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DIN 1.4845 Stainless Steel: High-Temperature Heat-Resistant Austenitic Alloy for Industrial Furnaces
DIN 1.4845 (UNS S30815) is a high-carbon austenitic stainless steel specifically engineered for elevated temperature applications up to 1150°C. This grade combines 20% chromium and 11% nickel with controlled silicon and rare earth element additions to deliver exceptional oxidation resistance, creep strength, and thermal fatigue performance. Widely adopted in furnace components, heat treatment equipment, and thermal processing systems, DIN 1.4845 outperforms standard 304/316 grades in continuous high-temperature service while maintaining structural integrity under cyclic heating conditions.
1. Chemical Composition (DIN EN 10095 Standard)
| Element | Content Range | Function |
|---|---|---|
| Carbon (C) | 0.08 – 0.12% | Enhances high-temperature strength via carbide formation; higher than 304 for improved creep resistance |
| Chromium (Cr) | 19.00 – 21.00% | Forms protective Cr₂O₃ oxide layer; critical for oxidation resistance above 800°C |
| Nickel (Ni) | 10.00 – 12.00% | Stabilizes austenitic microstructure; improves ductility and thermal shock resistance |
| Silicon (Si) | 1.40 – 2.00% | Enhances oxide scale adhesion; increases resistance to spalling during thermal cycling |
| Manganese (Mn) | ≤ 2.00% | Deoxidizer; improves hot workability during rolling/forging |
| Phosphorus (P) | ≤ 0.040% | Minimized to prevent embrittlement at grain boundaries |
| Sulfur (S) | ≤ 0.015% | Ultra-low to prevent hot cracking and improve weldability |
| Cerium (Ce) | 0.03 – 0.08% | Rare earth addition; refines oxide scale microstructure for improved spallation resistance |
2. Mechanical Properties at Elevated Temperatures
| Property | Room Temp | 600°C | 800°C | 1000°C |
|---|---|---|---|---|
| Tensile Strength (MPa) | ≥ 590 | ≥ 340 | ≥ 180 | ≥ 90 |
| Yield Strength (MPa) | ≥ 295 | ≥ 170 | ≥ 90 | ≥ 45 |
| Elongation (%) | ≥ 35 | ≥ 25 | ≥ 20 | ≥ 15 |
| Creep Rupture Strength (100,000h, MPa) | – | 120 | 60 | 25 |
3. Thermal and Physical Properties
- Density: 7.9 g/cm³ (identical to standard austenitic grades)
- Melting Range: 1400-1450°C (narrower than 304 due to controlled composition)
- Thermal Conductivity (20°C): 14.6 W/m·K (20% lower than carbon steel)
- Coefficient of Thermal Expansion (20-100°C): 16.5 μm/m·K (higher than ferritic grades)
- Specific Heat Capacity (20°C): 500 J/kg·K (enables efficient heat absorption)
- Maximum Continuous Service Temperature: 1150°C in air (1050°C in sulfurous atmospheres)
4. Manufacturing and Heat Treatment
- Melting Practice: Electric arc furnace (EAF) + AOD refining with vacuum degassing to achieve ultra-low sulfur and inclusion control. Rare earth metals added during ladle treatment.
- Hot Working: Forged or rolled at 1150-1250°C with minimum 20% reduction per pass. Final hot working temperature ≥ 950°C to prevent sigma phase formation.
- Solution Annealing: 1050-1150°C followed by water quenching or rapid air cooling to dissolve all carbides and restore corrosion resistance.
- Stabilization Treatment: Optional 850-900°C soak for 2-4 hours to precipitate chromium carbides at grain boundaries, enhancing resistance to intergranular corrosion after welding.
- Surface Finishing: Shot blasting or pickling (HNO₃/HF mixture) to remove oxide scale. Passivation with nitric acid (20-30%) for enhanced corrosion resistance.
5. Primary Industrial Applications
Furnace Components
Radiant tubes, muffles, retorts, and hearth plates in heat treatment furnaces. Resists oxidation and carburization in endothermic atmospheres up to 1100°C.
Petrochemical Processing
Reformer tubes, pyrolysis coils, and catalyst support grids in ethylene crackers. Withstands coke formation and thermal cycling in hydrocarbon environments.
Power Generation
Boiler superheater tubes, heat exchangers in waste-to-energy plants, and biomass gasification systems. Compatible with steam temperatures up to 650°C.
Glass Manufacturing
Regenerator checker bricks, molten glass contact components, and forehearth equipment. Resists alkali vapor corrosion from glass batch materials.
Automotive Exhaust Systems
Manifolds, turbocharger housings, and catalytic converter shells for high-performance vehicles. Maintains strength under thermal fatigue from exhaust gases.
Aerospace Components
Combustion chamber liners, afterburner parts, and thermal protection systems. Certified for applications requiring MIL-S-862 and AMS 5572 compliance.
6. Comparison with Competing High-Temperature Alloys
| Property | DIN 1.4845 | 309S (1.4833) | 310S (1.4845) | 253MA (1.4835) | Incoloy 800H |
|---|---|---|---|---|---|
| Max Service Temp (°C) | 1150 | 1050 | 1150 | 1150 | 1100 |
| Carbon Content (%) | 0.08-0.12 | ≤0.08 | ≤0.08 | 0.05-0.10 | 0.05-0.10 |
| Creep Strength (800°C) | Excellent | Good | Very Good | Excellent | Very Good |
| Oxidation Resistance | Excellent | Very Good | Excellent | Excellent | Excellent |
| Cost Relative to 304 | 2.2x | 1.8x | 2.5x | 2.8x | 3.5x |
| Weldability | Good (preheat 150°C) | Very Good | Good | Fair | Good |
7. Fabrication and Handling Recommendations
- Machining: Use carbide tools with positive rake angles. Maintain slow speeds (50-70 m/min) and heavy feeds to avoid work hardening. Coolant recommended.
- Forming: Hot forming preferred for complex shapes (900-1150°C). Cold forming requires intermediate annealing due to high work hardening rate.
- Welding: Preheat to 150-200°C for thick sections (>10mm). Use AWS E309-15 electrodes or ER309LSi filler wire. Post-weld annealing at 1050-1100°C for critical applications.
- Thermal Cycling: Avoid rapid cooling from temperatures above 700°C to prevent sigma phase formation. Controlled cooling rates <100°C/h recommended.
- Corrosive Environments: Not suitable for aqueous corrosion applications. In sulfur-bearing atmospheres (>50ppm S), maximum temperature reduces to 1000°C.
- Quality Certification: Verify material test reports (MTR) confirm DIN EN 10095 compliance. Ultrasound testing recommended for pressure-containing components.
8. Request DIN 1.4845 Stainless Steel Quotation
Require high-temperature stainless steel solutions for your industrial applications? Our inventory includes DIN 1.4845 in sheets, plates, bars, and custom fabricated components with full traceability and test certification. Contact our metallurgical specialists for technical support or competitive pricing on your next project.
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