An experimental investigation of the effect of process parameters on residual stress in laser surface melting of Austenitic stainless steel

Abstract

Laser surface melting (LSM) is a surface modification technique involving melting and resolidifying a thin surface layer. The high-temperature gradients involved results in unwanted residual stresses which affect the component performance. This experimental study explores the effect of laser process parameters viz., power, scan speed and scan overlap on the residual stress and surface topography in austenitic stainless steel. It was observer that the induced residual stress is least (~ 752 MPa) at the lowest scan speed of 0.2 m/s with power and overlap kept constant at 50W and 40%, respectively. It was also observed that least residual stress of ~ 655 MPa was obtained at the highest power of 70 W that resulted in deepest melt pools. These results indicate that melt pool dimensions and cooling rates are key determinants of the complex relationship between laser process parameters and residual stress. Higher laser power and lower scan speeds result in deeper, wider melt pools and slower cooling rates, reducing tensile residual stress. Conversely, higher scan speeds increase stress. This research offers valuable insights into optimizing LSM to enhance material properties and minimize tensile residual stress.