# UNS S32109 (321H) Forgings to ASTM A182 F321H and A965

**UNS S32109 is the UNS number for AISI 321H stainless steel, a titanium-stabilised austenitic grade with 17 to 19 percent chromium, 9 to 12 percent nickel and a controlled carbon range of 0.04 to 0.10 percent.** As a forging it is designated ASTM A182 Grade F321H for piping components up to 4,540 kg, or ASTM A965 Grade F321H for heavier pressure and high-temperature parts.

Titanium ties up carbon as titanium carbide, which keeps chromium in solution and lets the grade resist intergranular attack after exposure in the chromium-carbide precipitation range of 427 to 816 degrees C.

**S32109 is not 310H.** AISI 310H is UNS S31009, a 25Cr-20Ni grade. The two are often confused in online grade tables and cannot be substituted for one another.

Supplied by Jiangyin Jiangnan Metal Co., Ltd., an integrated melting works and open-die forge in Jiangyin, Jiangsu, China, operating since 1997.

| Field | Detail |
|---|---|
| UNS number | S32109 |
| Type | AISI 321H, titanium-stabilised 18Cr-8Ni austenitic |
| Forging specification | ASTM A182 F321H to 4,540 kg; ASTM A965 above that |
| ASME code | SA-182 / SA-965 F321H |
| EN material number | 1.4878 |
| Delivery condition | Solution treated and quenched |
| Tensile strength, minimum | 515 MPa / 75 ksi |
| Yield strength, minimum | 205 MPa / 30 ksi |
| Elongation, minimum | 30 percent |
| Reduction of area, minimum | 50 percent |
| Ring outside diameter | up to 6,000 mm |
| Single-piece weight | 10 kg to 30,000 kg |
| Minimum order | 10 kg, no minimum piece count |
| Lead time | 20 to 60 days |
| Pricing | Quoted per drawing, forged weight and quantity. No list price. |
| Certification | EN 10204 3.1, or 3.2 witnessed |
| Telephone | +86 189 2135 9659 |
| Email | sales@steelforgepieces.com |
| Page | https://www.steelforgepieces.com/Stainless-Steel/UNS-S32109.html |

## What the grade is

321H is the high-carbon, heat-resisting version of Type 321. Both carry the same chromium and nickel and both are stabilised with titanium. The difference is that 321H specifies a carbon range with a floor rather than only a ceiling. Carbon held in solution provides creep strength, so 321H keeps its load-carrying ability through long exposures above roughly 540 degrees C.

The titanium addition separates 321H from 304H. Titanium has a stronger affinity for carbon than chromium does, so titanium carbides form in preference to chromium carbides. Chromium stays dissolved and available for passivation, which is why stabilised grades come through the 427 to 816 degrees C sensitising window with their intergranular corrosion resistance intact. The same property makes Type 321 the usual answer where polythionic acid stress corrosion attacks unstabilised austenitic steels in refinery hydroprocessing circuits.

## Chemical composition

ASTM A182 Grade F321H chemical requirements, percentages by weight. Single figures are maxima.

| Element | Symbol | Composition % |
|---|---|---|
| Carbon | C | 0.04 to 0.10 |
| Manganese | Mn | 2.00 max |
| Phosphorus | P | 0.045 max |
| Sulfur | S | 0.030 max |
| Silicon | Si | 1.00 max |
| Nickel | Ni | 9.00 to 12.00 |
| Chromium | Cr | 17.00 to 19.00 |
| Titanium | Ti | 4 x C min, 0.70 max |
| Iron | Fe | Balance |

Many grade databases quote a flat 0.35 percent titanium for S32109. That is not a specification limit. A182 requires titanium of not less than four times the carbon content and not more than 0.70 percent, so at 0.10 percent carbon the titanium minimum is 0.40 percent and a heat certified at 0.35 percent would be non-conforming. Grade F321 without the H uses a five times carbon minimum.

