# AISI 310H Forgings: UNS S31009 / ASTM A182 F310H

> Open-die forged rings, seamless rolled rings, flanges, round bars, discs, shafts, sleeves and tube sheets in 25Cr-20Ni heat-resistant austenitic stainless steel.

**Manufacturer:** Jiangyin Jiangnan Metal Co., Ltd., Open-Die Forging Factory
**Address:** No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province 214400, China
**Tel:** 0086-189-2135-9659 | **Email:** sales@steelforgepieces.com
**Page:** https://www.steelforgepieces.com/Stainless-Steel/AISI-310H.html
**Updated:** 30 September 2026

## Summary

AISI 310H (UNS S31009) is the high-carbon modification of 25 percent chromium / 20 percent nickel austenitic heat-resistant stainless steel. Where 310S caps carbon at 0.08 percent, 310H holds it to a range of 0.04 to 0.10 percent, and that carbon is what raises the creep strength of the grade at elevated temperature.

Forgings are ordered as ASTM A182/A182M grade F310H, which calls for a minimum tensile strength of 75 ksi (515 MPa) and a minimum yield strength of 30 ksi (205 MPa) in the solution treated and quenched condition.

Jiangyin Jiangnan Metal Co., Ltd. forges this grade to customer drawings at its open-die shop in Jiangyin, Jiangsu, China, with EN 10204 3.1 or 3.2 certification and ultrasonic testing to EN 10228-3, SEP 1921 or ASTM A388.

| Item | Value |
| --- | --- |
| UNS number | S31009 |
| Forging specification | ASTM A182 / A182M grade F310H |
| Nominal alloy | 25Cr / 20Ni |
| Carbon range | 0.04 to 0.10 percent |
| Tensile strength, min | 515 MPa (75 ksi) |
| Structure | Austenitic |

## 310H compared with 310 and 310S

The three grades in the 310 family share the same 24.0 to 26.0 percent chromium and 19.0 to 22.0 percent nickel base and are separated almost entirely by carbon. Alloy 310 (S31000) permits carbon up to 0.25 percent. Alloy 310S (S31008) is the low-carbon version at 0.08 percent maximum, used for ease of fabrication, since less carbon lowers the risk of carbide precipitation in the weld heat-affected zone. Alloy 310H (S31009) is the high-carbon modification developed for enhanced creep resistance, and its carbon is specified as a minimum as well as a maximum. The bands overlap, so in most instances the grain size and carbon content of one heat can satisfy both the 310S and the 310H requirements, which is why dual-certified 310S/310H material is common.

The high carbon content that is present to enhance creep properties has a detrimental effect on aqueous corrosion resistance, and the alloy is prone to intergranular corrosion after long-term exposure at high temperatures. The 310 family is not designed for service in wet corrosive environments.

Carbon and silicon limits, weight percent, maximum unless a range is shown:

| Element | 310 (S31000) | 310S (S31008) | 310H (S31009) |
| --- | --- | --- | --- |
| Carbon | 0.25 | 0.08 | 0.04 min to 0.10 max |
| Chromium | 24.0 to 26.0 | 24.0 to 26.0 | 24.0 to 26.0 |
| Nickel | 19.0 to 22.0 | 19.0 to 22.0 | 19.0 to 22.0 |
| Manganese | 2.00 | 2.00 | 2.00 |
| Silicon | 1.50 | 1.50 | 0.75 |
| Iron | Balance | Balance | Balance |

Source: published data for Alloy 310/310S/310H plate on an ASTM A240 / ASME SA-240 basis.

## Chemical composition, ASTM A182 F310H

Grade symbol F310H, UNS S31009, described in the specification as 25 chromium, 20 nickel. Molybdenum and copper are not specified elements for this grade.

| Element | Requirement, weight percent |
| --- | --- |
| Carbon | 0.04 to 0.10 |
| Manganese | 2.00 max |
| Phosphorus | 0.045 max |
| Sulfur | 0.030 max |
| Silicon | 1.00 max |
| Nickel | 19.0 to 22.0 |
| Chromium | 24.0 to 26.0 |
| Iron | Balance |

Published composition data for 310H on an ASTM A240 plate basis applies a tighter silicon limit of 0.75 percent max, so confirm which specification governs the order.

