Stainless Steel 321
AISI/SAE 321 · UNS S32100 · ASTM A240 TP321 · EN 1.4541, X6CrNiTi18-10 · JIS SUS321
321 (EN 1.4541 / UNS S32100) is a titanium-stabilised 18Cr–8Ni austenitic stainless steel in which titanium binds carbon as TiC, suppressing chromium carbide precipitation and intergranular attack after welding or long service at 425–900 °C.
Values for the Solution Annealed condition
321 tempers and conditions
321 is supplied in 6 conditions, soft to hard. Solution Annealed is the default FabDigit quotes; the values on this page are for it.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
softened mill condition (sheet/strip/bar, ASTM A240/A276 minimums) | Generic annealed supply condition; use when only the standard minimum mechanical guarantees are needed. | 235 | 600 | 45 | 150 HB | 2.4 % IACS |
Solution AnnealedDefault 1010–1120 °C, rapid cooled (mill annealed) | Standard stocked condition for plate, sheet, bar, pipe and fittings — maximum ductility and corrosion resistance. | 240 | 620 | 45 | 150 HB | — |
321H | Choose 321H when ASME creep allowables above ~540 °C are needed (C 0.04–0.10 %); otherwise identical processing to 321. | 245 | 620 | 45 | 150 HB | 2.4 % IACS |
Cold Drawn Bar / Wire (lightly cold worked) | Pick for machined shafts and fasteners needing higher yield and better surface/straightness than annealed bar. | 550 | 760 | 22 | 215 HB | — |
Quarter hard | Use where moderate spring-back and higher yield are required but some bending is still needed. | 600 | 900 | 12 | 25 HRC | 2.4 % IACS |
Half hard | High-strength strip for clamps, shims and lightly formed springs; forming limited to gentle bends. | 760 | 1,035 | 8 | 32 HRC | 2.4 % IACS |
Supply forms, finishes and certifications
Ways 321 is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
CW Tube | Cold Worked (as-drawn) tube / hydraulic line | Supply form |
2B | Cold Rolled, Annealed, 2B finish | Surface finish |
HRAP | Hot Rolled, Annealed and Pickled | Surface finish |
What is 321?
321 (EN 1.4541 / UNS S32100) is a titanium-stabilised 18Cr–8Ni austenitic stainless steel in which titanium binds carbon as TiC, suppressing chromium carbide precipitation and intergranular attack after welding or long service at 425–900 °C. Typical forms are sheet, plate, tube and bar for exhaust manifolds, heat exchangers, expansion joints, annealing covers and boiler piping. Room-temperature corrosion resistance matches 304, so chloride pitting and hot concentrated hydrochloric or sulfuric acid above 60–80 °C remain limits, and the grade can only be strengthened by cold work. Titanium inclusions slightly reduce machinability and mirror-polish quality; 347 is the niobium-stabilised alternative. 321 has a density of 7.9 g/cm³ (0.285 lb/in³), heavier than 68% of stainless steel grades. It melts at 1,398°C (2,548 °F). 321 has a yield strength of 240 MPa (34.8 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 96% of stainless steel grades. Elongation at break is 45% and the elastic modulus is 193 GPa (28 Msi).
What is 321 used for?
- Aircraft exhaust manifolds
- Chemical process piping
- Heat exchanger tubing
- Expansion joints and bellows
- Annealing furnace hoods
- Boiler components
- Welded high-temperature ducting
Advantages
- Readily welded — 88/100, better than 91% of stainless steel grades
- Forms and bends easily — 78/100, better than 90% of stainless steel grades
- Tough — resists crack growth — 200 MPa·√m (182 ksi·√in), better than 86% of stainless steel grades
- High service temperature — 870°C (1,598 °F), better than 83% of stainless steel grades
- Ductile — tolerates forming and impact — 45%, better than 76% of stainless steel grades
Limitations
- Low strength — 240 MPa (34.8 ksi), worse than 96% of stainless steel grades
- High embodied carbon — 6 kg CO₂/kg, worse than 88% of stainless steel grades
321 properties
Typical room-temperature values for 321-Solution Annealed; bars are the position among stainless steel grades.
Physical3
321 has a density of 7.9 g/cm³ (0.285 lb/in³), heavier than 68% of stainless steel grades. It melts at 1,398°C (2,548 °F).
Mechanical16
321 has a yield strength of 240 MPa (34.8 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 96% of stainless steel grades. Elongation at break is 45% and the elastic modulus is 193 GPa (28 Msi).
Thermal6
321 is rated for continuous service to 870°C (1,598 °F). It conducts heat at 16.1 W/m·K (9.3 BTU/hr·ft·°F), better than 61% of stainless steel grades. Thermal expansion is 16.6 µm/m·K (9.22 µin/in·°F).
Electrical3
321 conducts electricity at 2.4 % IACS, better than 67% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is good (64/100), better than 54% of stainless steel grades.
Sustainability4
Producing a kilogram of 321 takes about 60 MJ of energy and emits 6 kg of CO₂ — more than 70% of stainless steel grades. Typical recycled content is 60%.
Manufacturability7
321's machinability is fair (38/100, better than 63% of stainless steel grades); weldability excellent (88/100); formability very good (78/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the stainless steel family
Yield strength against density for every stainless steel grade FabDigit runs. 321 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 321
Is 321 easy to machine?
