309Si2 High-Temperature Austenitic Stainless Steel Plate
Premium high-temperature austenitic stainless steel plate for extreme thermal and corrosive environments
309Si2 stainless steel plate is engineered for exceptional performance in extreme high-temperature environments exceeding 1,000°C. Combines superior oxidation resistance with excellent corrosion protection in thermal cycling applications including furnace liners, combustion chambers, and industrial thermal processing equipment.
Quick Specifications
- Werkstoff Number
- 1.4833
- Yield Strength (Annealed at 20°C)
- 260 MPa (38 ksi) minimum
- Tensile Strength (Annealed at 20°C)
- 540 MPa (78 ksi) minimum
- Elongation (Annealed)
- 40% minimum
- Tensile Strength (at 800°C)
- 150 MPa (maintaining integrity)
- Tensile Strength (at 1,000°C)
- 50 MPa (retaining structural capability)
Standards & Certifications
Product Description
309Si2 is a premium high-temperature austenitic stainless steel specifically developed for applications requiring sustained service at temperatures exceeding 1,000°C. The composition with 23% chromium and 20% nickel provides exceptional oxidation resistance and maintains adequate strength at extreme temperatures where conventional stainless steels would lose mechanical integrity. The addition of silicon significantly enhances the growth of protective oxide scales and improves scaling resistance during thermal cycling between elevated temperature and ambient conditions.
The microstructure of 309Si2 develops through controlled casting, hot rolling, and precise annealing to eliminate all deleterious carbides and create a stable austenitic matrix. The 23% chromium content exceeds that of 310 stainless, allowing development of highly protective chromium oxide layers that resist oxidation at temperatures approaching 1,100°C. The higher nickel content compared to standard 304 ensures retention of austenitic stability at extreme temperatures where ferrite formation could occur in lower-nickel compositions.
309Si2 plate demonstrates exceptional resistance to cyclic oxidation, a critical requirement for furnace liners, combustion chambers, and thermal processing equipment that experiences temperature cycling between operating temperature and ambient conditions. Each thermal cycle creates mechanical stress as the oxide layer expands and contracts differently than the substrate metal. The silicon addition promotes the formation of dense, protective oxide scales that resist spalling and maintain adhesion to the substrate even after repeated thermal cycling.
The material is available in multiple thicknesses for both structural and pressure vessel applications. Heavy plate sections (up to 50 mm) are readily available from qualified suppliers for fabrication into large furnace liners and thermal equipment components. The material is readily machinable in the annealed condition and can be precision cut to complex shapes for application-specific requirements. Vacuum induction melting and casting ensure internal cleanliness essential for reliable high-temperature service.
Specifications
| Werkstoff Number | 1.4833 |
| Yield Strength (Annealed at 20°C) | 260 MPa (38 ksi) minimum |
| Tensile Strength (Annealed at 20°C) | 540 MPa (78 ksi) minimum |
| Elongation (Annealed) | 40% minimum |
| Tensile Strength (at 800°C) | 150 MPa (maintaining integrity) |
| Tensile Strength (at 1,000°C) | 50 MPa (retaining structural capability) |
| Density | 8.1 g/cm³ |
| Modulus of Elasticity | 190 GPa |
| Thermal Conductivity (at 20°C) | 17 W/m·K |
| Thermal Conductivity (at 800°C) | 28 W/m·K |
| Coefficient of Linear Expansion (0-100°C) | 16.0 × 10⁻⁶ /°C |
| Maximum Continuous Service Temperature | 1,100°C (2,010°F) |
Chemical Composition
| Element | Content (%) |
|---|---|
| Chromium (Cr) | 22.0-24.0 |
| Nickel (Ni) | 19.0-21.0 |
| Silicon (Si) | 2.0-3.0 |
| Carbon (C) | 0.08 max |
| Manganese (Mn) | 2.0 max |
| Phosphorus (P) | 0.045 max |
| Sulfur (S) | 0.030 max |
| Nitrogen (N) | 0.10 max |
| Iron (Fe) | Balance |
Mechanical Properties
| Property | Value |
|---|---|
| Hardness (Annealed) | 217-268 HV |
| Impact Strength (Charpy V-notch) | 100+ J at room temperature |
| Creep Strength (100,000 hours at 900°C) | 90 MPa |
| Oxidation Resistance (Scaling Resistance) | Excellent to 1,100°C |
| Thermal Fatigue Resistance | Superior to standard austenitic stainless steels |
| Thermal Shock Resistance | Excellent with controlled cooling |
Key Features & Advantages
Applications
Industrial Furnace Liners
High-temperature furnace liners, retorts, and combustion chamber components in steel mills, heat treatment facilities, and industrial furnaces operating continuously at 1,000-1,100°C with frequent thermal cycling requirements.
Thermal Processing Equipment
Radiant tubes, heating elements supports, and furnace internals in heat treatment, annealing, and industrial processing applications requiring sustained high-temperature exposure and excellent oxidation resistance.
Recuperators and Heat Exchangers
High-temperature heat recovery equipment, waste heat boilers, and thermal exchange systems recovering heat from furnace exhaust gases at extreme temperatures.
Combustion Systems
Industrial burner components, combustion chamber liners, and thermal oxidizer internals in industrial heating and waste gas incineration systems.
Petrochemical Equipment
Reformer furnace tubes, cracking furnace components, and high-temperature reactor vessels in petroleum refining and chemical processing.
Power Generation
Boiler superheater components, high-temperature piping, and thermal equipment in power plants and industrial steam generation systems.
Frequently Asked Questions
What is the maximum temperature 309Si2 can withstand continuously?
How does 309Si2 compare to 310 stainless steel?
Can 309Si2 plate be welded, and what special procedures are required?
How does 309Si2 perform in thermal cycling applications?
What is the expected service life of 309Si2 furnace liners?
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