alumina was modified using a newly developed laser-assisted preheating process and subsequent melting of the ceramic’s surface using a CO 2 -laser and modification by additives such as TiC, TiN, B 4 C, WC, ZrB 2 , Cr, Ni, Cu, and Ti. A systematic variation of additives and process parameters led to different multiphase microstructures. Subsequently, these were characterized using scanning electron microscopy and surface analysis methods (wavelength dispersive X-ray spectroscopy, energy dispersive X-ray spectroscopy). Finally, the tribological properties were investigated using a laboratory tribometer. The surface-modified ceramics were tested in unidirectional sliding motion against steel disks. The tribological results of the surface-modified ceramics were compared to those of monolithic Al 2 O 3 and SiC ceramics and showed a reduced dependence of friction coefficient on sliding velocity. Moreover, the multi-phase ceramics possessed a higher wear resistance than the monolithic ones. Content Type Journal Article Pages 1-13 DOI 10.1007/s11665-012-0215-2 Authors R. Wallstabe, BAM Federal Institute for Materials Research and Testing, Unter den Eichen 87, 12200 Berlin, Germany Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung:    The aim of the study was to evaluate the accuracy of heat treatment guidelines, generally followed in industrial practices, about the T6 heat treatment of A356 aluminum alloy. In particular, the effect of the delay between quenching and artificial aging (pre-aging time) on microstructure, hardness, and tensile behavior was studied using specimens extracted from different locations of a cylinder head, characterized by different cooling rates and, consequently, by different secondary dendrite arm spacing values. Hardness and tensile tests confirmed the detrimental effect of pre-aging with a 20% reduction in hardness and strength after approximately 1 h of pre-aging, both for samples with fine and large SDAS. Differential scanning calorimetry analyses on samples that were solutionized, quenched, and pre-aged between 0 and 96 h, suggested that the nature and composition of the clusters formed during pre-aging, rather than their size, influenced the subsequent precipitation process and the final mechanical properties of the alloy. Content Type Journal Article Pages 1-6 DOI 10.1007/s11665-012-0208-1 Authors Lorella Ceschini, SMETEC Department, University of Bologna, V. le Risorgimento 4, 40136 Bologna, Italy Alessandro Morri, SMETEC Department, University of Bologna, V. le Risorgimento 4, 40136 Bologna, Italy Andrea Morri, SMETEC Department, University of Bologna, V. le Risorgimento 4, 40136 Bologna, Italy Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung:    The objective of this study is to evaluate the combined effect of sulfide and acetate on the corrosion behavior of X52 steel in a CO 2 environment. The tests were conducted in a 0.5 M NaCl solution (25 °C). Corrosion rate and behavior were investigated using the following three electrochemical techniques: (a) linear polarization resistance, (b) potentiodynamic polarization, and (c) electrochemical impedance spectroscopy. The morphology of surface corrosion products were analyzed using field emission scanning electron microscopy/energy dispersive spectroscopy and X-ray diffraction tests. The results show that the addition of sulfide ions decreased the corrosion rate of X52 steel sample. The inhibitive effect of sulfide ions was related to protective pyrite FeS layer on the electrode surface. Furthermore, in the presence of sulfide, acetate increased the X52 steel corrosion rate by enhancing the cathodic reaction. On the contrary, in the absence of sulfide, acetate decreased the corrosion rate of the X52 steel sample when the pH solution was increased. Content Type Journal Article Pages 1-9 DOI 10.1007/s11665-012-0211-6 Authors M. C. Fatah, Centre for Corrosion Research, Department of Mechanical Engineering, Universiti Teknologi PETRONAS, 31750 Tronoh, Perak, Malaysia M. C. Ismail, Centre for Corrosion Research, Department of Mechanical Engineering, Universiti Teknologi PETRONAS, 31750 Tronoh, Perak, Malaysia B. Ari-Wahjoedi, Department of Fundamental and Applied Sciences, Universiti Teknologi PETRONAS, 31750 Tronoh, Perak, Malaysia Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung:    Statistical characteristics of strength distribution in ceramic components should be clarified because of large scatter in ceramics strength. Characteristics of strength distribution, however, depend on sample size, i.e., the number of tested specimens. In this study, a numerical procedure in the framework