# A182 F309S / 309S (UNS S30908) Open-Die Forgings

Heat-resisting austenitic stainless steel. Open-die forgings, rolled rings, flanges, shafts, discs, sleeves, bushings, tube sheets and round bars.

- **Supplier:** Jiangyin Jiangnan Metal Co., Ltd. — integrated melting and open-die forging works, established 1997
- **Address:** No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China
- **Phone / WhatsApp / WeChat:** 0086-189-2135-9659
- **Email:** sales@steelforgepieces.com
- **Page:** https://www.steelforgepieces.com/Stainless-Steel/A182-F309S.html
- **Last reviewed:** 29 September 2026

## Summary

309S is the low-carbon version of heat-resisting austenitic stainless 309. Chromium runs 22.0 to 24.0 percent and nickel 12.0 to 15.0 percent, with carbon held to 0.08 percent maximum. The UNS number is S30908 and the EN number is 1.4833. The grade is chosen for oxidation resistance at high temperature, and the reduced carbon gives better weldability and better resistance to intergranular attack than standard 309. Forgings of the 309-type analysis supplied under ASTM A182/A182M must meet 75 ksi (515 MPa) tensile, 30 ksi (205 MPa) yield, 30 percent elongation and 50 percent reduction of area after solution treatment and quench.

| Item | Value |
|---|---|
| Grade | 309S, A182 F309 type |
| UNS | S30908 |
| EN number | 1.4833 |
| EN name | X12CrNi23-13 |
| JIS | SUS 309S |
| Carbon | 0.08 % max |
| Chromium | 22.0–24.0 % |
| Nickel | 12.0–15.0 % |
| Structure | Austenitic, non-hardenable |
| Melting | EAF + LF + VOD, ESR option |
| Certificate | EN 10204 3.1 / 3.2 |

## Designation note

The austenitic 309-type grade symbol listed in ASTM A182/A182M is **F309H (UNS S30909)**, with carbon at 0.04 to 0.10 percent. The S suffix in 309S denotes the low-carbon analysis, **UNS S30908**. The term "A182 F309S" is used commercially, including in stockist and fittings catalogues, for A182-type forgings made to that low-carbon chemistry. Where a specification, code stamp or PED file depends on the exact grade symbol, state on enquiry whether F309H to the letter of A182 is required or a 309S / S30908 analysis is acceptable.

## Chemical composition

Weight percent, balance iron. Per published 309S / S30908 data, SSINA composition tables and the Sandmeyer Steel 309 / 309S / 309H datasheet.

| Grade | C | Mn | P | S | Si | Cr | Ni |
|---|---|---|---|---|---|---|---|
| 309S (S30908) | 0.08 max | 2.00 max | 0.045 max | 0.030 max | 1.00 max | 22.0–24.0 | 12.0–15.0 |
| 309 (S30900) | 0.20 max | 2.00 max | 0.045 max | 0.030 max | 1.00 max | 22.0–24.0 | 12.0–15.0 |
| 309H / F309H (S30909) | 0.04–0.10 | 2.00 max | 0.045 max | 0.030 max | 1.00 max | 22.0–24.0 | 12.0–15.0 |

Only carbon separates the three variants. For comparison, 310S (S31008) steps up to 24.0–26.0 percent chromium and 19.0–22.0 percent nickel.

## Mechanical properties

Specified minimums for the austenitic 309-type grade under ASTM A182/A182M, as published for F309H.

| Property | US units | SI units |
|---|---|---|
| Tensile strength, min | 75 ksi | 515 MPa |
| Yield strength, 0.2 % offset, min | 30 ksi | 205 MPa |
| Elongation in 2 in. (50 mm) or 4D, min | 30 % | 30 % |
| Reduction of area, min | 50 % | 50 % |

Annealed 309S normally tests above these values; published typical figures include tensile around 90 ksi and yield around 40–45 ksi. Acceptance is against the specification minimum on the certified test. Heavy sections are tested on sacrificial prolongations representative of the thickest part.

## Heat treatment

ASTM A182 Table 3 requires austenitic grades to be solution treated and quenched, with a minimum solution temperature of 1900 F (1040 C). Published practice for 309S places the solution anneal in the approximate range 1040 to 1175 C, held around 30 minutes per inch of section, followed by rapid cooling. Heavy forgings are water quenched.

