Micromagnetic characteristic changes and mechanism induced by plastic deformation of 304 austenitic stainless steel

An in–situ magnetic monitoring technology was used to observe the surface magnetic induction intensity variation of 304 stainless steel specimens during the tensile process. A magnetization test was conducted to investigate the relationship between the strain and magnetization characteristic parameters. The change mechanism of micromagnetic signal induced by plastic deformation was analyzed through microstructure morphology observation. Results suggested that the magnetic induction intensity changed nonlinearly with the strain, which corresponded to the elastic, strengthening, and necking stages of engineering stress–strain curve until fracture. The magnetic susceptibility and remanence were positively correlated with the strain, and the two parameters presented an abrupt change when the specimen was close to the yield state. The microstructure morphology showed that the austenite structure of 304 stainless steel transformed to martensite after plastic deformation, and the content of this strain-induced martensite increased with the increase in strain.