310S Stainless Steel (UNS S31008)
Austenitic (heat-resistant) · ASTM A240/A240M · Density 7.98 g/cm³
310S (UNS S31008) is a 25% chromium / 20% nickel austenitic stainless steel designed for high-temperature service. It resists oxidation up to about 1050 °C, making it the workhorse grade for furnace components, heat-treatment fixtures, radiant tubes and kiln linings.
Chemical Composition (wt%)
| C | Mn | Si | Cr | Ni | P | S |
|---|---|---|---|---|---|---|
| ≤0.08 | ≤2.00 | ≤1.50 | 24.0–26.0 | 19.0–22.0 | ≤0.045 | ≤0.030 |
Single values are maximums unless a range is shown. Balance: Fe. Per ASTM A240/A240M.
Mechanical Properties
| Tensile strength | ≥515 MPa (75 ksi) |
|---|---|
| Yield strength (0.2%) | ≥205 MPa (30 ksi) |
| Elongation (50 mm) | ≥40% |
| Oxidation resistance | up to ≈1050 °C |
Room-temperature minimum values are summarized for annealed flat product under ASTM A240/A240M unless a condition is named in the property label; product form and thickness can change the requirement.
Physical Properties & Structure
| Density | 7.98 g/cm³ |
|---|---|
| Magnetic response | Essentially non-magnetic after solution annealing; cold work can introduce a measurable magnetic response. |
| Microstructure | Austenitic (heat-resistant) |
Corrosion Resistance & Limits
- General corrosion resistance comes from the chromium-rich passive film; nickel, molybdenum, nitrogen and copper change performance by grade.
- Check chlorides, temperature, crevices, deposits, process chemistry and cleaning conditions. A grade designation alone is not a service-life guarantee.
Fabrication & Heat Treatment
| Welding | Generally weldable with a qualified procedure and matching or over-alloyed filler where required; remove heat tint when corrosion service demands it. |
|---|---|
| Forming | Good ductility is typical, but rapid work hardening increases forming load and springback; bend radius and intermediate annealing depend on grade and reduction. |
| Machining | Use rigid tooling, positive feeds and controlled heat because the material work-hardens; free-machining grades require separate corrosion and welding review. |
| Heat treatment | Solution annealing and rapid cooling restore the intended condition where applicable. Austenitic grades are not hardened by conventional quench-and-temper treatment. |
Equivalent Grades
The closest international equivalents of 310S Stainless Steel are 1.4845 (X8CrNi25-21) in the EN system, SUS310S in the JIS system, 06Cr25Ni20 in the GB system.
These are common corresponding designations, not unconditional substitutes. Verify chemistry, mechanical properties, product standard, delivery condition, dimensions and project approval before changing designation.
| System | Designation |
|---|---|
| UNS | S31008 |
| EN | 1.4845 (X8CrNi25-21) |
| JIS | SUS310S |
| GB | 06Cr25Ni20 |
Reference Product Forms & Dimensional Ranges
Common reference product forms for 310s stainless steel: Sheet / Plate, Coil / Strip, Pipe / Tube, Bar.
| Finishes | No.1, 2B |
|---|---|
| Sheet / coil thickness | 0.5–6.0 mm |
| Plate thickness | 6–60 mm |
Common surface and delivery options: No.1, 2B, BA or mechanically polished finish when supported by the product route; Annealed and pickled, descaled or polished tube finish as specified; Hot rolled, peeled, bright drawn, ground or polished bar condition according to tolerance.
These published ranges are engineering references, not a live-stock or production-capability promise. Confirm the required product form, dimensions, condition, finish and supply route in the quotation.
Typical Applications
- Furnace parts and muffles
- Heat treatment baskets and fixtures
- Radiant tubes and burner parts
- Kiln and boiler internals
Frequently Asked Questions
What temperature can 310S withstand?
310S resists scaling in air up to roughly 1050 °C continuous service, with short excursions higher. Thermal cycling lowers the practical limit, so fixture design and atmosphere matter as much as the alloy.
310 vs 310S — what is the difference?
310S is the lower-carbon version (C ≤0.08% versus ≤0.25% for 310). The lower carbon limit can improve weldability and reduce carbide-related effects; specify the required designation and verify it on the MTC.
Is 310S resistant to carburizing atmospheres?
Its high nickel gives moderate resistance to carburization, better than 304 or 321. For severely carburizing or reducing furnace atmospheres, nickel alloys (e.g. 330, 600 series) outperform any 300-series stainless.
310S Compared With Other Grades
Organizational author: Tsingshan (Shandong) Iron & Steel Co., Ltd..Review method, status and limitations.
Other stainless steel grades:
304304L316316L2013214104302205202301309S316Ti347904L409L4204394414442507303317L254 SMO440C17-4 PH2304
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