JIS G4304 / G4312 SUS 309 Stainless Steel Composition & High‑Temperature Austenitic Properties
SUS 309 is a heat‑resistant austenitic stainless steel defined in JIS G4304 / G4312. With 22–24% chromium and 12–15% nickel, it offers significantly better oxidation resistance than SUS 304 and is suitable for long‑term service at 900–1000°C.
309 performs reliably in oxidizing atmospheres, thermal cycling, and mildly sulfur‑containing environments. It is widely used in industrial furnaces, heating equipment, heat‑treatment fixtures, insulation structures, and high‑temperature transfer components. SUS 309 is supplied as sheets, plates, tubes, bars, and strips. It is a preferred material for petrochemical plants, thermal‑processing equipment, and high‑temperature structural applications.
309 performs reliably in oxidizing atmospheres, thermal cycling, and mildly sulfur‑containing environments. It is widely used in industrial furnaces, heating equipment, heat‑treatment fixtures, insulation structures, and high‑temperature transfer components. SUS 309 is supplied as sheets, plates, tubes, bars, and strips. It is a preferred material for petrochemical plants, thermal‑processing equipment, and high‑temperature structural applications.