Stainless Steel 254 SMO HF-SA
Heat-treated state
UNS S31254 · ASTM A240/A312 · EN 1.4547, X1CrNiMoCuN20-18-7 · GB 022Cr20Ni18Mo6CuN, 015Cr20Ni18Mo6CuN
HF-SA = hot Finished + Solution Annealed
Heavy plate, forged flanges and thick bar; slightly lower strength than thin annealed product but same corrosion performance.
Values for the HF-SA condition
Other 254 SMO tempers and conditions
254 SMO is listed in 5 conditions; see the grade overview at 254 SMO.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
HF-SAThis page Hot Finished + Solution Annealed | Heavy plate, forged flanges and thick bar; slightly lower strength than thin annealed product but same corrosion performance. | 330 | 680 | 45 | 180 HB | 2 % IACS |
Solution AnnealedDefault 1150–1200 °C, rapid quench (plate, sheet, bar, tube) | Standard supply condition for all product forms; maximum corrosion resistance and toughness. | 350 | 700 | 45 | 190 HB | — |
joint made with over-alloyed Ni-base filler (ERNiCrMo-3 / -4), no PWHT | Condition of fabricated vessels and piping; expect weld-metal properties governed by the Ni-base filler. | 400 | 700 | 35 | 205 HB | 2 % IACS |
Cold Rolled 1/4 Hard | Use for springy strip, gaskets and thin-gauge parts needing extra yield strength with some remaining ductility. | 600 | 860 | 25 | 26 HRC | 2 % IACS |
Cold drawn | Pick for higher-strength fasteners, shafts and pump parts where tight tolerance and bright finish are needed. | 620 | 850 | 25 | 25 HRC | 2 % IACS |
What is 254 SMO HF-SA?
254 SMO HF-SA is 254 SMO heat treated to HF-SA — heavy plate, forged flanges and thick bar; slightly lower strength than thin annealed product but same corrosion performance. 254 SMO HF-SA has a yield strength of 330 MPa (47.9 ksi) and a tensile strength of 680 MPa (98.6 ksi) — weaker than 57% of stainless steel grades. Elongation at break is 45% and the elastic modulus is 195 GPa (28.3 Msi). 254 SMO HF-SA has a density of 8 g/cm³ (0.289 lb/in³), heavier than 92% of stainless steel grades. It melts at 1,325°C (2,417 °F). Solution Annealed is the default condition FabDigit quotes; HF-SA is available on request or by drawing note.
Advantages
- Tough — resists crack growth — 220 MPa·√m (200.2 ksi·√in), better than 97% of stainless steel grades
- Good corrosion resistance — 85/100, better than 92% of stainless steel grades
- Polishes to a fine finish — 80/100, better than 89% of stainless steel grades
- Ductile — tolerates forming and impact — 45%, better than 76% of stainless steel grades
Limitations
- High embodied carbon — 6.5 kg CO₂/kg, worse than 93% of stainless steel grades
- Limited service temperature — 400°C (752 °F), worse than 78% of stainless steel grades
- Low electrical conductivity — 2 % IACS, worse than 77% of stainless steel grades
254 SMO HF-SA properties
Typical room-temperature values for 254 SMO HF-SA; 23 are specific to this condition. Other listed values are 254 SMO reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
254 SMO HF-SA has a density of 8 g/cm³ (0.289 lb/in³), heavier than 92% of stainless steel grades. It melts at 1,325°C (2,417 °F).
Mechanical16
254 SMO HF-SA has a yield strength of 330 MPa (47.9 ksi) and a tensile strength of 680 MPa (98.6 ksi) — weaker than 57% of stainless steel grades. Elongation at break is 45% and the elastic modulus is 195 GPa (28.3 Msi).
Thermal6
254 SMO HF-SA is rated for continuous service to 400°C (752 °F). It conducts heat at 14 W/m·K (8.09 BTU/hr·ft·°F), worse than 80% of stainless steel grades. Thermal expansion is 16.5 µm/m·K (9.17 µin/in·°F).
Electrical3
254 SMO HF-SA conducts electricity at 2 % IACS, worse than 77% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is excellent (85/100), better than 92% of stainless steel grades.
Sustainability4
Producing a kilogram of 254 SMO HF-SA takes about 85 MJ of energy and emits 6.5 kg of CO₂ — more than 92% of stainless steel grades. Typical recycled content is 45%.
