X-ray diffraction study on microstructures of shot/laser-peened AISI316 stainless steel

Microstructural features of AISI316 stainless steels processed by shot peening (SP) and laser peening (LP) were studied using X-ray diffraction line profile analyses. Both specimens exhibited similar compressive residual stress profiles. Although the number of dislocations was increased and the crystallites were refined with both processes, the dislocation density in the SP specimen was significantly greater than that in the LP specimen. The crystallite size in the SP specimen was one-third that in the LP specimen. The SP process induced martensite transformation. The variations in the microstructural features differed between samples subjected to the two processes. The SP process resulted in a greater variation in the microstructural features in a sample in which residual stresses similar to that induced by the LP process were induced. Thus, the variations in the microstructural features differed depending on the deformation process.