Effect of Laser Shock Peening on the Microstructure of P265GH Steel and X6CrNiTi18-10 Stainless Steel Dissimilar Welds

The aim of this study was to verify the laser shock peening (LSP) on the microstructure of P265GH steel and X6CrNiTi18-10 stainless steel. The LSP surface treatment was done underwater on the dis-similar weld joint of the P265GH and X6CrNiTi18-10 tubes. The metallographic analysis then focuses on the evaluation of microstructure in heat-affected zones of both materials. The results of our analysis are possibly summarised as follows. Light and scanning electron microscopy have shown grain refinement in the treated surface of the HAZ region of X6CrNiTi18-10 steel. For P265GH steel, it was possible to find a remelted surface layer with a thickness of 3.3±0.6 micrometers in the peened areas. For P265GH steel was also possible to observe a significant increase in dislocation density in the grains with straight contact with the peened surface. In the case of X6CrNiTi18-10 steel, this area extended to a depth of over 50 micrometers from the peened surface.