Multiaxial low-cycle thermo-mechanical fatigue of a low-alloy martensitic steel: Cyclic mechanical behaviour, damage mechanisms and life prediction

Axial-torsional Low-Cycle Fatigue tests (LCF) and Thermo-Mechanical Fatigue tests (TMF) were performed on a low-alloy martensitic steel for temperatures between 300 degrees C and 600 degrees C, as both proportional and nonproportional. The results show that non-proportional loading leads to an increase in fatigue damage and to a decrease in the observed lifetime. The TMF damage model is proposed here in order to incorporate the effects of multiaxial loading and varying temperatures. This damage model is based on a critical plane approach, and it incorporates the fatigue, oxidation and creep forms of damage. Finally, the proposed model is validated for a large experimental database.