of fracture mechanics was developed to estimate strength distribution of ceramics by assuming the same statistical distribution of cracks in a material. Experimental results in four-point bending tests of alumina, which were reported in a previous work, were cited to verify the validity of the developed procedure. Smooth specimens of distinct sizes as well as notched specimens with different notch shapes were used in the experiment. Monte Carlo simulations using the developed procedure were carried out to investigate effects of the sample size on strength properties of alumina specimens with various shapes. The simulated result revealed that the experimental strength for various types of specimens was almost covered within a range of upper and lower bounds of strength simulated for the alumina. The experimental mean strength correlated with the effective volume was also included in a band range between the maximum and the minimum of mean strength obtained by the simulation. Content Type Journal Article Pages 1-8 DOI 10.1007/s11665-012-0214-3 Authors Toshihiko Hoshide, Department of Energy Conversion Science, Graduate School of Energy Science, Kyoto University, Sakyo-ku, Kyoto, 606-8501 Japan Hiroyuki Sugiyama, Department of Energy Conversion Science, Graduate School of Energy Science, Kyoto University, Sakyo-ku, Kyoto, 606-8501 Japan Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung:    Reduction in grain size in weld fusion zones (FZs) presents the advantages of increased resistance to solidification cracking and improvement in mechanical properties. Transverse mechanical arc oscillation was employed to obtain grain refinement in the weldment during tungsten inert gas welding of Al-Mg-Si alloy. Electron backscattered diffraction analysis was carried out on AA6061-AA4043 filler metal tungsten inert gas welds. Grain size, texture evolution, misorientation distribution, and aspect ratio of weld metal, PMZ, and BM have been observed at fixed arc oscillation amplitude and at three different frequencies levels. Arc oscillation showed grain size reduction and texture formation. Fine-grained arc oscillated welds exhibited better yield and ultimate tensile strengths and significant improvement in percent elongation. The obtained results were attributed to reduction in equivalent circular diameter of grains and increase in number of subgrain network structure of low angle grain boundaries. Content Type Journal Article Pages 1-8 DOI 10.1007/s11665-012-0207-2 Authors N. S. Biradar, Department of Metallurgical Engineering and Materials Science, Welding and Equipment Design Laboratory, Indian Institute of Technology, Bombay, Powai, Mumbai, 400076 India R. Raman, Department of Metallurgical Engineering and Materials Science, Welding and Equipment Design Laboratory, Indian Institute of Technology, Bombay, Powai, Mumbai, 400076 India Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung:    In this paper, fatigue crack propagation life of resistance spot welds in tensile-shear specimens is investigated based on the calculation of stress intensity factors and J -integral using three-dimensional finite element method. For comparison, experimental works on 5083-O aluminum alloy spot-welded joints have been carried out to verify the numerical predictions of fatigue crack propagation of welded joints. A lot of analyses have been performed to obtain stress intensity factors and J -integral in tensile-shear specimens of spot-welded joints by using commercial software ANSYS. These gathered data have been formulated by using statistical software SPSS. The results of fatigue propagation life and predicted fatigue crack path revealed very good agreement with the experimental fatigue test data and photograph of cross-section of the fatigued spot-weld specimens. Content Type Journal Article Pages 1-6 DOI 10.1007/s11665-012-0220-5 Authors S. Hassanifard, Faculty of Mechanical Engineering, University of Tabriz, Tabriz, Iran M. A. Mohtadi Bonab, University of Bonab, Bonab, Iran Gh. Jabbari, Institute of Energy and Hydro Technology, Tehran, Iran Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung:    This paper preliminarily investigates the general transport properties (i.e., water sorptivity, water permeability, and gas permeability) of carbon-nanotube/cement composites. Carboxyl multi-walled carbon nanotubes (MWNTs) are dispersed into cement mortar to fabricate the carbon nanotubes (CNTs) reinforced cement-based composites by applying ultrasonic energy in combination with the use of surfactants (sodium dodecylbenzene sulfonate and sodium dodecyl sulfate). Experimental results indicate