The critical temperature range where carbide precipitation occurs in austenitic stainless steels is between which temperatures?

The critical temperature range where carbide precipitation occurs in austenitic stainless steels is between which temperatures?

• A. 800-1500 F
• B. 500-900 F
• C. 1500-2000 F
• D. 100-400 F

Answer: (A)

Carbide precipitation in austenitic stainless steels happens when the metal is held at temperatures where chromium and carbon can diffuse enough to form chromium carbides at grain boundaries. The most relevant window for this precipitation is about 800–1500 °F (roughly 427–816 °C). In this range, chromium carbide Cr23C6 forms along grain boundaries, which removes chromium from adjacent areas and makes the steel susceptible to intergranular corrosion (sensitization). If you go below this range, diffusion is too slow for significant carbide formation; if you go above it, carbides can dissolve or other transformations occur, reducing the tendency to precipitate. So this temperature window correctly identifies where carbide precipitation is most active.