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What is SS 310S Stainless Steel?
Quick answer
- Definition
- SS 310S is the low-carbon version of SS 310 (25Cr-20Ni), the go-to stainless flat product for continuous service up to about 1,100 °C.
- Family
- Heat-resisting austenitic stainless steel
- Key strength
- Low carbon for weldability
- Main forms
- Pipes, Tubes, Plates, Sheets, Coils, Bars
- Typical uses
- Furnace components, hearths and dampers; Heat exchangers for hot gases; Kiln and calciner parts
SS 310S limits carbon to 0.08%, which improves weldability and reduces embrittlement from carbide precipitation during service. It keeps the 24–26% chromium and 19–22% nickel that give outstanding oxidation resistance.
Long exposure between about 650 and 900 °C can precipitate sigma phase and reduce room-temperature toughness, so designers consider thermal cycling and shutdown loads. SS 310S is also used in some fuel-cell and cryogenic applications.
Key characteristics
- Low carbon for weldability
- Top oxidation resistance among standard stainless grades
- Sigma-phase risk in long service at 650–900 °C
- Stable austenite, tough at low temperatures
What are the specifications and equivalents of SS 310S?
| Product form | Specification / designation | Product page |
|---|---|---|
| Pipes | ASTM A312 / ASME SA312 TP310S (seamless & welded); A358 EFW | SS 310S pipes → |
| Tubes | ASTM A213 TP310S (seamless); A249 / A269 TP310S (welded) | SS 310S tubes → |
| Plates | ASTM A240 / ASME SA240 310S | SS 310S plates → |
| Sheets | ASTM A240 / ASME SA240 310S | SS 310S sheets → |
| Coils | ASTM A240 / ASME SA240 310S | SS 310S coils → |
| Bars | ASTM A276 / A479 310S | SS 310S bars → |
| Fittings | ASTM A403 WP310S | SS 310S fittings → |
| Flanges | ASTM A182 F310 | SS 310S flanges → |
UNS S31008 · EN 1.4845 (cross-reference; limits are similar but not identical)
Standards: ASTM A312, ASTM A358, ASTM A213, ASTM A240, ASTM A276, ASTM A182, ASTM A403.
What is the chemical composition of SS 310S?
| Element | Limit (%) |
|---|---|
| C | 0.08 max |
| Mn | 2.00 max |
| P | 0.045 max |
| S | 0.030 max |
| Si | 1.50 max |
| Cr | 24.0 – 26.0 |
| Ni | 19.0 – 22.0 |
What are the mechanical properties of SS 310S?
| Property | Value |
|---|---|
| Tensile strength | 515 MPa (75 ksi) |
| Yield strength (0.2% offset) | 205 MPa (30 ksi) |
| Elongation | 40% |
| Hardness | 217 HBW / 95 HRB |
Physical properties and service temperature
| Property | Value |
|---|---|
| Density (typical) | 7.9 g/cm³ (7900 kg/m³) |
| Magnetism | Non-magnetic when annealed. |
| Heat treatment | Solution annealed. High-temperature exposure may form sigma phase, which reduces room-temperature toughness. |
| Service temperature | About 1,100 °C continuous in oxidising atmospheres (indicative). |
How is SS 310S welded and fabricated?
Weldable with matching high-alloy fillers; keep heat input moderate to limit hot cracking.
Always follow a qualified welding procedure (for example ASME Section IX) and the filler-metal recommendations for SS 310S. Verify incoming material by PMI and check the mill test certificate against the specification.
Which SS 310S products do we supply?
SS 310S Stainless Steel is available in 8 product forms, from ready stock or mill-sourced to your specification, with EN 10204 3.1 mill test certificates (3.2 with third-party inspection on request).
SS 310S SheetsASTM A240 310SSpecification & sizes
How it's madeHot-rolled coil is cold-rolled to final thickness, then annealed and pickled (2B/2D) or bright annealed (BA), temper-passed, and polished or textured as needed. Coils are then levelled and cut into sheets.
- Specification
- ASTM A240 / ASME SA240 310S
- Size range
- Thickness about 0.3 – 6 mm, standard sizes 1,000 × 2,000, 1,219 × 2,438 (4 × 8 ft), 1,250 × 2,500 and 1,500 × 3,000 mm; custom cut lengths
- Finish
- 2B, 2D, BA, No.4 (brushed), HL (hairline), No.8 (mirror), embossed, PVC or laser-film protected
- Ends
- Sheared or slit edges; laser-cut blanks on request
Testing & documents
- Chemical and mechanical tests
- Surface and finish inspection
- Thickness and flatness checks
- Hardness and bend tests as specified
- EN 10204 3.1 certificate; 3.2 with third-party inspection
SS 310S CoilsASTM A240 310SSpecification & sizes
How it's madeHot-rolled coil (HRC) comes from the hot-strip mill. Cold-rolled coil (CRC) is further reduced on a cold mill, then annealed and pickled or bright annealed, and skin-passed. Slitting lines cut master coils into narrow strips to the width you order.
