Multiaxial thermo-mechanical fatigue damage mechanism of TC4 titanium alloy.

• Multiaxial thermo-mechanical fatigue behavior of titanium alloy is understood. • Effects of tensile and compressive dwell time on fatigue behavior are found out. • Fast cracking mode may be activated by multiaxial thermo-mechanical loading. • Failure life of material is reduced by non-proportional additional hardening. • Fatigue and oxidation damages are increased by tensile mean stress. In this paper, the experimental investigation was carried out on the TC4 titanium alloy to understand the cyclic deformation behavior and fatigue damage mechanism of materials under multiaxial thermo-mechanical loading. The results showed that the fast cracking mode of the material may be activated by the combined action of high temperature, tensile stress and shear stress, inducing a fast degradation in the axial mechanical properties of the material, which results in a drastic decrease in the failure life of the material. Moreover, it is also found that the non-proportional additional hardening and the tensile mean stress can increase the fatigue and oxidation damages of the material, and the material damage behavior is temperature dependent and time dependent. It should be pointed out that the damage mechanisms identified in this paper can reasonably explain the life law under uniaxial isothermal fatigue loading with and without dwell time, uniaxial and multiaxial thermo-mechanical fatigue loadings. [ABSTRACT FROM AUTHOR]