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:
The efficiency of aircraft and industrial gas turbines and combustion engines depends onthe maximum operation temperature and, therefore, on the properties of the commercial hightemperature materials. In the temperature range 500°C to 750°C γ-titanium aluminides especiallyalloys of the third generation represent an attractive alternative to the established nickel-basesuperalloys which have the double density. Due to superimposed cyclic thermal and cyclicmechanical loadings during start-up and shut-down operations structural components in gas turbinesand combustion engines may not only be exposed to isothermal but also to thermo-mechanical fatigue(TMF). In this study the cyclic deformation and fatigue behaviour under thermo-mechanical load ofthe γ-TiAl alloy TNB-V5 with near-gamma microstructure is evaluated. To set a fatigue-life relationstrain-controlled thermo-mechanical fatigue tests were carried out with two different strain ranges,different temperature-strain cycles and different temperature ranges from 400°C to 800°C. Additionallow-cycle fatigue (LCF) tests were performed at 400°C, 600°C and 800°C for comparison. Cyclicdeformation curves, stress-strain hysteresis loops and fatigue lives of the tests are presented. Theshortest fatigue lives are always observed in out-of phase (OP) tests, the longest in in-phase (IP) tests.Clockwise-diamond (CD) and counter-clockwise diamond (CCD) testing yield similar fatigue livesintermediate between those of OP and IP tests. For a general life prediction the double-logarithmicplot of the damage parameter by Smith, Watson and Topper vs. fatigue life is well suitable
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/02/15/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.539-543.1559.pdf
