The Effects of Local Microscale Deformation on the Surface Quality of Laser Shock Peened TC4 Titanium Alloy
B-Y. Su, H. Wang, G-R. Hua, Y-P. Cao and J-B. Wang
Local microscale deformation and plastic flow are induced by laser shock peening (LSP) and the effects thereof on surface quality (surface roughness, residual stress) were investigated in detail. The experimental results showed that the local microscale deformation is induced in the margin of the spot due to the plastic flow of the material. During the massive LSP process the local microscale deformation has a significant influence on the surface quality. The secondary plastic flow of local microscale deformation in the margin repeatedly regulated the surface profile. The average surface roughness during massive LSP treatment initially increased as the overlapping rate increased from 0 to 33%, and then decreased as the overlapping rate rose to 50%. The peak-to-valley surface roughness decreased with the increasing overlapping rate. It personifies that the evolution of surface profile and residual stress are significantly affected by the repeated plastic flow.
Keywords: Nd:YAG laser, TC4 titanium alloy, laser shock peening (LSP), local microscale deformation, surface profile, residual stress, plastic flow