Introduction of Compressive Residual Stress into Alloy Tool Steel by Submerged Laser Peening Utilizing Laser Cavitation Impact

At submerged laser peening, laser cavitation is generated after laser abrasion and it produces impact at cavitation collapse. In order to demonstrate mechanical surface treatment by submerged laser peening utilizing laser cavitation impact, alloy tool steel was treated and the residual stress was measured by X-ray diffraction methods. At submerged laser peening, Nd:YAG laser of wave length at 1,064 nm was used. The impacts induced by laser abrasion and laser cavitation were evaluated by a PVDF sensor which was installed in target. It was revealed that the submerged laser peening can introduce compressive residual stress into alloy tool steel.