904L (N08904) Austenitic Stainless Steel Plate & Coil
904L (N08904) Austenitic Stainless Steel Plate & Coil - Complete Material Guide
In-depth material properties of 904L (UNS N08904) stainless steel plate/coil, featuring chemical composition, mechanical/physical performance, equivalent grades, and application guidance.
Hot rolling, cold rolling, forming, welding, machining
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904L Austenitic Stainless Steel Plate & Coil Introduction
904L (UNS N08904, EN 1.4539) is a high-alloy, low-carbon austenitic stainless steel specifically developed for outstanding resistance to reducing acids such as sulfuric, phosphoric, and acetic acids. The addition of copper (1.0–2.0%) enhances resistance to strong reducing environments, while high nickel (23–28%) and molybdenum (4.0–5.0%) contents provide excellent resistance to chloride-induced pitting and crevice corrosion. Key features:
- Superior corrosion resistance in severe acid environments
- Very low carbon content minimizes intergranular corrosion after welding
- Good formability and weldability
- Non-magnetic in annealed condition
- Excellent performance in chemical processing, pollution control, and seawater applications
It is typically supplied as plate, sheet, coil, or strip in solution-annealed and descaled condition.
904L Austenitic Stainless Steel Plate & Coil Chemical Composition
The nominal chemical composition according to ASTM A240/A240M for UNS N08904. All values represent maximum unless a range is specified. The high nickel, chromium, molybdenum, and deliberate copper addition define the alloy?s unique corrosion resistance in reducing acid media.
| Element | Standard Value | Remarks |
|---|---|---|
| Carbon (C) | ≤ 0.020 | Low carbon prevents sensitization |
| Manganese (Mn) | ≤ 2.00 | Austenite stabilizer |
| Phosphorus (P) | ≤ 0.045 | Impurity |
| Sulfur (S) | ≤ 0.035 | Impurity |
| Silicon (Si) | ≤ 1.00 | Deoxidizer |
| Chromium (Cr) | 19.0 - 23.0 | Key for corrosion resistance |
| Nickel (Ni) | 23.0 - 28.0 | Austenite phase former |
| Molybdenum (Mo) | 4.0 - 5.0 | Enhances pitting resistance |
| Copper (Cu) | 1.0 - 2.0 | Improves resistance to reducing acids |
| Nitrogen (N) | ≤ 0.10 | May be present as residual |
904L Austenitic Stainless Steel Plate & Coil Physical Properties
Typical physical data for 904L in annealed condition. These values represent nominal behavior and are suitable for engineering calculations. Thermal properties are temperature-dependent; representative values at 20°C and 100°C are provided where applicable.
| Property | Typical Value | Unit | Test Condition / Temperature |
|---|---|---|---|
| Density (ρ) | 7.95 | g/cm³ | 20°C |
| Elastic Modulus (E) | 195 | GPa | 20°C |
| Shear Modulus (G) | 75 | GPa | 20°C (calculated from E and ν) |
| Poisson's Ratio (ν) | 0.29 | - | 20°C |
| Thermal Expansion (α) | 14.9 | 10⁻⁶ /°C | 20–100°C |
| Thermal Expansion (α) | 16.0 | 10⁻⁶ /°C | 20–300°C |
| Thermal Conductivity (λ) | 12.0 | W/m·K | 20°C |
| Thermal Conductivity (λ) | 14.0 | W/m·K | 100°C |
| Specific Heat Capacity | 460 | J/kg·K | 20°C |
| Electrical Resistivity (ρ_e) | 0.85 | Ω·mm²/m | 20°C |
| Melting Range | 1300–1390 | °C | Approximate |
904L Austenitic Stainless Steel Plate & Coil Mechanical Properties
Tensile properties per ASTM A240/A240M for plate, sheet, and strip in solution-annealed condition. No hardness or impact requirements are imposed by the standard, but typical annealed hardness is ≤ RB 95 (HBW 215). The alloy exhibits excellent ductility and toughness.
