Overview
SS309 (AISI 309 Stainless Steel) is a high-temperature austenitic stainless steel belonging to the 300 Series Stainless Steel Family. With higher chromium and nickel content than SS304, SS309 provides outstanding oxidation resistance, excellent heat resistance, and good corrosion resistance in elevated-temperature environments.
SS309 is specifically designed for continuous service at temperatures up to 1000°C–1100°C, making it a preferred material for furnaces, heat treatment equipment, combustion systems, thermal processing machinery, and petrochemical applications.
Compared with SS304, SS309 offers significantly better heat resistance. Compared with SS310, SS309 provides slightly lower temperature capability but at a more economical cost.
Material Specification
| Property | Value |
|---|---|
| Material Designation | AISI 309 |
| Material Family | Austenitic Heat-Resistant Stainless Steel |
| UNS Number | S30900 |
| EN Grade | 1.4828 |
| Density | 7.90 g/cm³ |
| Magnetic Property | Non-Magnetic (Annealed) |
| Standard Forms | Sheet, Plate, Coil, Pipe, Tube, Bar, Wire |
Chemical Composition
| Element | Content (%) |
|---|---|
| Iron (Fe) | Balance |
| Chromium (Cr) | 22.0–24.0 |
| Nickel (Ni) | 12.0–15.0 |
| Carbon (C) | ≤0.20 |
| Manganese (Mn) | ≤2.00 |
| Silicon (Si) | ≤1.00 |
| Phosphorus (P) | ≤0.045 |
| Sulfur (S) | ≤0.030 |
| Nitrogen (N) | ≤0.10 |
Mechanical Properties
Annealed Condition
| Property | Value |
|---|---|
| Tensile Strength | ≥515 MPa |
| Yield Strength | ≥205 MPa |
| Elongation | ≥40% |
| Hardness | ≤95 HRB |
| Elastic Modulus | 200 GPa |
Physical Properties
| Property | Value |
|---|---|
| Density | 7.90 g/cm³ |
| Melting Point | 1400–1455°C |
| Thermal Conductivity | 14.6 W/m·K |
| Electrical Resistivity | 0.78 μΩ·m |
| Thermal Expansion Coefficient | 15.6 × 10⁻⁶/K |
| Specific Heat Capacity | 500 J/kg·K |
High Temperature Performance
| Temperature | Performance |
|---|---|
| 600°C | Excellent |
| 800°C | Excellent |
| 900°C | Excellent |
| 1000°C | Very Good |
| 1050°C | Good |
| 1100°C | Intermittent Service |
Maximum Service Temperature
| Condition | Temperature |
|---|---|
| Continuous Service | 1000°C |
| Intermittent Service | 1095°C |
Corrosion Resistance
| Environment | Performance |
|---|---|
| Atmospheric Exposure | Excellent |
| Industrial Environment | Excellent |
| High Temperature Oxidation | Outstanding |
| Sulfidation Resistance | Very Good |
| Marine Environment | Good |
| Chloride Environment | Moderate |
The high chromium content provides excellent oxidation resistance under cyclic and continuous high-temperature exposure.
International Equivalent Grades
| Standard | Equivalent Grade |
|---|---|
| ASTM / AISI (USA) | 309 |
| UNS | S30900 |
| EN (Europe) | 1.4828 |
| DIN (Germany) | X15CrNiSi20-12 |
| JIS (Japan) | SUS309 |
| GB/T (China) | 0Cr23Ni13 |
| ISO | X15CrNiSi20-12 |
Available Forms
| Product Type | Availability |
|---|---|
| Stainless Steel Sheet | Yes |
| Stainless Steel Plate | Yes |
| Stainless Steel Coil | Yes |
| Stainless Steel Pipe | Yes |
| Stainless Steel Tube | Yes |
| Stainless Steel Bar | Yes |
| Stainless Steel Wire | Yes |
| Heat Resistant Castings | Yes |
Typical Applications
Heat Treatment Industry
- Furnace Components
- Furnace Liners
- Furnace Doors
- Heat Treatment Fixtures
- Retorts
Petrochemical Industry
- Refinery Equipment
- Thermal Reactors
- Heat Exchangers
- Combustion Systems
Power Generation
- Boiler Components
- Burner Assemblies
- Flue Gas Systems
- Exhaust Equipment
Industrial Heating Equipment
- Kilns
- Ovens
- Incinerators
- Thermal Processing Systems
Metallurgical Industry
- Annealing Equipment
- Heat Shields
- Furnace Conveyors
- Material Handling Systems
Cement & Glass Industry
- Kiln Components
- Thermal Chambers
- High Temperature Supports
Manufacturing Characteristics
| Manufacturing Process | Rating |
|---|---|
| Laser Cutting | Excellent |
| Plasma Cutting | Excellent |
| Waterjet Cutting | Excellent |
| CNC Machining | Good |
| Welding | Excellent |
| TIG Welding | Excellent |
| MIG Welding | Excellent |
| Forming | Good |
| Bending | Good |
| Polishing | Good |
Advantages
Excellent Heat Resistance
Maintains strength and oxidation resistance at elevated temperatures.
