ASME SA240 904L Stainless Steel Plate | SA240 Type 904L
What is ASME SA240 904L Stainless Steel Plate?
As a professional stainless steel plate supplier and China Mill-Direct Supply / Mill Direct Exporter, SHH STEEL is pleased to present ASME SA240 904L Stainless Steel Plate, also known as SA240 Type 904L or UNS N08904.
ASME SA240 Type 904L is a high-alloy super austenitic stainless steel containing high levels of chromium, nickel, molybdenum and copper. The combination of approximately 20% chromium, 25% nickel, 4.5% molybdenum and 1.5% copper provides outstanding resistance to strong reducing acids (particularly sulfuric acid in intermediate concentrations), excellent resistance to pitting and crevice corrosion, and good resistance to chloride stress corrosion cracking. Type 904L bridges the performance gap between conventional austenitic grades (316L/317L) and more expensive nickel-base alloys.
It is widely used in chemical processing, fertilizer production, pharmaceutical, petrochemical, and pollution-control equipment where resistance to aggressive reducing and chloride-containing media is required. Although its strength is lower than that of duplex or super duplex grades, its unique corrosion profile makes it the material of choice for many specific acid and mixed-media environments.
SHH STEEL supplies ASME SA240 904L as true Mill Direct Supply, sourcing directly from major Chinese stainless steel mills. This model delivers competitive mill pricing, consistent quality, full heat traceability and shorter lead times. We offer a wide dimensional range and a complete selection of surface finishes to meet project requirements.
Material Specification
| Specification Element | Requirement | SHH STEEL Compliance |
|---|---|---|
| Primary Standard | ASME SA240 / SA240M | Full compliance |
| Steel Grade | Type 904L (UNS N08904) | Confirmed |
| Product Form | Plate, Sheet | Available |
| Delivery Condition | Solution Annealed | Standard |
| Thickness Range | 1 mm – 60 mm (thicker available on request) | Custom sizes supported |
| Width | Up to 2000–3000 mm | Available |
| Length | Up to 12000 mm or cut-to-length | Available |
| Surface Finish | No.1, 2B, No.4, and others on request | Available |
| Certification | EN 10204 3.1 / ASME Mill Test Certificate | Available |
Chemical Composition
Heat Analysis (Ladle Analysis) according to ASME SA240 Type 904L (UNS N08904):
| Element | Content (%) |
|---|---|
| Carbon (C) | ≤ 0.020 |
| Silicon (Si) | ≤ 1.00 |
| Manganese (Mn) | ≤ 2.00 |
| Phosphorus (P) | ≤ 0.045 |
| Sulfur (S) | ≤ 0.035 |
| Chromium (Cr) | 19.00 – 23.00 |
| Nickel (Ni) | 23.00 – 28.00 |
| Molybdenum (Mo) | 4.00 – 5.00 |
| Copper (Cu) | 1.00 – 2.00 |
| Nitrogen (N) | ≤ 0.10 |
| Iron (Fe) | Balance |
Product Analysis (typical permissible variations):
| Element | Content (%) |
|---|---|
| Carbon (C) | ≤ 0.020 |
| Silicon (Si) | ≤ 1.00 |
| Manganese (Mn) | ≤ 2.00 |
| Phosphorus (P) | ≤ 0.045 |
| Sulfur (S) | ≤ 0.035 |
| Chromium (Cr) | 19.00 – 23.00 |
| Nickel (Ni) | 23.00 – 28.00 |
| Molybdenum (Mo) | 4.00 – 5.00 |
| Copper (Cu) | 1.00 – 2.00 |
The very low carbon content, high nickel, elevated molybdenum and deliberate copper addition are the defining features of Type 904L. Copper significantly improves resistance to sulfuric acid, while the high Mo and Ni contents enhance resistance to pitting and stress corrosion cracking.