- Specification
- ASTM A240 / ASME SA240 310S
- Size range
- Thickness about 0.3 – 12 mm; widths from narrow slit strip (about 10 mm) to 1,250 / 1,500 / 2,000 mm; coil ID 508 / 610 mm; coil weights to order
- Finish
- No.1 (hot-rolled, annealed, pickled), 2B, 2D, BA, No.4 for stainless; HR black, pickled & oiled, CR for carbon steel
- Ends
- Mill edge or slit edge
Testing & documents
- Chemical and mechanical tests
- Thickness profile and surface inspection
- Hardness and bend tests
- EN 10204 3.1 certificate; 3.2 with third-party inspection
SS 310S FittingsASTM A403 WP310SSpecification & sizes
How it's madeButt-weld fittings are formed from seamless or welded pipe or plate by hot or cold forming (mandrel bending, hydraulic bulging, pressing), then heat treated, bevelled and finished. Socket-weld and threaded fittings are machined from forgings or bar.
- Specification
- ASTM A403 WP310S
- Size range
- Butt-weld ½" – 48" (larger fabricated to order) in schedules matching the pipe; socket-weld and threaded ⅛" – 4" in Class 2000, 3000, 6000 and 9000
- Finish
- Annealed & pickled, shot-blasted, black painted or galvanised (by material)
- Ends
- Bevelled (butt-weld), socket-weld, threaded NPT/BSP
Testing & documents
- Chemical and mechanical tests of the starting material
- Dimensional inspection to B16.9 / B16.11
- Radiography of welded fittings (seamed WPW/WX)
- Hardness, IGC and impact tests as specified
- EN 10204 3.1 certificate; 3.2 with third-party inspection
SS 310S FlangesASTM A182 F310Specification & sizes
How it's madeFlanges are forged from billets (or cut from plate for some blind and plate flanges), heat treated to the material specification, and machined: bore, face, raised face or ring groove, bolt holes and hub bevel.
- Specification
- ASTM A182 F310
- Size range
- NPS ½" – 24" (B16.5), 26" – 60" (B16.47 Series A/B); Class 150, 300, 600, 900, 1500, 2500; EN 1092-1 PN 6 – PN 100 on request
- Finish
- Raised face (RF), flat face (FF) or ring-type joint (RTJ); serrated spiral or concentric face finish (typically 3.2 – 6.3 µm Ra)
- Ends
- Weld-neck bevel matched to pipe schedule; socket bore; threaded
Testing & documents
- Chemical and mechanical tests of the forging
- Dimensional inspection to ASME B16.5 / B16.47
- Hardness, impact and IGC tests as specified
- Ultrasonic testing of forgings on request
- EN 10204 3.1 certificate; 3.2 with third-party inspection
Where is SS 310S used?
Typical applications
- Furnace components, hearths and dampers
- Heat exchangers for hot gases
- Kiln and calciner parts
- Oil-burner parts and combustion chambers
- Thermal processing fixtures
Where do we supply SS 310S?
SS 310S is regularly requested for projects in these markets:
What should you specify when buying SS 310S?
- Grade and specification, e.g. ASTM A312 TP310S
- Product form, size and tolerance
- Heat treatment / condition and surface finish
- Quantity, delivery location and required date
- Tests: PMI, hydro/NDT, IGC, impact or hardness as required
- Certificate type (EN 10204 3.1 / 3.2) and third-party inspection
See our RFQ checklist guide and what drives metal prices.
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Frequently asked questions
What is SS 310S stainless steel used for?
Mainly high-temperature equipment such as furnace parts, burners, kilns and heat-treatment fixtures, where it resists scaling up to about 1,100 °C.
Is SS 310S good for corrosion resistance?
It has good general corrosion resistance, but it's selected mainly for heat resistance. For aqueous chloride corrosion, molybdenum-bearing grades such as SS 316L or SS 904L are better.
What is SS 310S used for?
Furnace components, hearths and dampers, Heat exchangers for hot gases, Kiln and calciner parts, Oil-burner parts and combustion chambers. It's used across Cement, Heavy Engineering, Petrochemical & Refining, Power Generation.
What is the UNS number of SS 310S?
SS 310S is designated UNS S31008; the closest EN cross-reference is 1.4845.
Which product forms is SS 310S available in?
Pipes, Tubes, Plates, Sheets, Coils, Bars, Fittings, Flanges, to ASTM A312 TP310S, ASTM A213 TP310S, ASTM A240 310S and related specifications.
What is the density of SS 310S?
About 7.9 g/cm³ (7900 kg/m³), used for weight calculations.
Is SS 310S magnetic?
Non-magnetic when annealed.
What temperature can SS 310S withstand?
About 1,100 °C continuous in oxidising atmospheres (indicative).