Laser driven substructural modification of austenitic stainless steel

In this paper, the technique of high energy and short pulse duration laser impact is adopted. The substructural transformation characteristics and mechanisms of the austenitic stainless steel, subjected to strain-rate of 106s(-1) order and stress of 2.70GPa, are investigated. SEM observations, there exists regular arrangement of chapped and equiaxed subgrain regions within the original grains. The size of the subgrain ranges from 0.1 to 0.5um; Meanwhile, the compacted deformation twin bundles with about turn width each twin have been examined in the regions treated. It indicates that the equiaxed subgrains, close to nanometer scale, had evolved in the surface of austenitic stainless steel, and they belong to dynamic rotational recrystallization; Although, twinning deformation is not a frequent phenomenon in terms of austenitic stainless steel at room temperature, it will play a significant role when austenitic stainless steels are submitted to high strain rate and stress. Additionally, X-ray diffraction reveals that the crystal lattice constant is up 1.12% compared to the normal one and no deformation-induced alpha-martensite and amorphous phase are spotted within the processed regions.