## Mechanical properties

Specification minima are what a forging must achieve to be certified. Typical values are what annealed material usually tests at. Purchase orders and code calculations use the minima.

| Property | Metric | Imperial |
|---|---|---|
| Tensile strength, min | 515 MPa | 75 ksi |
| Yield strength, 0.2% offset, min | 205 MPa | 30 ksi |
| Elongation in 4D, min | 30 percent | 30 percent |
| Reduction of area, min | 50 percent | 50 percent |
| Brinell hardness | Not specified by A182 for this grade | |

Two errors are copied across many supplier datasheets. Yield strength is often listed as 205 MPa with an imperial figure of 29,700 ksi; the imperial value is psi, not ksi. Elongation is often listed as 29 percent, which is a typical annealed value and sits below the 30 percent A182 minimum.

## Melting, forging and heat treatment

S32109 is melted in the 25 t electric arc furnace, refined in a ladle furnace and decarburised under vacuum on the 30 t or 60 t VOD units. Maximum heat size is 60 tonnes. Electroslag remelting is available on the 3 t and 6 t protective-atmosphere furnaces where an order calls for improved cleanliness.

Hot working runs at roughly 1,149 to 1,260 degrees C, then the work is cooled below 538 degrees C before heat treatment begins.

| Heat treatment parameter | Requirement |
|---|---|
| Heat treat type | Solution treat and quench |
| Solution temperature, minimum | 1095 C / 2000 F |
| Cooling media | Liquid |
| Quench cool below | 260 C / 500 F |
| Tempering | Not applicable |

321H is not age-hardenable. Any offer of solution treatment plus ageing for this grade describes a precipitation-hardening cycle that does not apply. A182 also excludes F321H from the shortcut that lets some austenitic grades be quenched straight from the forging heat, so the grade is reheated and solution treated as a separate operation.

The 1,095 degrees C minimum sits above the range of the standard car-bottom furnaces, so F321H work is treated in the high-temperature car-bottom furnaces, working chamber 3,500 by 1,300 by 1,100 mm. For 321H this is usually the binding size limit rather than the press or the ring mill.

A182 warns that solution annealing above 1,065 degrees C can reduce resistance to intergranular corrosion in F321H after later sensitising exposure. Where the service environment is sensitising, specify a lower-temperature stabilisation or re-solution anneal under supplementary requirement S10.

## Equivalent and related grades

| System | Designation | Note |
|---|---|---|
| UNS | S32109 | The grade described here |
| AISI type | 321H | High-carbon heat-resisting 321 |
| ASTM forgings to 4,540 kg | A182 F321H | Flanges, fittings, valves, piping parts |
| ASTM forgings, heavier | A965 F321H | Pressure and high-temperature parts |
| ASME code | SA-182 / SA-965 F321H | Section II |
| EN number | 1.4878 | Heat-resistant titanium-stabilised 18-10 |
| Lower-carbon version | S32100 / 321 / 1.4541 | Less creep strength |
| Niobium-stabilised | 347H / A182 F347H | Niobium in place of titanium |
| Not equivalent | 310H / S31009 | 25Cr-20Ni, a different grade |

## Products and size limits

Seamless rolled rings, forged flanges, shafts and bars, discs and tube sheets, sleeves and bushings, and valve and wellhead parts.

| Product | Limit | Set by |
|---|---|---|
| Seamless rolled rings | OD 50 to 6,000 mm | 6 m radial-axial mill |
| Shafts, turned length | to 14,000 mm | C61160 horizontal lathe |
| Discs and tube sheets | to 5,000 mm machined | 5,000 mm vertical turning lathe |
| Bored cylinders | to 1,600 mm dia x 10,000 mm | CNC deep-hole drilling machine |
| Single-piece weight | 10 kg to 30,000 kg | 60 t heat size, 6,300 t press |
| Solution treatment envelope | 3,500 x 1,300 x 1,100 mm | High-temperature car-bottom furnaces |

## Service behaviour

Suited to sensitising exposure in the 427 to 816 degrees C range, to polythionic acid stress corrosion conditions in refinery hydroprocessing service, and to sustained hot load in the 540 to 870 degrees C region.

Not suited to hydrofluoric acid. Common 18-8 austenitic stainless steels, including 321H, should be treated as non-resistant to hydrofluoric acid at any concentration and any temperature, and fluoride ions can promote stress corrosion cracking. Monel 400 is the usual alternative.

