Study on corrosion resistance mechanisms of gradient-structured austenitic stainless steel materials based on passivation behavior

Abstract

SMAT treatment produced gradient-structured deformation layers of a certain thickness, and the gradient structure and residual stresses were then characterized using SEM and XRD. A layer-by-layer electrochemical test method was created and employed to study the impact of the gradient structure on the passivated film and the corrosion resistance mechanism of the deformed layers at various depths. The findings demonstrate that when depth is increased, both residual stresses and grain size decrease. The layer-by-layer experiments reveal that residual compressive stress and grain size reduction work together to produce a passivation film with fewer flaws and more stability, as indicated by MS. This is primarily attributable to grain size reduction's increased number of nucleation sites in the passivation film and the residual compressive stress acting as a driving force for passivation film growth.