Stainless Steel 321 · heat-treated state · default condition
Stainless Steel 321 Solution Annealed
Properties of the Solution Annealed condition, compared with the other 321 tempers.
Standard stocked condition for plate, sheet, bar, pipe and fittings — maximum ductility and corrosion resistance.
What is 321 Solution Annealed?
321 Solution Annealed is 321 heat treated to Solution Annealed — standard stocked condition for plate, sheet, bar, pipe and fittings — maximum ductility and corrosion resistance. 321 Solution Annealed 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). 321 Solution Annealed has a density of 7.9 g/cm³ (0.285 lb/in³), heavier than 67% of stainless steel grades. It melts at 1,398°C (2,548 °F).
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 84% of stainless steel grades
- High service temperature — 870°C (1,598 °F), better than 82% 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 Solution Annealed properties
Typical room-temperature values for 321 Solution Annealed — 15 properties are specific to this condition; the rest are grade-level values shared by every 321 temper. Each bar shows where the value sits among the stainless steel grades in FabDigit's library — further right is higher.
Physical3
321 Solution Annealed has a density of 7.9 g/cm³ (0.285 lb/in³), heavier than 67% of stainless steel grades. It melts at 1,398°C (2,548 °F).
Mechanical16
321 Solution Annealed 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 Solution Annealed 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 Solution Annealed conducts electricity at 2.4 % IACS, better than 67% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is good (64/100), better than 53% of stainless steel grades.
Sustainability4
Producing a kilogram of 321 Solution Annealed 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 Solution Annealed'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.
Other 321 tempers and conditions
321 is also supplied in 8 other conditions. The full side-by-side table is on the 321 overview.
- Solution AnnealedDefaultStandard stocked condition for plate, sheet, bar, pipe and fittings — maximum ductility and corrosion resistance.240 MPa yield · 150 HB
- Cold DrawnPick for machined shafts and fasteners needing higher yield and better surface/straightness than annealed bar.550 MPa yield · 215 HB
- AnnealedGeneric annealed supply condition; use when only the standard minimum mechanical guarantees are needed.235 MPa yield · 150 HB
Working with 321 Solution Annealed
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.
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.
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 | — |
321 Solution Annealed — frequently asked
What is 321 Solution Annealed used for?
321 Solution Annealed 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 Solution Annealed?
321 Solution Annealed 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 9 listed tempers.
Is 321 Solution Annealed 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 Solution Annealed 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 Solution Annealed?
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 Solution Annealed 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 Solution Annealed?
321 Solution Annealed 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.
What is the difference between 321 Solution Annealed and 321 2B?
Solution Annealed is the default condition — standard stocked condition for plate, sheet, bar, pipe and fittings — maximum ductility and corrosion resistance. 2B: thin sheet and strip for exhaust, bellows and heat-exchanger fabrication where a smooth mill finish is wanted. Yield strength is 240 MPa in Solution Annealed versus 255 MPa in 2B.
Can FabDigit make parts in 321 Solution Annealed?
Yes — 321 Solution Annealed 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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.