ASME SA240 309H Stainless Steel Plate | SA240 Type 309H
What is ASME SA240 309H 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 309H Stainless Steel Plate, also known as SA240 Type 309H.
ASME SA240 Type 309H is the higher-carbon version of the high-chromium, high-nickel austenitic stainless steel Type 309. While Type 309S is limited to a maximum of 0.08% carbon for improved weldability, Type 309H is deliberately specified with a carbon range of 0.04–0.10%. This controlled higher carbon content provides significantly improved strength at elevated temperatures, particularly above 500°C, while the high chromium (22–24%) and nickel (12–15%) contents continue to deliver excellent resistance to high-temperature oxidation.
Type 309H is selected for furnace components, heat-treatment equipment, radiant tubes, high-temperature pressure vessels, and process equipment that operate continuously at elevated temperatures and require higher allowable stresses than standard 309S. It offers a practical balance of high-temperature strength, oxidation resistance, fabricability, and cost compared with higher-alloy grades such as 310H.
SHH STEEL supplies ASME SA240 309H 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 309H (UNS S30909) | Confirmed |
| Product Form | Plate, Sheet | Available |
| Delivery Condition | Solution Annealed | Standard |
| Thickness Range | 3 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, 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 309H:
| Element | Content (%) |
|---|---|
| Carbon (C) | 0.04 – 0.10 |
| 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) | 0.04 – 0.10 |
| 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 controlled carbon range of 0.04–0.10% is the key feature that distinguishes Type 309H from Type 309S. This carbon level provides solid-solution strengthening and improved creep and stress-rupture properties at elevated temperatures, while the high chromium and nickel contents maintain excellent oxidation resistance.
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 309H is specifically intended for service at elevated temperatures. The higher carbon content delivers better tensile and yield strength above approximately 500°C and improved long-term creep strength compared with Type 309S. It retains excellent oxidation resistance in continuous service up to approximately 1000–1100°C in oxidizing atmospheres.
Physical Properties
- Density: approximately 7.90 g/cm³
- Melting Range: approximately 1400–1450°C
- Magnetic: Non-magnetic in the annealed condition
Material Comparison
| Grade | Carbon Content | Cr / Ni Content | Primary Advantage | Typical Service Focus |
|---|---|---|---|---|
| SA240 Type 309S | ≤ 0.08% | 23Cr-13Ni | Excellent oxidation resistance + good weldability | Furnace & heat-treatment equipment |
| SA240 Type 309H | 0.04 – 0.10% | 23Cr-13Ni | Higher strength at elevated temperature | Continuous high-temperature service |
| SA240 Type 310S | ≤ 0.08% | 25Cr-20Ni | Superior oxidation resistance | Most severe high-temp oxidizing service |
| SA240 Type 310H | 0.04 – 0.10% | 25Cr-20Ni | Highest high-temp strength + oxidation resistance | Severe continuous high-temp service |
| SA240 Type 304H | 0.04 – 0.10% | 18Cr-8Ni | Economical high-temperature strength | Moderate high-temp service |
When both elevated-temperature strength and good oxidation resistance are required, ASME SA240 309H is a logical upgrade from 309S. For the most demanding continuous high-temperature oxidizing service, astm a240 type 310s stainless steel sheet plate or the high-carbon version 310H is preferred. For general high-temperature service without the need for higher chromium and nickel, astm a240 type 304h stainless steel sheet plate remains a more economical option.
High-Temperature
The higher carbon content that gives Type 309H its elevated-temperature strength also increases its susceptibility to sensitization compared with 309S. Prolonged exposure in the temperature range of approximately 450–850°C can lead to chromium carbide precipitation at grain boundaries. In continuous high-temperature service where the environment is oxidizing and not aqueous-corrosive, this is usually acceptable. However, if the equipment will encounter corrosive media during shutdowns or in process streams, additional precautions should be considered.
Corrosion Resistance
In the annealed condition, ASME SA240 Type 309H 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.
Weldability
ASME SA240 Type 309H can be welded by all standard fusion and resistance welding methods. When high-temperature strength of the weld metal is required, matching high-carbon filler metals (E309H / ER309H) are recommended. Standard E309 / ER309 or E309L fillers may be used when corrosion resistance of the weld is the higher priority.
Due to the higher carbon content, the heat-affected zone is more prone to sensitization than in 309S. For critical corrosive service after welding, post-weld solution annealing may be advisable.
ASME SA240 Type 309H Heat Treatment
ASME SA240 Type 309H is supplied in the solution-annealed condition. Proper heat treatment is essential to achieve optimum properties.
