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Sensitization
A metallurgical condition where chromium carbides precipitate at grain boundaries when stainless steel is exposed to temperatures between 450-850C, making it susceptible to intergranular corrosion.
Sensitization in Stainless Steel
When austenitic stainless steel is held in the 450-850C range (during welding, heat treatment, or service), carbon combines with chromium to form chromium carbides (Cr23C6) at grain boundaries. This depletes chromium in adjacent zones below the 12% needed for corrosion protection.
Prevention
- Use L-grades (304L, 316L) with carbon < 0.03%
- Use stabilized grades (321, 347)
- Post-weld solution annealing
- Minimize time in sensitization range