SUS310S Stainless Steel Knowledge

SUS310S is a premium high-temperature austenitic stainless steel (24-26% Cr, 19-22% Ni), known as "heat-resistant stainless steel". It offers exceptional oxidation resistance up to 1200°C and creep resistance, suitable for the harshest high-temperature industrial environments.

: C ≤0.08, Si ≤1.50, Mn ≤2.00, P ≤0.045, S ≤0.030, Cr=24.00-26.00, Ni=19.00-22.00, Fe=Balance

: Tensile Strength ≥515MPa, Yield Strength ≥205MPa, Elongation ≥40%, Hardness (HB) ≤217

: Excellent oxidation resistance at 1000-1200°C; superior creep resistance at 800-1100°C; strong thermal shock resistance; good corrosion resistance in high-temp gases.

: ASTM A240 310S, EN 1.4845, UNS S31008

: Industrial furnace cores, jet engine exhaust components, high-temperature heat exchanger tubes, incinerator linings, nuclear power plant high-temp parts.

1. Q: Why can SUS310S withstand 1200°C? A: Its high Cr (24-26%) and Ni (19-22%) content is key. At 1200°C, it forms a dense, stable Cr₂O₃-NiO composite oxide layer, preventing further oxidation. High Ni stabilizes the austenitic structure, avoiding brittle sigma phase formation at high temps. The alloy's grain boundary strength resists creep, even under constant load at 1100°C. This makes it the top choice for ultra-high-temp industrial equipment.

2. Q: Is SUS310S suitable for high-temperature corrosive gases? A: Yes, it resists most high-temp gases (combustion flue gas, steam, carbon dioxide). It handles sulfur-containing gases (up to 5% SO₂) at 800°C, better than SUS309S. However, in high-temp hydrogen sulfide (H₂S) or chlorine gas, it may corrode-use Hastelloy instead. For waste incinerator flue gas (complex components), it's the most cost-effective material, resisting acid gases and high temps.

3. Q: What are the welding challenges of SUS310S? A: High Ni content increases weld pool viscosity, requiring higher heat input (150-200A for TIG). Use ER310 filler metal to match Cr/Ni. Preheat to 150-200°C for plates ≥20mm to prevent cold cracking. Post-weld annealing at 1050-1100°C relieves stress and restores corrosion resistance. Avoid rapid cooling, as it may cause hot cracking. Welders need experience to control pool flow and avoid defects.

4. Q: How to distinguish SUS310S from SUS309S? A: Two methods. First, chemical analysis: SUS310S has Ni≥19% and Cr≥24%, while SUS309S has Ni≤15% and Cr≤24%. Second, high-temp test: heat samples to 1150°C for 1 hour-SUS310S has no significant scaling, SUS309S shows light scaling. For practical use, check material certificates, as visual distinction is impossible.

5. Q: When to choose SUS310S over other heat-resistant materials? A: Choose it for temps ≥1100°C, or 800-1100°C with harsh conditions (corrosive gases, high stress). For example, incinerator linings (1100°C) or jet engine parts (1200°C) need its performance. It's cheaper than nickel-based alloys (Inconel 600) but more expensive than SUS309S. For temps ≤1100°C and mild environments, SUS309S is cost-effective; for ultra-high temps or harsh conditions, SUS310S is necessary.