Effects of Fine Particle Bombarding on Surface Characteristics and Fatigue Strength of Commercial Pure Titanium

Abstract

This study investigated the effects of fine particle bombarding (FPB) on the surface characteristics and fatigue strength of commercial pure titanium. For comparison, conventional shot peening (SP) was also performed. The surface microstructure was nano-crystallized by FPB and SP. The grain size of nano-crystals reduced with decreasing particle diameter or increasing air pressure for accelerating particles. The surface hardness and compressive residual stress markedly increased by FPB. The surface layers were uniformly generated along the surface, and effectively suppressed the initiation of fatigue cracks. As a result, the fatigue strength greatly increased. Since the surface layers acted as a barrier to subsurface cracks, its improvement ratio was closely related to the surface characteristics.