Alloy 904L was originally developed to resist environments containing dilute sulfuric acid. It also has good resistance to other inorganic acids such as hot phosphoric acid as well as most organic acids.
Due to its highly alloyed chemical composition – 25% nickel and 4.5% molybdenum – 904L has good resistance to chloride stress corrosion cracking, pitting and general corrosion resistance, superior to 316L and 317L molybdenum-reinforced stainless steels.
Alloy 904L can be easily welded and machined by standard shop fabrication methods.
Alloy 904L (UNS N08904) is a super austenitic stainless steel designed for moderate to high corrosion resistance in a wide range of process environments. The combination of high chromium and nickel content, along with the addition of molybdenum and copper, ensures good to excellent corrosion resistance.