Influence of shot peening on fatigue property of TC21 titanium alloy

The TC21 fatigue specimens were shot peened and S-N curves of the unpeened and shot-peened specimens were tested by rotating bending fatigue.The fatigue limits of the unpeened and shot-peened specimens under 1×107cycles were determined by stair-step method.Moreover,the residual stresses in the surface hardened layer were analyzed by X-ray diffraction with polishing layer by layer,and fatigue fractographs were observed by SEM.The results show that the shot peening can enhance the fatigue strength and prolong fatigue life,and the fatigue crack source are located under the surface hardened layers.