Effect of Laser Shock Peening on Surface Integrity of GH3039 Superalloys

In order to study the effect of laser shock peening (LSP) on the surface integrity of GH3039 superalloys, the GH3039 superalloy samples have been treated by LSP for different times. The surface roughness, microhardness, residual stress, microstructure and phase composition of GH3039 superalloys before and after LSP were characterized by the surface profiler, microhardness tester and X-ray diffractometer. The results indicate that compared with those of the base metal, after one, two, and three impacts, the surface roughness of LSP samples is increased by 28. 5%, 54. 1%, and 109. 1%, the surface microhardness is increased by 21.4%, 26.5%, and 28.6%, and the average grain size in the near surface layer is decreased by 54. 5%, 57. 1%, and 59. 3%, respectively. The residual stress of the sample surface is transformed from tensile stress (75 MPa) into compressive stress ( - 275 MPa for one impact, -302. 4 MPa for two impacts, and -335 MPa for three impacts). The deformation layer depth of the LSP sample increases from around 1.2 mm (for one impact) to around 1.5 mm ( for three impacts). With the increase in the number of impacts, the full widths at half maximum of diffraction peaks increase obviously, which is attributed to grain refinement and micro-strain enhancement.