Stainless Steel 312 HF-SA
Heat-treated state
AISI/SAE 312 · UNS S31200 · ASTM A789/A790 UNS S31200
HF-SA = hot Finished / Forged + Solution Annealed Bar & Forgings
Bar, forged flanges and valve bodies solution annealed after hot work — general machined-component stock.
Values for the HF-SA condition
Other 312 tempers and conditions
312 is listed in 3 conditions; see the grade overview at 312.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
SADefault Solution Annealed + Quenched | Standard delivery condition for all wrought product forms — balanced ~50/50 austenite/ferrite, best corrosion resistance and toughness. | 530 | 760 | 30 | 24 HRC | 2.2 % IACS |
HF-SAThis page Hot Finished / Forged + Solution Annealed Bar & Forgings | Bar, forged flanges and valve bodies solution annealed after hot work — general machined-component stock. | 540 | 760 | 28 | 25 HRC | 2.2 % IACS |
Cold drawn | Cold-drawn bar or tube for higher strength, tighter tolerance and better surface — reduced ductility and toughness. | 720 | 880 | 20 | 30 HRC | 2.2 % IACS |
What is 312 HF-SA?
312 HF-SA is 312 heat treated to HF-SA — bar, forged flanges and valve bodies solution annealed after hot work — general machined-component stock. 312 HF-SA has a yield strength of 540 MPa (78.3 ksi) and a tensile strength of 760 MPa (110 ksi) — stronger than 82% of stainless steel grades. Elongation at break is 28% and the elastic modulus is 200 GPa (29 Msi). 312 HF-SA has a density of 7.8 g/cm³ (0.282 lb/in³), heavier than 50% of stainless steel grades. It melts at 1,385°C (2,525 °F). SA is the default condition FabDigit quotes; HF-SA is available on request or by drawing note.
Advantages
- High strength — 540 MPa (78.3 ksi), better than 82% of stainless steel grades
Limitations
- Limited service temperature — 280°C (536 °F), worse than 96% of stainless steel grades
312 HF-SA properties
Typical room-temperature values for 312 HF-SA; 23 are specific to this condition. Other listed values are 312 reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
312 HF-SA has a density of 7.8 g/cm³ (0.282 lb/in³), heavier than 50% of stainless steel grades. It melts at 1,385°C (2,525 °F).
Mechanical17
312 HF-SA has a yield strength of 540 MPa (78.3 ksi) and a tensile strength of 760 MPa (110 ksi) — stronger than 82% of stainless steel grades. Elongation at break is 28% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
312 HF-SA is rated for continuous service to 280°C (536 °F). It conducts heat at 15 W/m·K (8.67 BTU/hr·ft·°F), worse than 59% of stainless steel grades. Thermal expansion is 13 µm/m·K (7.22 µin/in·°F).
Electrical3
312 HF-SA conducts electricity at 2.2 % IACS, worse than 61% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is very good (71/100), better than 70% of stainless steel grades.
Sustainability4
Producing a kilogram of 312 HF-SA takes about 55 MJ of energy and emits 4.6 kg of CO₂ — more than 50% of stainless steel grades. Typical recycled content is 60%.
Manufacturability7
312 HF-SA's machinability is fair (35/100, better than 51% of stainless steel grades); weldability very good (70/100); formability fair (40/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 312 HF-SA
Is 312 easy to machine?
Work-hardens rapidly and cuts tough like 2205 — use rigid setups, sharp coated carbide, heavy positive feeds, ~25 % of 1212 speeds and copious coolant; avoid dwelling.
Can 312 be welded?
Weldable by GTAW/GMAW/SMAW with 25Cr over-alloyed or 2209-type filler and N-bearing shielding; hold heat input ~0.5–2.5 kJ/mm, interpass <150 °C to keep ferrite 35–65 % and avoid σ-phase; no PWHT unless full re-solution anneal.
Can 312 be formed, bent or molded?
Cold form with ~2× the force of 304 and generous springback allowance; hot form 950–1150 °C followed by full solution anneal 1020–1100 °C and rapid water quench.
What surface finishes work on 312?
Pickle and passivate (HNO₃/HF) after hot work or welding to restore the passive film; electropolishes and mechanically polishes well; never anodized.
312 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 |
|---|---|---|
| Clow-carbon duplex | ≤ 0.03 | 0.02 |
| Mn | ≤ 2 | 1.2 |
| Si | ≤ 1 | 0.5 |
| P | ≤ 0.05 | — |
| S | ≤ 0.03 | — |
| Cr | 24 – 26 | 25 |
| Ni | 5.5 – 6.5 | 6 |
| Mo | 1.2 – 2 | 1.7 |
| Naustenite stabiliser, boosts pitting resistance | 0.14 – 0.2 | 0.17 |
| Fe | balance | — |
312 HF-SA — frequently asked
What is 312 HF-SA used for?
312 HF-SA is typically used for chemical process piping, heat exchangers, pressure vessels and marine equipment. In short: early-generation duplex; higher strength than 316L; 280 °C service limit.
What is the yield strength of 312 HF-SA?
312 HF-SA has a typical yield strength of 540 MPa (78.3 ksi) and a tensile strength of 760 MPa (110 ksi) — stronger than 82% of stainless steel grades. Strength varies by condition: see the 3 listed tempers.
Is 312 HF-SA easy to machine?
Not especially — machinability is rated fair (35/100, better than 51% of stainless steel grades). Work-hardens rapidly and cuts tough like 2205 — use rigid setups, sharp coated carbide, heavy positive feeds, ~25 % of 1212 speeds and copious coolant; avoid dwelling.
Can 312 HF-SA be welded?
Yes — weldability is rated very good (70/100). Weldable by GTAW/GMAW/SMAW with 25Cr over-alloyed or 2209-type filler and N-bearing shielding; hold heat input ~0.5–2.5 kJ/mm, interpass <150 °C to keep ferrite 35–65 % and avoid σ-phase; no PWHT unless full re-solution anneal.
What surface finishes work on 312 HF-SA?
Pickle and passivate (HNO₃/HF) after hot work or welding to restore the passive film; electropolishes and mechanically polishes well; never anodized.
Can 312 HF-SA be formed, bent or molded?
Cold form with ~2× the force of 304 and generous springback allowance; hot form 950–1150 °C followed by full solution anneal 1020–1100 °C and rapid water quench.
What is the maximum service temperature of 312 HF-SA?
312 HF-SA is rated for continuous use to about 280°C (536 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 312-SA and 312-CD?
SA is the default condition — standard delivery condition for all wrought product forms — balanced ~50/50 austenite/ferrite, best corrosion resistance and toughness. CD: cold-drawn bar or tube for higher strength, tighter tolerance and better surface — reduced ductility and toughness. Yield strength is 530 MPa in SA versus 720 MPa in CD.
Sources
- ASTM A790/A790M Seamless and Welded Ferritic/Austenitic Stainless Steel Pipe — ASTM International (2023)
- ASTM A789/A789M Seamless and Welded Ferritic/Austenitic Stainless Steel Tubing for General Service — ASTM International (2023)
- ASTM A240/A240M Chromium and Chromium-Nickel Stainless Steel Plate, Sheet and Strip — ASTM International (2022)
- SAE J1086 / ASTM DS-56 Unified Numbering System (UNS S31200) — SAE/ASTM (2017)
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- Practical Guidelines for the Fabrication of Duplex Stainless Steels — IMOA (2014)
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.