ASTM A240 904L Stainless Steel Composition & Super‑Austenitic Corrosion Resistance
ASTM A240 904L (UNS N08904) is a super‑austenitic stainless steel grade under ASTM standards. With 19–23% chromium, 23–28% nickel, 4–5% molybdenum, and added copper, it provides exceptional corrosion resistance in highly aggressive environments such as sulfuric acid, phosphoric acid, chlorides, and seawater.
904L offers superior resistance to pitting, crevice corrosion, and stress‑corrosion cracking compared with 316L and 317L. It is widely used in chemical reactors, pickling systems, marine engineering, pharmaceutical installations, and premium architectural structures. Weldability is good, though strict process control is recommended. 904L is supplied as sheets, plates, tubes, bars, and strips. As a high‑nickel, high‑molybdenum super‑austenitic alloy, it provides reliable performance where conventional stainless steels cannot meet corrosion requirements.
904L offers superior resistance to pitting, crevice corrosion, and stress‑corrosion cracking compared with 316L and 317L. It is widely used in chemical reactors, pickling systems, marine engineering, pharmaceutical installations, and premium architectural structures. Weldability is good, though strict process control is recommended. 904L is supplied as sheets, plates, tubes, bars, and strips. As a high‑nickel, high‑molybdenum super‑austenitic alloy, it provides reliable performance where conventional stainless steels cannot meet corrosion requirements.