Intergranular Corrosion of Stainless Steel and Its Research Methods

Stainless steel, known for its excellent corrosion resistance, is widely used in various fields such as energy, chemical processing, and marine engineering. However, under certain environmental conditions—especially high temperature and high chloride environments—intergranular corrosion (IGC) remains one of the primary causes of stainless steel failure, posing serious safety risks in critical applications. This paper reviews recent advances in the study of IGC in stainless steels. It first introduces classical mechanisms such as the chromium depletion effect, and then discusses newly proposed mechanisms including sigma (σ) phase precipitation and impurity element segregation. Subsequently, the article summarizes detection methods for IGC, with a focus on techniques such as electrochemical potentiokinetic reactivation (EPR) and localized electrochemical methods (SVET/LEIS), which offer improved precision and broader applicability. Finally, strategies for enhancing IGC resistance are discussed, including alloy composition optimization, heat treatment processes, and data-driven service life prediction models. Future research directions include the development of innovative testing technologies and advanced corrosion-resistant stainless steel design to address challenges under complex service conditions.