## Mechanical properties

Specification minimums required of a 310H forging, tested in the final heat-treated condition:

| Property | Imperial | Metric |
| --- | --- | --- |
| Tensile strength, min | 75 ksi | 515 MPa |
| Yield strength, min | 30 ksi | 205 MPa |
| Elongation in 2 in. [50 mm] or 4D, min | 30 % | 30 % |
| Reduction of area, min | 50 % | 50 % |

Tensile and yield minimums as listed for grade F310H. Elongation and reduction of area as listed for the austenitic stainless steel group in ASTM A182 Table 2. A182 also attaches thickness footnotes to certain austenitic grades that reduce the minimum tensile strength for sections over 5 in. [130 mm]; check the current edition for heavy sections.

Typical properties of annealed 310H, indicative only:

| Property | Value |
| --- | --- |
| Tensile strength | 515 MPa (74,694 psi) |
| Yield strength | 205 MPa (29,732 psi) |
| Modulus of elasticity | 200 GPa (29,000 ksi) |
| Shear modulus | 77.0 GPa (11,200 ksi) |
| Poisson's ratio | 0.3 |
| Elongation at break, 50 mm | 40 % |
| Hardness | 95 HRB / 217 HB |

Plate datasheets for the 310/310S/310H family quote typical values at 68 F (20 C) of 35,000 psi (245 MPa) yield, 80,000 psi (550 MPa) tensile, 45 percent elongation in 2 in. and 217 Brinell maximum.

### Creep properties

Typical creep strain and creep rupture stress in MPa for the 310 family:

| Temperature | Creep strain 1,000 h | 10,000 h | 100,000 h | Creep rupture 1,000 h | 10,000 h | 100,000 h |
| --- | --- | --- | --- | --- | --- | --- |
| 600 C / 1112 F | 120 | 100 | 40 | 200 | 140 | 80 |
| 700 C / 1292 F | 50 | 35 | 20 | 80 | 45 | 20 |
| 800 C / 1472 F | 20 | 10 | 8 | 35 | 20 | 8 |
| 900 C / 1652 F | 10 | 6 | 3 | 15 | 10 | 5 |
| 1000 C / 1832 F | 5 | 3 | 1.5 | 9 | 4 | 2 |

Pressure-retaining design has to use code allowable stresses from the governing design code, not these typical values.

## Physical properties

| Property | Value |
| --- | --- |
| Density | 7.89 g/cm3 (0.285 lb/in3) |
| Melting range | 1354 to 1402 C (2470 to 2555 F) |
| Modulus of elasticity | 196 GPa (28.5 x 10^6 psi) |
| Specific heat | 502 J/kg-K at 0 to 100 C (0.12 BTU/lb-F at 32 to 212 F) |
| Thermal conductivity at 100 C | 10.8 W/m-K (8.0 BTU/hr/ft2/ft/F) |
| Electrical resistivity at 20 C | 78.0 microhm-cm (30.7 microhm-in) |

## Service temperature and high-temperature corrosion

The alloy resists oxidation up to 2010 F (1100 C) under mildly cyclic conditions. Frequent thermal cycling reduces oxidation resistance. The high chromium (25 percent) and silicon (0.6 percent) content is what makes the alloy resistant to high-temperature corrosion in most in-service environments.

| Atmosphere | Limit |
| --- | --- |
| Oxidizing, max sulfur 2 g/m3, continuous service | 1922 F (1050 C) |
| Oxidizing, max sulfur 2 g/m3, peak temperature | 2012 F (1100 C) |
| Oxidizing, sulfur greater than 2 g/m3 | 1742 F (950 C) maximum |
| Low oxygen atmosphere, max sulfur 2 g/m3 | 1832 F (1000 C) maximum |
| Nitriding or carburizing atmospheres | 1562 to 1742 F (850 to 950 C) maximum |

A separate datasheet for grade 310H states good resistance to oxidation up to 1150 C (2102 F) in continuous service and 1040 C (1904 F) in intermittent service, and notes wide use where sulfur dioxide gas is present at high temperature.

Two limits to design around. Between 1202 and 1742 F (650 to 950 C) the alloy is subject to sigma phase precipitation, which embrittles it; a solution annealing treatment at 2012 to 2102 F (1100 to 1150 C) restores a degree of toughness. Continuous use of 310H in the 425 to 860 C (797 to 1580 F) range is not recommended because of carbide precipitation. In reducing, nitriding or carburizing atmospheres the alloy does not perform as well as Alloy 600 (UNS N06600) or Alloy 800 (UNS N08800), and severe carburizing atmospheres in thermal process equipment usually require nickel alloys such as 330 (UNS N08330).

