Effect of Pickling on Surface Morphology, Corrosion Resistance and Surface Optical Constants of 316L Stainless Steel

The effect of pickling time on the surface morphology, surface optical constants and corrosion resistance of 316L stainless steel in 3.5% NaCl solution. The results show that proper pickling can improve the corrosion resistance of 316L stainless steel, but excessive pickling is prone to pitting corrosion. The increase in corrosion resistance is due to the formation of a passivation film rich in Cr2O3 on the surface of 316L stainless steel after pickling. It appears because the micropores on the surface promote the nucleation of pitting corrosion. The pickling solution remaining on the surface will generate a thicker passivation film on the local surface of 316L stainless steel, which has different optical constants, resulting in the appearance of macroscopic surface white spots.