ISSN:
1662-9752
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Impact properties and fatigue crack growth behavior of a newly developed Al-Zn-Mgfunctionally graded material (FGM) is studied. The gradient in terms of hardness (about 85 to 130VHN) and yield strength (about 260 to 360 MPa) is established along the width of the Charpy-impactand Compact Tension specimens. In both these test specimens two types of FGMs, depending on thedirection of crack propagation, are produced. In the first case, FGM-I, the notched surface is madeharder and the hardness value decreases towards the other surface in the direction of crack growth. Inthe second case, FGM-II, the hardness gradient is reversed and the crack propagation takes place fromthe softer side to the harder side. The impact and fatigue crack growth experiments are also carried outfor the homogeneous materials with different hardness values and the results obtained from the FGMsare compared with them.The results of impact tests show that FGM-II absorbs about 20% greater energy than the highestenergy absorbed by any of the isothermally aged homogeneous materials. Fatigue crack growth studiesfor the FGM-I show a reduction in crack growth rate as the crack propagates towards softer (ductile)side and finally crack arrest is observed. On the other hand, for the case of FGM-II, where the crackpropagates towards the harder side, the crack growth rate first increases and then decreases. However,in this case the crack follows a tortuous path and it starts bending upwards after about 20 mm cracklength, which might be responsible for higher energy absorption in impact tests
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/02/13/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.519-521.1539.pdf
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