SS 310 / 310S: properties, composition, uses and standards
SS 310 / 310S is a heat-resisting austenitic stainless steel with 25% chromium and 20% nickel, chosen for furnaces, burners and heat treatment at high temperature. UNS S31008, W.Nr 1.4845, PREN ≈ 25, density 7.9 g/cm³.
What is SS 310 / 310S?
SS 310 / 310S is a heat-resisting austenitic stainless steel with 25% chromium and 20% nickel. Engineers choose it for furnaces, burners and heat treatment at high temperature. It is also known as AISI 310S, UNS S31008, W.Nr 1.4845, Heat-resisting stainless.
- UNS
- S31008 (310S) · S31000 (310)
- W.Nr
- 1.4845
- EN
- X8CrNi25-21
- JIS
- SUS 310S
- BS
- 310S16
- Density
- 7.9 g/cm³
- Melting range
- 1400 – 1450 °C
- Magnetic
- Non-magnetic annealed
- PREN (approx.)
- ≈ 25
Chemical composition and what each element does
| Element | Weight % |
|---|---|
| Chromium | 24.0 – 26.0 |
| Nickel | 19.0 – 22.0 |
| Carbon | 0.08 max |
| Manganese | 2.00 max |
| Silicon | 1.50 max |
| Phosphorus | 0.045 max |
| Sulphur | 0.030 max |
| Iron | Balance |
Per ASTM A240 for UNS S31008.
25% chromium builds a tight scale that resists oxidation in continuous service up to about 1100 °C.
20% nickel keeps the alloy austenitic and strong at furnace temperatures.
Silicon improves resistance to scaling and carburising atmospheres.
Without molybdenum, 310S is not a chloride grade — use it for heat, not for seawater.
Mechanical properties
| Property | Value |
|---|---|
| Tensile strength | 515 MPa · 75 ksi |
| Yield strength 0.2% | 205 MPa · 30 ksi |
| Elongation | 40% |
| Hardness | 217 HB max |
Annealed plate & sheet, minimum values. Values for pipe, bar and forgings differ slightly — see the product standard.
Where SS 310 / 310S is used
- Furnace parts. Muffles, retorts, radiant tubes and conveyor belts. Industry →
- Heat treatment. Baskets, fixtures and trays. Industry →
- Burners & kilns. Nozzles and liners in cement and ceramic kilns. Industry →
- Petrochemical. Tube hangers and furnace internals. Industry →
Welding 310S
The matching filler is ER310 (AWS A5.9). ERNiCr-3 for joints to nickel alloys.
Keep heat input moderate and interpass temperature low, clean joints thoroughly, and pickle or passivate after welding where the service is corrosive.
SS 310 / 310S compared with similar grades
| Grade | PREN | Choose it for |
|---|---|---|
| SS 310 / 310S | ≈ 25 | Furnaces, burners and heat treatment at high temperature |
| SS 304 | ≈ 18 | General corrosion resistance, food, water and architectural work |
| SS 321 | ≈ 18 | High-temperature service between 425 and 815 °C |
| Incoloy 800 / 800H / 800HT | — | Furnaces, petrochemical heaters and high-temperature piping |
SS 310 / 310S standards by product
Buying SS 310 / 310S: what to specify
- The product standard and the UNS or designation — for example ASTM A240 UNS S31008.
- Size, thickness or schedule, and quantity in pieces and kg or metres.
- Heat-treatment condition where the standard offers a choice.
- Certificate: EN 10204 3.1 as standard, 3.2 if a third party must witness.