Mechanical Properties
Room-Temperature Mechanical Properties (Solution Annealed Condition)
| Property | Value |
|---|---|
| Tensile Strength | ≥ 490 MPa (71 ksi) |
| Yield Strength (0.2%) | ≥ 220 MPa (31 ksi) |
| Elongation (in 50 mm) | ≥ 35% |
| Hardness | ≤ 220 HB / ≤ 90 HRB |
Physical Properties
- Density: approximately 8.00 g/cm³
- Melting Range: approximately 1300–1390°C
- Magnetic: Non-magnetic in the annealed condition
Type 904L offers good toughness and formability characteristic of high-alloy austenitic stainless steels.
Material Comparison
| Grade | Structure | Key Alloying Feature | Primary Advantage | Typical Preference |
|---|---|---|---|---|
| SA240 Type 316L | Austenitic | 2–3% Mo | Economical chloride resistance | Moderate chloride service |
| SA240 Type 317L | Austenitic | 3–4% Mo | Higher pitting resistance | Aggressive chloride service |
| SA240 Type 2205 | Duplex | 22Cr-5Ni-3Mo-N | High strength + good SCC resistance | High-strength chloride service |
| SA240 Type 904L | Super Austenitic | High Ni + 4.5% Mo + Cu | Outstanding resistance to reducing acids | Sulfuric acid & mixed aggressive media |
| SA240 Type 2507 | Super Duplex | 25Cr-7Ni-4Mo-N | Very high strength + superior pitting resistance | Severe seawater / high-chloride service |
ASME SA240 904L is selected when resistance to strong reducing acids (especially sulfuric acid) is the dominant requirement. For pure chloride / seawater service where high strength is also needed, astm a240 type 2507 stainless steel sheet plate or astm a240 type 2205 stainless steel sheet plate may be more suitable. For less severe chloride environments, astm a240 type 317l stainless steel sheet plate often provides a more economical solution.
Corrosion Resistance
ASME SA240 Type 904L is particularly well known for its excellent resistance to sulfuric acid across a wide concentration range, especially in the intermediate concentrations where many other stainless steels suffer rapid attack. The copper addition plays a key role in this performance.
It also offers very good resistance to pitting and crevice corrosion in chloride media (PREN typically around 35) and better resistance to chloride stress corrosion cracking than standard 300-series austenitic grades. Performance in phosphoric acid, organic acids and many mixed chemical environments is also strong.
Weldability
ASME SA240 Type 904L can be welded by all standard fusion and resistance welding methods. Matching high-alloy filler metals (e.g., ER385 / E385) are recommended to maintain corrosion resistance in the weld metal.
Because of the very low carbon content, the grade has good resistance to intergranular corrosion in the as-welded condition. Proper cleaning and protection against contamination are important to preserve the high corrosion performance of this alloy.
Heat Treatment
ASME SA240 Type 904L is supplied in the solution-annealed condition.
Recommended Solution Annealing Parameters
- Temperature range: 1090 – 1175°C (typically 1100 – 1150°C)
- Holding (soaking) time: – Plates ≤ 25 mm: minimum 15–30 minutes after the section reaches temperature – Plates 25–50 mm: minimum 30–45 minutes – Plates > 50 mm: 45–90 minutes or longer to ensure uniformity
- Cooling: Rapid cooling is required. Water quenching is preferred for thicker plates to retain maximum corrosion resistance and prevent precipitation of intermetallic phases.
Proper solution annealing is essential to achieve the optimum corrosion performance of Type 904L.
Surface Finishes
| Finish | Description | Typical Use / Keywords |
|---|---|---|
| No.1 | Hot-rolled, annealed and pickled | SA240 904L No.1 – most common for industrial and process equipment plate |
| 2B | Cold-rolled, annealed, pickled, skin-passed | SA240 904L 2B – thinner plates and general fabrication |
| No.4 | Brushed finish | SA240 904L No.4 – when improved surface appearance is required |
| Special | Ground or custom finishes | SA240 904L Special – on request |
SHH STEEL regularly supplies ASME SA240 904L in No.1 and 2B finishes, and can provide other finishes according to project requirements.
Tolerances
Dimensional tolerances for ASME SA240 904L Stainless Steel Plate conform to ASME SA240 and the general requirements of ASTM A480.
