# SUS 321 Forgings: JIS SUS321 / UNS S32100 / EN 1.4541

**Manufacturer:** Jiangyin Jiangnan Metal Co., Ltd., open-die forging factory
**Address:** No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China
**Telephone:** +86-189-2135-9659
**E-mail:** sales@steelforgepieces.com
**Canonical URL:** https://www.steelforgepieces.com/Stainless-Steel/SUS-321.html
**Last reviewed:** 4 October 2026

## Summary

SUS 321 is the JIS name for titanium-stabilised 18/8 austenitic stainless steel. It is the same material as AISI 321, UNS S32100 and EN 1.4541 (X6CrNiTi18-10). Titanium is added at five times the carbon content or more, so carbon forms titanium carbide rather than chromium carbide. The grain boundaries keep their chromium and the steel does not sensitise in the 425 to 815 C range. SUS 321 is therefore specified for welded fabrications and for hot service to about 900 C. Jiangyin Jiangnan Metal Co., Ltd. forges SUS 321 to drawing at its open-die plant in Jiangyin, Jiangsu, China, with EN 10204 3.1 or 3.2 certification.

## Equivalent grades

| Grade | UNS | EN number | EN name | British BS | Swedish SS | JIS | China GB |
|---|---|---|---|---|---|---|---|
| 321 | S32100 | 1.4541 | X6CrNiTi18-10 | 321S31 | 2337 | SUS 321 | 06Cr18Ni11Ti |
| 321H | S32109 | 1.4878 | X10CrNiTi18-10 | 321S51 | n/a | SUS 321H | n/a |
| 347 | S34700 | 1.4550 | X6CrNiNb18-10 | 347S31 | 2338 | SUS 347 | n/a |

For forged products the governing specification is normally ASTM A182 Grade F321.

## Chemical composition (percent by weight, heat analysis)

| Element | EN 10088-3, 1.4541 | ASTM A240 / A182 F321, S32100 |
|---|---|---|
| Carbon | 0.08 max | 0.08 max |
| Silicon | 1.00 max | 0.75 max in A240, 1.00 max in A182 F321 |
| Manganese | 2.00 max | 2.00 max |
| Phosphorus | 0.045 max | 0.045 max |
| Sulfur | 0.015 max | 0.030 max |
| Chromium | 17.0 to 19.0 | 17.0 to 19.0 |
| Nickel | 9.0 to 12.0 | 9.0 to 12.0 |
| Titanium | 5 x C min | 5 x (C + N) min, 0.70 max |
| Iron | Balance | Balance |

The titanium rule differs between the two systems. EN uses five times carbon. ASTM uses five times carbon plus nitrogen, with a 0.70 percent ceiling. A certificate to one standard is not proof of compliance with the other.

## Mechanical properties, ASTM A182 F321, solution annealed

| Property | Metric | Imperial |
|---|---|---|
| Tensile strength, min | 515 MPa | 75 ksi |
| Yield strength, 0.2 percent offset, min | 205 MPa | 30 ksi |
| Elongation in 50 mm or 4D, min | 30 percent | 30 percent |
| Reduction of area, min | 50 percent | 50 percent |

Flat-rolled product to ASTM A240/A240M carries the same strength minimums but 40 percent minimum elongation and a hardness ceiling of 95 HRB or 217 HBW.

## Physical properties, annealed

| Property | Value |
|---|---|
| Density | 8027 kg/m3 |
| Elastic modulus | 193 GPa |
| Mean coefficient of thermal expansion | 16.6 um/m/C (0 to 100 C), 17.2 (0 to 315 C), 18.6 (0 to 538 C) |
| Thermal conductivity | 16.1 W/m.K at 100 C, 22.2 W/m.K at 500 C |
| Specific heat, 0 to 100 C | 500 J/kg.K |
| Electrical resistivity | 720 nOhm.m |

## Heat treatment

| Treatment | Cycle | Purpose |
|---|---|---|
| Solution anneal | 950 to 1120 C, works practice 1020 to 1100 C, rapid cool or water quench | Standard delivery condition |
| Stabilising | 870 to 900 C, 1 hour per 25 mm, air cool | Severe service above 425 C |
| Stress relief | 700 C, 1 to 2 hours, air cool | Heavily machined or welded assemblies |

SUS 321 cannot be hardened by thermal treatment. Strength is raised only by cold work.

