Stainless Steel 309 · finish state
Stainless Steel 309 hot_finished
Properties of the hot_finished condition, compared with the other 309 tempers.
Hot-rolled or hot-forged 309 bar and section in the mill-finished (softened) state: lower strength, maximum ductility and best high-temperature stability.
What is 309 hot_finished?
309 hot_finished is 309 supplied in the hot_finished condition — hot-rolled or hot-forged 309 bar and section in the mill-finished (softened) state: lower strength, maximum ductility and best high-temperature stability. 309 hot_finished has a yield strength of 275 MPa (39.9 ksi) and a tensile strength of 585 MPa (84.8 ksi) — weaker than 77% of stainless steel grades. Elongation at break is 45% and the elastic modulus is 200 GPa (29 Msi). 309 hot_finished has a density of 7.98 g/cm³ (0.288 lb/in³), heavier than 85% of stainless steel grades. It melts at 1,400°C (2,552 °F). Solution Annealed is the default condition FabDigit quotes; hot_finished is available on request or by drawing note.
Advantages
- High service temperature — 1,000°C (1,832 °F), better than 88% 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
- Hard to polish — 60/100, worse than 80% of stainless steel grades
- Low strength — 275 MPa (39.9 ksi), worse than 77% of stainless steel grades
309 hot_finished properties
Typical room-temperature values for 309 hot_finished — 36 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 hot_finished has a density of 7.98 g/cm³ (0.288 lb/in³), heavier than 85% of stainless steel grades. It melts at 1,400°C (2,552 °F).
Mechanical15
309 hot_finished has a yield strength of 275 MPa (39.9 ksi) and a tensile strength of 585 MPa (84.8 ksi) — weaker than 77% of stainless steel grades. Elongation at break is 45% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
309 hot_finished is rated for continuous service to 1,000°C (1,832 °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 15 µm/m·K (8.33 µin/in·°F).
Electrical3
309 hot_finished conducts electricity at 2.2 % IACS, worse than 61% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is very good (70/100), better than 68% of stainless steel grades.
Sustainability4
Producing a kilogram of 309 hot_finished takes about 53 MJ of energy and emits 5 kg of CO₂ — less than 67% of stainless steel grades. Typical recycled content is 65%.
Manufacturability8
309 hot_finished's machinability is poor (33/100, worse than 57% of stainless steel grades); weldability very good (78/100); formability good (65/100).
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 hot_finished
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 hot_finished — frequently asked
What is 309 hot_finished used for?
309 hot_finished 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 hot_finished?
309 hot_finished has a typical yield strength of 275 MPa (39.9 ksi) and a tensile strength of 585 MPa (84.8 ksi) — weaker than 77% of stainless steel grades. Strength varies by condition: see the 7 listed tempers.
Is 309 hot_finished easy to machine?
Not especially — machinability is rated poor (33/100, worse 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 hot_finished be welded?
Yes — weldability is rated very good (78/100). 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 hot_finished?
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 hot_finished 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 hot_finished?
309 hot_finished is rated for continuous use to about 1,000°C (1,832 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in 309 hot_finished?
Yes — 309 hot_finished 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.