Stainless Steel 309 · heat-treated state · default condition
Stainless Steel 309 Solution Annealed
Properties of the Solution Annealed condition, compared with the other 309 tempers.
Standard stocked condition for plate, sheet, bar and pipe; maximum ductility, homogeneous austenite before high-temperature service.
What is 309 Solution Annealed?
309 Solution Annealed is 309 heat treated to Solution Annealed — standard stocked condition for plate, sheet, bar and pipe; maximum ductility, homogeneous austenite before high-temperature service. 309 Solution Annealed has a yield strength of 310 MPa (45 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 63% of stainless steel grades. Elongation at break is 45% and the elastic modulus is 200 GPa (29 Msi). 309 Solution Annealed has a density of 7.9 g/cm³ (0.285 lb/in³), heavier than 67% of stainless steel grades. It melts at 1,400°C (2,552 °F).
Advantages
- High service temperature — 1,050°C (1,922 °F), better than 91% of stainless steel grades
- Tough — resists crack growth — 200 MPa·√m (182 ksi·√in), better than 84% of stainless steel grades
- Ductile — tolerates forming and impact — 45%, better than 76% of stainless steel grades
Limitations
- High embodied carbon — 6 kg CO₂/kg, worse than 88% of stainless steel grades
309 Solution Annealed properties
Typical room-temperature values for 309 Solution Annealed — 16 properties are specific to this condition; the rest are grade-level values shared by every 309 temper. Each bar shows where the value sits among the stainless steel grades in FabDigit's library — further right is higher.
Physical3
309 Solution Annealed has a density of 7.9 g/cm³ (0.285 lb/in³), heavier than 67% of stainless steel grades. It melts at 1,400°C (2,552 °F).
Mechanical15
309 Solution Annealed has a yield strength of 310 MPa (45 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 63% of stainless steel grades. Elongation at break is 45% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
309 Solution Annealed is rated for continuous service to 1,050°C (1,922 °F). It conducts heat at 15.6 W/m·K (9.01 BTU/hr·ft·°F), better than 55% of stainless steel grades. Thermal expansion is 14.9 µm/m·K (8.28 µin/in·°F).
Electrical3
309 Solution Annealed conducts electricity at 2.2 % IACS, worse than 61% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is good (66/100), better than 58% of stainless steel grades.
Sustainability4
Producing a kilogram of 309 Solution Annealed takes about 56 MJ of energy and emits 6 kg of CO₂ — more than 59% of stainless steel grades. Typical recycled content is 60%.
Manufacturability8
309 Solution Annealed's machinability is fair (36/100, better than 57% of stainless steel grades); weldability very good (70/100); formability good (68/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other 309 tempers and conditions
309 is also supplied in 6 other conditions. The full side-by-side table is on the 309 overview.
- Solution AnnealedDefaultStandard stocked condition for plate, sheet, bar and pipe; maximum ductility, homogeneous austenite before high-temperature service.310 MPa yield · 165 HB
- Cold DrawnChoose for bar/shaft stock needing closer tolerance, better surface and higher strength than annealed; ductility and formability reduced.450 MPa yield · 200 HB
- cold_finishedCold-drawn / turned-and-ground 309 bar: work-hardened surface, tighter tolerances and roughly 40 % higher strength than the hot-finished condition.415 MPa yield · 200 HB
- AnnealedGeneral mill-annealed stock (functionally equivalent to solution annealed for this grade); pick for forming and welding fabrication.295 MPa yield · 160 HB
- Hot Rolled AnnealedStandard heavy plate condition (ASTM A240 No.1 finish) for furnace hearths, retorts and fabricated heat-resisting structures.285 MPa yield · 170 HB
- hot_finishedHot-rolled or hot-forged 309 bar and section in the mill-finished (softened) state: lower strength, maximum ductility and best high-temperature stability.275 MPa yield · 170 HB
Working with 309 Solution Annealed
Is 309 easy to machine?
