Stainless Steel 904L
SS 904L is a high-alloy austenitic stainless steel with low carbon content. The grade is intended for use under severe corrosive conditions. It has been application proved over many years and was originally developed to resist corrosion in dilute sulphuric acid. It is standardized and approved for pressure vessel use in several countries. Structurally, 904L is fully austenitic and is less sensitive to precipitation ferrite and sigma phases than conventional austenitic grades with high molybdenum content.
Characteristically, due to the combination of relatively high contents of chromium, nickel, molybdenum and copper 904L has good resistance to general corrosion, particularly in sulphuric and phosphoric conditions.
SS904L has good resistance to pitting and crevice corrosion and very good resistance to stress corrosion cracking. This can be used for a maximum service temperatures of 450 deg.C.
SS904L fabricated equipment are mostly used in production and transport of sulphuric acid, metal pickling in sulphuric acid, production and concentration of phosphoric acid. This can also be used in seawater, brackish water, condensers, heat exchangers and pipe work in paper and allied industries.