ASME SA240 309S Stainless Steel Plate | SA240 Type 309S
What is ASME SA240 309S 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 309S Stainless Steel Plate, also known as SA240 Type 309S.
ASME SA240 Type 309S is a low-carbon austenitic stainless steel containing high levels of chromium (22–24%) and nickel (12–15%). The elevated chromium and nickel contents provide outstanding resistance to high-temperature oxidation and significantly better strength at elevated temperatures compared with standard 304 or 316 grades. The low carbon content (≤ 0.08%) improves weldability and reduces the risk of intergranular corrosion after welding.
Type 309S is widely used for furnace components, heat-treatment equipment, radiant tubes, kiln parts, high-temperature process equipment, and other applications involving continuous or intermittent service at temperatures up to approximately 1000–1100°C in oxidizing atmospheres. It offers a good balance of high-temperature performance, oxidation resistance, fabricability, and cost compared with higher-alloy grades such as 310S.
SHH STEEL supplies ASME SA240 309S 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 practical dimensional range and a full 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 309S (UNS S30908) | Confirmed |
| Product Form | Plate, Sheet | Available |
| Delivery Condition | Solution Annealed | Standard |
| Thickness Range | 1 mm – 80 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 309S:
| Element | Content (%) |
|---|---|
| Carbon (C) | ≤ 0.08 |
| Silicon (Si) | ≤ 0.75 |
| Manganese (Mn) | ≤ 2.00 |
| Phosphorus (P) | ≤ 0.045 |
| Sulfur (S) | ≤ 0.030 |
| Chromium (Cr) | 22.00 – 24.00 |
| Nickel (Ni) | 12.00 – 15.00 |
| Nitrogen (N) | ≤ 0.10 |
| Iron (Fe) | Balance |
Product Analysis (typical permissible variations):
| Element | Content (%) |
|---|---|
| Carbon (C) | ≤ 0.08 |
| Silicon (Si) | ≤ 0.75 |
| Manganese (Mn) | ≤ 2.00 |
| Phosphorus (P) | ≤ 0.045 |
| Sulfur (S) | ≤ 0.030 |
| Chromium (Cr) | 21.90 – 24.10 |
| Nickel (Ni) | 11.90 – 15.10 |
| Nitrogen (N) | ≤ 0.10 |
The high chromium and nickel contents are the key factors that give Type 309S its excellent high-temperature oxidation resistance and elevated-temperature strength. The low carbon limit improves weldability and reduces sensitization risk.
Mechanical Properties
Room-Temperature Mechanical Properties (Annealed Condition)
| Property | Value |
|---|---|
| Tensile Strength | ≥ 515 MPa (75 ksi) |
| Yield Strength (0.2%) | ≥ 205 MPa (30 ksi) |
| Elongation (in 50 mm) | ≥ 40% |
| Hardness | ≤ 217 HB / ≤ 95 HRB |
Elevated-Temperature Performance ASME SA240 309S retains useful strength and excellent oxidation resistance at temperatures up to approximately 1000–1100°C in continuous service in oxidizing atmospheres. It offers better high-temperature strength and scaling resistance than 304H or 316H.
Physical Properties
- Density: approximately 7.90 g/cm³
- Melting Range: approximately 1400–1450°C
- Magnetic: Non-magnetic in the annealed condition
Material Comparison
| Grade | Cr / Ni Content | Key Advantage | Typical Service Focus |
|---|---|---|---|
| SA240 Type 304H | 18Cr-8Ni | Economical high-temperature strength | Moderate high-temp service |
| SA240 Type 316H | 16Cr-10Ni-2Mo | High-temp strength + better chloride resistance | High-temp with mild chlorides |
| SA240 Type 309S | 23Cr-13Ni | Excellent oxidation resistance + good strength | Furnace & heat-treatment equipment |
| SA240 Type 310S | 25Cr-20Ni | Superior oxidation resistance at higher temperatures | Most severe high-temp oxidizing service |
| SA240 Type 321 / 347 | Stabilized 18Cr-8Ni | Sensitization resistance | Welded high-temp process equipment |
ASME SA240 309S is selected when better high-temperature oxidation resistance and strength than 304H/316H are required, but the higher cost and performance of 310S are not necessary. For the most demanding continuous high-temperature oxidizing service, astm a240 type 310s stainless steel sheet plate is preferred. For welded high-temperature process equipment where sensitization resistance is critical, stabilized grades such as astm a240 type 321 stainless steel sheet plate or astm a240 type 347 stainless steel sheet plate are often considered.
Corrosion Resistance
In the annealed condition, ASME SA240 Type 309S offers good general corrosion resistance in many atmospheric and mild chemical environments. Its primary strength lies in high-temperature oxidation resistance rather than aqueous corrosion performance.
It resists oxidation and scaling in continuous service up to approximately 1000–1100°C in air or oxidizing atmospheres. Resistance to sulfidation and carburization is moderate. In aqueous chloride environments its pitting resistance is lower than molybdenum-bearing grades such as 316L or 317L.