Gummy and strongly work-hardening: run rigid setups, positive-rake sharp carbide, 20–30 % lower speed than 304, heavy feed and flood coolant to avoid glazing and work-hardened skins.
Can 309 be welded?
Readily welded by GTAW/GMAW/SMAW with 309/309L filler; no preheat needed, keep interpass low, limit heat input and avoid 600–900 °C holds to reduce sigma-phase and carbide embrittlement.
Can 309 be formed, bent or molded?
Cold forms like 304 but needs about 20 % more power and generous bend radii due to the high work-hardening rate; hot work at 1150–1200 °C followed by solution anneal at 1040–1150 °C.
What surface finishes work on 309?
Pickle and passivate after hot working or welding to restore the chromium oxide film; can be ground, brushed, electropolished or mirror-polished — not anodizable.
309 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 |
|---|---|---|
| C309S (S30908) limits C to 0.08 max | ≤ 0.2 | 0.12 |
| SiEN 1.4828 runs 1.5–2.5 % Si for extra scaling resistance | ≤ 1 | 0.6 |
| Mn | ≤ 2 | 1.4 |
| P | ≤ 0.05 | — |
| S | ≤ 0.03 | — |
| Cr | 22 – 24 | 23 |
| Ni | 12 – 15 | 13.5 |
| Moresidual only in some specs | ≤ 0.75 | — |
| Fe | balance | — |
309 Solution Annealed — frequently asked
What is 309 Solution Annealed used for?
309 Solution Annealed is typically used for furnace parts and muffles, heat-treatment fixtures and baskets, radiant tubes and burner components, kiln and furnace linings, boiler baffles and supports and high-temperature exhaust systems. In short: high-temperature heat expert.
What is the yield strength of 309 Solution Annealed?
309 Solution Annealed has a typical yield strength of 310 MPa (45 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 63% of stainless steel grades. Strength varies by condition: see the 7 listed tempers.
Is 309 Solution Annealed easy to machine?
Not especially — machinability is rated fair (36/100, better than 57% of stainless steel grades). Gummy and strongly work-hardening: run rigid setups, positive-rake sharp carbide, 20–30 % lower speed than 304, heavy feed and flood coolant to avoid glazing and work-hardened skins.
Can 309 Solution Annealed be welded?
Yes — weldability is rated very good (70/100). Readily welded by GTAW/GMAW/SMAW with 309/309L filler; no preheat needed, keep interpass low, limit heat input and avoid 600–900 °C holds to reduce sigma-phase and carbide embrittlement.
What surface finishes work on 309 Solution Annealed?
Pickle and passivate after hot working or welding to restore the chromium oxide film; can be ground, brushed, electropolished or mirror-polished — not anodizable.
Can 309 Solution Annealed be formed, bent or molded?
Cold forms like 304 but needs about 20 % more power and generous bend radii due to the high work-hardening rate; hot work at 1150–1200 °C followed by solution anneal at 1040–1150 °C.
What is the maximum service temperature of 309 Solution Annealed?
309 Solution Annealed is rated for continuous use to about 1,050°C (1,922 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in 309 Solution Annealed?
Yes — 309 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 — Cr and Cr-Ni Stainless Plate, Sheet and Strip — ASTM International (2023)
- ASTM A276/A479 — Stainless Steel Bars and Shapes — ASTM International (2022)
- EN 10095 — Heat resisting steels and nickel alloys (1.4828) — CEN (1999)
- JIS G 4304 / G 4303 (SUS309S) — JISC (2021)
- GB/T 4237 / GB/T 1220 (0Cr23Ni13, 06Cr23Ni13) — SAC (2015)
- ASM Specialty Handbook: Stainless Steels — ASM International (1994)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- 309/309S heat-resisting stainless datasheets (Outokumpu, AK Steel/Cleveland-Cliffs, Sandmeyer) — various producers (2022)
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.