904L

904L (UNS N08904) is a super austenitic stainless steel with high nickel, chromium, molybdenum, and copper content. It is renowned for exceptional corrosion resistance (especially to strong acids and chloride-containing media), good high-temperature stability, and excellent mechanical properties. It maintains structural integrity during long-term service in harsh corrosive and high-temperature environments (up to 1000 °C), making it a premium material for critical applications requiring superior corrosion resistance..

Behaviour that matters in service

• Superior Corrosion Resistance — Excels in resisting corrosion from strong acids (e.g., sulfuric acid, phosphoric acid, acetic acid), chloride-containing media (e.g., seawater, brine), and organic acids. It effectively prevents pitting, crevice corrosion, and intergranular corrosion, even in high-concentration and high-temperature corrosive environments..
• High-Temperature Stability — Maintains good oxidation resistance at temperatures up to 1000 °C; forms a dense, adherent oxide film on the surface to resist high-temperature gas erosion and thermal cycling spalling..
• Mechanical Strength — Possesses high tensile strength, yield strength, and toughness at both room and elevated temperatures. It exhibits minimal creep deformation during long-term high-temperature service, ensuring reliable structural performance of components..
• Excellent Formability — Can be easily processed via cold working (e.g., rolling, stamping, bending) and hot working (e.g., forging, extrusion). It adapts well to complex shape forming without cracking or material degradation, suitable for customized product manufacturing..
• Good Weldability — Compatible with standard welding methods (e.g., TIG welding, MIG welding). Welded joints retain excellent corrosion resistance and mechanical properties, with no significant performance gap compared to the base material, supporting the fabrication of large-scale equipment.

Typical applications

• Chemical & Petrochemical Industry — Widely used in equipment handling strong corrosive media, such as sulfuric acid production reactors, phosphoric acid concentration tanks, chemical pipelines, and heat exchangers. It is also suitable for offshore oil and gas platforms (resisting seawater and corrosive hydrocarbons)..
• Seawater Desalination Industry — Applied to key components of desalination plants, including reverse osmosis membranes, pressure vessels, and seawater pipelines, due to its exceptional resistance to chloride corrosion..
• Pharmaceutical & Food Industry — Used in pharmaceutical reaction kettles, sterile pipelines, and food processing equipment (e.g., acid pickling tanks, beverage production lines). Its high purity and corrosion resistance meet strict hygiene standards..
• Power Generation Industry — Employed in flue gas desulfurization (FGD) systems of thermal power plants, waste incineration power generation equipment, and nuclear power plant auxiliary systems, resisting corrosive flue gas and chemical additives..
• Other Fields — Used in high-corrosion environments such as pulp and paper industry (digesters, bleaching equipment), mining industry (acid leaching tanks), and aerospace industry (corrosion-resistant structural parts). It is also an ideal material for high-purity water treatment systems and chemical storage tanks.