Austenitic stainless steel (ASS) is commonly used in supercritical boiler tubing finishing, where intergranular corrosion (IGC) resistance is important. ASS application is restricted to 600 °C due to sensitization-induced IGC failure. Sensitization refers to corrosion resistance failure caused by chromium (Cr) depletion and chromium carbide (Cr23C6) precipitation at grain boundaries. Unstabilized ASS undergoes sensitization when cooled progressively from annealing zone (1100 °C) or re-heated (welding and post-weld heat treatment) in range 400–800 °C. Cr-depleted zone across the grain boundary is reduced and is called recovery from sensitization, healing, desensitization, which can occur for several causes. The progressive cooling of unstabilized ASS allows sufficient time for chromium carbides to form at grain boundaries, leading to chromium depletion and subsequent sensitization. This review article discusses studies on sensitization recovery, healing in ASS and corrosion assessment methodologies. The sensitization and healing examine the impact of factors such as preceding grain size, cold work, martensite, grain orientation, temperature, and time. These factors affect carbon (C) and Cr activities in the ASS, affecting carbide nucleation and growth. Additionally, different destructive and non-destructive sensitization assessment methods have been investigated, recommending practices that accurately quantify Cr segregation and depletion width to discover desensitization. This study highlights the importance of desensitization in improving IGC resistance and recognizing the need for further research to enhance the capabilities of ASS in supercritical boiler technology.