904L [1] super austenitic stainless steel case of low-carbon high nickel, molybdenum austenitic stainless acid-resistant steel, for the introduction of the French H • S's proprietary material. Has a good active - passive transition ability excellent corrosion resistance, has good corrosion resistance in a non-oxidizing acid such as sulfuric acid, acetic acid, formic acid, phosphoric acid, and chlorine ions having a neutral medium good the pitting resistance, but also has good resistance to crevice corrosion and stress corrosion resistance. Applicable to various concentrations of acid below 70 ℃ resistant any concentration at atmospheric pressure and at any temperature in acetic acid with acetic acid in the mixed acid is also very good corrosion resistance.