Effect of laser shock peening on the microstructure of GX4CrNi13-4 martensitic stainless steel

Abstract

This study investigates the effect of laser shock peening (LSP) on the microstructure and properties of GX4CrNi13-4 martensitic stainless steel. Three different conditions of surface preparation were examined in this study. First, a control group was left with a ground surface. The two remaining groups were treated with LSP. In one case, a single pass of LSP was applied and in the other case, a double pass of LSP was concerned. The samples were subsequently subjected to corrosion-fatigue testing in a water solution of 0.5 g/l NaCl, metallographic analysis, X-ray diffraction, and microhardness measurements. Experimental results of the corrosion-fatigue test showed that the LSP-treated samples exhibited fatigue cracking at higher force amplitude. Roughness measurements showed that the surface after LSP was rougher compared to the initial ground surface but with a lower proportion of grooves. Greater plastic surface deformation resulted in an increase in microhardness in the near-surface region, which was accompanied by an increase in the calculated density of geometrically necessary dislocations, a decrease in the proportion of retained austenite and coarsening of the martensite phase crystallite.