Outstanding Oxidation Resistance
Suitable for continuous exposure to high-temperature atmospheres.
Good Corrosion Resistance
Performs well in industrial and chemical environments.
Excellent Weldability
Suitable for fabricated high-temperature equipment.
Thermal Shock Resistance
Handles repeated heating and cooling cycles.
Long Service Life
Ideal for industrial thermal processing systems.
Limitations
Higher Cost Than SS304
Due to increased nickel and chromium content.
Lower Corrosion Resistance Than SS316
Not optimized for chloride-rich environments.
Lower Maximum Temperature Than SS310
Not suitable for the highest temperature applications.
Moderate Machinability
More difficult to machine than SS303.
Comparison with Other Stainless Steels
| Property | SS309 | SS304 | SS310 | SS316 | SS321 |
|---|---|---|---|---|---|
| Heat Resistance | Excellent | Good | Outstanding | Good | Excellent |
| Oxidation Resistance | Excellent | Good | Outstanding | Good | Excellent |
| Corrosion Resistance | Excellent | Excellent | Excellent | Outstanding | Excellent |
| Weldability | Excellent | Excellent | Excellent | Excellent | Excellent |
| Continuous Service Temperature | 1000°C | 870°C | 1150°C | 870°C | 900°C |
| Cost | High | Medium | Very High | High | High |
Comparison with Common Heat Resistant Materials
| Material | Max Service Temp | Corrosion Resistance | Cost |
|---|---|---|---|
| SS309 | 1000°C | Excellent | High |
| SS310 | 1150°C | Excellent | Very High |
| SS321 | 900°C | Excellent | High |
| Inconel 600 | 1175°C | Outstanding | Very High |
| Carbon Steel | 500°C | Poor | Low |
| Cast Iron | 600°C | Poor | Low |
Available Surface Finishes
Mill Finishes
- No.1 Finish
- 2B Finish
- BA Finish
- Hot Rolled Finish
Industrial Finishes
- Pickled Finish
- Descaled Surface
- Passivated Surface
Decorative Finishes
- Satin Finish
- Brushed Finish
- Mirror Polish
- Glass Bead Finish
Frequently Asked Questions (FAQ)
What is SS309 stainless steel?
SS309 is a high-temperature austenitic stainless steel designed for oxidation resistance and elevated-temperature service.
What is SS309 used for?
Typical applications include:
- Industrial Furnaces
- Heat Treatment Equipment
- Petrochemical Systems
- Kilns
- Burners
- High Temperature Exhaust Systems
Is SS309 better than SS304?
For high-temperature applications, yes.
| Property | SS309 | SS304 |
|---|---|---|
| Heat Resistance | Much Higher | Moderate |
| Oxidation Resistance | Better | Lower |
| Continuous Service Temp | 1000°C | 870°C |
What is the difference between SS309 and SS310?
| Property | SS309 | SS310 |
|---|---|---|
| Chromium Content | 22–24% | 24–26% |
| Nickel Content | 12–15% | 19–22% |
| Max Temperature | 1000°C | 1150°C |
| Cost | Lower | Higher |
Is SS309 suitable for furnace applications?
Yes. SS309 is widely used for industrial furnace components and heat treatment fixtures.
Can SS309 be welded?
Yes. SS309 offers excellent weldability and is commonly fabricated into high-temperature equipment.
Is SS309 food grade?
While technically corrosion resistant, SS309 is generally selected for thermal applications rather than food processing equipment.
Why is SS309 used in heat treatment furnaces?
Because it combines:
- High Temperature Strength
- Excellent Oxidation Resistance
- Good Weldability
- Long Service Life
making it ideal for thermal processing environments.
Does GCNOV provide custom manufacturing services for SS309?
Yes. GCNOV provides:
- CNC Machining
- Laser Cutting
- Plasma Cutting
- Sheet Metal Fabrication
- Furnace Component Manufacturing
- Welding & Assembly
- Heat Resistant Fabrication
- Prototype Development
- Low-Volume Production
- Mass Production