| Property | Specified Minimum Value | Unit | Test Condition |
|---|---|---|---|
| Tensile Strength (Rm) | 490 | MPa | Room temperature, longitudinal or transverse |
| Yield Strength (Rp0.2 / ReH) | 220 | MPa | Room temperature, 0.2% offset |
| Elongation (A) | 35 | % | 50 mm (2 in.) gauge length |
| Hardness (typ.) | ≤ 90 HRB (≤ 200 HBW) | - | Typical annealed condition, for reference only |
904L Austenitic Stainless Steel Plate & Coil Completely Equivalent Material Standards & Substitutable Grades
| Country/Region | Standard | Designation/Grade | Remarks |
|---|---|---|---|
| Europe | EN 10088-2 / EN 10028-7 | X1NiCrMoCu25-20-5 (1.4539) | Chemically identical, same application fields |
| International | ISO 15510 | X1NiCrMoCu25-20-5 | Equivalent to EN grade |
| USA | ASTM A240/A240M | UNS N08904 (904L) | Original specification for plate/sheet/coil |
| Japan | JIS G4304 / G4305 | SUS 890L | Japanese equivalent, minor compositional tolerance differences |
| China | GB/T 3280 / GB/T 4237 | 00Cr20Ni25Mo4.5Cu (S39042 equivalent) | Domestic 904L grade, conforms to UNS N08904 |
904L Austenitic Stainless Steel Plate & Coil Application Introduction
904L is the material of choice when standard stainless steels like 316L or 317L fail due to corrosion in reducing acid environments. Its copper addition grants exceptional resistance to sulfuric, phosphoric, and acetic acids across a wide range of concentrations and temperatures. It also performs well in chloride-bearing solutions, though superduplex or 6% Mo stainless steels may be preferred for extreme chloride pitting resistance. Typical industries and products include:
Product Applications: Sulfuric acid storage tanks and tanker vessels, Heat exchangers and condensers in acid plants, Reactor vessels and agitators for chemical reactors, Scrubber systems for power plant emissions control, Piping systems for corrosive chemical transfer, Pharmaceutical reaction equipment (clean, crevice-free designs), Bleach washers and digesters in pulp mills, Plate-type heat exchangers for cooling aggressive media
Processed into products: Welded pressure vessel shells and heads (fabricated from plate), Tube sheets and baffles for shell-and-tube heat exchangers, Flanges, gaskets, and fasteners requiring high corrosion resistance, Pump casings, valve bodies, and impellers (cast or wrought), Process piping spools and elbows (from plate/coil), Tank linings and clad plate applications, Compensators and expansion joints in acidic gas ducts, Semiconductor wet bench components
Application industries: Chemical processing, Petrochemical & oil refining, Pharmaceutical manufacturing, Pollution control (flue gas desulfurization), Pulp & paper bleaching equipment, Seawater and brine handling, Food and beverage (high-acid processes), Fertilizer production
904L Austenitic Stainless Steel Plate & Coil Similar / Alternative Materials with Proximate Performance
| Country/Region | Standard | Designation/Grade | Remarks |
|---|---|---|---|
| USA | ASTM A240 | UNS S31603 (316L) | Lower Mo (2.0-3.0%), no Cu; less resistant to reducing acids and chloride pitting; cost-effective alternative for mild environments |
| USA | ASTM A240 | UNS S31703 (317L) | Mo 3.0-4.0%, no Cu; improved pitting resistance over 316L but inferior to 904L in sulfuric acid |
| USA | ASTM A240 | UNS S31254 (254 SMO) | Higher Mo (6.0-6.5%) and N; very high pitting resistance; often used instead of 904L in chloride-rich media |
| Europe | EN 10088-2 | 1.4438 (X2CrNiMo18-15-4 / 317L) | Similar Ni and Cr, but lacks Cu and has lower Mo; limited use in strong reducing acids |
| USA | ASTM A240 | UNS N08367 (AL-6XN) | High Mo (6.0-7.0%) and N, no Cu; superior to 904L in seawater but may be over-alloyed for sulfuric acid |
Notes:
Welding: 904L can be welded using common processes (GTAW, GMAW, SMAW, SAW) with matching filler metal (e.g., ER 385, EN 1.4456). Low heat input and interpass temperature below 100°C are recommended to avoid hot cracking. Post-weld heat treatment is typically not required for corrosion resistance, but solution annealing restores full properties. Forming: Excellent cold formability; heavy bending or deep drawing may require intermediate annealing. Machining: Work-hardens rapidly; requires sharp tools, adequate lubrication, and slower speeds compared to carbon steels. Availability: Commonly stocked as plate and coil in thicknesses from 0.5 mm up to 50 mm; wider dimensions and custom lengths on request.
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