Stainless Steel 255 · heat-treated state
Stainless Steel 255 Cast+SA
Properties of the Cast+SA condition, compared with the other 255 tempers.
Cast counterpart of 255 for seawater pump casings and impellers; lower strength and ductility than wrought product but same alloy chemistry family.
What is 255 Cast+SA?
255 Cast+SA is 255 heat treated to Cast+SA — cast counterpart of 255 for seawater pump casings and impellers; lower strength and ductility than wrought product but same alloy chemistry family. 255 Cast+SA has a yield strength of 550 MPa (79.8 ksi) and a tensile strength of 760 MPa (110 ksi) — stronger than 83% of stainless steel grades. Elongation at break is 20% and the elastic modulus is 205 GPa (29.7 Msi). 255 Cast+SA has a density of 7.81 g/cm³ (0.282 lb/in³), heavier than 57% of stainless steel grades. It melts at 1,400°C (2,552 °F). Solution Annealed is the default condition FabDigit quotes; Cast+SA is available on request or by drawing note.
Advantages
- Good corrosion resistance — 85/100, better than 92% of stainless steel grades
- High strength — 550 MPa (79.8 ksi), better than 83% of stainless steel grades
Limitations
- Difficult to machine — 22/100, worse than 95% of stainless steel grades
- Limited service temperature — 300°C (572 °F), worse than 90% of stainless steel grades
- High embodied carbon — 5.6 kg CO₂/kg, worse than 82% of stainless steel grades
- Limited ductility — 20%, worse than 79% of stainless steel grades
255 Cast+SA properties
Typical room-temperature values for 255 Cast+SA — 8 properties are specific to this condition; the rest are grade-level values shared by every 255 temper. Each bar shows where the value sits among the stainless steel grades in FabDigit's library — further right is higher.
Physical3
255 Cast+SA has a density of 7.81 g/cm³ (0.282 lb/in³), heavier than 57% of stainless steel grades. It melts at 1,400°C (2,552 °F).
Mechanical16
255 Cast+SA has a yield strength of 550 MPa (79.8 ksi) and a tensile strength of 760 MPa (110 ksi) — stronger than 83% of stainless steel grades. Elongation at break is 20% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal5
255 Cast+SA is rated for continuous service to 300°C (572 °F). It conducts heat at 13.5 W/m·K (7.8 BTU/hr·ft·°F), worse than 83% of stainless steel grades. Thermal expansion is 13 µm/m·K (7.22 µin/in·°F).
Electrical3
255 Cast+SA conducts electricity at 2.2 % IACS, worse than 61% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is excellent (85/100), better than 92% of stainless steel grades.
Sustainability4
Producing a kilogram of 255 Cast+SA takes about 85 MJ of energy and emits 5.6 kg of CO₂ — more than 91% of stainless steel grades. Typical recycled content is 50%.
Manufacturability8
255 Cast+SA's machinability is poor (22/100, worse than 95% of stainless steel grades); weldability very good (70/100); formability fair (40/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other 255 tempers and conditions
255 is also supplied in 4 other conditions. The full side-by-side table is on the 255 overview.
- Solution AnnealedDefaultStandard stocked condition for plate, hot-finished bar, forgings, pipe and fittings; balanced 50/50 ferrite–austenite with best corrosion resistance and toughness.610 MPa yield · 27 HRC
- SA+CWPick for small-diameter bar, shafting and fasteners needing higher strength and tighter tolerance; ductility and toughness are reduced.760 MPa yield · 32 HRC
- Cast+SACast counterpart of 255 for seawater pump casings and impellers; lower strength and ductility than wrought product but same alloy chemistry family.550 MPa yield · 23 HRC
Working with 255 Cast+SA
Is 255 easy to machine?
Machine like a super duplex: rigid setup, 30–50 % of 316 cutting speed, heavy positive feed to cut under the work-hardened layer, sharp coated carbide and flood coolant.
Can 255 be welded?
Weldable by GTAW/GMAW/SMAW with 25.10.4.L or Ferralium 255 matching filler; keep interpass below ~150 °C, heat input roughly 0.5–1.5 kJ/mm, Ar+2 %N₂ backing, and no post-weld stress relief below 1040 °C.
Can 255 be formed, bent or molded?
