AISI 309 Stainless Steel Plate | 309 China steel mill-Direct Supply
What is AISI 309 Stainless Steel Plate?
As a professional China steel mill-Direct Supply and stainless steel plate supplier, SHH STEEL is pleased to present AISI 309 Stainless Steel Plate.
AISI 309 (UNS S30900) is a heat-resisting austenitic stainless steel containing approximately 22–24% chromium and 12–15% nickel. The higher alloy content provides significantly better oxidation resistance and high-temperature strength compared with the 304 and 308 families. It is widely used for furnace components, heat-treatment equipment, radiant tubes, kiln parts and other applications involving continuous or intermittent exposure to elevated temperatures.
The grade is non-magnetic in the annealed condition and offers good toughness and formability. While the standard AISI 309 has a higher carbon content, the low-carbon version 309S is often preferred for welded constructions to minimize the risk of intergranular corrosion. AISI 309H is selected when higher creep strength is required.
SHH STEEL supplies AISI 309 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 309 in plate and sheet form across a practical range of thicknesses and surface finishes suitable for high-temperature service.
AISI 309 is frequently compared with a240 304, a240 304l, a240 309s, a240 310s, a240 310h 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 309 / UNS S30900 | 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 309 dual-certified to ASTM A240 / ASME SA240 when required by the project. Related low-carbon and high-carbon variants such as a240 309s are also available.
Chemical Composition
Typical Chemical Composition of AISI 309 (UNS S30900):
| Element | Content (%) |
|---|---|
| Carbon (C) | ≤ 0.20 |
| 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 high chromium (22–24%) and nickel (12–15%) contents are the defining features of AISI 309. These elevated levels provide excellent resistance to oxidation and scaling at temperatures up to approximately 1000–1100°C in continuous service (depending on the environment and cycle conditions). SHH STEEL carefully controls composition to ensure reliable high-temperature performance.
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 309 retains useful strength and excellent oxidation resistance. For applications requiring higher creep strength, the controlled high-carbon version or related grades such as a240 310h may be preferred. SHH STEEL supplies material with consistent high-temperature 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
Material Comparison
| Grade | Cr (%) | Ni (%) | Max Service Temp (approx.) | Oxidation Resistance | Typical Preference |
|---|---|---|---|---|---|
| AISI 304 | 18–20 | 8–10.5 | ~870°C | Good | General purpose |
| AISI 308 | 19–21 | 10–12 | ~900°C | Better | Moderate high-temp / welding |
| AISI 309 | 22–24 | 12–15 | ~1000–1100°C | Very Good | High-temperature oxidizing service |
| AISI 309S | 22–24 | 12–15 | ~1000–1100°C | Very Good | Welded high-temperature service |
| AISI 310S | 24–26 | 19–22 | ~1100°C | Excellent | Severe high-temperature service |
| AISI 321 | 17–19 | 9–12 | ~900°C | Good | Stabilized high-temp welded service |
AISI 309 offers a significant improvement in oxidation resistance and high-temperature capability over a240 304 and a240 304l. For welded constructions, SHH STEEL often recommends the low-carbon version a240 309s. For the most severe high-temperature oxidizing environments, a240 310s or a240 310h is preferred.
Corrosion Resistance
AISI 309 provides excellent resistance to oxidation and scaling in air and oxidizing atmospheres at elevated temperatures. It also offers good resistance to atmospheric corrosion and many mild chemical environments at room temperature.
In sulfur-containing or carburizing atmospheres, performance may be limited. For more aggressive high-temperature environments or when higher nickel is beneficial, SHH STEEL recommends a240 310s. In chloride-rich aqueous service, a240 316l or a240 2205 should be considered.
Weldability
AISI 309 has good weldability using standard fusion welding methods. Matching or 309/309L filler metals are commonly used. Due to the higher carbon content of standard 309, the low-carbon version a240 309s is preferred for welded constructions to reduce the risk of intergranular corrosion.
SHH STEEL recommends proper welding procedures and, where necessary, post-weld solution annealing for critical high-temperature service.
Heat Treatment
AISI 309 is normally supplied in the solution-annealed condition by SHH STEEL.
Recommended solution annealing temperature range is 1040–1150°C, followed by rapid cooling. Proper annealing optimizes both room-temperature ductility and high-temperature performance. SHH STEEL controls heat treatment to ensure consistent quality for elevated-temperature applications.
Surface Finishes
| Finish | Description | Typical Use / Keywords |
|---|---|---|
| No.1 | Hot-rolled, annealed and pickled | AISI 309 No.1 – most common for industrial high-temp plate |
| 2B | Cold-rolled, annealed, pickled, skin-passed | AISI 309 2B – thinner plates |
| Special | Ground or custom finishes | AISI 309 Special – on request |
SHH STEEL regularly supplies AISI 309 in No.1 finish, which is the preferred condition for most high-temperature plate applications.
Tolerances
Dimensional tolerances for AISI 309 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 309 | — | — |
| UNS S30900 | — | Unified Numbering System |
| ASTM A240 Type 309 | ASTM A240 | When dual certified |
| Related 309 / 309S / 309H | 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 309 is selected for applications requiring excellent high-temperature oxidation resistance and good strength at elevated temperatures. Typical applications of AISI 309 include:
| Industry / Sector | Typical Components / Equipment (with keywords) |
|---|---|
| Heat Treatment & Furnaces | AISI 309 furnace components, radiant tubes, fixtures, trays |
| Industrial Heating | AISI 309 kiln parts, muffles, supports and retorts |
| Power Generation | AISI 309 high-temperature ducting and structural parts |
| Petrochemical & Refining | AISI 309 furnace linings and process equipment |
| Chemical Processing | AISI 309 high-temperature vessels and components |
| General High-Temperature Service | AISI 309 equipment operating in oxidizing atmospheres |
SHH STEEL supplies AISI 309 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 309 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)
- Material optimized for high-temperature oxidation resistance
- Flexible dimensions and surface finishes (including AISI 309 No.1 and AISI 309 2B)
- Technical support for selection among 309, 309S, 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 309 over AISI 304?The significantly higher chromium and nickel contents provide much better oxidation resistance and high-temperature strength. SHH STEEL recommends 309 for continuous or intermittent service at elevated temperatures.
- Should I choose AISI 309 or AISI 309S?AISI 309S (low carbon) is preferred for welded constructions to reduce the risk of intergranular corrosion. SHH STEEL can supply both versions according to project requirements.
- How does AISI 309 compare with AISI 310S?AISI 310S offers even higher chromium and nickel contents and superior oxidation resistance for more severe high-temperature service. SHH STEEL recommends 310S when maximum performance is required.
Conclusion
AISI 309 Stainless Steel Plate is a high-chromium, high-nickel austenitic grade specifically designed for elevated-temperature service. It offers excellent oxidation resistance and good strength at high temperatures, making it an outstanding choice for furnace components, heat-treatment equipment, radiant tubes and other industrial heating applications.
As a professional China steel mill-Direct Supply, SHH STEEL provides high-quality AISI 309 Stainless Steel Plate with competitive pricing, full certification and complete technical support.
Contact SHH STEEL today for stock availability, surface finish options (including AISI 309 No.1 and AISI 309 2B), or a competitive quotation.
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