that even at a very small dosage the addition of MWNTs can help decrease water sorptivity coefficient, water permeability coefficient, and gas permeability coefficient of cement mortar, which suggests that CNTs can effectively improve the durability properties of cement-based composites. Content Type Journal Article Pages 1-6 DOI 10.1007/s11665-012-0228-x Authors Baoguo Han, Department of Mechanical and Energy Engineering, University of North Texas, Denton, TX 76203, USA Zhengxian Yang, Corrosion and Sustainable Infrastructure Laboratory, Western Transportation Institute, College of Engineering, Montana State University, P.O. Box 174250, Bozeman, MT 59717-4250, USA Xianming Shi, Corrosion and Sustainable Infrastructure Laboratory, Western Transportation Institute, College of Engineering, Montana State University, P.O. Box 174250, Bozeman, MT 59717-4250, USA Xun Yu, Department of Mechanical and Energy Engineering, University of North Texas, Denton, TX 76203, USA Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung:    Slurry erosion (SE) is commonly observed in almost all kinds of components and machineries involved in fluid (liquid) transfer and delivery. During design and development phase of these components, test rigs are usually required to evaluate their performance; however, only few detailed designs of test rigs are available for SE investigations. Among the existing designs of SE test rigs, most of them belong to rotary type. In the present study, design of a new type of SE test rig has been proposed, which is simpler in construction and working. This newly designed test rig could possibly eliminate some of the limitations (velocity-concentration interdependence and lack of acceleration distance) found in the existing set-ups. Calibration of the test rig was done for jet velocity and erodent concentration. Commissioning of the rig was undertaken by evaluating the effect of operating parameters (concentration and impingement angle) on the erosion rates of aluminum and cast iron. Results show that the rig was able to capture the traditional responses of ductile and brittle erosion behaviors being observed for these materials. Repeatability of the test rig was ensured, and the results were found to be within the acceptable error limits. Content Type Journal Article Pages 1-10 DOI 10.1007/s11665-012-0219-y Authors H. S. Grewal, School of Mechanical, Materials and Energy Engineering, Indian Institute of Technology Ropar, Nangal Road, Rupnagar, 140001 Punjab, India Anupam Agrawal, School of Mechanical, Materials and Energy Engineering, Indian Institute of Technology Ropar, Nangal Road, Rupnagar, 140001 Punjab, India H. Singh, School of Mechanical, Materials and Energy Engineering, Indian Institute of Technology Ropar, Nangal Road, Rupnagar, 140001 Punjab, India Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung:    The microstructure and mechanical properties of iron-based powder metallurgical steels jointed by CO 2 laser-metal active gas (MAG) hybrid welding were investigated. The cross-sectional morphology of hybrid weld bead consisted of arc zone and laser zone. The microstructure of arc zone consisted of columnar dendrite and fine acicular dendrite between the columnar dendrites, but that of laser zone was composed of fine equiaxed dendrite. The MAG weld had obvious heat-affected zone (HAZ) zone, while hybrid weld had very narrow HAZ zone because of the rapid cooling rate. The phase constitutions of the joint determined by x-ray diffraction were α-Fe (ferrite) and Cu. The 2θ value of α-Fe (200) peaks of hybrid weld was smaller than that of sintering compact. Compared to MAG weld, hybrid weld had finer grain size, higher micro-hardness, and higher micro-strain, which was caused by the difference of cooling rate and crystallizing. Content Type Journal Article Pages 1-7 DOI 10.1007/s11665-012-0222-3 Authors Shuangyu Liu, College of Mechanical and Electric Engineering, Changchun University of Science and Technology, No. 7089 WeiXing Road, Changchun, 130022 People’s Republic of China Hong Zhang, College of Mechanical and Electric Engineering, Changchun University of Science and Technology, No. 7089 WeiXing Road, Changchun, 130022 People’s Republic of China Jiandong Hu, The Key Lab of Automobile Materials, Ministry of Education, College of Materials Science and Engineering, Jilin University, Changchun, 130025 People’s Republic of China Yan Shi, College of Mechanical and Electric Engineering, Changchun University of Science and Technology, No. 7089 WeiXing Road, Changchun, 130022 People’s Republic of China Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung:    