AISI 309H Stainless Steel Plate | 309H China steel mill-Direct Supply
What is AISI 309H Stainless Steel Plate?
As a professional China steel mill-Direct Supply and stainless steel plate supplier, SHH STEEL is pleased to present AISI 309H Stainless Steel Plate.
AISI 309H is the high-carbon variant of the heat-resisting austenitic stainless steel AISI 309. It contains approximately 22–24% chromium and 12–15% nickel, with carbon intentionally controlled in a higher range (typically 0.04–0.10%). This elevated carbon content significantly improves high-temperature strength and creep resistance compared with standard 309 and the low-carbon 309S grade, while retaining excellent resistance to oxidation and scaling.
AISI 309H is particularly suitable for long-term elevated-temperature service where both oxidation resistance and higher mechanical strength under load are required. Typical applications include furnace components, radiant tubes, heat-treatment fixtures, superheater parts and petrochemical process equipment operating in oxidizing atmospheres at high temperature.
SHH STEEL supplies AISI 309H as true China steel mill-Direct Supply, sourcing directly from major Chinese stainless steel mills. This model delivers competitive mill pricing, consistent quality, complete heat traceability and reliable delivery. SHH STEEL offers AISI 309H in plate and sheet form across a practical range of thicknesses and surface finishes optimized for high-temperature service.
AISI 309H is frequently compared with a240 309s, a240 310s, a240 310h, a240 304, a240 304l and a240 321 when selecting materials for elevated-temperature applications. SHH STEEL provides technical support to help customers choose the most appropriate grade.
Material Specification
| Specification Element | Requirement | SHH STEEL Compliance |
|---|---|---|
| Grade | AISI 309H / UNS S30909 | Confirmed |
| Related Standards | ASTM A240, ASME SA240, related high-temperature specs | Available |
| 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, and others on request | Available |
| Certification | EN 10204 3.1 / Mill Test Certificate | Available |
SHH STEEL can supply AISI 309H dual-certified to ASTM A240 / ASME SA240 when required by the project.
Chemical Composition
Typical Chemical Composition of AISI 309H:
| Element | Content (%) |
|---|---|
| Carbon (C) | 0.04 – 0.10 |
| Silicon (Si) | ≤ 1.00 |
| 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 |
The controlled higher carbon content (0.04–0.10%) is the defining feature of AISI 309H. Combined with high chromium (22–24%) and nickel (12–15%), it delivers excellent oxidation resistance together with improved high-temperature strength and creep resistance. SHH STEEL carefully controls carbon content to meet the requirements of elevated-temperature service under load.
Mechanical Properties
Annealed Condition (typical values)
| Property | Value |
|---|---|
| Tensile Strength | ≥ 515 MPa (75 ksi) |
| Yield Strength (0.2%) | ≥ 205 MPa (30 ksi) |
| Elongation (in 50 mm) | ≥ 40% |
| Hardness | ≤ 217 HB |
At elevated temperatures, AISI 309H retains higher strength than standard 309 or 309S due to the controlled carbon content. This makes it suitable for long-term service where creep resistance is important. For even higher alloy content and oxidation resistance, a240 310h may be considered. SHH STEEL supplies material with consistent high-temperature mechanical properties.
Physical Properties Density is approximately 7.90 g/cm³. The grade is non-magnetic in the annealed condition. Melting range is approximately 1400–1450°C.
Material Comparison
| Grade | Carbon | Cr (%) | Ni (%) | High-Temp Strength | Oxidation Resistance | Typical Preference |
|---|---|---|---|---|---|---|
| AISI 309S | ≤ 0.08 | 22–24 | 12–15 | Good | Very Good | Welded high-temperature service |
| AISI 309H | 0.04–0.10 | 22–24 | 12–15 | Higher | Very Good | High-temp strength + oxidation |
| AISI 310S | ≤ 0.08 | 24–26 | 19–22 | Good | Excellent | Severe high-temperature service |
| AISI 310H | 0.04–0.10 | 24–26 | 19–22 | Higher | Excellent | Maximum high-temp strength + oxidation |
| AISI 304 | ≤ 0.08 | 18–20 | 8–10.5 | Lower | Good | General purpose |
| AISI 321 | ≤ 0.08 | 17–19 | 9–12 | Good | Good | Stabilized high-temp welded service |
AISI 309H is selected when improved high-temperature strength and creep resistance are required in addition to excellent oxidation resistance. Compared with a240 309s, it offers higher strength at elevated temperature. For more severe oxidizing environments or higher alloy content, SHH STEEL recommends a240 310s or a240 310h.
Corrosion Resistance
AISI 309H provides excellent resistance to oxidation and scaling in air and oxidizing atmospheres at elevated temperatures up to approximately 1000–1100°C in continuous service (depending on conditions). The high chromium and nickel contents form a stable protective oxide scale.
Because of the higher carbon content, AISI 309H is more susceptible to intergranular corrosion after welding or prolonged exposure in the sensitization range than the low-carbon 309S grade. For welded constructions where intergranular corrosion is a concern, SHH STEEL recommends a240 309s or stabilized grades such as a240 321.