Machines like 304 but titanium carbides accelerate tool wear — use rigid setups, sharp carbide/coated tools, positive rake, 30–60 m/min, heavy feed and flood coolant to avoid work hardening and gumming.
Can 321 be welded?
Excellent by GTAW/GMAW/SMAW/plasma with ER321/ER347 filler; Ti stabilization means no post-weld solution anneal is needed for service in the 425–900 °C sensitization band, but keep interpass temperature low and avoid over-heating to limit distortion.
Can 321 be formed, bent or molded?
Good deep-drawing and bending in the annealed condition; work-hardens rapidly (n ≈ 0.4), so allow generous spring-back, intermediate anneals for severe draws, and expect higher press loads than mild steel.
Manufacturability
The process limits FabDigit's quote engine applies to 321. Design inside these and the part quotes instantly; outside them it routes to an engineer.
CNC machining
| Machinability | Fair38 / 100 |
|---|---|
| ISO material group | M.1 |
| Cutting speed (rough / finish) | 150 / 180 m/min |
| Minimum wall | 0.8 mm |
| Minimum internal radius | 1.5 mm |
| Drill depth limit | 4× diameter |
| Best surface (machined / polished) | Ra 1.6 / — |
| Hardenable after machining | No |
Sheet metal
| Formability | Better78 / 100 |
|---|---|
| Weldability | Better88 / 100 |
| Bendable | Yes |
| Minimum bend radius | 1× thickness |
| Spring-back | High |
| Welding processes | TIG, MIG, SPOT, SEAM, LASER |
321 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| C0.04–0.10 for 321H | ≤ 0.08 | 0.05 |
| Si | ≤ 0.75 | 0.5 |
| Mn | ≤ 2 | 1.3 |
| P | ≤ 0.05 | 0.03 |
| S | ≤ 0.03 | 0.01 |
| Cr | 17 – 19 | 17.8 |
| Ni | 9 – 12 | 10 |
| Timin 5×(C+N) per ASTM A240; min 4×(C+N) for 321H | ≤ 0.7 | 0.35 |
| N | ≤ 0.1 | 0.02 |
| Fe | balance |
What surface finishes work on 321?
Pickle and passivate (ASTM A967) or electropolish after welding to restore the chromium oxide film; No.4/mirror polishing is achievable but Ti inclusions can leave faint streaks on bright-annealed or mirror finishes.
Surface treatments FabDigit runs on stainless steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Plating
Organic Coating
CVD Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Stainless Steel 321 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- S32100
- ASTM
- A240 TP321
- EN / DIN / Werkstoff-Nr.
- 1.4541X6CrNiTi18-101.4878
- GB (China)
- 06Cr18Ni11Ti1Cr18Ni9Ti
- JIS
- SUS321
How much does 321 cost?
321 is a high-cost stainless steel ($$$$), cheaper than about 51% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
321 — frequently asked
What is 321 used for?
321 is typically used for aircraft exhaust manifolds, chemical process piping, heat exchanger tubing, expansion joints and bellows, annealing furnace hoods and boiler components. In short: creep resistant high-temp.
What is the yield strength of 321?
321 has a typical yield strength of 240 MPa (34.8 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 96% of stainless steel grades. Strength varies by condition: see the 6 listed tempers.
Is 321 easy to machine?
Not especially — machinability is rated fair (38/100, better than 63% of stainless steel grades). Machines like 304 but titanium carbides accelerate tool wear — use rigid setups, sharp carbide/coated tools, positive rake, 30–60 m/min, heavy feed and flood coolant to avoid work hardening and gumming.
Can 321 be welded?
Yes — weldability is rated excellent (88/100). Excellent by GTAW/GMAW/SMAW/plasma with ER321/ER347 filler; Ti stabilization means no post-weld solution anneal is needed for service in the 425–900 °C sensitization band, but keep interpass temperature low and avoid over-heating to limit distortion.
What surface finishes work on 321?
Pickle and passivate (ASTM A967) or electropolish after welding to restore the chromium oxide film; No.4/mirror polishing is achievable but Ti inclusions can leave faint streaks on bright-annealed or mirror finishes.
Can 321 be formed, bent or molded?
Good deep-drawing and bending in the annealed condition; work-hardens rapidly (n ≈ 0.4), so allow generous spring-back, intermediate anneals for severe draws, and expect higher press loads than mild steel.
What is the maximum service temperature of 321?
321 is rated for continuous use to about 870°C (1,598 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does 321 cost?
321 is a high-cost stainless steel ($$$$), cheaper than about 51% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Can FabDigit make parts in 321?
Yes — 321 is available for CNC machining and sheet metal with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- ASTM A240/A240M — Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip — ASTM International (2023)
- ASTM A276/A479 — Stainless Steel Bars and Shapes — ASTM International (2022)
- EN 10088-2 (X6CrNiTi18-10, 1.4541) — CEN (2014)
- GB/T 20878 / GB/T 4237 (06Cr18Ni11Ti) — SAC (2015)
- JIS G 4304/G 4305 (SUS321) — JSA (2021)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- Outokumpu Stainless Steel Handbook — Outokumpu (2013)
- Sandvik / Alleima 321 and 321H alloy datasheets — Alleima (2023)
- (SMM) / Mysteel — SMM / Mysteel (2025)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.