Cobalt-Chrome Alloy Ultimet-SA
Heat-treated state · default condition
UNS R31233
SA = solution annealed (≈1120 °C, rapid quench), sheet/strip
Standard stocked condition for sheet and strip: best combination of ductility, corrosion resistance and weldability.
Values for the SA condition
Other Ultimet tempers and conditions
Ultimet is listed in 4 conditions; see the grade overview at Ultimet.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
SA | Choose for pressure-retaining parts, wear liners and machined valve/pump bodies from plate. | 440 | 970 | 42 | 26 HRC | 2 % IACS |
SADefaultThis page Solution annealed (≈1120 °C, rapid quench), sheet/strip | Standard stocked condition for sheet and strip: best combination of ductility, corrosion resistance and weldability. | 490 | 1,000 | 39 | 28 HRC | — |
As-welded deposit | Ultimet filler wire deposited by GTAW/GMAW/PTA as a corrosion-plus-wear overlay on steel or stainless substrates. | 520 | 830 | 25 | 33 HRC | 2 % IACS |
Cold worked | Pick when maximum strength, springiness or surface hardness is needed and no welding or deep forming follows. | 1,200 | 1,400 | 10 | 45 HRC | 2 % IACS |
What is Ultimet-SA?
Ultimet-SA is Ultimet heat treated to SA — standard stocked condition for sheet and strip: best combination of ductility, corrosion resistance and weldability. Ultimet-SA has a yield strength of 490 MPa (71.1 ksi) and a tensile strength of 1,000 MPa (145 ksi) — weaker than 69% of cobalt-chrome alloy grades. Elongation at break is 39% and the elastic modulus is 224 GPa (32.5 Msi). Ultimet-SA has a density of 8.47 g/cm³ (0.306 lb/in³), heavier than 54% of cobalt-chrome alloy grades. It melts at 1,330°C (2,426 °F).
Advantages
- Readily welded — 75/100, better than 98% of cobalt-chrome alloy grades
- Forms and bends easily — 60/100, better than 95% of cobalt-chrome alloy grades
- Low embodied carbon — 9 kg CO₂/kg, better than 93% of cobalt-chrome alloy grades
- Ductile — tolerates forming and impact — 39%, better than 89% of cobalt-chrome alloy grades
- High service temperature — 900°C (1,652 °F), better than 86% of cobalt-chrome alloy grades
Limitations
- Poor heat conductor — 11 W/m·K (6.36 BTU/hr·ft·°F), worse than 89% of cobalt-chrome alloy grades
Ultimet-SA properties
Typical room-temperature values for Ultimet-SA; 10 are specific to this condition. Other listed values are Ultimet reference data and may not represent this condition. Bars are the position among cobalt-chrome alloy grades.
Physical3
Ultimet-SA has a density of 8.47 g/cm³ (0.306 lb/in³), heavier than 54% of cobalt-chrome alloy grades. It melts at 1,330°C (2,426 °F).
Mechanical14
Ultimet-SA has a yield strength of 490 MPa (71.1 ksi) and a tensile strength of 1,000 MPa (145 ksi) — weaker than 69% of cobalt-chrome alloy grades. Elongation at break is 39% and the elastic modulus is 224 GPa (32.5 Msi).
Thermal6
Ultimet-SA is rated for continuous service to 900°C (1,652 °F). It conducts heat at 11 W/m·K (6.36 BTU/hr·ft·°F), worse than 89% of cobalt-chrome alloy grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical3
Ultimet-SA conducts electricity at 2 % IACS, better than 79% of cobalt-chrome alloy grades.
Chemical & Environmental3
Corrosion resistance is very good (82/100), better than 70% of cobalt-chrome alloy grades.
Sustainability4
Producing a kilogram of Ultimet-SA takes about 130 MJ of energy and emits 9 kg of CO₂ — less than 89% of cobalt-chrome alloy grades. Typical recycled content is 30%.
