# AISI 310S Forgings (UNS S31008, 1.4845, X8CrNi25-21)

**Jiangyin Jiangnan Metal Co., Ltd. — Open-Die Forging Factory**
No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China
Phone: +86-189-2135-9659 · Email: sales@steelforgepieces.com
Page: https://www.steelforgepieces.com/Stainless-Steel/AISI-310S.html
Data last reviewed: 30 September 2026

AISI 310S is a 25 percent chromium, 20 percent nickel heat resistant austenitic
stainless steel for parts that must resist oxidation, sulphidation and
carburisation at high temperature. We forge 310S to customer drawings as
seamless rolled rings, flanges, shafts, discs, bars, sleeves and tube sheets.

## Key data

| Item | Value |
|---|---|
| Grade type | Heat resistant austenitic stainless steel, 25Cr 20Ni |
| Equivalent designations | 310S, UNS S31008, EN 1.4845, X8CrNi25-21, SAE 30310S |
| Carbon limit | 0.08 percent max, the low carbon version of grade 310 |
| Service in air | 1050 C per EN 10095 for 1.4845; up to 1149 to 1150 C in other published data |
| Hot working | Heat to 1177 C, do not forge below 982 C |
| Annealing | 1038 to 1121 C, water quench |
| Hardening | Does not respond to heat treatment; strength raised only by cold work |
| Main limitation | No molybdenum, so pitting resistance is poor; sensitises between 550 and 800 C |
| Forging standards | ASTM A473 for S31008; ASTM A182 and A965 cover F310 and F310H |

## Where AISI 310S is used

The high chromium and nickel content resists oxidation, sulphidation and
carburisation, including reducing sulphur atmospheres containing hydrogen
sulphide and moderately carburising petrochemical atmospheres. For more severe
carburising duty, other heat resisting alloys should be selected. The grade is
also used at cryogenic temperatures because it keeps its toughness and has low
magnetic permeability. It is not recommended for frequent liquid quenching, as
it suffers from thermal shock.

| Sector | Components we forge |
|---|---|
| Furnaces and heat treatment | Seamless rolled rings, radiant tube flanges, muffle and retort parts, annealing cover fittings, saggers, roller and fan shafts, oven lining parts |
| Petroleum refining and petrochemical | Tube hangers, refractory anchor bolts, thermowells, burner and combustion chamber parts, forged nozzles and blocks |
| Pressure equipment | Forged flanges, tube sheets, shell and tube heat exchanger parts, forged pipe and tube blanks |
| Valves | Bodies, seat rings, stems and blocks for ball, gate, globe, check and plug valves |
| Power and rotating equipment | Shafts, spindles, gear blanks, discs, sleeves and bushings |
| Cryogenic and food processing | Rings, wheels, manifolds and structural blocks |

## Chemical composition

Composition limits differ slightly between product standards. Silicon is the
element to watch: plate and bar specifications allow up to 1.50 percent, while
ASTM A182 grade F310 restricts silicon to 1.00 percent maximum.

Weight percent, balance iron.

| Element | 310S, UNS S31008 | 310, UNS S31000 | ASTM A182 F310 |
|---|---|---|---|
| Carbon | 0.08 max | 0.25 max | 0.25 max |
| Chromium | 24.00 to 26.00 | 24.00 to 26.00 | 24.00 to 26.00 |
| Nickel | 19.00 to 22.00 | 19.00 to 22.00 | 19.00 to 22.00 |
| Manganese | 2.00 max | 2.00 max | 2.00 max |
| Silicon | 1.50 max | 1.50 max | 1.00 max |
| Phosphorus | 0.045 max | 0.045 max | 0.045 max |
| Sulphur | 0.030 max | 0.030 max | 0.030 max |

Molybdenum is not a specified element in this grade. The absence of molybdenum
is the reason pitting resistance is limited.

## Mechanical properties

Minimum room temperature values. These are specification minima rather than
typical test results. Actual values from each heat are reported on the material
certificate supplied with the order.

| Property | ASTM A182 F310, forgings | 310S, general product data |
|---|---|---|
| Tensile strength, min | 75 ksi / 515 MPa | 515 MPa |
| Yield strength, 0.2 percent offset, min | 30 ksi / 205 MPa | 205 MPa |
| Elongation, min | 30 percent | 40 percent |
| Reduction of area, min | 50 percent | 50 percent |

## Physical properties

| Property | Value |
|---|---|
| Density | 8.0 g/cm3, 0.289 lb/in3 |
| Melting point | 1455 C, 2650 F |
| Elastic modulus | 190 to 210 GPa |
| Poisson's ratio | 0.27 to 0.30 |
| Thermal conductivity | 14.2 W/m K |
| Specific heat | 490 to 530 J/kg K |

## Forging, annealing and machining

**Forging and hot working.** 310S is hot worked after heating to 1177 C and
should not be forged below 982 C. Rapid cooling after hot work helps restore
corrosion resistance. Annealing after forging relieves forming stresses.

**Annealing.** Anneal at 1038 to 1121 C and quench in water. There is no ageing
or precipitation step. 310S does not respond to heat treatment, so hardness
cannot be raised that way. Cold working is the only route to higher strength,
and 310S can be headed, upset, drawn and stamped despite its high work
hardening rate, with annealing afterwards to reduce internal stress.

**Machining.** Machinability is similar to grade 304. Work hardening is the main
difficulty. Slow speeds, heavy cuts with sharp tools, good lubrication and
rigid machines give the best result, because the aim is to cut below the work
hardened layer rather than rub against it.