Weldability
AISI 309H can be welded by standard fusion welding methods. Matching or 309H-type filler metals are preferred to maintain high-temperature strength in the weld metal. Due to the higher carbon content, the risk of sensitization is greater than with 309S.
Post-weld solution annealing is recommended for critical corrosive or high-temperature service. When maximum as-welded corrosion resistance is required, SHH STEEL recommends a240 309s.
Heat Treatment
AISI 309H is normally supplied in the solution-annealed condition by SHH STEEL.
Recommended solution annealing temperature range is 1040–1150°C (often toward the higher end), followed by rapid cooling. Proper annealing is important to dissolve carbides and optimize both room-temperature and elevated-temperature properties. SHH STEEL controls heat treatment to ensure consistent performance for high-temperature applications under load.
Surface Finishes
| Finish | Description | Typical Use / Keywords |
|---|---|---|
| No.1 | Hot-rolled, annealed and pickled | AISI 309H No.1 – most common for industrial high-temp plate |
| 2B | Cold-rolled, annealed, pickled, skin-passed | AISI 309H 2B – thinner plates |
| Special | Ground or custom finishes | AISI 309H Special – on request |
SHH STEEL regularly supplies AISI 309H in No.1 finish, which is the preferred condition for most high-temperature plate applications.
Tolerances
Dimensional tolerances for AISI 309H Stainless Steel Plate supplied by SHH STEEL generally conform to ASTM A480 practices.
Typical available size range is thickness 1 mm – 80 mm, width up to 2000–3000 mm, and length up to 12000 mm or cut-to-length. SHH STEEL provides precise dimensional control and can support tighter tolerances when required.
Equivalent Material Grades
| Grade / Designation | Standard / UNS | Notes |
|---|---|---|
| AISI 309H | — | — |
| UNS S30909 | — | Unified Numbering System |
| ASTM A240 Type 309H | ASTM A240 | When dual certified |
| Related high-carbon 309 | EN / JIS / GB | Approximate national equivalents |
Related grades for comparison include a240 309s, a240 310s, a240 310h, a240 304, a240 321 and a240 316l.
Applications
AISI 309H is selected for applications requiring both excellent high-temperature oxidation resistance and improved strength/creep resistance. Typical applications of AISI 309H include:
| Industry / Sector | Typical Components / Equipment (with keywords) |
|---|---|
| Heat Treatment & Furnaces | AISI 309H furnace components, radiant tubes, fixtures, trays |
| Industrial Heating | AISI 309H kiln parts, muffles, supports and retorts |
| Power Generation | AISI 309H high-temperature ducting and load-bearing parts |
| Petrochemical & Refining | AISI 309H furnace linings and process equipment under load |
| Chemical Processing | AISI 309H high-temperature vessels and structural components |
| General High-Temperature Service | AISI 309H equipment requiring strength at elevated temperature |
SHH STEEL supplies AISI 309H for these elevated-temperature applications with consistent quality. For related industry solutions, see our energy industry, petrochemical industry and equipment manufacturing pages. Supporting services include steel cutting services and steel welding services.
Why Choose SHH STEEL
SHH STEEL is a China steel mill-Direct Supply specializing in stainless steel plate and sheet. By working directly with major Chinese stainless steel mills, SHH STEEL supplies AISI 309H with the following advantages:
- Genuine China steel mill-Direct Supply pricing
- Consistent quality and complete heat traceability
- Full Mill Test Certificates (EN 10204 3.1)
- High-carbon material optimized for high-temperature strength and oxidation resistance
- Flexible dimensions and surface finishes (including AISI 309H No.1 and AISI 309H 2B)
- Technical support for selection among 309S, 309H, 310S, 310H and related grades
- Value-added services including steel cutting services, steel welding services and worldwide shipping service
For more information about our company and full product range, please visit China steel Mill Agent-SHH STEEL.
FAQ
- What is the main advantage of AISI 309H over AISI 309S?The controlled higher carbon content provides improved high-temperature strength and better creep resistance while retaining excellent oxidation resistance. SHH STEEL recommends 309H when long-term strength under load at elevated temperature is important.
- How does AISI 309H compare with AISI 310H?AISI 310H has higher chromium and nickel contents and offers superior oxidation resistance together with high-temperature strength. SHH STEEL recommends 310H for more severe high-temperature service.
- Is AISI 309H magnetic?Non-magnetic in the annealed condition. SHH STEEL supplies fully annealed material as standard.
- What is the density of AISI 309H?Approximately 7.90 g/cm³. SHH STEEL provides material certificates confirming physical and mechanical properties.
Conclusion
AISI 309H Stainless Steel Plate is the high-carbon version of the heat-resisting 309 grade. It combines excellent high-temperature oxidation resistance with improved strength and creep resistance, making it an outstanding choice for furnace components, radiant tubes, heat-treatment equipment and other applications requiring long-term performance under load at elevated temperatures.
As a professional China steel mill-Direct Supply, SHH STEEL provides high-quality AISI 309H Stainless Steel Plate with competitive pricing, full certification and complete technical support.
Contact SHH STEEL today for stock availability, surface finish options (including AISI 309H No.1 and AISI 309H 2B), or a competitive quotation.
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