904L (N08904, 14539) belongs to super austenitic stainless steel containing 14.0-18.0% chromium, 24.0-26.0% nickel and 4.5% molybdenum. It belongs to low carbon, high nickel and molybdenum austenitic stainless and acid-resistant steel.Iwh a good activation-passivation transformation ability and excellent corrosion resistance.

Super austenitic stainless steel 904L
(00Cr20Ni25Mo4.5Cu; UNS: N08904; EN: 1.4539) is a kind of high alloy austenitic stainless steel with low carbon content. It has good corrosion resistance in dilute sulfuric acid and is specially designed for severe corrosion conditions. It has high chromium content and enough nickel content. The addition of copper makes it have strong acid resistance.
Especially, it has high resistance to chloride interstitial corrosion and stress corrosion cracking. It is not easy to appear corrosion spots and cracks. Its pitting resistance is slightly better than other steels. It has good machinability and weldability and can be used in pressure vessels.
Weldability :
Like stainless steel, 904L can be welded by various welding methods. The most commonly used welding method is manual arc welding or inert gas shielded welding. Electrode or wire metal is based on the composition of base metal and has higher purity, and the requirement of molybdenum content is higher than that of base metal. Preheating is generally not necessary before welding, but in cold outdoor operation, in order to avoid condensation of water vapor, the joint or adjacent area can be heated uniformly. Attention should be paid to the local temperature not exceeding 100 in order to avoid carbon accumulation and intergranular corrosion. Small linear energy, continuous and fast welding speed should be adopted in welding. There is no need for heat treatment after welding. If heat treatment is needed, it must be heated to 1100-1150 C and then cooled rapidly.
Machinability :
The machining characteristics of 904L are similar to those of other austenitic stainless steels, and there is a tendency of sticking knife and hardening during the processing. Carbide cutter with positive front corner should be used, sulfide and chlorinated oil should be used as cutting coolant, and equipment and technology should be based on reducing work hardening. Slow cutting speed and feed rate should be avoided in cutting process .

Chemical composition and Mechanical property

Available for  904L  grade