Properties of Super Austenitic Stainless Steel (904l)

Process Performance

Super austenitic stainless steel (904l) exhibits excellent cold and hot working properties similar to other Cr-Ni austenitic steels.

Hot Forging: The maximum heating temperature is 1180°C, and the minimum forging stop temperature is 900°C.
Hot Forming: This steel can be hot-formed at temperatures between 1000°C and 1150°C.
Heat Treatment: The heat treatment process involves heating the steel to 1100-1150°C, followed by rapid cooling.

While general welding techniques can be used, manual arc welding and tungsten arc welding are preferred.

Manual Arc Welding: For plates up to 6mm thick, use an electrode diameter no greater than 2.5mm. For plates thicker than 6mm, use an electrode diameter of less than 3.2mm. Post-welding heat treatment involves heating at 1075-1125°C and then cooling quickly.
Tungsten Arc Welding: Use filler metal of the same material as the electrode. The weld must be pickled and passivated after welding.

The 00Cr20Ni25Mo4.5Cu steel is primarily developed to resist sulfuric acid corrosion and shows excellent resistance to other acids as well.

Acid Resistance: It resists corrosion by acetic acid at any concentration and temperature under normal pressure. It also performs well in formic acid, phosphoric acid, and mixed acids of formic and acetic acids.
Intergranular Corrosion: Tested using the T method in GB1223-75, the steel containing 0.038% carbon requires more than 1 hour of sensitization to show intergranular corrosion. With proper welding processes, components up to 30mm thick can be welded without risking intergranular corrosion.
Pitting Corrosion: Pitting corrosion potential and tests show that 00Cr20Ni25Mo4.5Cu outperforms lower-grade Cr-Ni austenitic steels like 00Cr18Ni10 and 00Cr18Ni14Mo2.
Stress Corrosion: With 25% nickel content, 00Cr20Ni25Mo4.5Cu offers better stress corrosion resistance compared to general Cr-Ni austenitic steels. In chloride ion-containing water media, where 18-8 and 18-12-Mo stainless steels may suffer stress corrosion cracking, 00Cr20Ni25Mo4.5Cu can prevent such failures.