Manufacturability7
Ultimet-SA's machinability is poor (18/100, better than 91% of cobalt-chrome alloy grades); weldability very good (75/100); formability good (60/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Ultimet-SA
Is Ultimet easy to machine?
Machine like a high work-hardening superalloy: rigid setup, positive-rake sharp carbide, low speed / heavy positive feed, never dwell, flood coolant; grinding and EDM are common for finished wear surfaces.
Can Ultimet be welded?
Readily welded by GTAW/GMAW/PAW with matching Ultimet filler; no preheat or PWHT required, keep interpass temperature low and heat input moderate to limit sensitization.
Can Ultimet be formed, bent or molded?
Cold forms well when annealed but work-hardens very rapidly — allow extra press capacity, generous radii and intermediate solution anneals at ~1120 °C with rapid cooling.
What surface finishes work on Ultimet?
Not anodizable; finish by grinding, polishing or electropolishing — the passive Cr-Mo film self-heals, so no plating or coating is normally needed.
Ultimet 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 |
|---|---|---|
| Cr | 25 – 27 | 26 |
| Ni | 8 – 10 | 9 |
| Mo | 4 – 6 | 5 |
| Fe | ≤ 4 | 3 |
| W | 1.5 – 2.5 | 2 |
| Mn | ≤ 1 | 0.8 |
| Si | ≤ 0.5 | 0.3 |
| Nnitrogen strengthening / pitting resistance | ≤ 0.12 | 0.08 |
| C | ≤ 0.08 | 0.06 |
| Cobalance, ~54 % | balance | — |
Ultimet-SA — frequently asked
What is Ultimet-SA used for?
Ultimet-SA is typically used for oilfield valve seats and trim, pump shafts, surgical instruments and downhole tools. In short: most weldable Co-Cr alloy; corrosion plus wear resistance; highest ductility in family.
What is the yield strength of Ultimet-SA?
Ultimet-SA has a typical yield strength of 490 MPa (71.1 ksi) and a tensile strength of 1,000 MPa (145 ksi) — weaker than 69% of cobalt-chrome alloy grades. Strength varies by condition: see the 4 listed tempers.
Is Ultimet-SA easy to machine?
Not especially — machinability is rated poor (18/100, better than 91% of cobalt-chrome alloy grades). Machine like a high work-hardening superalloy: rigid setup, positive-rake sharp carbide, low speed / heavy positive feed, never dwell, flood coolant; grinding and EDM are common for finished wear surfaces.
Can Ultimet-SA be welded?
Yes — weldability is rated very good (75/100). Readily welded by GTAW/GMAW/PAW with matching Ultimet filler; no preheat or PWHT required, keep interpass temperature low and heat input moderate to limit sensitization.
What surface finishes work on Ultimet-SA?
Not anodizable; finish by grinding, polishing or electropolishing — the passive Cr-Mo film self-heals, so no plating or coating is normally needed.
Can Ultimet-SA be formed, bent or molded?
Cold forms well when annealed but work-hardens very rapidly — allow extra press capacity, generous radii and intermediate solution anneals at ~1120 °C with rapid cooling.
What is the maximum service temperature of Ultimet-SA?
Ultimet-SA is rated for continuous use to about 900°C (1,652 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between Ultimet-SA and Ultimet-CW?
SA is the default condition — standard stocked condition for sheet and strip: best combination of ductility, corrosion resistance and weldability. CW: pick when maximum strength, springiness or surface hardness is needed and no welding or deep forming follows. Yield strength is 490 MPa in SA versus 1,200 MPa in CW.
Sources
- ULTIMET alloy (UNS R31233) technical brochure — Haynes International (2020)
- ASTM B818 / UNS R31233 chemistry registration — ASTM / SAE-ASTM UNS (2018)
- ASM Handbook Vol.2 — Properties and Selection: Nonferrous Alloys (Cobalt Alloys) — ASM International (1990)
- ASM Handbook Vol.19 — Fatigue and Fracture — ASM International (1996)
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.