Typical available size range for SA240 904L plate:
- Thickness: 1 mm – 60 mm (thicker plates available on request)
- Width: up to 2000–3000 mm
- Length: up to 12000 mm or cut-to-length according to customer requirements
Thickness, width, length and flatness tolerances are controlled within standard limits. Tighter tolerances for SA240 904L plate can be arranged for specific project needs. SHH STEEL provides precise dimensional control for both standard and custom-size SA240 904L plates to ensure suitability for fabrication and pressure equipment applications.
Equivalent Material Grades
| Grade / Designation | Standard | Notes |
|---|---|---|
| SA240 Type 904L | ASME SA240 | — |
| A240 Type 904L | ASTM A240 | Essentially identical |
| UNS N08904 | — | Unified Numbering System |
| 1.4539 / X1NiCrMoCu25-20-5 | EN 10088-2 | European equivalent |
| Related 904L grades | JIS / GB | Approximate national equivalents |
Related grades frequently evaluated with ASME SA240 904L include astm a240 type 317l stainless steel sheet plate, astm a240 type 2205 stainless steel sheet plate, astm a240 type 2507 stainless steel sheet plate, and astm a240 type 316l stainless steel sheet plate.
Applications
ASME SA240 Type 904L is widely used in aggressive chemical and acid environments:
| Industry / Sector | Typical Components / Equipment |
|---|---|
| Chemical Processing | Reactors, tanks, piping in sulfuric and mixed acids |
| Fertilizer Production | Equipment handling phosphoric and sulfuric media |
| Pharmaceutical | Process vessels and piping in corrosive service |
| Petrochemical | Acid-handling equipment and heat exchangers |
| Pollution Control / FGD | Critical components in aggressive scrubber environments |
| Heat Exchangers | Shells and components in reducing acid service |
| Pressure Vessels | ASME Code vessels requiring high alloy corrosion resistance |
| Pulp & Paper | Bleaching and chemical handling equipment |
Why Choose SHH STEEL
SHH STEEL is a China Mill-Direct Supply and Mill Direct Exporter of stainless steel plate. We maintain long-term strategic cooperation with major Chinese stainless steel mills and supply ASME SA240 Type 904L with the following advantages:
- Competitive mill-direct pricing
- Consistent quality and complete heat traceability
- Full Mill Test Certificates (EN 10204 3.1 / ASME)
- Flexible dimensions and surface finishes (including SA240 904L No.1 and SA240 904L 2B)
- Technical support for high-alloy material selection in aggressive media
- Reliable worldwide logistics and export documentation
FAQ
- What is the main advantage of SA240 904L over SA240 317L?Type 904L offers significantly better resistance to strong reducing acids (especially sulfuric acid) due to its high nickel and copper content, while also providing excellent pitting resistance.
- Is ASME SA240 904L magnetic?Non-magnetic in the annealed condition.
- What is the typical PREN of Type 904L?Approximately 35, comparable to some duplex grades but with a different corrosion profile optimized for reducing acids.
- Can 904L replace higher nickel alloys in some applications?In many sulfuric acid and mixed-media environments, 904L can provide a cost-effective alternative to more expensive nickel-base alloys, depending on the exact conditions.
- What is the density of SA240 Type 904L?Approximately 8.00 g/cm³.
- an SHH STEEL supply dual-certified ASME SA240 / ASTM A240 Type 904L?Yes, dual certification is commonly available.
Conclusion
ASME SA240 904L Stainless Steel Plate (SA240 Type 904L / UNS N08904) is a high-alloy super austenitic stainless steel specifically designed for outstanding resistance to strong reducing acids and excellent performance in aggressive chemical environments. It fills the gap between conventional molybdenum-bearing austenitic grades and nickel-base alloys.
As a professional China Mill-Direct Supply and Mill Direct Exporter, SHH STEEL provides high-quality ASME SA240 Type 904L plate with competitive pricing, full certification and complete technical support.
Contact SHH STEEL today for stock availability, surface finish options (including SA240 904L No.1 and SA240 904L 2B), dimensional details, or a competitive quotation.
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