904L Stainless Steel Sheet

904L stainless steel sheet (Model: 904L, Chemical formula: 00Cr20Ni25Mo4.5Cu) is a low-carbon high-nickel-molybdenum austenitic stainless corrosion-resistant steel, belonging to a copper-containing alloy material. Its carbon content is ≤ 0.020%, and no carbides are precipitated during welding and heat treatment, avoiding the risk of intergranular corrosion. This steel has good resistance to pitting and crevice corrosion in non-oxidizing acids (such as sulfuric acid and acetic acid) and media containing chloride ions, and can be used in a 70°C environment with all concentrations of sulfuric acid. However, its corrosion resistance to nitric acid and high-concentration hydrochloric acid is relatively weak.

904L stainless steel sheet, with its high chromium-nickel-molybdenum content and copper element addition, can still achieve passivation in reducing environments. The usage temperature in 0-98% sulfuric acid can reach 40°C. Its completely austenitic microstructure is insensitive to the precipitation of ferrite and α phase. This material is widely used in petroleum and petrochemical equipment reactors, sulfuric acid storage and transportation heat exchangers, and power plant flue gas desulfurization systems, and can also be used as the material for washing equipment in organic acid treatment systems. 904L stainless steel sheet is also applied in high-tech fields such as aviation and chemical industry.

The corrosion resistance of 904L stainless steel: Due to the very low carbon content (maximum 0.020%) of 904L, no carbides will be precipitated during general heat treatment and welding. This eliminates the risk of intergranular corrosion that usually occurs after heat treatment and welding. Due to the high chromium, nickel, and molybdenum content, and the addition of copper, 904L can be passivated even in reducing environments such as sulfuric acid and formic acid. The high nickel content makes it have a lower corrosion rate even in an active state. In a 0-98% concentration range of pure sulfuric acid, the operating temperature of 904L can reach up to 40 degrees Celsius. In a 0-85% concentration range of pure phosphoric acid, its corrosion resistance is very good. In industrial phosphoric acid produced by wet process, impurities have a strong influence on corrosion resistance. Among all kinds of phosphoric acid, 904L has better corrosion resistance than ordinary stainless steel. In strong oxidizing nitric acid, 904L has lower corrosion resistance compared to steel types with high alloying without molybdenum. In hydrochloric acid, the use of 904L is limited to a lower concentration of 1-2%. In this concentration range, the corrosion resistance of 904L is better than that of conventional stainless steel. 904L steel has high resistance to pitting corrosion. Its resistance to crevice corrosion is also very good in chloride solution. The high nickel content of 904L reduces the corrosion rate at cracks and crevices. Ordinary austenitic stainless steel is sensitive to stress corrosion at temperatures above 60 degrees Celsius in an environment rich in chloride when the nickel content of the stainless steel is increased, this sensitization can be reduced. Due to the high nickel content, 904L has high resistance to stress corrosion cracking in chloride solution, concentrated hydroxide solution, and sulfuric acid-rich environments.