Recommended Solution Annealing Parameters
- Temperature range: 1040 – 1120°C (typically 1050 – 1100°C)
- Holding (soaking) time: – Plates ≤ 25 mm thick: minimum 10–20 minutes after the entire cross-section has reached the target temperature – Plates 25–50 mm thick: minimum 20–40 minutes – Plates above 50 mm: 30–60 minutes or longer, depending on thickness and furnace loading, to ensure uniform temperature
- Cooling: Rapid cooling is mandatory. Water quenching is strongly preferred for thicker plates to avoid re-precipitation of carbides and to restore maximum corrosion resistance and ductility.
Proper solution annealing dissolves chromium carbides and returns the material to its optimum condition for high-temperature service.
Tolerances
Dimensional tolerances for ASME SA240 309H Stainless Steel Plate conform to ASME SA240 and the general requirements of ASTM A480.
Typical available size range for SA240 309H plate:
- Thickness: 3 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 309H plate can be arranged for specific project needs. SHH STEEL provides precise dimensional control for both standard and custom-size SA240 309H plates.
Equivalent Material Grades
| Grade / Designation | Standard | Notes |
|---|---|---|
| SA240 Type 309H | ASME SA240 | — |
| A240 Type 309H | ASTM A240 | Essentially identical |
| UNS S30909 | — | Unified Numbering System |
| Related high-carbon 309 | EN / JIS / GB | Approximate national equivalents |
Related grades frequently evaluated with ASME SA240 309H include astm a240 type 309s stainless steel sheet plate, astm a240 type 310s stainless steel sheet plate, astm a240 type 304h stainless steel sheet plate, and astm a240 type 310h stainless steel sheet plate.
Applications
ASME SA240 Type 309H is selected for equipment that requires both elevated-temperature strength and good oxidation resistance:
| Industry / Sector | Typical Components / Equipment |
|---|---|
| Heat Treatment Equipment | Furnace parts, radiant tubes, muffles, retorts, baskets |
| Industrial Furnaces | Kiln components, fixtures, supports |
| Boilers & Pressure Vessels | High-temperature shells, headers, components |
| Power Generation | Boiler components, high-temperature ducting |
| Chemical & Petrochemical | High-temperature reactors and process equipment |
| Cement & Metallurgical | Kiln parts and high-temperature structural components |
| General High-Temperature Use | Thermal processing equipment requiring higher strength |
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 309H 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 309H No.1 and SA240 309H 2B)
- Technical support for high-temperature material selection
- Reliable worldwide logistics and export documentation
FAQ
- What is the main difference between SA240 309S and SA240 309H?The carbon content. Type 309H has a controlled higher carbon range (0.04–0.10%) to improve high-temperature strength, while Type 309S has a maximum of 0.08% carbon for better weldability and lower sensitization risk.
- When should I choose 309H instead of 309S?Choose 309H when the equipment will operate continuously at elevated temperatures and the design requires higher allowable stresses, while still needing excellent oxidation resistance.
- Is ASME SA240 309H suitable for ASME Code pressure vessels?Yes. It is listed in ASME SA240 and can be used for Code-stamped vessels and equipment operating at elevated temperatures.
- Does 309H require special welding procedures?It can be welded with standard austenitic procedures. Matching high-carbon filler metals (309H) are preferred when high-temperature strength of the weld is required. Attention must be paid to possible sensitization in the heat-affected zone.
- What is the density of SA240 Type 309H?Approximately 7.90 g/cm³.
Conclusion
ASME SA240 309H Stainless Steel Plate (SA240 Type 309H) is the high-carbon high-chromium, high-nickel austenitic grade optimized for elevated-temperature strength while retaining excellent oxidation resistance. It is the material of choice when design conditions demand higher allowable stresses at temperature together with reliable performance in high-temperature oxidizing environments.
As a professional China Mill-Direct Supply and Mill Direct Exporter, SHH STEEL provides high-quality ASME SA240 Type 309H plate with competitive pricing, full certification, and complete technical support.
Contact SHH STEEL today for stock availability, surface finish options (including SA240 309H No.1 and SA240 309H 2B), or a competitive quotation for your high-temperature stainless steel requirements.
ASME SA240 309H Stainless Steel Plate, SA240 Type 309H, SA240 309H, ASME SA240 Type 309H, 309H stainless steel plate, SA240 309H supplier
Quality Steel Needed? Inquire for Offers
Related Products
