Effect of laser shock peening on microstructural, mechanical and corrosion properties of laser beam welded commercially pure titanium

Abstract

In the present study, laser beam welding of commercially pure titanium has been carried out at different scan speeds in the range from 2.4 m/min to 4 m/min at 2.15 kW laser power and its influence on molten pool thermal history, microstructure, residual stress, mechanical and corrosion properties has been studied. Weld thermals cycles were monitored using a single wavelength infrared pyrometer. Effect of laser shock peening on laser welded specimens was also studied. Laser shock peening inducted significant amount of compressive residual stress through plastic deformation. Strain hardening and changes in microstructure such as formation of twining lead to significant improvement in tensile and fatigue properties. Micro-hardness in the fusion zone at sub-surface region got improved by ~26% and fatigue strength increased by ~24%. Corrosion resistance also got increased due to high compressive residual stress and grain refinement after LSP.