In the intense heat of steel mills or the complex high-temperature piping systems of chemical plants, what material can withstand these extreme conditions while ensuring safe and stable equipment operation? The answer lies in 310/310S/310H heat-resistant stainless steel plates. With exceptional high-temperature oxidation resistance and excellent corrosion resistance, these alloys have become the ideal choice for demanding thermal applications.
The 310/310S/310H stainless steel represents a versatile austenitic heat-resistant stainless steel that offers oxidation resistance up to 1100°C (2010°F) under mild cyclic conditions. Its high chromium and moderate nickel content provide resistance to sulfidation, making it suitable for moderately carburizing atmospheres. For more severe carburizing conditions in heat treatment equipment, nickel alloys like 330 (UNS N08330) are typically required.
This alloy performs well in mildly oxidizing, nitriding, carburizing, and thermal cycling applications, though maximum service temperatures must be reduced accordingly. It also demonstrates effectiveness in cryogenic applications, maintaining low magnetic permeability and toughness down to -268°C (-450°F).
When heated between 650–950°C (1202–1742°F), the alloy becomes susceptible to sigma phase precipitation. Solution annealing at 1100–1150°C (2012–2102°F) can restore some degree of toughness.
The 310S (UNS S31008) variant features lower carbon content for improved fabricability, while 310H (UNS S31009) contains higher carbon levels to enhance creep resistance. In most cases, the plate's grain size and carbon content can meet both 310S and 310H specifications.
- Exceptional high-temperature performance: Maintains excellent oxidation resistance and strength at temperatures up to 1100°C, ensuring stable operation in extreme thermal environments.
- Superior corrosion resistance: Effectively resists corrosion even in sulfide-containing or carburizing atmospheres, significantly extending equipment service life.
- Excellent fabrication characteristics: Easy to weld and form, accommodating various manufacturing processes to meet diverse application requirements.
- Good cryogenic toughness: Retains excellent toughness in low-temperature environments, suitable for cryogenic equipment and components.
- Multiple grade options: Available in 310, 310S, and 310H variants to address different application scenarios and customer-specific needs.
The 310 series stainless steel offers three variants, each optimized for specific applications:
- 310 (UNS S31000): The standard grade featuring balanced properties for general high-temperature applications requiring both strength and corrosion resistance.
- 310S (UNS S31008): A low-carbon version that improves weldability and reduces carbide precipitation risk during welding processes.
- 310H (UNS S31009): A high-carbon modification that enhances creep strength for long-term high-temperature exposure applications like furnace components.
- Cryogenic components
- Food processing equipment
- Furnace systems (burners, doors, fans, piping, regenerators)
- Fluidized bed furnaces (coal burners, grates, piping, windboxes)
- Mineral processing/steel plants (smelting equipment, continuous casting systems)
- Petroleum refining (catalytic recovery systems, flares, regenerators, pipe supports)
- Power generation (coal gasifier internals, pulverized coal burners, tube supports)
- Sintering/cement plants (burners, shields, feed/discharge systems, windboxes)
- Heat treatment (annealing covers/boxes, burner grates, doors, fans, muffles, retorts, regenerators, walking beams)
The 310 alloy isn't designed for wet corrosive environments. Its high carbon content (for creep resistance) adversely affects aqueous corrosion resistance. After prolonged high-temperature exposure, the alloy becomes susceptible to intergranular corrosion. However, its 25% chromium content provides better corrosion resistance than most heat-resistant alloys.
The alloy's high chromium (25%) and silicon (0.6%) content enhance its resistance to high-temperature corrosion in most service environments. Maximum working temperatures vary by conditions:
| Environment | Maximum Temperature |
|---|---|
| Oxidizing conditions (≤2g/m³ sulfur) | 1050°C continuous / 1100°C peak |
| Oxidizing conditions (>2g/m³ sulfur) | 950°C maximum |
| Low-oxygen atmospheres (≤2g/m³ sulfur) | 1000°C maximum |
| Nitriding or carburizing atmospheres | 850–950°C maximum |
| Element | 310 | 310S | 310H |
|---|---|---|---|
| Chromium | 24.0–26.0 | 24.0–26.0 | 24.0–26.0 |
| Nickel | 19.0–22.0 | 19.0–22.0 | 19.0–22.0 |
| Carbon | ≤0.25 | ≤0.08 | 0.04–0.10 |
| Manganese | ≤2.00 | ≤2.00 | ≤2.00 |
| Phosphorus | ≤0.045 | ≤0.045 | ≤0.045 |
| Sulfur | ≤0.030 | ≤0.030 | ≤0.030 |
| Silicon | ≤1.50 | ≤1.50 | ≤0.75 |
| Iron | Balance | Balance | Balance |
- Density: 7.89 g/cm³ (0.285 lb/in³)
- Specific heat capacity: 502 J/kg·K (0–100°C) [0.12 BTU/lb·°F (32–212°F)]
- Elastic modulus: 196 GPa (28.5×10⁶ psi)
- Thermal conductivity: 10.8 W/m·K [8.0 BTU·hr/ft²/ft/°F] at 100°C (212°F)
- Melting range: 1354–1402°C (2470–2555°F)
- Electrical resistivity: 78.0 μΩ·cm at 20°C (30.7 μΩ·in at 68°F)
| Yield Strength (0.2% offset) | Tensile Strength | Elongation (2") | Hardness |
|---|---|---|---|
| 35,000 psi (245 MPa) | 80,000 psi (550 MPa) | 45% min | 217 HB max |
The 310 alloy demonstrates excellent weldability and can be processed using standard shop fabrication techniques.
- Hot forming: Heat uniformly at 950–1200°C (1742–2192°F). After forming, final anneal at 1000–1150°C (1832–2101°F) followed by rapid quenching is recommended.
- Cold forming: The alloy shows good ductility and forms similarly to 316 stainless. Cold forming isn't recommended for components destined for long-term high-temperature service due to potential carbide and sigma phase precipitation.
- Welding: All standard processes including TIG, plasma, MIG, SMAW, SAW, and FCAW are suitable.