Comparison of corrosion behavior between coarse grained and nano/ultrafine grained 304 stainless steel by EWF, XPS and EIS

The electron work function in coarse grained stainless steel was higher than that in nano/ultrafine grained one. More M₂O₃ types oxides and thicker passive film were observed in nano/ultrafine grained 304 stainless steel. The electrochemical impedance spectroscopy results showed that grain refinement improved corrosion resistance of 304 stainless steel. The results obtained indicated that the impedance increase was attributed to decreased electron work function. Lower electron work function facilitated to form thicker passive films. The same characteristics were observed with the increasing of chloride ion concentration.