What is the term used to describe the loss of corrosion resistance due to the formation of carbides at grain boundaries in certain stainless steels?

The term that describes the loss of corrosion resistance due to the formation of carbides at grain boundaries in certain stainless steels is sensitization. This phenomenon typically occurs in austenitic stainless steels when they are exposed to temperatures between about 800°F (427°C) and 1500°F (816°C). In this temperature range, chromium carbide can form at the grain boundaries, which depletes the surrounding areas of chromium, a key element that contributes to corrosion resistance. As a result, the affected areas become more susceptible to corrosion and localized attack, such as intergranular corrosion.

Understanding sensitization is crucial for welders and metallurgists working with stainless steels, as it impacts the material's performance and lifespan in corrosive environments. Proper heat treatment and control during welding processes can help mitigate sensitization, ensuring the integrity of the stainless steel material is maintained.