SUS310S Stainless Steel

SUS310S is a high-chromium, high-nickel austenitic stainless steel renowned for its exceptional high-temperature oxidation resistance and creep strength. As a low-carbon variant of SUS310, it minimizes sensitization and intergranular corrosion risk, making it the top choice for extreme thermal environments where other stainless steel grades fail. Its balanced alloy composition ensures stability in both oxidizing and reducing atmospheres.

Chemical Composition (wt%): 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.

Mechanical Properties (Annealed): Tensile Strength ≥ 520 MPa, Yield Strength ≥ 205 MPa, Elongation ≥ 40%, Hardness (HB) ≤ 201.

Performance Advantages: Outstanding oxidation resistance up to 1150°C; excellent creep strength at high temperatures; low-carbon design reduces intergranular corrosion; good weldability and formability; resistance to sulfur-containing and carburizing atmospheres.

Equivalent Grades: ASTM A240 310S, EN 1.4845, UNS S31008.

Applications: Furnace muffles, radiant tubes, heat treatment equipment, incinerators, petrochemical reactors, and high-temperature conveyor systems.

FAQ

Q: What is the maximum continuous operating temperature of SUS310S?A: SUS310S can operate continuously at temperatures up to 1150°C in oxidizing atmospheres, making it one of the most heat-resistant austenitic stainless steel grades available. This exceptional high-temperature performance is attributed to its high chromium and nickel content, which stabilizes the austenitic structure and forms a dense, protective chromium oxide film on the surface. At temperatures above 1150°C, the oxide layer may start to break down, leading to accelerated oxidation and scaling, but the steel can still withstand short-term exposure to higher temperatures in emergency situations. In reducing atmospheres, the maximum operating temperature is slightly lower, around 1040°C, to prevent carbide precipitation and embrittlement. The steel's ability to maintain its mechanical properties and corrosion resistance at such high temperatures makes it ideal for critical applications like furnace muffles and radiant tubes, where other grades would quickly degrade.

Q: How does SUS310S perform in carburizing atmospheres?A: SUS310S has excellent resistance to carburizing atmospheres, which are common in heat treatment processes like carburizing and carbonitriding. In these environments, carbon atoms diffuse into the steel surface, but the high chromium content of SUS310S forms a stable chromium carbide layer that prevents excessive carbon penetration and maintains the steel's structural integrity. Unlike lower-chromium grades like SUS304, which can become brittle or lose their corrosion resistance in carburizing atmospheres, SUS310S retains its toughness and ductility, ensuring long-term durability. The low-carbon content of SUS310S also minimizes the risk of internal carbide formation, which could compromise the steel's mechanical properties. This resistance to carburization makes SUS310S a preferred choice for furnace components that are exposed to high temperatures and carbon-rich gases, such as retorts and heating elements.

Q: What welding methods are suitable for SUS310S?A: SUS310S can be welded using all standard fusion welding techniques, including TIG, MIG, SMAW, and submerged arc welding. Its high nickel content ensures good weld pool fluidity and reduces the risk of hot cracking, a common issue in high-chromium steels. When welding SUS310S, it is recommended to use a filler metal with a similar or higher chromium and nickel content to maintain the steel's high-temperature performance and corrosion resistance. For example, using a 310 or 310L filler metal ensures that the weld joint has the same oxidation resistance as the base metal, preventing premature failure in high-temperature applications. The low-carbon content of SUS310S also means that the heat-affected zone (HAZ) has good intergranular corrosion resistance, eliminating the need for post-weld heat treatment in most cases. However, for thick sections or applications involving exposure to corrosive environments, a post-weld anneal may be recommended to further enhance the corrosion resistance of the HAZ.

Q: How does SUS310S compare to nickel-based alloys in high-temperature applications?A: SUS310S offers a cost-effective alternative to nickel-based alloys like Inconel and Hastelloy in many high-temperature applications, while providing comparable oxidation resistance up to 1150°C. Nickel-based alloys have higher nickel content and often include additional alloying elements like molybdenum and tungsten, which give them superior resistance to corrosion in aggressive chemical environments and higher creep strength at extreme temperatures. However, these alloys are significantly more expensive than SUS310S, making them less practical for cost-sensitive applications. SUS310S is an excellent choice for applications where oxidation resistance is the primary requirement, such as furnace liners and radiant tubes, while nickel-based alloys are better suited for applications involving corrosive chemicals or extremely high temperatures above 1150°C. In terms of weldability and formability, SUS310S is easier to fabricate than most nickel-based alloys, reducing manufacturing costs and lead times.

Q: Can SUS310S be used in acidic environments?A: SUS310S has moderate resistance to dilute acids like sulfuric acid and hydrochloric acid at room temperature, but it is not recommended for use in concentrated acidic environments or at elevated temperatures. Its high chromium content provides some protection against acid attack, but it lacks the molybdenum content found in grades like SUS316, which is essential for resisting pitting and crevice corrosion in acidic media. In dilute acids, SUS310S can be used for short-term applications, but prolonged exposure will lead to gradual corrosion and degradation. For acidic environments, grades like SUS316 or nickel-based alloys are more suitable, as they have better corrosion resistance and can withstand higher acid concentrations. However, SUS310S performs well in neutral and alkaline environments, making it ideal for applications like boiler components and chemical reactors that handle non-acidic fluids at high temperatures.