Influence of Cold Work on Pitting Corrosion Behavior of a High Nitrogen Stainless Steel

Abstract

The effects of cold work on the pitting corrosion resistance of a nickel-free high-nitrogen stainless steel in chloride solution have been investigated by electrochemical tests, surface chemical analysis, immersion tests, and microscopic observations. Potentiodynamic polarization revealed that pitting resistance was degraded by cold work as convinced by the decreased critical pitting potential. This could be due to a less compact and protective anodic passive film based on the results of electrochemical impedance spectroscopy, Mott–Schottky measurement, and X-ray photoelectron spectroscopy analysis. The growth of such an imperfect passive film could be attributed to a high density of deformation bands and other defects introduced by cold work. Scanning electron microscopy observation of the pitted specimens after polarization tests showed no obvious change in size and density of corrosion pits with increasing cold work level, whereas immersion tests showed varied pit density with cold work although the average size of pits did not increase linearly as a function of cold work level. The effects of cold work on the characteristics of passive films are discussed.