1.  904L, domestic brand00 cr20ni25mo4s. 5 cu. A，merican standard NO8904, vary with different usages.

C content < = 0.02% or 0.03% ,with high content of chromium and enough nickel conten. The

addition of copper makes  it has strong acid resistance, especially highly resistance to

 chloride clearance corrosion and stress corrosion cracking.  2.   Its pitting resistance also

 slightly better with other types of steel,with good machinability and weldability. Application: pressure vessels.    3. This kind of steel developed with the application and development of of all kinds of sulfuric acid corrosion. Steel is gradually popularized on the market at present.

Main features: have high content of chromium and enough nickel content, especially highly resistance to chloride clearance  corrosion and stress corrosion cracking.The pitting corrosion resistance is slightly better with other materials.