Deformation microstructures of austenitic stainless steel 2Cr13Mn9Ni4 under ultrafast strain rate by laser shock processing

The microstructure of the austenitic stainless steel 2Cr13Mn9Ni4 by laser shock processing was investigated mainly using a transmission electron microscope. Results show that the micro-hardness of the laser shocked area of the austenitic stainless steel is strongly increased by the refined grains and the reconstruction of microstructures. The typical deformation microstructure is the mix of high-density dislocations and deformation twin grains. The amorphous structures, surrounding the refined broken crystals, were also observed in parts of the laser shock processing area. The stress concentration in the twin grain regions is further released by the formation of stair-like structures. The repeated LSP will result in the increase of the surface roughness and the amount of slip bands, deformation twin grains and stacking faults but decrease the width of the stacking faults.