Effect of Heat Treatment Variation on Grain Boundary Corrosion of Austenitic Stainless Steel

Abstract

Austenitic stainless steel is valued for its exceptional corrosion resistance and mechanical properties, making it versatile in applications like offshore installations, medical devices, and chemical tanks. However, it faces challenges in strong acid and vapor environments, and is susceptible to chloride-induced stress corrosion cracking and intergranular corrosion due to chromium carbides at grain boundaries. Enhancements such as adding nickel and plasma nitriding treatments improve its utility but do not fully resolve these issues. By applying treatments at 1000 °C for 1 hour, followed by cooling at 450 °C for 2 hours and ice water quenching, the research seeks to find optimal parameters. The study involves hardness tests, microstructure analysis, SEM-EDS testing, and corrosion rate measurements to improve the material's durability in corrosive environments. As the duration of exposure of SS304 and SS316 stainless steels to their sensitization temperatures (500-900 ℃ and 450-900 ℃, respectively) increases, there is a greater formation of chromium carbides (Cr2O3) along the boundaries between the grains.