Weldability
ASME SA240 Type 309S has good weldability by all standard fusion and resistance welding methods. The low carbon content reduces the risk of intergranular corrosion after welding.
Matching or slightly over-alloyed filler metals (E309 / ER309 or E309L / ER309L) are commonly used. The grade can be welded to other austenitic stainless steels and to carbon steels using appropriate procedures. Post-weld heat treatment is generally not required for most high-temperature applications.
Heat Treatment
ASME SA240 Type 309S is supplied in the solution-annealed condition.
Recommended Solution Annealing Parameters
- Temperature range: 1040 – 1120°C (typically 1050 – 1100°C)
- Holding (soaking) time: – Plates ≤ 25 mm: minimum 10–20 minutes after the section reaches temperature – Plates 25–50 mm: minimum 20–40 minutes – Plates > 50 mm: 30–60 minutes or longer to ensure uniformity
- Cooling: Rapid cooling (water quench preferred for thicker plates) to restore maximum corrosion resistance and ductility.
Proper solution annealing dissolves any carbides that may have formed and optimizes the microstructure for high-temperature service.
Surface Finishes
| Finish | Description | Typical Use / Keywords |
|---|---|---|
| No.1 | Hot-rolled, annealed and pickled | SA240 309S No.1 – most common for furnace and high-temperature plate |
| 2B | Cold-rolled, annealed, pickled, skin-passed | SA240 309S 2B – thinner plates and general fabrication |
| No.4 | Brushed finish | SA240 309S No.4 – when improved surface appearance is required |
| Special | Ground or custom finishes | SA240 309S Special – on request |
SHH STEEL regularly supplies ASME SA240 309S in No.1 and 2B finishes, and can provide other finishes according to project requirements.
Tolerances
Dimensional tolerances for ASME SA240 309S Stainless Steel Plate conform to ASME SA240 and the general requirements of ASTM A480.
Typical available size range for SA240 309S plate:
- Thickness: 1 mm – 80 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 309S plate can be arranged for specific project needs. SHH STEEL provides precise dimensional control for both standard and custom-size SA240 309S plates.
Equivalent Material Grades
| Grade / Designation | Standard | Notes |
|---|---|---|
| SA240 Type 309S | ASME SA240 | — |
| A240 Type 309S | ASTM A240 | Essentially identical |
| UNS S30908 | — | Unified Numbering System |
| 1.4833 / X12CrNi23-13 | EN 10088-2 | European equivalent |
| SUS309S | JIS G4305 | Japanese equivalent |
| 06Cr23Ni13 | GB/T 3280 | Chinese equivalent |
Related grades frequently evaluated with ASME SA240 309S include astm a240 type 310s stainless steel sheet plate, astm a240 type 304h stainless steel sheet plate, astm a240 type 321 stainless steel sheet plate, and astm a240 type 347 stainless steel sheet plate.
Applications
ASME SA240 Type 309S is widely used in high-temperature oxidizing environments:
| Industry / Sector | Typical Components / Equipment |
|---|---|
| Heat Treatment Equipment | Furnace parts, radiant tubes, muffles, retorts, baskets |
| Industrial Furnaces | Kiln components, fixtures, supports |
| Power Generation | Boiler components, high-temperature ducting |
| Chemical & Petrochemical | High-temperature reactors and process equipment |
| Cement & Metallurgical | Kiln parts and high-temperature structural components |
| Automotive & Exhaust | High-temperature exhaust components |
| General High-Temperature Use | Thermal processing equipment and structural parts |
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 309S 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 309S No.1 and SA240 309S 2B)
- Technical support for high-temperature material selection
- Reliable worldwide logistics and export documentation
FAQ
- What is the main advantage of SA240 309S over SA240 304H?Type 309S has significantly higher chromium and nickel contents, providing much better oxidation resistance and higher strength at elevated temperatures (up to approximately 1000–1100°C).
- What is the difference between 309S and 310S?Type 310S contains higher chromium (24–26%) and nickel (19–22%), offering superior oxidation resistance at the highest temperatures. Type 309S is a more economical choice for many furnace and heat-treatment applications.
- Is ASME SA240 309S magnetic?Non-magnetic in the annealed condition.
- What is the density of SA240 Type 309S?Approximately 7.90 g/cm³.
- Can SHH STEEL supply dual-certified ASME SA240 / ASTM A240 Type 309S?Yes, dual certification is commonly available.
Conclusion
ASME SA240 309S Stainless Steel Plate (SA240 Type 309S) is a low-carbon high-chromium, high-nickel austenitic stainless steel optimized for high-temperature oxidation resistance and elevated-temperature strength. It is a cost-effective and reliable choice for furnace components, heat-treatment equipment, and many high-temperature process applications.
As a professional China Mill-Direct Supply and Mill Direct Exporter, SHH STEEL provides high-quality ASME SA240 Type 309S plate with competitive pricing, full certification, and complete technical support.
Contact SHH STEEL today for stock availability, surface finish options (including SA240 309S No.1 and SA240 309S 2B), or a competitive quotation.
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