321h Stainless Steel Sheet & Plate

321H stainless steel, identified as UNS S32109 and EN 1.4878, is a high-carbon variant of Type 321 stainless steel. It is a stabilized austenitic stainless steel alloy primarily used in applications requiring enhanced strength at elevated temperatures. The addition of titanium as a stabilizing element provides excellent resistance to intergranular corrosion, especially after exposure to temperatures in the carbide precipitation range (425–850°C or 800–1560°F).

The “H” in 321H denotes a higher carbon content (0.04–0.10%), which improves its strength at high temperatures. This makes it particularly suitable for pressure vessels, heat exchangers, and piping systems operating in extreme thermal environments. The alloy also offers good oxidation resistance up to approximately 900°C (1650°F), enabling its use in environments involving repeated thermal cycling.

In sheet and plate forms, 321H is widely employed in industries such as petrochemical, aerospace, and power generation. It is often used for making furnace components, exhaust manifolds, and other structural parts requiring both strength and resistance to corrosion at high temperatures.