Austenitic stainless · Titanium stabilised
UNS S32109 Forgings AISI 321H to ASTM A182 Grade F321H and ASTM A965, melted and forged in one works
Seamless rolled rings, flanges, shafts, discs, tube sheets, sleeves and bored cylinders in 321H. The steel is melted here on the electric arc furnace, ladle furnace and vacuum oxygen decarburisation route, so the certificate traces back to a melt number rather than to a purchased billet.
- UNS
- S32109
- Type
- AISI 321H, titanium-stabilised 18Cr-8Ni austenitic
- Forging spec
- ASTM A182 F321H to 4,540 kg; ASTM A965 above that
- EN number
- 1.4878
- Condition
- Solution treated and quenched
- Tensile min
- 515 MPa / 75 ksi
- Yield min
- 205 MPa / 30 ksi
- Ring OD
- up to 6,000 mm
- Piece weight
- 10 kg to 30,000 kg
- Certification
- EN 10204 3.1, or 3.2 witnessed
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 °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.
What UNS S32109 is
321H is the high-carbon, heat-resisting version of Type 321. Both carry the same 17 to 19 percent chromium and 9 to 12 percent nickel, and both are stabilised with titanium. The difference is that 321H specifies a carbon range with a floor rather than only a ceiling.
That carbon floor is the point of the H grade. Carbon held in solution is what provides creep strength, so 321H keeps its load-carrying ability through long exposures above roughly 540 °C, where a low-carbon austenitic would relax.
The titanium addition is what 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 in the matrix and available for passivation, which is why stabilised grades come through the 427 to 816 °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, a familiar shutdown problem in refinery hydroprocessing circuits.
This works produces S32109 as open-die forgings and seamless rolled rings rather than as stock plate, bar or tube. That suits one-off and short-run parts, sections outside standard mill product, and shapes where grain flow needs to follow the part.
Chemical composition
Chemical requirements for Grade F321H in ASTM A182. 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 × C min, 0.70 max |
| Iron | Fe | Balance |
Source: ASTM A182 / A182M, chemical requirements table and the titanium footnote for Grade F321H.
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. At the top of the carbon range, 0.10 percent carbon, that sets a 0.40 percent titanium minimum, so a heat certified at 0.35 percent would be non-conforming.
Grade F321 without the H uses a five times carbon minimum, so the two grades are not checked the same way. Our heat analysis reports the titanium to carbon ratio alongside the raw figures so the check can be made from the certificate.
Mechanical properties
Two sets of numbers circulate for this grade and the difference matters. 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 % | 30 % |
| Reduction of area, min | 50 % | 50 % |
| Brinell hardness | Not specified by A182 for this grade | |
Source: ASTM A182 / A182M, mechanical requirements table, Grade F321H.
Yield strength is widely listed as 205 MPa with an imperial figure of 29,700 ksi. The imperial value is psi, not ksi. 205 MPa is close to 30 ksi.
Elongation is widely listed as 29 percent. That is a typical annealed value and it sits below the 30 percent A182 minimum. A supplier quoting 29 percent as a datasheet figure has copied a reference table rather than read the specification.
Test specimens for austenitic grades may be taken from any convenient location, but they are not removed until all heat treatment is complete, and one tension test is run per heat. Results are reported on the mill certificate against the specified minima.
Melting, forging and heat treatment
Melting
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, which is the standard route for stainless and duplex grades here. Maximum heat size is 60 tonnes. Where an order calls for improved cleanliness or reduced segregation, electroslag remelting is available on the 3 t and 6 t protective-atmosphere furnaces without going outside the works. Sufficient discard is taken from the ingot to keep piping and segregation out of the forged product.
Forging
Hot working runs at roughly 1,149 to 1,260 °C for forging and upsetting. Work is then cooled below 538 °C before heat treatment begins. Rings are rolled on the 6 m, 3 m or 1 m radial-axial mills depending on size; sections outside the ring-mill envelope are upset and punched on the 6,300 t, 4,000 t or 2,000 t presses.
Solution 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 |
Source: ASTM A182 / A182M heat treating table. Grade F321 without the H is solution treated from 1040 °C minimum, a different requirement.
Any offer of solution treatment plus ageing for S32109 describes a precipitation-hardening cycle that does not apply. Austenitic stainless steels are strengthened by cold work, not by ageing.
A182 also excludes F321H from the shortcut that lets some austenitic grades be quenched straight from the forging heat. The grade has to be reheated and solution treated as a separate operation, which is how it is run here.
The 1,095 °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 size limit rather than the press or the ring mill, so larger pieces are confirmed against furnace availability at enquiry stage.
One further point is worth raising at order stage. A182 carries a warning that solution annealing above 1,065 °C can reduce resistance to intergranular corrosion in F321H after later exposure to sensitising conditions. Where the service environment is sensitising, the purchaser can specify a lower-temperature stabilisation or re-solution anneal after the initial high-temperature cycle, under supplementary requirement S10. The furnaces here will run that second cycle; it needs stating on the order.
