Surface and Electrochemical Performance Variations of 2205 Duplex Stainless Steel in Multistep Surface Processing

This study aims to elucidate the impact of different surface processing techniques on the corrosion resistance of 2205 duplex stainless steel. The samples were subsequently treated by mechanical grinding (S_grd), water-sandpaper sanding (S_wap), and mechanical polishing (S_pol) and characterized by XRD, AFM, XPS, and a series of electrochemical tests. Due to the grinding-induced residual compressive stress and low donor density in the passive film, S_grd exhibited the lowest corrosion current among the three. Nevertheless, the lattice defects and the high content of Cr(III) hydroxide not only weakened the stability of the passive film but also resulted in the decreased trend of corrosion resistance. Sanding and mechanical polishing with a lower power input removed the residual stress left by grinding and inhibited the occurrence of selective oxidation. The lower surface roughness facilitated the formation of homogeneous passive layers with fewer defects, which can enhance the pitting resistance and provide a gradually enhanced protection from corrosion.