Effects of laser shock peening on microstructure and residual stress evolution in Ti-45Al-2Cr-2Nb-0.2B alloy

Laser peening is a novel surface treatment technique for improving the mechanical properties of metal parts' surface. To investigate and evaluate the effect of laser peening on the microstructural changes, texture evolution, and residual stress distribution changes, laser peening experiment was undertaken using Nd:YAG laser system with the pulse-width of 20 ns and max pulse-energy of 9 J. Micro-hardness measurements of the untreated and treated specimens were carried out with Vickers indenter. Depth-resolved characterization of the residual stresses and strains was achieved using X-ray diffraction. The structure-texture-phase-stress combined analysis was performed based on the X-ray diffraction patterns using the whole pattern fitting method. The relationship between laser peening processing parameters, microstructure, texture, residual stress distribution and hardness are presented and discussed. The results showed that laser peening could improve microstructures and properties of TiAl alloy.