Investigation of microstructure and tribological property of Ti-6Al-4V alloy by laser shock peening processing

Abstract

Laser shock peening (LSP) is a process to introduce compressive residual stresses for improved surface properties of materials. In this study, the effect of LSP on the microstructure and tribological property of Ti-6Al-4V alloy was investigated. The surface and cross-sectional microstructure of the samples show that the shape of the β phase changes from a long strip to a short bar and granular after the LSP treatment. With the increase of laser energy, the surface roughness decreases gradually while the surface microhardness is increased. The maximum hardness is on the surface, and with the increase of the depth, the hardness decreases until a stable value of 339.4 HV which is the microhardness of the matrix. The thickness of the high-microhardness layer is about 350 μm. LSP treatment can decrease the average friction coefficient and effectively improve the tribological property of Ti-6Al-4V alloy. The higher the laser energy, the better the wear resistance. This study is helpful for further study and applications of the LSP process in improving the tribological property of Ti alloys.