Effect of laser shock processing on residual stress of strain steel welded joints

There exists residual tensile stress in the stainless steel welded joints, which makes the stainless steel welded joints sensitive to stress corrosion cracking. Laser shock processing is used to treat stainless steel welded joints. The effect of laser shock processing on optimization of surface residual stress is researched, and the test of stress corrosion is carried out to examine optimization result. With increasing of laser power density, the surface residual tensile stress decreases, but the increment of the decrease is gradually reduced. For example, when impacted with 4.24 GW/cm2 and 2.83 GW/cm2, the residual stress has not obviously changed; moreover, there still exists residual tensile stress in the fluxional zone. It indicates that residual tensile stress cant be eliminated entirely when impacted individually with high power density. With increasing of the impact times, the residual tensile stress will be eliminated absolutely, and the stress gradient decreases from 54.7 MPa/mm to 11.7 MPa/mm. When treated by laser shock processing, the stress corrosion rupture time of the welded specimen increases by 33.48%, which is attributed to residual compressive stress generated by laser shock processing.