The purpose of this study is to investigate the effects of Ti addition (1 and 2% Ti) and aging heat treatment on the mechanical and wear characteristics of Al-12Si-20Mg cast alloys. In preliminary studies conducted to determine the aging parameters, cast alloys were kept at 550 °C for 2 h before being quenched into water and aged at 200 °C for five different periods (3, 6, 9, 12, and 15 h). As the specimen aged for 12 h had the highest hardness value, all the specimens were aged at 200 °C for 12 h. The microstructures of the as-cast and aged specimens were analyzed using an optical microscope and a scanning electron microscope. The hardness of the investigated alloys was measured by micro-hardness test. The wear tests were carried out using the pin-on-disk model wear test apparatus, and the results were evaluated according to weight loss. According to the wear test results, the wear behavior of the investigated alloys changed depending on the aging heat treatment applied and the load. While Ti addition and the aging heat treatment applied reduce the weight loss at low loads (5 N), they increase the weight loss at higher loads (10 and 20 N). Content Type Journal Article Pages 1-8 DOI 10.1007/s11665-012-0217-0 Authors Yavuz Sun, Engineering Faculty, Karabuk University, Karabuk, Turkey Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung:    In this study, SiC p containing composite powders were used as the reinforcement carrier media for manufacturing cast Al356/5 vol.% SiC p composites. Untreated SiC p , milled particulate Al-SiC p composite powder, and milled particulate Al-SiC p -Mg composite powder were injected into Al356 melt. The resultant composite slurries were then cast from either a fully liquid state (stir casting) or semisolid state (compocasting). The results revealed that by injection of composite powders, the uniformity of the SiC p in the Al356 matrix was greatly improved, the particle-free zones in the matrix were disappeared, the SiC particles became smaller, the porosity was decreased, and the matrix microstructure became finer. Compocasting changed the matrix dendritic microstructure to a finer non-dendritic one and also slightly improved the distribution of the SiC p . Simultaneous utilization of Al-SiC p -Mg composite powder and compocasting method increased the macro- and micro-hardness, impact energy, bending strength, and bending strain of Al356/SiC p composite by 35, 63, 20, 20, and 40%, respectively, as compared with those of the composite fabricated by injection of untreated SiC p and stir casting process. Content Type Journal Article Pages 1-9 DOI 10.1007/s11665-012-0223-2 Authors Sajjad Amirkhanlou, Department of Materials Engineering, Isfahan University of Technology, Isfahan, 84156-83111 Iran Behzad Niroumand, Department of Materials Engineering, Isfahan University of Technology, Isfahan, 84156-83111 Iran Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung:    In recent years, two-layer metallic sheets have been increasingly used in various industries to create combined functions. Among cladding methods, the cold rolling is most widely used in producing bimetallic sheets. In this research, to thoroughly provide guidelines for cold rolling of bimetal strip, an attempt has been made to develop an analytical model based on upper bound method. Also, the bonding strength and critical reduction were calculated using upper bound theorem and the finite element simulation was used for Al/St bimetallic strip. Finally, an experimental study was run for our model to be verified analytically and numerically. Results show that the bonding strength of strips increases with increasing the total thickness reduction of bimetal strips and because of subsequent occurrence of strips bonding in roll gap, increasing the yield strength of base layer gives rise to critical reduction. Through the study, it becomes clear that the proposed analytical model is applicable for simulating the cold rolling process of the two-layer strips and is capable to broaden our knowledge in manufacturing and production of bimetal strips and sheets. Content Type Journal Article Pages 1-9 DOI 10.1007/s11665-012-0342-9 Authors H. Maleki, Department of Mechanical Engineering, Amirkabir University of Technology, 424 Hafez Avenue, P.O. Box 4413-15875, Tehran, Iran S. Bagherzadeh, Department of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran B. Mollaei-Dariani, Department of Mechanical Engineering, Amirkabir University of Technology, 424 Hafez Avenue, P.O. Box 4413-15875, Tehran, Iran K. Abrinia, Department of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, Iran Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung:    