904L Description
904L (N08904,14539) super austenitic stainless steel contains 14.0-18.0% chromium, 24.0-26.0% nickel, 4.5% molybdenum. 904L super austenitic stainless steel is a low carbon, high nickel, molybdenum austenitic stainless steel, which is a special material introduced from H·S Company in France. It has good activation-passivation transformation ability and excellent corrosion resistance. It has good corrosion resistance in non-oxidizing acids such as sulfuric acid, acetic acid, formic acid and phosphoric acid. It has good pitting resistance in neutral medium containing chloride ions, and has good crevice corrosion resistance and stress corrosion resistance. It is suitable for various concentrations of sulfuric acid below 70℃. It is resistant to acetic acid at any concentration and at any temperature under atmospheric pressure, and the corrosion resistance of mixed acid of formic acid and acetic acid is also very good.
904L Chemical compositon:
Alloy | % | Ni | Cr | Mo | Cu | Fe | C | Mn | Si | P | S |
904L | Min. | 23 | 19 | 4 | 1 | Balance | |||||
Max. | 28 | 23 | 5 | 2 | 0.02 | 2 | 1 | 0.045 | 0.035 |
904L Physical properties:
Density | 8.0 g/cm3 |
Melting point | 1300-1390 ℃ |
904L Alloy minimum mechanical properties in the room temperature:
Status | Tensile strength Rm N/mm2 | Yield strength RP0.2N/mm2 | Elongation A5 % |
904L | 490 | 216 | 35 |
Alloy | % | Ni | Cr | Mo | Cu | Fe | C | Mn | Si | P | S |
904L | Min. | 23 | 19 | 4 | 1 | Balance | |||||
Max. | 28 | 23 | 5 | 2 | 0.02 | 2 | 1 | 0.045 | 0.035 |
904L Physical properties:
Density | 8.0 g/cm3 |
Melting point | 1300-1390 ℃ |
904L Alloy minimum mechanical properties in the room temperature:
Status | Tensile strength Rm N/mm2 | Yield strength RP0.2N/mm2 | Elongation A5 % |
904L | 490 | 216 | 35 |
Characteristic：
904L is a fully austenitic organizations, 904L of ferrite and the precipitation of α phase insensitive compared to the general molybdenum high austenitic stainless steel.
Corrosion resistance
In general welding and heat treatment, there will not be carbide precipitation because of the carbon content is very low (0.020% maximum).
This eliminates the intergranular corrosion after the welding and heat treatment. Due to high nickel chromium molybdenum content, and copper element, so even if the 904L in reducing environments, such as in sulfuric acid and formic acid can be deactivationcan be deactivation.
High nickel content also has a lower corrosion rate in the activity state. In the range of 0 ~ 98% concentration pure sulfuric acid , the use of temperature can be as high as 40℃. In the range of 0 ~ 85% concentration pure sulfuric acid, its corrosion resistance is very good. In the industrial phosphoric acid production of Wet method,the impurities are strongly influence of corrosion.
Ordinary austenitic stainless steel in the temperature higher than 60 ℃, maybe sensitive of the stress corrosion resistance in a rich chloride environment, by increasing the nickel content in stainless steel, can reduce this sensitivity. Due to the high content of nickel, 904L with high stress corrosion cracking capacity in chloride solution, the concentration hydroxid solution and rich sulfureted hydrogen environment.
Applied field：Alloy is a multi-purpose material can be applied in many industrial :
1. Petroleum, petrochemical equipment, such as the reactor in petrochemical equipment.
2. Sulfuric acid storage and transportation equipment, such as heat exchanger.
3. Power plant flue gas desulphurization equipment, the main parts: the absorption tower, flue , stopping plate, internal part, spray system.
4. The scrubber and the fans in the organic acid treatment system.