Manufacturability8
254 SMO HF-SA's machinability is poor (26/100, worse than 84% of stainless steel grades); weldability very good (75/100); formability good (58/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 254 SMO HF-SA
Is 254 SMO easy to machine?
Machine like a nickel alloy: rigid setup, sharp positive-rake carbide, low speed with heavy positive feed, flood coolant, and never dwell — the surface work-hardens instantly.
Can 254 SMO be welded?
Weld with over-alloyed Ni-base filler (ERNiCrMo-3/625 or ERNiCrMo-4/C-276), low heat input, interpass < 100 °C, argon backing; no preheat or PWHT, and pickle/passivate the heat tint.
Can 254 SMO be formed, bent or molded?
Cold forms well but needs ~50 % more press force than 316L and generous springback allowance; hot work 1150–1200 °C followed by mandatory solution anneal and quench.
What surface finishes work on 254 SMO?
Pickle in HNO₃–HF or electropolish to restore the passive film; mechanical polish to Ra < 0.5 µm gives best crevice performance — do not use carbon-steel-contaminated abrasives.
254 SMO 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 for intergranular resistance | ≤ 0.02 | 0.01 |
| Si | ≤ 0.8 | 0.4 |
| Mn | ≤ 1 | 0.6 |
| P | ≤ 0.03 | 0.02 |
| S | ≤ 0.01 | 0 |
| Cr | 19.5 – 20.5 | 20 |
| Ni | 17.5 – 18.5 | 18 |
| Mo | 6 – 6.5 | 6.2 |
| Cu | 0.5 – 1 | 0.7 |
| N | 0.18 – 0.22 | 0.2 |
| Febalance, ~54 % | balance | — |
254 SMO HF-SA — frequently asked
What is 254 SMO HF-SA used for?
254 SMO HF-SA is typically used for seawater pipework and manifolds, offshore platform piping and tubing, flue-gas desulfurization scrubbers, heat exchanger plates and tubesheets, desalination evaporator components and chemical tanker cargo tanks. In short: pitting-resistant super-austenitic.
What is the yield strength of 254 SMO HF-SA?
254 SMO HF-SA has a typical yield strength of 330 MPa (47.9 ksi) and a tensile strength of 680 MPa (98.6 ksi) — weaker than 57% of stainless steel grades. Strength varies by condition: see the 5 listed tempers.
Is 254 SMO HF-SA easy to machine?
Not especially — machinability is rated poor (26/100, worse than 84% of stainless steel grades). Machine like a nickel alloy: rigid setup, sharp positive-rake carbide, low speed with heavy positive feed, flood coolant, and never dwell — the surface work-hardens instantly.
Can 254 SMO HF-SA be welded?
Yes — weldability is rated very good (75/100). Weld with over-alloyed Ni-base filler (ERNiCrMo-3/625 or ERNiCrMo-4/C-276), low heat input, interpass < 100 °C, argon backing; no preheat or PWHT, and pickle/passivate the heat tint.
What surface finishes work on 254 SMO HF-SA?
Pickle in HNO₃–HF or electropolish to restore the passive film; mechanical polish to Ra < 0.5 µm gives best crevice performance — do not use carbon-steel-contaminated abrasives.
Can 254 SMO HF-SA be formed, bent or molded?
Cold forms well but needs ~50 % more press force than 316L and generous springback allowance; hot work 1150–1200 °C followed by mandatory solution anneal and quench.
What is the maximum service temperature of 254 SMO HF-SA?
254 SMO HF-SA is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 254 SMO Solution Annealed and 254 SMO-CD?
Solution Annealed is the default condition — standard supply condition for all product forms; maximum corrosion resistance and toughness. CD: pick for higher-strength fasteners, shafts and pump parts where tight tolerance and bright finish are needed. Yield strength is 350 MPa in Solution Annealed versus 620 MPa in CD.
Can FabDigit make parts in 254 SMO HF-SA?
Yes — 254 SMO HF-SA is available for CNC machining and sheet metal; every part is priced by an engineer rather than instantly. 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 (S31254) — ASTM International (2023)
- ASTM A182/A182M — Forged Fittings and Flanges (Grade F44) — ASTM International (2022)
- EN 10088-2 — Stainless steels, sheet/plate (1.4547) — CEN (2014)
- 254 SMO / Outokumpu Ultra 254 SMO alloy datasheet — Outokumpu (2022)
- Sandvik SANICRO 28 / 254 SMO-class 6Mo austenitic tube data — Alleima (Sandvik Materials Technology) (2021)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
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.