Effect of SO42- on the passive and pitting behavior of 316L austenite stainless steel in a Cl--containing solution

Abstract

The effect of SO42- on the passive and pitting behavior of 316L austenite stainless steel was investigated in a Cl--containing solution using potentiodynamic polarization tests, electrochemical impedance spectroscopy tests, potentiostatic polarization tests, and galvanostatic polarization tests. In addition, scanning electron microscopy was used to observe the pitting morphology. The results show that the increased SO42- concentration increases the passive region of 316L, makes the pitting potential more positive, and decreases the current density, indicating an improved pitting resistance. However, the pitting morphology shows a more complicated trend, and the roughness of the pits increases with the increased SO42- concentration after pitting occurred.

Keywords

• austenite stainless steel
• sulphate ion
• chloride ion
• polarization
• pitting