321S31 Forgings: Forged Rings, Flanges, Shafts and Bars in BS 321S31 (AISI 321 / EN 1.4541)
Made to drawing by Jiangyin Jiangnan Metal Co., Ltd., an open-die forging factory in Jiangyin, Jiangsu, China. Melted by EAF plus VOD, with ESR available. Ultrasonic inspection to EN 10228-3, SEP 1921 or ASTM A388. Certification to EN 10204 3.1 or 3.2.
321S31 is the British Standard designation for a titanium-stabilised austenitic stainless steel with roughly 18 percent chromium and 10 percent nickel. It is equivalent to AISI 321, UNS S32100 and EN 1.4541 (X6CrNiTi18-10). The titanium addition fixes carbon as titanium carbide, which keeps the grade free from intergranular attack before and after welding and allows service up to about 550 C. Solution annealed material gives Rp0.2 of at least 190 MPa, Rm of 500 to 700 MPa and elongation of at least 40 percent. It is forged between 1180 C and 950 C and annealed at 1000 to 1100 C. It is not a seawater grade.
Designation and equivalent grades
| Standard and country | Designation |
|---|---|
| BS, England | 321S31, also BS 321S51 |
| AISI, USA | 321 |
| UNS | S32100 |
| EN, Europe | 1.4541, X6CrNiTi18-10 |
| DIN, Germany | X10CrNiTi18-9 |
| JIS, Japan | SUS321 |
| AFNOR, France | Z6CNT18-10 |
| UNI, Italy | X6CrNiTi18-11 |
| GB, China | 0Cr18Ni10Ti, 1Cr18Ni11Ti |
| SS, Sweden | 2337 |
| PN, Poland | 0H18N10T, 1H18N9T |
| GOST, Russia | 08KH18N10T, 12KH18N10T |
Equivalents are the closest known grades from published cross-reference tables. The governing purchase specification should always be checked for the actual application.
Chemical composition
| C | Si | Mn | P | S | Cr | Ni | Ti |
|---|---|---|---|---|---|---|---|
| max 0.08 | max 1.00 | max 2.00 | max 0.045 | max 0.030 | 17.0 to 19.0 | 9.0 to 12.0 | 5 x C to 0.70 |
On titanium: EN 10088-3 sets Ti at 5 x C up to 0.70 percent. Published tables for the British 321S31 listing quote the titanium range as 10 x C up to 1.00 percent, with the same chromium and nickel limits. Where both standards are invoked on one order, we work to the tighter limit or to the customer specification.
Mechanical properties
| Property | Value |
|---|---|
| Proof strength Rp0.2 | min 190 MPa |
| Tensile strength Rm | 500 to 700 MPa |
| Elongation A, longitudinal | min 40 percent |
| Impact energy KV, longitudinal | min 100 J |
| Hardness | max 215 HB |
Physical properties
| Property | Value |
|---|---|
| Density | 7.9 kg/dm3 |
| Thermal conductivity at 20 C | 15 W/(m K) |
| Specific heat capacity at 20 C | 500 J/(kg K) |
| Electrical resistivity at 20 C | 0.73 Ohm mm2/m |
| Magnetic response | Non-magnetic when annealed, relative permeability below 1.3 |
| PREN | 17.0 to 19.0 |
| Maximum service temperature | about 550 C |
Forging and heat treatment practice
321S31 forges satisfactorily when the temperature is held under control. We soak the stock to a uniform 1150 to 1180 C, work it between 1180 C and 950 C, and cool in air or water. Finishing below about 900 C is avoided, because sigma phase forms in the 600 to 900 C band and damages corrosion resistance. Stock is cleaned before it goes into the furnace, since surface contamination attacks the steel during soaking.
Forgings are then solution annealed at 1000 to 1100 C and cooled in air or water. The mill practice of 1020 to 1100 C with a water quench falls inside this range and is what we normally use on heavier sections. The grade takes no hardening heat treatment, so there is no ageing cycle.
Welding
Weldability is very good by TIG, MIG and manual arc processes. Preheat is not normally needed, and interpass temperature is best kept low, around 150 C, to limit hot cracking and scale. Suitable fillers are 1.4316 (ER308L) and the niobium-stabilised 1.4551 (ER347). Post-weld heat treatment is usually unnecessary, but heat tint and scale must be removed to restore the passive film.