Equivalent and related grades
| System | Designation | Note |
|---|---|---|
| UNS | S32109 | The grade on this page |
| 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 of the boiler and pressure vessel code |
| EN number | 1.4878 | Heat-resistant titanium-stabilised 18-10 |
| Lower-carbon version | S32100 / 321 / 1.4541 | Less creep strength, lower solution temperature |
| Niobium-stabilised | 347H / A182 F347H | Niobium in place of titanium |
| Not equivalent | 310H / S31009 | 25Cr-20Ni, a different grade |
If a drawing calls out 1.4541 and the part runs hot under load, 1.4878 or 321H is worth raising. Oxidation resistance in air is similar, but the higher carbon and the titanium give better strength retention at temperature.
S32109 forged products and sizes
Every piece is forged from steel melted on site. No welding, no casting, no purchased billet of unknown origin.
Seamless rolled rings
Rolled from a punched preform on the radial-axial mills. Rectangular or contoured section for furnace work, flange blanks, casing rings and bearing races.
Forged flanges
Weld neck, blind, slip-on, long weld neck, orifice and special-bore flanges to ASME B16.5, B16.47 or to drawing.
Shafts and bars
Stepped shafts, spindles, eccentric shafts, round and flat bar, turned length to 14,000 mm between centres.
Discs and tube sheets
Upset-forged discs, tube sheets and covers to 5,000 mm machined diameter, supplied proof-machined for volumetric inspection.
Sleeves and bushings
Hollow forged sleeves, bushings and couplings, bored on the deep-hole drilling machine to 1,600 mm diameter by 10,000 mm.
Valve and wellhead parts
Bodies, bonnets, seat rings, stems, blocks, spools and nozzles for ball, gate, globe and check valves.
Working envelope
| Product | Limit | Set by |
|---|---|---|
| Seamless rolled rings | OD 50 to 6,000 mm | 6 m radial-axial mill; upset and punch below mill range |
| 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 × 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 × 1,300 × 1,100 mm | High-temperature car-bottom furnaces, for the 1,095 °C cycle |
Where a 321H part exceeds the high-temperature furnace chamber, say so at enquiry and the heat-treatment route will be confirmed before a price is given rather than after.
Service behaviour and limits
Where the grade performs
Sensitising exposure. Titanium carbides form in preference to chromium carbides, so S32109 keeps its intergranular corrosion resistance after exposure in the 427 to 816 °C chromium-carbide precipitation range, where unstabilised 304 would sensitise.
Polythionic acid stress corrosion. Type 321 is specifically useful under the conditions that cause polythionic acid stress corrosion cracking in unstabilised austenitic grades, which is why stabilised grades are so common in refinery hydroprocessing service.
Sustained hot load. The controlled carbon range gives better creep resistance and longer life than unstabilised austenitic grades in continuous service in the 540 to 870 °C region.
Where the grade is the wrong choice
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. Any datasheet claiming S32109 has excellent resistance to hydrofluoric acid is wrong and should not be used for material selection.
Warm chloride service. Like all standard austenitic stainless steels, S32109 is open to chloride stress corrosion cracking, and practical limits in oxygenated chloride-bearing environments are low. Duplex and super-duplex grades such as A182 F51, F53 and F55 are the normal route there, and are forged here as well.
Hot concentrated caustic. We make no caustic-service claim for this grade. Selection depends on concentration and temperature and belongs with a corrosion engineer; nickel alloys are usual for severe hot caustic.
Machining
S32109 machines like other austenitic stainless steels: it work-hardens quickly, so cutting forces are high and the machined surface hardens as the tool passes. Rigid setups, sharp tooling, positive rake, consistent feeds and no dwelling keep the cut below the hardened layer. It is a process-planning question, not a reason to avoid the grade, and it forges readily in the 1,149 to 1,260 °C range.
Testing, inspection and certification
Non-destructive examination
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, a detail that a good number of suppliers get wrong on their grade sheets. On the ASTM side, A388 applies, and it notes that heavy austenitic forgings are harder to penetrate ultrasonically than comparable carbon or low-alloy forgings because of the coarse, directional grain structure. For thick austenitic sections, acceptance levels and probe frequency are worth agreeing before the forging is made rather than after. Surface examination is by liquid penetrant to ASTM E165, since the grade is non-magnetic and magnetic particle methods do not apply.
In-house laboratory
| Discipline | Equipment | Standard |
|---|---|---|
| Chemical analysis | Optical emission spectrometer | ASTM E415 |
| Carbon and sulphur | Infrared carbon-sulphur analyser | ASTM E1019 |
| Alloy verification | Handheld analyser for positive material identification | PMI |
| Tensile | 600 kN and 300 kN universal testing machines | ASTM A370, ISO 6892 |
| Impact | Pendulum machine with low-temperature bath | ASTM A370 |
| Ultrasonic | Digital flaw detectors | ASTM A388, EN 10228-4 |
| Grain size | Metallographic microscope and preparation line | ASTM E112 |
Intergranular corrosion testing to ASTM A262 is placed with an accredited third-party laboratory and the report is issued alongside the mill certificate. For a stabilised grade this is the test most often specified, so flag it on the enquiry and it will be scheduled before shipment rather than added at the end.