Not suited to warm chloride service. Like all standard austenitic stainless steels, S32109 is open to chloride stress corrosion cracking. Duplex and super-duplex grades such as A182 F51, F53 and F55 are the normal route.

S32109 work-hardens quickly during machining. Rigid setups, sharp tooling, positive rake, consistent feeds and no dwelling keep the cut below the hardened layer.

## Testing and certification

For austenitic stainless forgings the applicable European ultrasonic standard is EN 10228-4, which covers austenitic and austenitic-ferritic stainless steel forgings. EN 10228-3 covers ferritic and martensitic forgings and is not the correct part for S32109. ASTM A388 also applies, and notes that heavy austenitic forgings are harder to penetrate ultrasonically than carbon or low-alloy forgings. Surface examination is by liquid penetrant to ASTM E165, since the grade is non-magnetic.

Chemical analysis to ASTM E415, carbon and sulphur to ASTM E1019, positive material identification, tensile testing to ASTM A370 and ISO 6892, Charpy impact, ultrasonic examination and grain size to ASTM E112 are run in the on-site laboratory. Intergranular corrosion testing to ASTM A262 is placed with an accredited third-party laboratory and reported alongside the mill certificate.

EN 10204 3.1 mill test certificates are standard. EN 10204 3.2 witnessed by BV, DNV, LR, SGS, TUV or the customer's own inspector is available on request. The works holds CCS, BV, DNV, LR and NK classification society approvals. Traceability starts at the melt number because the steel is melted on site.

## Questions

**Is UNS S32109 the same as 310H?**
No. S32109 is 321H, an 18Cr-8Ni grade stabilised with titanium. AISI 310H is UNS S31009, a 25Cr-20Ni grade with different chemistry, oxidation limits and allowable stresses. They are not substitutable.

**What is the difference between 321 and 321H?**
Chromium and nickel are the same. Type 321 caps carbon while 321H specifies 0.04 to 0.10 percent, which gives creep strength above roughly 540 degrees C. A182 also solution treats F321H from 1,095 degrees C minimum against 1,040 degrees C for F321, and requires titanium at four times carbon minimum against five times carbon for F321.

**What heat treatment does ASTM A182 F321H require?**
Solution treatment at 1,095 degrees C minimum, liquid quench, cooled below 260 degrees C. The grade is not age-hardenable, and it must be reheated and solution treated as a separate operation rather than quenched from the forging heat.

**Should the order cite ASTM A182 or ASTM A965?**
A182 is limited to products weighing a maximum of 4,540 kg and is scoped to piping components. Heavier austenitic forgings and general pressure and high-temperature parts fall under A965. Single pieces up to 30 tonnes are forged here, well above the A182 ceiling.

**Is 321H suitable for hydrofluoric acid service?**
No. Standard 18-8 austenitic stainless steels should be treated as non-resistant to hydrofluoric acid at any concentration and temperature. Nickel-base alloys such as Monel 400 are normally specified.

**What is the minimum titanium content for F321H?**
Not less than four times the carbon content and not more than 0.70 percent. A flat figure such as 0.35 percent is not a specification limit.

**Which ultrasonic testing standard applies?**
EN 10228-4 for austenitic stainless forgings, or ASTM A388. EN 10228-3 covers ferritic and martensitic forgings and does not apply to this grade.

**What is the minimum order quantity and lead time?**
Minimum order is 10 kg with no minimum piece count, so a single part is quotable. Lead time is 20 to 60 days from order confirmation.

**How is a quotation priced?**
Against the drawing. There is no list price for an open-die forging. Cost is driven by forged weight including machining allowance, the number of heating and forging operations, the heat treatment cycle, machining, and the testing and certification specified. Quotations normally follow within two working days.

**How large can a 321H forging be?**
Rings roll to 6,000 mm outside diameter and the heaviest single forging is 30 tonnes. For 321H the binding constraint is usually the 1,095 degrees C solution treatment, which calls for the high-temperature car-bottom furnaces with a 3,500 by 1,300 by 1,100 mm chamber.

## Contact

Jiangyin Jiangnan Metal Co., Ltd.
No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China
Telephone +86 189 2135 9659
Email sales@steelforgepieces.com