In the present study, 30MSV6 microalloyed steel was heat treated under different conditions, and the relation between its microstructure and mechanical properties was investigated. Scanning electron microscopy and transmission electron microscopy were used to characterize the microstructure of the heat-treated steel, and the effect of microstructure on tensile strength and fatigue behavior was determined. Microstructural analysis indicated that precipitates were formed at different sites such as grain boundaries and sub-grain boundaries. Furthermore, microstructural studies accompanied by the evaluation of mechanical properties revealed that the optimal heat treatment cycle of 30MSV6 microalloyed steel involved austenitization at 1223 K for 1 h and cooling in air to room temperature, followed by aging at 873 K for 1.5 h. The optimal heat treatment cycle resulted in significant improvement in the fatigue strength, tensile strength, and ductility because of the development of a uniform distribution of fine precipitates in a refined microstructure. The fatigue limit under optimum conditions (~384 MPa) was greater than that under other conditions (~321 and 312 MPa). Content Type Journal Article Pages 1-10 DOI 10.1007/s11665-012-0324-y Authors M. Hajisafari, Department of Materials Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran S. Nategh, Department of Materials Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran H. Yoozbashizadeh, Department of Materials Science and Engineering, Sharif University of Technology, Tehran, Iran A. Ekrami, Department of Materials Science and Engineering, Sharif University of Technology, Tehran, Iran Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung:    The inhibition effect of mild steel (MS) corrosion in 1 M HCl was studied by the addition of indole alkaloids (crude) isolated from Alstonia angustifolia var. latifolia ( A. latifolia ) leaves at 303 K. Potentiodynamic polarization, impedance spectroscopy, scanning electron microscopy (SEM), and Fourier transform infrared (FTIR) analyses were used for this study. Results show that the isolated alkaloid extract of A. latifolia is a good inhibitor and exhibited maximum inhibition efficiency (above 80%) at concentrations between 3 and 5 mg/L. Polarization measurements indicated that the inhibitor does not alter the mechanism of either anodic or cathodic reactions and acted as mixed-type inhibitor. The inhibition efficiencies of both electrochemical techniques are found to be in good agreement and adsorption of inhibitor follows Langmuir isotherm. Adsorption of inhibitor over metal surface was well supported by the SEM studies, while FTIR studies evidenced the presence of indole alkaloids as green inhibitor that reduces the rate of corrosion. Content Type Journal Article Pages 1-7 DOI 10.1007/s11665-012-0347-4 Authors Pandian Bothi Raja, School of Chemical Sciences, Universiti Sains Malaysia (USM), 11800 Pulau Pinang, Malaysia Ahmad Kaleem Qureshi, Department of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia Afidah Abdul Rahim, School of Chemical Sciences, Universiti Sains Malaysia (USM), 11800 Pulau Pinang, Malaysia Khalijah Awang, Department of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia Mat Ropi Mukhtar, Department of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia Hasnah Osman, School of Chemical Sciences, Universiti Sains Malaysia (USM), 11800 Pulau Pinang, Malaysia Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung:    Presence of hydrogen in materials is known to affect their mechanical properties due to hydrogen embrittlement problem. Steels used in various applications are prone to be exposed to aqueous electrochemical environments, which may introduce hydrogen into the alloy. These alloys are also prone to be simultaneously exposed to magnetic field, which may affect the hydrogen embrittlement susceptibility of these alloys. Therefore, it is important to examine the effect of hydrogen and magnetic field on the mechanical behavior of iron-based alloys. In this work, the effect of hydrogen and magnetic field on the fracture behavior of high strength AISI 4340 steel was examined. Three-point bend test was used to study the fracture behavior. In all the cases, the samples tested with hydrogen charging show a drastic reduction in ductility and fracture stress values. The effect of magnetic field was seen to be negligible. The hydrogen embrittlement was characterized by a change in the fracture surface from a ductile-type fracture to a brittle cleavage-type fracture. Acoustic emission signals collected