Documentation
EN 10204 3.1 mill test certificates are standard. EN 10204 3.2 certificates witnessed by BV, DNV, LR, SGS, TÜV or the customer's own inspector are available on request. The works holds CCS, BV, DNV, LR and NK classification society approvals. Certificates record the melt number, melting route, full heat analysis with the titanium to carbon ratio, the solution treatment temperature and quench record, tensile results per heat, and the non-destructive examination reports. Because the steel is melted here, traceability starts at the furnace rather than at a purchased billet.
Request a quotation for S32109 forgings
Send a drawing or a written specification. Quotations normally come back within two working days. Minimum order is 10 kg with no minimum piece count, so a single part is quotable, and normal lead time is 20 to 60 days from order confirmation.
Every piece is made to order, so there is no list price. Cost follows the drawing, the forged weight including machining allowance, the quantity, the heat treatment condition and the testing and certification required.
Include the grade or specification, the dimensions or a drawing in PDF, DWG, DXF or STEP, the quantity, the delivery condition, any heat treatment and testing requirements, and the certification and destination port. For 321H it also helps to state whether the service is sensitising, since that decides whether a stabilisation anneal and ASTM A262 testing are needed.
Jiangyin Jiangnan Metal Co., Ltd.
No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China
Questions about UNS S32109
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 much higher alloy content, different oxidation limits and different allowable stresses. They are not substitutable.
This pairing appears on a number of supplier pages, usually in the page title. Check the UNS number rather than the heading.
What is the difference between 321 and 321H?
Chromium and nickel are the same. Carbon is not: Type 321 caps it, while 321H specifies 0.04 to 0.10 percent. The carbon floor gives creep strength for sustained service above roughly 540 °C.
ASTM A182 treats them differently too. F321H is solution treated from 1,095 °C minimum against 1,040 °C for F321, and F321H needs titanium at four times carbon minimum against five times carbon for F321.
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 flanges, fittings, valves and similar piping components. Heavier austenitic forgings, and pressure and high-temperature parts generally, fall under A965.
Single pieces up to 30 tonnes are forged here, well above the A182 ceiling, so tell us the finished weight and the correct specification will be confirmed with the quotation.
Can a stabilisation anneal be supplied after solution treatment?
Yes. A182 notes that solution annealing above 1,065 °C can reduce resistance to intergranular corrosion in F321H after later sensitising exposure, and allows the purchaser to specify a lower-temperature stabilisation or re-solution anneal afterwards, under supplementary requirement S10.
State S10 on the order if the service environment is sensitising. The second cycle is run in the same furnaces and is recorded on the heat-treatment chart.
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, and fluoride ions can promote stress corrosion cracking. Nickel-base alloys such as Monel 400 are the usual choice, and are forged here.
What is the minimum order quantity and the lead time?
Minimum order is 10 kg, with no minimum piece count. The limit is weight rather than quantity, so one small part is quotable and so is a single large ring. In practice very small parts are grouped into a batch to share furnace and setup time, which is why quantity still moves the unit price.
Lead time runs 20 to 60 days from order confirmation. Standard stainless grades on the electric arc furnace route sit at the lower end. Electroslag remelting, witnessed third-party inspection and outside corrosion testing all push towards the upper end, so flag them at enquiry stage and they will be built into the quoted date.
How is a quotation priced?
Against the drawing. There is no list price for an open-die forging, because the cost is driven by the forged weight including machining allowance, the number of heating and forging operations, the heat treatment cycle, the machining, and the testing and certification specified.
Send the drawing and quantity to sales@steelforgepieces.com and a firm price normally follows within two working days.
How large can a 321H forging be?
Rings roll up to 6,000 mm outside diameter on the 6 m radial-axial mill, and the heaviest single forging is 30 tonnes on the 6,300 t press.
For 321H specifically the binding constraint is usually heat treatment, not forging. The 1,095 °C minimum solution temperature calls for the high-temperature car-bottom furnaces, working chamber 3,500 by 1,300 by 1,100 mm. Larger 321H pieces are quoted only after the heat-treatment route has been confirmed.
Which ultrasonic standard should be specified?
EN 10228-4 for austenitic stainless forgings, or ASTM A388. EN 10228-3 is written for ferritic and martensitic forgings and does not apply to this grade.
Heavy austenitic sections are harder to examine ultrasonically than carbon or low-alloy forgings because of the coarse grain structure, so agree the acceptance class and the probe arrangement before manufacture.
Related grades
Grades commonly compared with S32109, all forged in this works.