Cold forming needs ~2× the press force of 304 with generous bend radii and springback allowance; hot working at 1000–1150 °C followed by full solution anneal and quench.
What surface finishes work on 255?
Pickle and passivate or electropolish after welding to restore the passive film; not anodizable, and grinding must avoid embedding carbon-steel contamination.
255 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 |
|---|---|---|
| C | ≤ 0.04 | 0.03 |
| Si | ≤ 1 | 0.5 |
| Mn | ≤ 1.5 | 0.8 |
| P | ≤ 0.04 | — |
| S | ≤ 0.03 | — |
| Cr | 24 – 27 | 25.5 |
| Ni | 4.5 – 6.5 | 5.7 |
| Mo | 2.9 – 3.9 | 3.4 |
| Cuimproves resistance in reducing acids | 1.5 – 2.5 | 2 |
| Nupper end for SD50 high-strength variant | 0.1 – 0.25 | 0.2 |
| Fe | balance | — |
255 Cast+SA — frequently asked
What is 255 Cast+SA used for?
255 Cast+SA is typically used for subsea oil and gas manifolds, FPSO seawater pipework, valve bodies and stems, pump casings and impellers, marine propeller and pump shafts and offshore flanges and fasteners. In short: premium duplex stainless plate.
What is the yield strength of 255 Cast+SA?
255 Cast+SA has a typical yield strength of 550 MPa (79.8 ksi) and a tensile strength of 760 MPa (110 ksi) — stronger than 83% of stainless steel grades. Strength varies by condition: see the 5 listed tempers.
Is 255 Cast+SA easy to machine?
Not especially — machinability is rated poor (22/100, worse than 95% of stainless steel grades). Machine like a super duplex: rigid setup, 30–50 % of 316 cutting speed, heavy positive feed to cut under the work-hardened layer, sharp coated carbide and flood coolant.
Can 255 Cast+SA be welded?
Yes — weldability is rated very good (70/100). Weldable by GTAW/GMAW/SMAW with 25.10.4.L or Ferralium 255 matching filler; keep interpass below ~150 °C, heat input roughly 0.5–1.5 kJ/mm, Ar+2 %N₂ backing, and no post-weld stress relief below 1040 °C.
What surface finishes work on 255 Cast+SA?
Pickle and passivate or electropolish after welding to restore the passive film; not anodizable, and grinding must avoid embedding carbon-steel contamination.
Can 255 Cast+SA be formed, bent or molded?
Cold forming needs ~2× the press force of 304 with generous bend radii and springback allowance; hot working at 1000–1150 °C followed by full solution anneal and quench.
What is the maximum service temperature of 255 Cast+SA?
255 Cast+SA is rated for continuous use to about 300°C (572 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 255 Solution Annealed and 255-SD50?
Solution Annealed is the default condition — standard stocked condition for plate, hot-finished bar, forgings, pipe and fittings; balanced 50/50 ferrite–austenite with best corrosion resistance and toughness. SD50: proprietary high-nitrogen variant used when 80 ksi (550 MPa) minimum yield must be guaranteed in heavy sections and forgings, with PREN at the top of the S32550 range. Yield strength is 610 MPa in Solution Annealed versus 660 MPa in SD50.
Can FabDigit make parts in 255 Cast+SA?
Yes — 255 Cast+SA 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 — Chromium and Chromium-Nickel Stainless Steel Plate, Sheet and Strip (S32550) — ASTM International (2023)
- ASTM A479/A479M — Stainless Steel Bars and Shapes for Boilers and Pressure Vessels — ASTM International (2021)
- ASTM A182/A182M — Forged or Rolled Alloy and Stainless Steel Pipe Flanges and Fittings (F61) — ASTM International (2022)
- ASTM A890/A995 — Castings, Iron-Chromium-Nickel-Molybdenum (Grade 1B, CD4MCuN) — ASTM International (2020)
- EN 10088-2/-3 — Stainless steels, grade 1.4507 (X2CrNiMoCuN25-6-3) — CEN (2014)
- Ferralium alloy 255 / 255-SD50 technical datasheet — Langley Alloys / Meighs (2022)
- ASM Handbook Vol.13B — Corrosion: Materials (duplex stainless steels) — ASM International (2005)
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.