Chemical composition

Physical properties

904L material properties

Because the carbon content of 904L is very low (0.020% maximum), there will be no carbide precipitation in the case of general heat treatment and welding. This eliminates the risk of intergranular corrosion that normally occurs after heat treatment and welding. Due to the high chromium-nickel-molybdenum content and the addition of copper, 904L can be passivated even in reducing environments such as sulfuric and formic acids. The high nickel content also results in a lower corrosion rate in the active state. In pure sulfuric acid in the concentration range of 0~98%, the operating temperature of 904L can be as high as 40 degrees Celsius. In pure phosphoric acid in the concentration range of 0~85%, its corrosion resistance is very good. In industrial phosphoric acid produced by the wet process, impurities have a strong effect on the corrosion resistance. Of all the various phosphoric acids, 904L is more corrosion resistant than ordinary stainless steel. In strong oxidizing nitric acid, 904L has lower corrosion resistance than highly alloyed steel grades that do not contain molybdenum. In hydrochloric acid, the use of 904L is limited to lower concentrations 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 in chloride solutions is also very good. The high nickel content of 904L reduces the rate of corrosion in pits and crevices. Ordinary austenitic stainless steels may be susceptible to stress corrosion in a chloride-rich environment at temperatures above 60°C, and this sensitization can be reduced by increasing the nickel content of the stainless steel. Due to the high nickel content, 904L is highly resistant to stress corrosion cracking in chloride solutions, concentrated hydroxide solutions and hydrogen sulfide rich environments.

Advantage

1. Exceptional corrosion resistance in a wide range of environments.

2. High resistance to pitting and crevice corrosion.

3. Excellent resistance to chloride-induced stress corrosion cracking.

4. Good weldability and formability for ease of fabrication.

5. Versatile applicability across industries like chemical processing and marine.

6. Excellent toughness and strength properties.

7. Long-term reliability and durability in harsh conditions.

8. Cost-effective solution due to its extended service life and low maintenance requirements.

904L material application areas

1. Petroleum, petrochemical equipment, such as reactors in petrochemical equipment, etc.

2. Storage and transportation equipment for sulfuric acid, such as heat exchangers, etc.

3. The flue gas desulfurization device in power plants is mainly used in: the tower body of the absorption tower, the flue, the shutter, the internal parts, the spray system, etc.

4. Scrubbers and fans in organic acid treatment systems.

5. Seawater treatment devices, seawater heat exchangers, paper industry equipment, sulfuric acid, nitric acid equipment, acid production, pharmaceutical industry and other chemical equipment, pressure vessels, food equipment.

6. Pharmaceutical plants: centrifuges, reactors, etc.

7. Plant food: soy sauce jars, cooking wine, salt jars, equipment and dressings.

8. 904L is the matching steel grade for the strong corrosive medium of dilute sulfuric acid.