UNS N08904 also known as 904L falls in the austenitic stainless steel group. It has high molybdenum and extremely low carbon content. Copper content in the alloy greatly improves resistance to strong reducing acids, especially (H2SO4) sulphuric acid. 904L has better resistance. Ti chloride attack against both stress corrosion cracking and crevice / pitting corrosion.

With excellent weldability and formability 904L also maintain non-magnetic state in all conditions. 904L provides excellent toughness, even down to cryogenic temperatures with its austenitic structure.