A detailed electrochemical analysis of sensitized AISI 410 martensitic stainless steel

Abstract

In the present work, the effect of sensitization heat treatment on the intergranular corrosion (IGC) behavior of AISI 410 martensitic stainless steel was investigated using potentiodynamic electrochemical impedance spectroscopy (PDEIS) in conjunction with conventional methods including acid etching test, anodic potentiodynamic polarization, double-loop electrochemical potentiodynamic reactivation (DLEPR) and electrochemical noise (EN). Microstructural studies by scanning electron microscopy revealed that increasing tempering time up to 2h would be followed by more severe localized attack, but desensitization state attributed to specimens undergone prolonged tempering cannot be interpreted based on the standard test method. Susceptibility to IGC via DLEPR experiments indicates differences in the degree of sensitization (DOS) of specimens with varying tempering time, revealing a healing effect arising from prolonged tempering. The EN results elucidated the alloy tendency for active dissolution, but no obvious correlation can be established between the EN results and IGC behavior. The PDEIS data clarified that the charge transfer resistance values related to the AC responses in the middle of transpassive potential region can be utilized to investigate and compare the IGC susceptibility of the alloy. Moreover, the surface morphology of corroded samples under such experimental conditions can be used to qualitatively compare the severity of intergranular attack.

Keywords

• Stainless steel
• Tempering heat treatment
• Intergranular corrosion
• EIS
• Polarization
• Electrochemical Noise