The object is to take chromium carbides into solution and pass quickly through the sensitisation range on cooling. Slow cooling through roughly 850 to 450 C re-precipitates carbides at grain boundaries and reduces intergranular corrosion resistance. No hardening treatment applies: 309S is non-hardenable, strengthened only by cold work, and essentially non-magnetic in the annealed condition.

## Product forms

Rolled rings; weld neck, slip-on, blind and custom-bore flanges; tube sheets, solid and drilled; shafts and spindles; round, square and stepped bars; discs and gear blanks; sleeves, bushings and hollows; forged pipe; valve bodies, bonnets, stems, seat rings and plugs.

## Applications

- **Thermal processing:** annealing boxes and covers, burner grids, muffles and retorts, furnace doors and fans, walking beams, neutral salt pots
- **Petroleum refining:** catalytic recovery systems, recuperators, polythionic acid service
- **Pulp and paper:** digesters, liquor tanks, paper machine hardware
- **Waste treatment:** thermal oxidisers
- **Other:** food processing equipment and storage, pharmaceutical and biochemical production, power generation, gas compression, shipbuilding, heavy machinery

Step up to AISI 330, Incoloy 800H / 800HT or Inconel 601 for higher temperature or sulphur. For aqueous corrosion rather than heat, consider A182 F347, 904L, or duplex F51 and F53.

## Equivalents

| System | Designation |
|---|---|
| UNS | S30908 |
| AISI / ASTM | 309S. A182 lists F309H, S30909 |
| EN / DIN number | 1.4833 |
| EN / DIN name | X12CrNi23-13 |
| Higher-carbon cross reference | 1.4835 / X6CrNi23-13 |
| JIS | SUS 309S |
| Welded fittings | WP309 series |

## Melting, forging, testing, certification

Melting in our own steel plant by EAF with LF and VOD refining, heats up to 60 t, with VIM, VAR and ESR available. Forging open-die on a 6,300 t press, ring rolling to 6 m diameter, then solution treatment and quench, machining to drawing and final inspection. One heat number carries through from ladle to certificate.

Ultrasonic testing to ASTM A388, EN 10228-3 or SEP 1921 at the class nominated. Supplementary PMI, liquid penetrant, ASTM A262 intergranular corrosion testing, hardness survey and impact testing. Certificates to EN 10204 3.1 or 3.2 with third-party witness. Works approvals: CCS, BV, DNV, LR, NK.

## FAQ

**What is the difference between 309, 309S and 309H?**
Carbon content. 0.20 percent max for 309, 0.08 percent max for 309S, 0.04 to 0.10 percent for 309H. Chromium and nickel are the same in all three. Lower carbon improves weldability and resistance to intergranular attack; higher carbon is retained for creep strength.

**Is A182 F309S a listed grade symbol?**
ASTM A182/A182M lists F309H, UNS S30909. "A182 F309S" is a commercial term for A182-type forgings made to the low-carbon 309S / S30908 analysis. Agree the exact designation on the order.

**What mechanical properties appear on the certificate?**
75 ksi (515 MPa) tensile min, 30 ksi (205 MPa) yield min, 30 percent elongation min, 50 percent reduction of area min.

**What are the UNS and EN equivalents?**
UNS S30908 and EN 1.4833, X12CrNi23-13. The 309 / 309H side cross-references to 1.4835 / X6CrNi23-13.

**How is it heat treated?**
Solution treated and quenched, minimum 1900 F (1040 C) per ASTM A182 Table 3; published 309S practice is roughly 1040 to 1175 C followed by rapid cooling.

**Can 309S forgings be welded?**
Yes. The low-carbon analysis exists largely to make welding easier. A post-weld solution anneal may be specified for heavy fabrications in aggressive service.

**What sizes can you forge?**
Heats to 60 t, 6,300 t open-die press, 6 m ring mill. Small machined components through to multi-tonne pieces.

**How do I get a quotation?**
Email sales@steelforgepieces.com or call 0086-189-2135-9659 with grade, dimensions or drawing, quantity, specification and NDT and certification level.

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Compiled by the engineering department, Jiangyin Jiangnan Metal Co., Ltd., from published 309S / S30908 and ASTM A182/A182M references. Figures are for guidance. The governing specification and the material certificate take precedence.