Microstructural and Magnetic Response of Austenitic Stainless Steels to Plastic Deformation

Abstract The study investigates the influence of pressure-induced plastic deformation on the microstructural evolution, microhardness, and magnetic behavior of AISI 304 and AISI 316L austenitic stainless steels. Samples were subjected to different levels of compressive deformation and subsequently analyzed using optical microscopy, microhardness testing, and vibrating sample magnetometry (VSM). The microstructure after solution annealing consisted of polyhedral austenitic grains with numerous annealing twins, while after deformation, distinct signs of plastic strain were observed within individual grains. The microhardness measured perpendicular to the loading direction increased with the degree of deformation, reaching the highest values in the core of the samples, which confirms the non-uniform distribution of plastic deformation. Magnetic measurements revealed a noticeable increase in both saturation and remanent magnetization after plastic deformation, confirming the presence of deformation-induced α′-martensite. The coercive field decreased for AISI 304 but slightly increased for AISI 316L. The results demonstrate a clear correlation between mechanical strengthening and the magnetic response of austenitic steels subjected to plastic deformation.