## Forging, heat treatment, welding and machining

**Hot forming.** Heat uniformly at 1742 to 2192 F (950 to 1200 C). After hot forming, a final anneal at 1832 to 2101 F (1000 to 1150 C) followed by rapid quenching is recommended.

**Heat treatment.** 310H is fully austenitic and cannot be hardened by precipitation or ageing. Under ASTM A182 the austenitic grades are supplied solution treated and quenched, with a minimum solution temperature of 1900 F (1040 C) followed by liquid quenching.

**Welding.** Readily welded by most standard processes including TIG, plasma, MIG, SMAW, SAW and FCAW. Where the best corrosion resistance after welding is required, the low-carbon 310S variant is preferred to minimise carbide precipitation.

**Cold forming and machining.** The alloy is quite ductile and forms in a manner similar to 316. Cold forming of pieces destined for long-term high-temperature exposure is not recommended, since the alloy is subject to carbide precipitation and sigma phase precipitates. The grade work hardens during cutting, so rigid setups, positive rake tooling, generous coolant and slow constant feeds are used.

## 310H forged product forms

| Category | Items |
| --- | --- |
| Rings | Forged rings, seamless rolled rings, retaining rings, valve seat rings |
| Flanges and closures | Weld neck, slip on, blind and threaded forged flanges, tube sheets, blanks |
| Round forms | Forged round bars, discs, disks, blanks, hubs, wheels |
| Hollow forms | Forged tubes, pipes, sleeves, bushings, hollow bars, cylinders |
| Shafts | Forged shafts, eccentric shafts, spindles, stems, crankshafts |
| Valve and equipment parts | Valve bodies, valve blocks, valve stems, nozzles, manifolds, gears, custom forged pieces |

Melting is by electric arc furnace with VOD refining, with ESR available where the application calls for improved cleanliness and structural homogeneity. Ultrasonic testing to EN 10228-3, SEP 1921 or ASTM A388 as specified. Certificates to EN 10204 3.1, or EN 10204 3.2 with third party witness. Positive material identification, impact testing, grain size determination, intergranular corrosion testing and dimensional reports available as supplementary requirements.

## Where 310H forgings are used

Furnace internals including burners, doors, fans, piping and recuperators. Fluidized bed furnaces: coal combustors, grids, piping, wind boxes. Ore processing and steel plants: smelter and steel melting equipment, continuous casting equipment. Petroleum refining: catalytic recovery systems, flares, recuperators, tube hangers. Power generation: coal gasifier internals, pulverized coal burners, tube hangers. Sintering and cement plants: burners, burner shields, feeding and discharging systems, wind boxes. Thermal processing: annealing covers and boxes, burner grids, doors, fans, muffles and retorts, recuperators, walking beams. Heat treatment industry hardware: fans, trays, baskets, rollers, burner parts, oven linings, retort linings, conveyor belts, refractory supports, tube hangers. Containers for hot concentrated acids, ammonia and sulfur dioxide, and use alongside hot acetic and citric acid in food processing. Cryogenic components, with low magnetic permeability and toughness down to minus 450 F (minus 268 C).

## Cross reference and equivalent designations

| System | Designation | Note |
| --- | --- | --- |
| UNS | S31009 | Definitive identifier for 310H |
| ASTM and ASME forgings | A182 / SA-182 grade F310H | Governing specification for forged pressure parts |
| ASTM and ASME plate | A240 / SA-240 grade 310H | Silicon limited to 0.75 percent max |
| AMS | AMS 5521 | Listed for the 310/310S/310H family |
| Werkstoff | 1.4845 | Listed against the family as a group, normally cross referenced to 310S (S31008) |

Published specification sheets list W. Nr. 1.4845 against Alloy 310/310S/310H collectively, and the number is normally cross referenced to 310S / UNS S31008. Since 310H also requires a carbon minimum of 0.04 percent, a 1.4845 heat meets 310H only when its actual carbon falls inside the 0.04 to 0.10 percent band. Order to ASTM A182 F310H or UNS S31009 and require the certificate to state that grade.

## Common questions

**What is AISI 310H stainless steel?**
AISI 310H (UNS S31009) is the high-carbon modification of 25 percent chromium / 20 percent nickel austenitic heat-resistant stainless steel. Carbon is held to 0.04 to 0.10 percent rather than a simple maximum, which raises high-temperature strength and creep resistance. Forgings are ordered to ASTM A182/A182M grade F310H.

