Effect of Chloride and Iodide on the Corrosion Behavior of 13Cr Stainless Steel

The corrosion behavior and mechanism of 13Cr stainless steel in the solution with 1 mol/L NaCl and 5 mmol/L KI were investigated by weight loss method, scanning electrochemical microscopy (SECM), the phase analysis (XRD) of inclusions, and surface analysis technique (SEM and EDS). Results showed that the corrosion rate was a linear relationship with the time and Cl- concentration. The corrosion became serious with the increase in time and Cl- concentration. The corrosion occurred in the unstable electroactive points that contained aluminum oxide and metallic phase inclusions. The generation and disappearance of the electroactive points simultaneously occurred with the corrosion. The active dissolved level on different areas of the surface of 13Cr stainless-steel sample was different. The oxidation current peak of the sample presented the strip shape. The corrosion dissolution was mainly caused by aluminum oxide inclusions (Al2O3) and FeAl phase.