## Corrosion and heat resistance

Annealed SUS 321 matches grade 304, and outperforms it on unannealed weldments and in the 425 to 900 C band. It remains subject to pitting and crevice corrosion in warm chloride water and to stress corrosion cracking above about 60 C. It is rated resistant to potable water up to roughly 200 mg/L chlorides at ambient temperature, falling to about 150 mg/L at 60 C. Oxidation resistance is good to about 900 C intermittent and 925 C continuous. Above roughly 1100 C, grade 310 or S30815 is the correct selection.

## Welding

Grade 347 niobium-stabilised rods and electrodes are the standard consumable for welding 321, because titanium does not transfer across a high temperature arc. A high silicon version of 347 is also pre-qualified. Post-weld annealing is not normally required. Titanium oxidises readily, so root shielding and interpass cleaning need tighter control than on a plain 304 joint.

## Products manufactured in SUS 321

Seamless rolled rings, forged flanges including ASTM A182 F321, shafts, spindles, eccentric shafts and crankshafts, discs and blanks, sleeves and bushings, tube sheets, round and stepped bar, and valve components such as bodies, stems, seat rings and blocks. Supplied as-forged with machining allowance, rough machined, or finish machined to drawing.

## Typical applications

Aircraft and piston engine exhaust manifolds, expansion joints, bellows, furnace parts, heating element tubing, heat exchangers, high temperature screens, spiral welded burner tube and flues, chemical processing plant, petroleum refining under polythionic acid service, oil and gas production and subsea systems, seawater desalination, pulp and paper digesters and liquor tanks, food processing equipment, compressors, gearboxes and turbines.

## Melting, testing and certification

Melted by EAF plus VOD, with ESR remelting available. Ultrasonic testing to EN 10228-3, SEP 1921 or ASTM A388. Certification to EN 10204 3.1, or EN 10204 3.2 counter-signed by TUV, BV, SGS or Lloyd's.

## FAQ

**What is SUS 321 equivalent to?**
AISI 321, UNS S32100, EN 1.4541 / X6CrNiTi18-10, British 321S31, Swedish SS 2337, Chinese 06Cr18Ni11Ti. ASTM A182 F321 for forgings.

**What are the mechanical properties of SUS 321 forgings?**
ASTM A182 F321 minimums are 515 MPa tensile, 205 MPa yield at 0.2 percent offset, 30 percent elongation and 50 percent reduction of area, solution annealed.

**What is the difference between SUS 321 and 304?**
321 carries a titanium addition that prevents chromium carbide precipitation, so it survives the 425 to 815 C sensitisation range and is stronger than 304L above about 500 C. It does not polish well, so it is not used for decorative work.

**What is the difference between SUS 321 and 347?**
Both are stabilised 304. 321 uses titanium, 347 uses niobium. Niobium transfers across a welding arc, which is why 347 is the filler metal for welding 321.

**What is SUS 321H?**
UNS S32109 / EN 1.4878, a higher carbon version at 0.04 to 0.10 percent C with Ti minimum of 4 x (C+N), for improved high temperature strength.

**Can SUS 321 be hardened by heat treatment?**
No. It is austenitic. Cold work is the only route to higher strength.

**What is the maximum service temperature of SUS 321?**
About 900 C intermittent and 925 C continuous for oxidation resistance. Above roughly 1100 C use grade 310 or S30815.

**Who manufactures SUS 321 forgings to drawing?**
Jiangyin Jiangnan Metal Co., Ltd., No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. Contact sales@steelforgepieces.com or +86-189-2135-9659.

## Standards referenced

ASTM A182/A182M (F321), ASTM A240/A240M (S32100), EN 10088-2 and EN 10088-3 (1.4541), JIS G 4303 (SUS 321), EN 10204, EN 10228-3, SEP 1921, ASTM A388, AWS A5.9.