Microstructure evolution and fatigue properties subjected to optimized coverage areas of laser shock peened TB10 titanium alloy

Laser shock peening (LSP) is an advanced surface modification technology, which can induce the high-strain-rate plastic deformation on the metal surface to improve mechanical properties. In this work, the effects of LSP on the microstructure, microhardness, residual stress and fatigue crack growth (FCG) properties of TB10 titanium alloy were investigated. The results showed that LSP could induce high density dislocations and realize the nano-crystallization on the titanium alloy surface. The magnitudes of compressive residual stress and microhardness increased with increasing LSP energy and impact times. The fatigue test showed that the LSP coverage area significantly affected the FCG performance, especially the fatigue life increased by 40.2 % when the LSP area was perpendicular to the cracks. This was attributed to the fact that the FCG rate of early cracks was significantly reduced by a wider region of the compressive residual stress field perpendicular to the crack direction.