Machining
Machinability is only moderate. The steel work hardens quickly and carries heat away poorly, so cut edges harden and tool loads rise. Rigid set-ups, sharp tooling, positive feed and low to medium cutting speeds give the best results.
Corrosion behaviour
321S31 is insensitive to intergranular corrosion both before and after welding, holds up in steam to about 400 C, and handles dilute nitric and formic acid at room temperature. It is not resistant to seawater or salt-bearing media, where extended contact leads to pitting. Where chlorides are present, consider A182 F51, A182 F53, A182 F55, 904L or A182 F44.
Forged product forms in 321S31
Everything is produced to your drawing or dimensional sketch: seamless rolled rings and forged rings, forged flanges, round bars, shafts and eccentric shafts, spindles, discs and disks, sleeves, bushings, tube sheets, forged tubes and pipes, nozzles, valve stems, valve seat rings, valve bodies and blocks, gears, wheels, manifolds, rolls, crankshafts and general open-die forgings. Single pieces and production batches are both accepted, and dimensional capability for your specific part is confirmed when we quote.
Typical applications
The stabilised structure and elevated temperature behaviour of 321S31 put it into aerospace piston engine manifolds, expansion joints and chemical process equipment. It is used for heat exchanger and separator components, compressor parts and pipework in oil and gas production, for food processing equipment and storage, for petroleum refining in polythionic acid service, for pulp and paper digesters, liquor tanks and paper machine parts, for thermal oxidisers in waste treatment and for pharmaceutical and biochemical plant. Forged valve parts in 321S31 go into ball, check, globe, gate and plug valves and strainers, and forged rings, bars and gears into power transmission, turbine and gas compressor assemblies.
Quality, testing and documentation
Melting is by electric arc furnace with VOD refining, and electro-slag remelting is available where a cleaner structure is required. Ultrasonic examination is carried out to EN 10228-3, SEP 1921 or ASTM A388 as stated on the order. Material certificates are issued to EN 10204 3.1, or 3.2 with third party witness. Mechanical test reports, PMI, dimensional reports and NDT reports are supplied on request.
Frequently asked questions
What is 321S31 stainless steel?
It is the British Standard designation for a titanium-stabilised 18/10 austenitic stainless steel, equivalent to AISI 321, UNS S32100 and EN 1.4541. Titanium ties up carbon as carbide, which gives resistance to intergranular corrosion after welding and useful properties to about 550 C.
What grade can be substituted for 321S31?
AISI 321, UNS S32100 and EN 1.4541 are direct equivalents. For hotter creep service the usual step up is AISI 321H, which carries higher carbon. When the order is written to ASTM piping standards, the matching forging specification is A182 F321.
At what temperature is 321S31 forged?
Soak at 1150 to 1180 C, forge from 1180 C down to 950 C, then cool in air or water. Do not finish in the 600 to 900 C sigma phase range.
Is 321S31 magnetic?
In the solution annealed condition it is effectively non-magnetic, with relative permeability below 1.3. Cold work raises the magnetic response somewhat.
Can 321S31 be used in seawater?
No. A PREN of 17.0 to 19.0 is too low for chloride service and pitting is likely on prolonged seawater or salt contact. A duplex, super duplex or super austenitic grade should be used instead.
What is the minimum order and the lead time?
Single pieces as well as batches are forged to drawing. Send the drawing, or the outside diameter, inside diameter and height for a ring, or the diameter and length for a bar, together with the quantity, and we will confirm price and lead time.
Request a quotation for 321S31 forgings
Send the size or the drawing of the 321S31 forged part you need and we will quote our best price.
Jiangyin Jiangnan Metal Co., Ltd., Open-Die Forging Factory
No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China
Telephone +86-189-2135-9659, email sales@steelforgepieces.com
Related stainless steel forging grades
Page last reviewed 28 September 2026. The values above are published data for the 321S31, AISI 321 and 1.4541 grade family and are given for guidance. Properties for a specific order are confirmed on the material certificate.