Study on microstructure and cavitation corrosion resistance of 304 stainless steel after surface rolling

The surface strengthening treatment of 304 austenitic stainless steel was carried out by rolling processing. The results show that, compared with the turned samples, the surface of the rolled samples undergoes martensitic transformation, and the surface area is obviously deformed. The main deformation modes are dislocation and slip. After rolling, the proportion of dislocations and small-angle grain boundaries increases, and the grains are refined without obvious texture. The surface residual stress of 304 stainless steel is transformed from tensile stress to compressive stress by rolling strengthening treatment, and the maximum residual compressive stress on the surface can reach 569 MPa. The depth of the hardened layer after rolling can reach 500 mu m. After rolling strengthening, the corrosion potential less negative and the corrosion current density decreased to 1.43 x 10- 7 A/cm2, showing better corrosion resistance. After rolling treatment, the cavitation erosion resistance of the surface is improved, and the fatigue resistance of crack initiation and plastic deformation during cavitation erosion (CE) is increased by 4.4 times. The grain refinement caused by rolling leads to the increase in the proportion of small-angle grain boundaries and the transformation of residual stress, which makes the rolled parts show good comprehensive properties, providing a solid theoretical basis for the research of corrosion protection in marine engineering.