Fatigue Damage Mechanism of Titanium in Inert Environments

Abstract

The fatigue damage of titanium has been studied on thin plate specimens subjected to alternating plane bending in argon gas. Fatigue strength in argon gas at Nf = 108 cycles was obtained to be 102 MPa. Fatigue behavior of titanium in argon gas has been attributed to the degradation of grain boundary cohesion with argon gas atoms/molecules. Fatigue cracks were propagated partly in intergranular mode. It has been plausible that argon gas atoms/molecules could penetrate into the distorted regions close to grain boundary through lattice defects and degrade grain boundary cohesion. Grain boundaries have been preferentially damaged in argon gas. The results in argon gas have been compared with those obtained in vacuum and in air.