Influence of shot peening on tension-tension fatigue property of two high strength Ti alloys

Surface roughness, residual compressive stress caused by shot peening and the effect of shot peening on fatigue property of Ti-5Al-5Mo-5V-1Cr-1Fe (TC18) and Ti-10V-2Fe-3Al (TB6) titanium alloys were investigated. The results show that fatigue limit for 1 x 10(7) cycles can be increased by 27 and 29% for TC18 and TB6 titanium alloys respectively. By comparing fatigue life under the same stress for different shot peening regimes treated specimens, the optimum shot peening process was determined. For a given material, there is an optimal shot peening intensity, and insufficient shot peening and over shot peening will not result in good fatigue performance. However, double shot peening, a shot peening process by which parts are peened initially with cast iron shot to induce a deep residual compressive stress field, followed by shot peening with glass shot to decrease the surface roughness and to remove the contaminants caused by the cast iron shot, can significantly improve fatigue performance.