GRADE PROFILE
310S — 1.4845 / X8CrNi25-21
310S carries 25% chromium and 20% nickel. That composition is not built for aqueous corrosion but for oxidation resistance up to around 1,100 °C. It is the reference heat-resistant austenitic, the low-carbon version of 310 and easier to weld.
- Heat-resistant
- PREN 24–28 †
- Cost index 165
When to choose it
On anything that runs red hot. Industrial furnace and radiant tubes, incineration and waste treatment, cement plants, heat treatment furnaces, high-temperature recuperators. High chromium forms an adherent scale that protects durably, and nickel keeps the structure austenitic up to service temperature.
It is also the motorsport manifold and exhaust grade where temperatures exceed what a 321 sustains over time.
When not to choose it
In aqueous chlorinated media. Despite 25% chromium, the absence of molybdenum lets pitting start, and the PREN of 25 is misleading: it looks like a 316L for entirely different in-service behaviour. In seawater and brines you need a duplex or a super austenitic.
In prolonged service between 600 and 900 °C, where sigma phase precipitates and embrittles the alloy. That is the paradox of heat-resistant grades: they hold better at 1,000 °C than at 750 °C continuously.
As a replacement for 310 where creep strength governs. The lower carbon of 310S improves weldability at the expense of creep: what you gain in fabrication you lose in service.
Composition
| Element | % |
|---|---|
| C | ≤ 0.1 |
| Si | ≤ 1.5 |
| Mn | ≤ 2 |
| P | ≤ 0.045 |
| S | ≤ 0.015 |
| Cr | 24–26 |
| Ni | 19–22 |
| N | ≤ 0.11 |
Mechanical properties
| Standard | Form | Rm (MPa) | Rp0.2 (MPa) | A (%) | Hardness |
|---|---|---|---|---|---|
| EN 10296-2:2005, tableau 5 | tube soudé, état hypertrempé (+AT) | ≥ 500 | ≥ 210 | ≥ 35 | — |
| EN 10297-2:2005, tableau | tube sans soudure, état hypertrempé (+AT) | ≥ 500 | ≥ 210 | — | — |
Designations and standards
| Reference | Designation |
|---|---|
| EN (numeric) | 1.4845 |
| EN (symbolic) | X8CrNi25-21 |
| ASTM / AISI | 310S |
| UNS | S31008 |
| JIS | SUS310S |
| AFNOR | Z8CN25-20 |
Tube product standards :
- EN 10095
- EN 10296-2
- EN 10297-2
- ASTM A312/A312M
- ASTM A213/A213M
Availability
Available in welded and seamless tube to EN 10095, EN 10296-2 and ASTM A312/A213. Structured dimensional data for this grade is not yet documented in our reference set: send us your sizes. EN 10204 3.1 material certificates supplied with the goods.
Related grades
- 253 MA (1.4835) — the same family with silicon and cerium, better cyclic performance for less nickel.
- 321 (1.4541) — the step below, to 600 °C, markedly cheaper.
- Alloy 800 (N08800) — the nickel-iron-chromium route when atmospheres turn carburising.
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Frequently asked questions
- Why does the PREN of 310S mean nothing?
- Because it measures pitting in aqueous chlorinated media, which is not this grade's service. A 310S works dry, at 900 °C, in a furnace. Its PREN of 25 would put it level with a 316L, which makes no practical sense.
- 310 or 310S?
- 310S, lower in carbon, welds better and sensitises less. 310, higher in carbon, creeps less. On a welded radiant tube, 310S; on a high-temperature load support, 310 has a case.
- Is it suitable for a motorsport exhaust manifold?
- Yes, it is one of its classic uses, where temperatures exceed the range of a 321. The trade-off is on price and on bending formability, which is less favourable than that of an ordinary austenitic.