ASTM A240 904L Stainless Steel Plate | UNS N08904
We supply ASTM A240 904L stainless steel plates for chemical processing, sulfuric acid service, petrochemical equipment, flue-gas cleaning, desalination and other severe corrosive environments.
904L / UNS N08904 / EN 1.4539 is a high-alloy, low-carbon austenitic stainless steel containing high levels of nickel and molybdenum together with copper. This alloy combination provides significantly improved resistance to many aggressive chemical environments compared with conventional 316L stainless steel.
Hot-rolled and cold-rolled 904L plates are available in standard and customized dimensions with EN 10204 3.1 material certification and project-specific inspection.
ASTM A240 904L Stainless Steel Plate
ASTM A240/A240M covers stainless steel plate, sheet and strip for pressure vessels and general applications.
Our typical 904L plate supply range includes:
| Product | Typical Supply |
|---|---|
| Standard | ASTM A240 / A240M |
| Grade | 904L |
| UNS | N08904 |
| EN / W.Nr. | 1.4539 |
| Microstructure | Austenitic |
| Thickness | 2–60 mm |
| Width | Up to 2000 mm / Customized |
| Length | Up to 6000 mm / Customized |
| Condition | Hot Rolled / Cold Rolled |
| Surface | No.1 / 2B / Special Finish |
| Certification | EN 10204 3.1 MTC available |
Special dimensions, cut-to-size plates and project-specific tolerances can be supplied according to purchase specifications.
What Is 904L Stainless Steel?
904L is a high-nickel, high-molybdenum, copper-alloyed austenitic stainless steel originally developed for demanding sulfuric acid environments.
Compared with standard 316L, 904L contains substantially higher levels of nickel and molybdenum, together with approximately 1–2% copper.
Key characteristics include:
- High resistance to general corrosion
- Excellent performance in many sulfuric acid environments
- Improved resistance to pitting and crevice corrosion
- Good resistance to chloride stress-corrosion cracking compared with conventional austenitic grades
- Low-carbon chemistry
- Good weldability and fabrication performance
- Fully austenitic microstructure
The actual corrosion performance must always be evaluated according to acid concentration, temperature, contaminants and operating conditions.
ASTM A240 904L Chemical Composition
Typical ASTM A240 composition limits for 904L / UNS N08904 are:
| Element | Composition, wt.% |
|---|---|
| Carbon (C) | 0.020 max |
| Manganese (Mn) | 2.00 max |
| Silicon (Si) | 1.00 max |
| Phosphorus (P) | 0.045 max |
| Sulfur (S) | 0.035 max |
| Chromium (Cr) | 19.0–23.0 |
| Nickel (Ni) | 23.0–28.0 |
| Molybdenum (Mo) | 4.0–5.0 |
| Copper (Cu) | 1.0–2.0 |
| Nitrogen (N) | 0.10 max |
| Iron (Fe) | Balance |
The combination of high nickel, 4–5% molybdenum and copper is central to the corrosion-resistant performance of 904L.
Mechanical Properties of 904L Plate
Typical minimum room-temperature requirements for annealed ASTM A240 904L plate include:
| Property | Requirement |
|---|---|
| Tensile Strength | 490 MPa / 71 ksi min |
| Yield Strength | 220 MPa / 31 ksi min |
| Elongation | 35% min |
| Hardness | 90 HRB max |
Actual certified values are reported on the Material Test Certificate supplied with the material.
Corrosion Resistance of 904L Plate
One of the main reasons for selecting 904L stainless steel plate is its resistance to aggressive acidic environments.
The copper addition contributes particularly to improved resistance in many sulfuric acid conditions, while the high molybdenum content improves resistance to localized corrosion such as pitting and crevice attack.
904L may be considered for environments containing:
- Sulfuric acid
- Phosphoric acid
- Acetic acid
- Chemical process solutions
- Chloride-containing fluids
- Flue-gas condensates
- Selected seawater and brine conditions
904L should not be described as universally resistant to hydrochloric acid. Performance in hydrochloric acid is strongly dependent on acid concentration, temperature and contaminants, and material selection should be confirmed using corrosion data for the actual process conditions.