during the test corresponds to the fracture behavior. Content Type Journal Article Pages 1-7 DOI 10.1007/s11665-012-0343-8 Authors Meenakshisundaram Ramanathan, Department of Metallurgical Engineering, University of Utah, 135 S 1460 E, Salt Lake City, UT 84112-0114, USA Biswadeep Saha, Department of Metallurgical Engineering, University of Utah, 135 S 1460 E, Salt Lake City, UT 84112-0114, USA Chai Ren, Department of Metallurgical Engineering, University of Utah, 135 S 1460 E, Salt Lake City, UT 84112-0114, USA Sivaraman Guruswamy, Department of Metallurgical Engineering, University of Utah, 135 S 1460 E, Salt Lake City, UT 84112-0114, USA Michael McCarter, Department of Mining Engineering, University of Utah, 135 S 1460 E, Salt Lake City, UT 84112-0114, USA Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung:    It is well known that drillpipe failures are a pendent problem in drilling engineering. Most of drillpipe failures are low amplitude-repeated impact fatigue failures. The traditional method is using Charpy impact test to describe the fracture property of drillpipe, but it cannot veritably characterize the impact fatigue property of drillpipe under low amplitude-repeated impact. Based on the Charpy impact and other methods, a repeated impact method and instrument have been proposed to simulate the low amplitude-repeated impact of downhole conditions for drillpipe. Then, a series of tests have been performed using this instrument. Test results demonstrate the drillpipe upset transition area nonhomogeneity is more severe than drillpipe body, which is the key factor that leads to washout and fracture frequently of it. As the one time impact energy increases, the repeated impact times decrease exponentially, therefore, the rotational speed has a great effect on the fatigue life of drillpipe, and it is vital to select a suitable rotational speed for drilling jobs. In addition, based on SEM fractographs we found that the fracture surface of repeated impact is similar to the fatigue fracture, and there are many low cycle fatigue characteristic features on fracture surface that reveal very good agreement with the features of drillpipe fatigue failures in the field. Content Type Journal Article Pages 1-8 DOI 10.1007/s11665-012-0349-2 Authors Yuanhua Lin, State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, 610500 Peolple’s Republic of China Qiang Li, CNPC Key Lab for Tubular Goods Engineering, Southwest Petroleum University, Chengdu, 610500 Peolple’s Republic of China Yongxing Sun, CNPC Key Lab for Tubular Goods Engineering, Southwest Petroleum University, Chengdu, 610500 Peolple’s Republic of China Hongjun Zhu, CNPC Key Lab for Tubular Goods Engineering, Southwest Petroleum University, Chengdu, 610500 Peolple’s Republic of China Ying Zhou, School of Material Science and Engineering, Southwest Petroleum University, Chengdu, 610500 Peolple’s Republic of China Juan Xie, School of Material Science and Engineering, Southwest Petroleum University, Chengdu, 610500 Peolple’s Republic of China Taihe Shi, State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, 610500 Peolple’s Republic of China Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung:    In this study, the Taguchi method was used as a design of experiment (DOE) technique to optimize the pulsed current gas tungsten arc welding (GTAW) parameters for improved pitting corrosion resistance of AA5083-H18 aluminum alloy welds. A L9 (3 4 ) orthogonal array of the Taguchi design was used, which involves nine experiments for four parameters: peak current ( P ), base current ( B ), percent pulse-on time ( T ), and pulse frequency ( F ) with three levels was used. Pitting corrosion resistance in 3.5 wt.% NaCl solution was evaluated by anodic polarization tests at room temperature and calculating the width of the passive region (∆ E pit ). Analysis of variance (ANOVA) was performed on the measured data and S / N (signal to noise) ratios. The “bigger is better” was selected as the quality characteristic (QC). The optimum conditions were found as 170 A, 85 A, 40%, and 6 Hz for P , B , T , and F factors, respectively. The study showed that the percent pulse-on time has the highest influence on the pitting corrosion resistance (50.48%) followed by pulse frequency (28.62%), peak current (11.05%) and base current (9.86%). The range of optimum ∆ E pit at optimum conditions with a confidence level of 90% was predicted to be between 174.81 and 177.74 mV SCE . Under optimum conditions, the confirmation test was carried out, and the experimental value of ∆ E pit of 176 mV SCE was in agreement with the predicted value from