Stainless Steel 309H-ANN (Annealed)
Heat-treated state · default condition
AISI/SAE 309H · UNS S30909
Standard stocked condition for plate, sheet, bar and pipe; required for ASME high-temperature (creep) service.
Values for the ANN condition
Other 309H tempers and conditions
309H is listed in 3 conditions; see the grade overview at 309H.
- FORGED-ANN
- ANN
- CD
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Forged and solution annealed (ASTM A473 / A182-type parts) | Flanges, rolls, tube sheets and heavy furnace fittings forged then re-annealed to restore corrosion/creep behaviour. | 290 | 585 | 42 | 165 HB | 2.2 % IACS |
ANNDefaultThis page Annealed | Standard stocked condition for plate, sheet, bar and pipe; required for ASME high-temperature (creep) service. | 310 | 620 | 45 | 155 HB | 2.2 % IACS |
Cold drawn | Choose for tighter tolerance and better surface on small-diameter bar; strength raised, ductility reduced. | 550 | 760 | 30 | 20 HRC | 2.2 % IACS |
What is 309H-ANN?
309H-ANN is 309H heat treated to ANN — standard stocked condition for plate, sheet, bar and pipe; required for ASME high-temperature (creep) service. 309H-ANN 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). 309H-ANN has a density of 7.89 g/cm³ (0.285 lb/in³), heavier than 60% of stainless steel grades. It melts at 1,400°C (2,552 °F).
Advantages
- High service temperature — 1,095°C (2,003 °F), better than 94% of stainless steel grades
- Tough — resists crack growth — 200 MPa·√m (182 ksi·√in), better than 86% of stainless steel grades
- Readily welded — 80/100, better than 80% of stainless steel grades
- Forms and bends easily — 70/100, better than 79% of stainless steel grades
- Ductile — tolerates forming and impact — 45%, better than 76% of stainless steel grades
309H-ANN properties
Typical room-temperature values for 309H-ANN; 23 are specific to this condition. Other listed values are 309H reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
309H-ANN has a density of 7.89 g/cm³ (0.285 lb/in³), heavier than 60% of stainless steel grades. It melts at 1,400°C (2,552 °F).
Mechanical16
309H-ANN 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
309H-ANN is rated for continuous service to 1,095°C (2,003 °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
309H-ANN conducts electricity at 2.2 % IACS, worse than 61% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is good (68/100), better than 63% of stainless steel grades.
Sustainability4
Producing a kilogram of 309H-ANN takes about 55 MJ of energy and emits 5 kg of CO₂ — more than 50% of stainless steel grades. Typical recycled content is 60%.
Manufacturability8
309H-ANN's machinability is fair (35/100, better than 51% of stainless steel grades); weldability very good (80/100); formability very good (70/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 309H-ANN
Is 309H easy to machine?
Machine like 310S — rigid setup, sharp positive-rake carbide, heavy constant feed to cut under the work-hardened layer, 25–60 m/min with flood coolant; ~40% of AISI 1212.
Can 309H be welded?
Readily welded by GTAW/GMAW/SMAW with ER309/E309 (or 309H for matching creep strength); no preheat, interpass <150 °C, no PWHT normally required, but re-solution-anneal restores ductility after long high-temperature service.
Can 309H be formed, bent or molded?
Good hot workability at 1150–1200 °C; cold forms well but work-hardens fast — allow larger bend radii, higher press loads and intermediate anneals at 1040–1100 °C followed by rapid cooling.
What surface finishes work on 309H?
Not anodizable; descale by pickling (HNO₃/HF) or blasting, then passivate per ASTM A967; can be ground and polished to No.4/No.8, and forms a protective Cr₂O₃ scale in service.
309H 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 |
|---|---|---|
| Ccontrolled higher carbon for creep strength (H grade) | 0.04 – 0.1 | 0.07 |
| Mn | ≤ 2 | 1.5 |
| Si | ≤ 1 | 0.6 |
| P | ≤ 0.05 | 0.03 |
| S | ≤ 0.03 | 0.01 |
| Cr | 22 – 24 | 23 |
| Ni | 12 – 15 | 13.5 |
| N | ≤ 0.1 | 0.04 |
| Fe | balance | — |
309H-ANN — frequently asked
What is 309H-ANN used for?
309H-ANN is typically used for high-temperature pressure vessels, boiler and superheater components, furnace retorts and muffles, hot-gas ducting and breeching, refinery heater internals and heat treatment fixtures. In short: creep-strength 309 variant; ASME pressure-part grade; 1095 °C service ceiling.
What is the yield strength of 309H-ANN?
309H-ANN 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 3 listed tempers.
Is 309H-ANN easy to machine?
Not especially — machinability is rated fair (35/100, better than 51% of stainless steel grades). Machine like 310S — rigid setup, sharp positive-rake carbide, heavy constant feed to cut under the work-hardened layer, 25–60 m/min with flood coolant; ~40% of AISI 1212.
Can 309H-ANN be welded?
Yes — weldability is rated very good (80/100). Readily welded by GTAW/GMAW/SMAW with ER309/E309 (or 309H for matching creep strength); no preheat, interpass <150 °C, no PWHT normally required, but re-solution-anneal restores ductility after long high-temperature service.
What surface finishes work on 309H-ANN?
Not anodizable; descale by pickling (HNO₃/HF) or blasting, then passivate per ASTM A967; can be ground and polished to No.4/No.8, and forms a protective Cr₂O₃ scale in service.
Can 309H-ANN be formed, bent or molded?
Good hot workability at 1150–1200 °C; cold forms well but work-hardens fast — allow larger bend radii, higher press loads and intermediate anneals at 1040–1100 °C followed by rapid cooling.
What is the maximum service temperature of 309H-ANN?
309H-ANN is rated for continuous use to about 1,095°C (2,003 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 309H-ANN and 309H-CD?
ANN is the default condition — standard stocked condition for plate, sheet, bar and pipe; required for ASME high-temperature (creep) service. CD: choose for tighter tolerance and better surface on small-diameter bar; strength raised, ductility reduced. Yield strength is 310 MPa in ANN versus 550 MPa in CD.
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)
- ASTM A213/A312 — Stainless Steel Tubes and Pipe (TP309H) — ASTM International (2022)
- ASME BPVC Section II Part D — Allowable stresses, S30909 — ASME (2023)
- ASM Specialty Handbook: Stainless Steels — ASM International (1994)
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- Type 309/309S/309H heat-resisting stainless datasheets — Outokumpu / Sandvik / NAS (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.