Available Shapes
904L Stainless Steel
Alloy 904L (UNS N08904) is a super austenitic stainless steel is designed for moderate to high corrosion resistance in a wide range of process environments. The combination of high chromium and nickel content, coupled with additions of molybdenum and copper, assure good to excellent corrosion resistance. With its highly alloyed chemistry—25% nickel and 4.5% molybdenum, 904L provides good chloride stress corrosion cracking resistance, pitting, and general corrosion resistance superior to 316L and 317L molybdenum enhanced stainless steels. Alloy 904L was originally developed to withstand environments containing dilute sulfuric acid. It also offers good resistance to other inorganic acids such as hot phosphoric acid as well as most organic acids. This Grade is better than 316 stainless in many environments.
Related Specifications
1.4539 BS EN 10088 1 3 EN 10272 NACE MR0175
UNS ASTM A182 UNS ASME SB649 N08904 AISI 904
Applications
Analysis
Corrosion Resistance
Welding
Typical Mechanical Properties
Applications
Air Pollution Control— scrubbers for coal-fired power plants
Chemical Processing—process equipment for the production of sulfuric, phosphoric, inorganic and organic acids and the production of phosphate-based fertilizers
Metallurgical Processing— pickling equipment using sulfuric acid
Oil and Gas Production— offshore process equipment
Pharmaceutical Industry— process equipment
Pulp and Paper—processing equipment
Seawater and Brackish Water— condensers, heat exchangers and piping systems
Analysis
| Carbon | 0.02% max | Chromium | 19.00-23.00% |
| Manganese | 2.00% max | Nickel | 23.00-28.00% |
| Silicon | 1.00% max | Molybdenum | 4.00-5.00% |
| Phosphorous | 0.045% max | Copper | 1.00-2.00% |
| Sulphur | 0.035% max |
Corrosion Resistance
The high content of alloying elements in 904L gives the alloy exceptionally good resistance to uniform corrosion. 904L was originally developed to withstand environments containing dilute sulfuric acid, and is one of the few stainless steels that, at temperatures up to 95°F (35°C), provides full resistance in such environments within the entire concentration range of 0 to 100%. 904L also offers good resistance to a number of other inorganic acids, such as phosphoric acid and most organic acids. However, acids and acid solutions containing halide ions can be very aggressive, and the corrosion resistance of 317L, 317LMN and 904L may be insufficient.
Welding
Alloy 904L is easily welded and processed by standard shop fabrication practices
Typical Mechanical Properties
| Temp °C | Density Kg/m³ | Mean Coefficient of Thermal Expansion | Modulus of Elasticity kg/mm | Electrical Resistivity Ωmm²/m | Specific Heat J/kg ºC |
|---|---|---|---|---|---|
| 20 | 8.0 | 16.1×10-6 | 19500 | 0.85 | 500 |
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