Hj. Shi et al., HIGH-TEMPERATURE ISOTHERMAL AND THERMOMECHANICAL FATIGUE ON A MOLYBDENUM-BASED ALLOY, Materials science & engineering. A, Structural materials: properties, microstructure and processing, 247(1-2), 1998, pp. 180-186
High temperature isothermaI fatigue and in-phase thermomechanical fati
gue (TMF) tests in stress control were performed on a molybdenum-based
alloy, TZM. Two temperature levels of 350 and 500 degrees C were chos
en for isothermal fatigue tests and a temperature interval of 350-500
degrees C was applied to thermomechanical fatigue tests.The stress-str
ain response and the hfe cycle of the material were measured during th
e tests. It appears that temperature variations influence the fatigue
life of the alloy and the material is further damaged with combined st
ress and temperature cycles. The analysis of the hysteresis loops show
ed that a ratcheting phenomenon and a cyclic softening behavior of the
material occurred during each kind of the fatigue tests. The observat
ions of the microstructure of the damaged specimens demonstrated that
the fracture of the alloy was, on the whole, a brittle process under h
igher cyclic stress conditions. (C) 1998 Elsevier Science S.A. All rig
hts reserved.