321 Stainless Steel Composition & Stabilized Welding Properties

321 is a titanium stabilized austenitic stainless steel specified in ASTM A240 and GB/T 4237, containing approximately 17–19% chromium, 9–12% nickel, and a controlled titanium addition of five times the carbon content. The titanium binds carbon as stable carbides, preventing chromium carbide precipitation at grain boundaries.

This stabilization gives the grade reliable intergranular corrosion resistance in the as-welded condition, eliminating the need for post-weld solution annealing in most applications. It is commonly used in welded pressure equipment, aircraft exhaust components, expansion joints, and furnace parts exposed to repeated temperature cycles.

321 is available as plates, coils, strips, and tubes. It is widely used in chemical processing, aviation systems, power generation, and industrial heating equipment operating from 400 to 800 °C.