Laser shock processing of an austenitic stainless steel and a nickel-base superalloy

An austenitic stainless steel 1Cr18Ni9Ti and a solid solution-strengthened Ni-base superalloy GH30 were shock-processed using a Q-switched pulsed Nd-glass laser. The microstructure, hardness and residual stress of the laser shock processed surface were investigated as functions of laser processing parameters. Results show that high density of dislocations and fine deformation twins are produced in the laser shock processed surface layers in both the austenitic stainless steel and the nickel-base superalloy. Extensive strain-induced martensite was also observed in the laser shock processed zone of the austenitic steel. The harness of the laser shock processed surface was significantly enhanced and the compressive stress as high as 400 MPa was produced in the laser shock processed surface.