904L vs 316L Stainless Steel Plate
The most important differences are the higher Ni, Mo and Cu contents of 904L.
| Property | 316L | 904L |
|---|---|---|
| Nickel | 10–14% | 23–28% |
| Molybdenum | 2–3% | 4–5% |
| Copper | Not intentionally alloyed | 1–2% |
| Pitting Resistance | Good | Higher |
| Sulfuric Acid Resistance | Condition-dependent | Improved in many conditions |
| Alloy Cost | Lower | Higher |
| Typical Positioning | General corrosion service | More severe chemical service |
904L is not automatically a replacement for 316L. Material selection should be based on fluid chemistry, chloride concentration, temperature, pressure and the applicable engineering specification.
Applications of ASTM A240 904L Plate
904L stainless steel plates are commonly used for:
- Sulfuric acid handling equipment
- Chemical processing equipment
- Petrochemical plants
- Process tanks and vessels
- Reactor vessels
- Flue-gas desulfurization systems
- Pulp and paper bleaching equipment
- Desalination equipment
- Selected seawater-handling equipment
- Hydrometallurgical equipment
- Heat exchangers
- Pharmaceutical processing
- Food and beverage equipment
Surface & Delivery Condition
ASTM A240 904L plate can be supplied as:
- No.1 Finish – Hot rolled, heat treated and pickled
- 2B Finish – Smooth cold-rolled finish
- Cold-rolled sheet
- Hot-rolled plate
- Cut-to-size plate
- Special surface finish when specified
For industrial vessels, tanks and chemical equipment, No.1 hot-rolled plate is one of the most common supply conditions.
ASTM A240 vs ASTM A480
ASTM A240/A240M defines the material requirements for stainless steel plate, sheet and strip, including chemical composition and mechanical properties.
ASTM A480/A480M provides general requirements for flat-rolled stainless steel products, including dimensional tolerances and other manufacturing provisions.
Plate thickness, width, length and flatness tolerances should therefore be confirmed according to the applicable ASTM A480/A480M requirements and purchase specification.
Inspection & Certification
904L plates can be supplied with project-specific inspection and documentation, including:
- EN 10204 3.1 Material Test Certificate
- Chemical composition analysis
- Mechanical property testing
- Dimensional inspection
- Surface inspection
- PMI testing
- Ultrasonic testing when specified
- Intergranular corrosion testing when required
- Third-party inspection
- Full heat-number traceability
Additional corrosion testing can be arranged when required by the project specification.
Frequently Asked Questions
What is ASTM A240 904L stainless steel plate?
ASTM A240 904L plate is a high-alloy austenitic stainless steel plate with UNS designation N08904 and European designation 1.4539. It contains high nickel and molybdenum together with copper for improved corrosion resistance.
Why is copper added to 904L stainless steel?
The 1–2% copper addition helps improve the corrosion resistance of 904L in many reducing acid environments, particularly sulfuric acid service.
What is the difference between 904L and 316L?
904L contains significantly more nickel and molybdenum and also contains copper. It therefore offers higher corrosion resistance than 316L in many aggressive chemical and localized-corrosion environments.
Is 904L resistant to hydrochloric acid?
904L can provide useful resistance under certain conditions, but it is not universally resistant to hydrochloric acid. Suitability depends strongly on acid concentration, temperature, contaminants and process conditions.
Related Stainless Steel & Alloy Products.
- ASTM A312 904L Stainless Steel Pipe – UNS N08904 process pipe for corrosive service.
- 904L Stainless Steel Pipe Fittings – Elbows, tees and reducers for high-alloy piping systems.
- ASTM A182 F904L Flanges – Forged 904L flanges for corrosive pressure piping.
ASTM A240 904L Plate Supplier
We supply ASTM A240 904L / UNS N08904 stainless steel plates for international chemical, petrochemical and corrosion-resistant equipment projects.
Customized sizes, cut-to-length plates, special testing and complete inspection documentation can be supplied according to customer specifications.
Order Example:
ASTM A240/A240M 904L Stainless Steel Plate, 10 × 1500 × 6000 mm, Qty. 10 pcs, No.1 Finish, EN 10204 3.1.
