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.
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. The specification 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.
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. Dual-certified 310S/310H material is common in the market for that reason.
For the designer this is a trade-off rather than a straight upgrade. 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. Its place is in hot, dry, oxidizing and sulfidizing atmospheres, where the 25 percent chromium content does the work.
| 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 |
Figures as published for Alloy 310/310S/310H plate on an ASTM A240 / ASME SA-240 basis.
Chemical composition, ASTM A182 F310H
For forgings the governing document is ASTM A182/A182M, where the grade symbol is F310H and the alloy is described as 25 chromium, 20 nickel. Molybdenum and copper are not specified elements for this grade. Where an application needs residual molybdenum or copper controlled, it has to be added as a purchase order restriction rather than assumed from the specification.
| Element | Requirement | Element | Requirement |
|---|---|---|---|
| Carbon | 0.04 to 0.10 | Nickel | 19.0 to 22.0 |
| Chromium | 24.0 to 26.0 | Manganese | 2.00 max |
| Silicon | 1.00 max | Phosphorus | 0.045 max |
| Sulfur | 0.030 max | Iron | Balance |
ASTM A182/A182M grade F310H chemical requirements. 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
The values below are specification minimums that a 310H forging has to meet, not typical mill results. Acceptance testing is carried out on material in its 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], so check the current edition of the standard for heavy sections.
| 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 |
Published datasheet values for grade 310H in the annealed condition. 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. Typical results sit above the ASTM minimums.
Creep properties
Creep data is the reason to specify 310H instead of 310S. The table shows typical creep strain and creep rupture stresses published for the 310 family, and how quickly load-bearing capability falls away above 700 C.
| Temperature | Creep strain (MPa) | Creep rupture (MPa) | ||||
|---|---|---|---|---|---|---|
| 1,000 h | 10,000 h | 100,000 h | 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 |
Published typical creep properties for Alloy 310/310S/310H. 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 (212 F) | 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) |
Published specification sheet for Alloy 310/310S/310H.
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, because repeated expansion and contraction spalls the protective chromium oxide scale. Atmosphere matters as much as temperature, and the high chromium (25 percent) and silicon (0.6 percent) content of the alloy is what makes it 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 |
Published high-temperature corrosion data for Alloy 310. 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 metallurgical limits are worth designing 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) will restore a degree of toughness. Separately, 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 the more severe carburizing atmospheres of thermal process equipment usually require nickel alloys such as 330 (UNS N08330). We forge all of those grades: see AISI 330, Inconel 600 and Incoloy 800H.
Forging, heat treatment, welding and machining
Hot forming
Heat uniformly at 1742 to 2192 F (950 to 1200 C) for hot working. 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. A supplier quoting a solution plus age cycle for this grade has confused it with a precipitation-hardening stainless such as 17-4PH or A286. 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
The alloy can be 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. That matters if a 310H forging is to be welded into a larger fabrication.
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 exposure to high temperatures is not recommended, since the alloy is subject to carbide precipitation and sigma phase precipitates. Like other high-nickel austenitic grades it work hardens during cutting, so we machine it with rigid setups, positive rake tooling, generous coolant and slow constant feeds.
310H forged product forms we make
Every item is produced to the customer drawing or size list at our Jiangyin open-die shop. There is no fixed catalogue: send the geometry and the specification and we quote against it.
| 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, testing and certification
310H is melted by electric arc furnace with VOD refining. ESR is available where the application calls for improved cleanliness and structural homogeneity. Ultrasonic testing is carried out to EN 10228-3, SEP 1921 or ASTM A388 as specified, and material certificates are issued to EN 10204 3.1, or to EN 10204 3.2 with third party witness. Positive material identification, impact testing, grain size determination, intergranular corrosion testing and dimensional reports can be added as supplementary requirements at order stage.
Where 310H forgings are used
310H is specified where components carry load in hot oxidizing or sulfidizing atmospheres for long periods. Typical service includes furnace internals such as burners, doors, fans, piping and recuperators, and fluidized bed furnaces, where forged rings, grids, wind boxes and piping see coal combustion products. Ore processing and steel plants use the grade in smelter and steel melting equipment and in continuous casting equipment. Petroleum refining applies it to catalytic recovery systems, flares, recuperators and tube hangers. Power generation uses it for coal gasifier internals, pulverized coal burners and tube hangers.
Sintering and cement plants specify it for burners, burner shields, feeding and discharging systems and wind boxes. Thermal processing equipment uses it for annealing covers and boxes, burner grids, doors, fans, muffles and retorts, recuperators and walking beams. In the heat treatment industry the grade appears as fans, trays, baskets, rollers, burner parts, oven linings, retort linings, conveyor belts, refractory supports and tube hangers. It is also used for containers for hot concentrated acids, ammonia and sulfur dioxide, and alongside hot acetic and citric acid in food processing. At the other end of the scale the 310 family finds use in cryogenic applications, with low magnetic permeability and toughness down to minus 450 F (minus 268 C).
Cross reference and equivalent designations
| System | Designation | Note |
|---|---|---|
| UNS | S31009 | The 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) |
On 1.4845: 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. To get 310H creep performance, order to ASTM A182 F310H or UNS S31009 and require the certificate to state that grade.
Common questions about AISI 310H
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. Its carbon is held to a range of 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. Alloy 310 (S31000) allows up to 0.25 percent carbon. 310S (S31008) is the low-carbon version at 0.08 percent maximum, used for ease of fabrication and better weldability. 310H (S31009) is the high-carbon modification with a 0.04 to 0.10 percent range, developed for enhanced creep resistance. Because the ranges overlap, in most instances the grain size and carbon content of 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?
ASTM A182 grade F310H requires a minimum tensile strength of 75 ksi (515 MPa) and a minimum yield strength of 30 ksi (205 MPa). For the austenitic grades in A182 Table 2 the minimum elongation in 2 in. or 4D is 30 percent and the minimum reduction of area is 50 percent.
What is the maximum service temperature of 310H?
The alloy resists oxidation up to 2010 F (1100 C) under mildly cyclic conditions. In oxidizing conditions with sulfur up to 2 g/m3 the limits are 1922 F (1050 C) continuous and 2012 F (1100 C) peak. The limit drops to 1742 F (950 C) where sulfur exceeds 2 g/m3, and to 1562 to 1742 F (850 to 950 C) in nitriding or carburizing atmospheres. A separate 310H datasheet quotes oxidation resistance to 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 annealing treatment 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. W. Nr. 1.4845 is listed against the 310, 310S and 310H family as a group, but it is normally cross referenced to 310S (UNS S31008). Because 310H also requires a carbon minimum of 0.04 percent, a 1.4845 heat meets 310H only if its actual carbon falls inside the 0.04 to 0.10 percent band. Orders for 310H should state ASTM A182 F310H or UNS S31009 explicitly.
Can 310H be used in wet corrosive service?
It is not designed for it. 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. Its 25 percent chromium content still makes it more corrosion resistant than most heat-resistant alloys. For wet corrosive duty look at 904L, Sanicro 28 or A182-F44.
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 for AISI 310H forgings
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
- 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, China
Tel 0086-189-2135-9659
Email sales@steelforgepieces.com
Related grades we forge
Technical data on this page is compiled from ASTM A182/A182M, ASTM A240 and published mill datasheets for UNS S31009 and the 310/310S/310H family. It is given for information, to help engineers make their own evaluation, and is not a warranty of suitability for any particular application. Confirm all design values against the governing specification and design code for the project.