the Taguchi model. In this regard, the model can be effectively used to predict the ∆ E pit of pulsed current gas tungsten arc welded joints. Content Type Journal Article Pages 1-12 DOI 10.1007/s11665-012-0346-5 Authors E. Rastkerdar, Department of Materials Engineering, Isfahan University of Technology, Isfahan, 84156-83111 Iran M. Shamanian, Department of Materials Engineering, Isfahan University of Technology, Isfahan, 84156-83111 Iran A. Saatchi, Department of Materials Engineering, Isfahan University of Technology, Isfahan, 84156-83111 Iran Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung:    An Al-11Mg 2 Si-Si in situ composite was prepared by a modified investment casting technique that employs sub-pressure for castability improvement and immersion of ceramic shell molds in fluidized beds of silica sand and iron particles for heat extraction improvement. The microstructure of the as-cast composite is explained according to the pseudoeutectic Al-Mg 2 Si phase diagram. The positive effect of a decreased number of mold investment layers and cooling assisted by immersion of the mold in a metallic bed on the tensile strength and hardness of the heat treated composite is noted. A minor presence of Fe in the master alloys constitutes an essential factor for the brittleness of the composite. Solution treatment notably improves the tensile strength of the composite; however, prolonged treatment deteriorates its ductility. The effect of time and temperature of the aging treatment on the hardness of the composite is investigated. The positive influence of cooling assisted by a metallic fluidized bed on the effectiveness of the aging treatment is noticed. Content Type Journal Article Pages 1-13 DOI 10.1007/s11665-012-0337-6 Authors E. Georgatis, Department of Materials Science and Engineering, University of Ioannina, 45110 Ioannina, Greece A. Lekatou, Department of Materials Science and Engineering, University of Ioannina, 45110 Ioannina, Greece A. E. Karantzalis, Department of Materials Science and Engineering, University of Ioannina, 45110 Ioannina, Greece H. Petropoulos, Department of Materials Science and Engineering, University of Ioannina, 45110 Ioannina, Greece S. Katsamakis, Department of Materials Science and Engineering, University of Ioannina, 45110 Ioannina, Greece A. Poulia, Department of Materials Science and Engineering, University of Ioannina, 45110 Ioannina, Greece Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495

Beschreibung:    Friction composite formulation consisting of decreasing nanoclay/lapinus fibres content, increasing graphite/aramid fibres content, and master batch of phenolic/barite is designed, fabricated, and characterized for their mechanical, thermo-mechanical, and tribological studies in braking situations. A standard test protocol is adopted for evaluating braking performance. The nanoclay content (≤2.25 wt.%) enhances hardness, impact strength, storage, and loss modulus characteristics of the friction composites. Such composites exhibit higher friction stability as well as variability coefficient. However, composites with higher content of nanoclay (~2.75 wt.%) exhibit moderate level of stability coefficient and minimum variability coefficient. Fade performance improves with nanoclay content whereas friction fluctuations increase continuously with increasing nanoclay content. The disc temperature continuously rises with nanoclay contents, it becomes maximum for nanoclay content 2.75 wt.%. The same composition found to be effective in arresting temperature rise, arrests fading, improves recovery, moderate stability with minimum variability coefficient, and higher level of μ-performance hence recommended. The wear performance deteriorates with lapinus/nanoclay content and improves with the amount of aramid/graphite in the friction composites. Worn surface morphology study (using SEM) reveals the associated wear mechanisms responsible for wear of investigated composites. XRD study confirms the presence and dispersion of nanoclay with other composite ingredients. Content Type Journal Article Pages 1-10 DOI 10.1007/s11665-012-0325-x Authors Tej Singh, Department of Mechanical Engineering, NIT, Hamirpur, H.P., India Amar Patnaik, Department of Mechanical Engineering, NIT, Hamirpur, H.P., India Bhabani K. Satapathy, Centre for Polymer Science and Engineering, IIT Delhi, Hauz Khas, India Mukesh Kumar, Department of Mechanical Engineering, NIT, Hamirpur, H.P., India Bharat S. Tomar, Allied Nippon Industries Limited, Sahibabad, U.P., India Journal Journal of Materials Engineering and Performance Online ISSN 1544-1024 Print ISSN 1059-9495