**Welding.** 310S is welded by fusion or resistance methods. Oxyacetylene
welding is not preferred for this alloy. Where the finished part will see
corrosive liquid, a full post weld anneal, pickling and passivation are needed
to remove high temperature oxides. For high temperature service that treatment
is not required, but welding slag must be removed thoroughly.

## Corrosion behaviour and grade selection

310S has better general corrosion resistance than 304 or 309 in most
environments because of its higher chromium and nickel. Three limits should
drive the grade decision. The alloy contains no molybdenum, so pitting
resistance is poor and it is generally not used for corrosive liquid duty. It
becomes sensitised to intergranular corrosion after service between 550 and
800 C. Chloride stress corrosion cracking can occur in chloride bearing liquids
above 100 C.

| Governing requirement | Grades to consider |
|---|---|
| Oxidation resistance in dry gas at high temperature | 310S, AISI 330 |
| Creep strength above 600 C | Incoloy 800H, 800HT, Inconel 617, Haynes 230 |
| Elevated temperature strength, stabilised carbon | AISI 347H, A182 F321 |
| Pitting and chloride resistance | A182 F51, F53, F44, 904L |
| Galling and wear resistance | Nitronic 60 |
| High strength, hardenable | 17-4PH, PH13-8Mo, A286 |

## How we make and certify 310S forgings

| Stage | What we provide |
|---|---|
| Melting | EAF and VOD as standard. ESR remelt where the specification or cleanliness requirement calls for it. |
| Forming | Open-die forging and seamless ring rolling, heated to 1177 C, finished above 982 C |
| Heat treatment | Anneal and water quench, with recorded furnace charts |
| Machining | Rough machined, proof machined or finish machined to drawing |
| Ultrasonic testing | EN 10228-4, the part covering austenitic and austenitic ferritic stainless forgings, or ASTM A388 |
| Certification | EN 10204 3.1 mill certificate, or 3.2 witnessed by a third party inspection body on request |

The same part can be quoted under its equivalent designations: 310S,
UNS S31008, EN 1.4845 and X8CrNi25-21, or as F310 and F310H where the
specification calls for the ASTM A182 or A965 forged grades.

## Questions we are often asked

**What is the difference between 310S and 310 stainless steel?**
Both contain 24 to 26 percent chromium and 19 to 22 percent nickel. The
difference is carbon. Grade 310 allows up to 0.25 percent, while 310S is capped
at 0.08 percent maximum. Lower carbon makes 310S less prone to sensitisation
and embrittlement in service. Higher carbon in 310 gives better high
temperature strength and creep resistance.

**What is the maximum service temperature of AISI 310S?**
Published limits differ, so it is worth stating the source. Austral Wright data
for 310 and 310S gives 1150 C continuous and 1035 C intermittent in air, AZoM
gives up to 1149 C for 310S, and EN 10095 lists 1.4845 for duty up to 1050 C.
For design work the 1050 C figure is the conservative basis. Above roughly
600 C the limit is normally creep strength, not oxidation.

**Can 310S forgings be hardened by heat treatment?**
No. The grade does not respond to heat treatment, so there is no solution and
age cycle. Annealing at 1038 to 1121 C with a water quench is the correct
treatment, and strength can only be raised by cold work, which is rarely
practical on heavy forgings.

**Which ASTM standard should I order 310S forgings to?**
ASTM A182 and A965 list the forged high temperature grades F310 and F310H
rather than 310S. Forgings in UNS S31008 are normally ordered to ASTM A473,
which covers stainless steel forgings for general use and for low or high
temperature service. Worth confirming which of the three the buyer intends,
since carbon limits and acceptance criteria differ.

**Is 310S suitable for wet chloride or seawater service?**
Usually not. With no molybdenum the pitting resistance is poor, chloride stress
corrosion cracking is possible above 100 C, and service between 550 and 800 C
sensitises the material. For chloride or pitting critical duty, 316L, 904L, a
duplex grade such as F51 or F53, or a nickel alloy is the better choice.

**What sizes of 310S forgings can you make?**
Size depends on the press and ring mill assigned to the job, so we quote against
your drawing rather than publish a blanket range. Send the drawing or the rough
dimensions, weight and quantity to sales@steelforgepieces.com and we will
confirm feasibility and price.

## Request a quotation

Send a drawing or the finished dimensions, quantity, applicable standard and any
testing or certification requirement, and we will quote.

Email: sales@steelforgepieces.com · Phone: +86-189-2135-9659

## References

- Grade 310S, UNS S31008, datasheet, AZoM — https://www.azom.com/article.aspx?ArticleID=6798
- Grades 310 and 310S properties and applications, AZoM and Austral Wright Metals — https://www.azom.com/article.aspx?ArticleID=4392
- ASTM A182 / A182M F310, composition and mechanical minima — https://ferrobend.com/specifications/astm/forgings/a182-a182m-f310/
- X8CrNi25-21, 1.4845, EN 10095, Virgamet — https://virgamet.com/offer/x12crni2521-x8crni2521-aisi-310s-uns-s31008-heat-resistant-steel
- BS EN 10228-4, ultrasonic testing of austenitic stainless steel forgings, BSI — https://knowledge.bsigroup.com/products/non-destructive-testing-of-steel-forgings-ultrasonic-testing-of-austenitic-and-austenitic-ferritic-stainless-steel-forgings

Technical data on this page is compiled from published standards and grade
datasheets and is given for general guidance. It is not a warranty of properties
for a specific application. Material is supplied to the standard stated on the
order and certificate.