Understanding the Tensile Deformation Behavior of a Serviced 304 Stainless Steel Based on Quasi In Situ EBSD Measurement

The microstructural evolution and strain-hardening mechanisms of a serviced 304 stainless steel during tensile deformation are investigated using quasi in situ EBSD measurements. This steel exhibits a high ultimate tensile strength of about 652 MPa alongside an exceptional fracture elongation of 83.4%. Its strain hardening behavior can be divided into three distinct stages. Deformation induces heterogeneous lattice rotation, which is dominated by the preferential activation of slip systems with the top two Schmid factors. With increasing strain, the deformation mechanism evolves sequentially from dislocation slip to mechanical twinning and then strain-induced martensite transformation. Mechanical twins act as the preferential nucleation sites for strain-induced martensite. In the latter two deformation stages, mechanical twinning serves as the primary driver of strain hardening, while strain-induced martensite merely contributes auxiliary hardening due to its limited volume fraction. This work elucidates the full-chain deformation mechanism of serviced 304 stainless steel. It provides experimental fundamentals for evaluating the residual ductility and failure risk of serviced austenitic stainless steel components.