**What is the difference between 310, 310S and 310H?**
All three are 24 to 26 percent chromium and 19 to 22 percent nickel and differ mainly in carbon. 310 allows up to 0.25 percent. 310S is the low-carbon version at 0.08 percent maximum, used for ease of fabrication and better weldability. 310H is the high-carbon modification at 0.04 to 0.10 percent, developed for enhanced creep resistance. The ranges overlap, so in most instances one heat can meet both the 310S and 310H requirements.

**What is the chemical composition of ASTM A182 F310H?**
Carbon 0.04 to 0.10 percent, manganese 2.00 percent max, phosphorus 0.045 percent max, sulfur 0.030 percent max, silicon 1.00 percent max, nickel 19.0 to 22.0 percent, chromium 24.0 to 26.0 percent, balance iron. Molybdenum and copper are not specified elements for this grade.

**What are the minimum mechanical properties of 310H forgings?**
Minimum tensile strength 75 ksi (515 MPa) and minimum yield strength 30 ksi (205 MPa). For the austenitic grades in A182 Table 2, minimum elongation in 2 in. or 4D is 30 percent and minimum reduction of area is 50 percent.

**What is the maximum service temperature of 310H?**
Oxidation resistance up to 2010 F (1100 C) under mildly cyclic conditions. In oxidizing conditions with sulfur up to 2 g/m3, 1922 F (1050 C) continuous and 2012 F (1100 C) peak. 1742 F (950 C) where sulfur exceeds 2 g/m3, and 1562 to 1742 F (850 to 950 C) in nitriding or carburizing atmospheres. A separate 310H datasheet quotes 1150 C (2102 F) continuous and 1040 C (1904 F) intermittent.

**How are 310H forgings heat treated?**
310H is austenitic and cannot be hardened by ageing. ASTM A182 requires the austenitic grades to be solution treated and liquid quenched from a minimum of 1900 F (1040 C). After hot forming, a final anneal at 1832 to 2101 F (1000 to 1150 C) with rapid quenching is recommended, and a solution anneal at 2012 to 2102 F (1100 to 1150 C) restores a degree of toughness after sigma phase exposure.

**Is 1.4845 the same as 310H?**
Not exactly. 1.4845 is listed against the family as a group but is normally cross referenced to 310S (S31008). It meets 310H only if actual carbon falls inside the 0.04 to 0.10 percent band. State ASTM A182 F310H or UNS S31009 on the order.

**Can 310H be used in wet corrosive service?**
It is not designed for it. The high carbon content present to enhance creep properties has a detrimental effect on aqueous corrosion resistance, and the alloy is prone to intergranular corrosion after long-term exposure at high temperatures. Its 25 percent chromium still makes it more corrosion resistant than most heat-resistant alloys.

**Who supplies AISI 310H open-die forgings?**
Jiangyin Jiangnan Metal Co., Ltd., an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, produces AISI 310H forged rings, seamless rolled rings, flanges, round bars, discs, shafts, sleeves and tube sheets to ASTM A182 F310H, with EN 10204 3.1 or 3.2 certification. Contact sales@steelforgepieces.com or 0086-189-2135-9659.

## Request a quotation

Send a drawing, a size list, or a sketch with dimensions. To quote accurately we need: form and finished dimensions (OD x ID x height, or length x diameter); specification and grade, for example ASTM A182 F310H or UNS S31009; quantity and required delivery date; machining condition, as forged, rough machined or finish machined; NDT and certification requirements (EN 10228-3, SEP 1921, ASTM A388, EN 10204 3.1 or 3.2); and service temperature and atmosphere if you want the grade choice checked.

Jiangyin Jiangnan Metal Co., Ltd., Open-Die Forging Factory
No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province 214400, China
Tel: 0086-189-2135-9659
Email: sales@steelforgepieces.com

## Related grades

AISI 347H, AISI 330, A182-F347, A182-F321, Sanicro 28, 904L, A182-F44, Incoloy 800H, Inconel 601, Alloy 602.

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Technical data compiled from ASTM A182/A182M, ASTM A240 and published mill datasheets for UNS S31009 and the 310/310S/310H family. Given for information, to help engineers make their own evaluation, and not a warranty of suitability for any particular application. Confirm all design values against the governing specification and design code for the project.