Cobalt-Chrome Alloy Ultimet-CW (Cold worked)
Supply condition
UNS R31233
Pick when maximum strength, springiness or surface hardness is needed and no welding or deep forming follows.
Values for the CW 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 |
SADefault 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 |
CWThis page 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-CW?
Ultimet-CW is Ultimet supplied in the CW condition — pick when maximum strength, springiness or surface hardness is needed and no welding or deep forming follows. Ultimet-CW has a yield strength of 1,200 MPa (174 ksi) and a tensile strength of 1,400 MPa (203 ksi) — stronger than 88% of cobalt-chrome alloy grades. Elongation at break is 10% and the elastic modulus is 224 GPa (32.5 Msi). Ultimet-CW 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). SA is the default condition FabDigit quotes; CW is available on request or by drawing note.
Advantages
- Low embodied carbon — 9 kg CO₂/kg, better than 93% of cobalt-chrome alloy grades
- Readily welded — 65/100, better than 89% of cobalt-chrome alloy grades
- High strength — 1,200 MPa (174 ksi), better than 88% of cobalt-chrome alloy grades
- Forms and bends easily — 25/100, better than 82% 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
- Limited service temperature — 500°C (932 °F), worse than 87% of cobalt-chrome alloy grades
Ultimet-CW properties
Typical room-temperature values for Ultimet-CW; 22 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-CW 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-CW has a yield strength of 1,200 MPa (174 ksi) and a tensile strength of 1,400 MPa (203 ksi) — stronger than 88% of cobalt-chrome alloy grades. Elongation at break is 10% and the elastic modulus is 224 GPa (32.5 Msi).
Thermal6
Ultimet-CW is rated for continuous service to 500°C (932 °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-CW conducts electricity at 2 % IACS, better than 79% of cobalt-chrome alloy grades.
Chemical & Environmental3
Corrosion resistance is very good (80/100), better than 63% of cobalt-chrome alloy grades.
Sustainability4
Producing a kilogram of Ultimet-CW 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-CW's machinability is not recommended (14/100, better than 71% of cobalt-chrome alloy grades); weldability good (65/100); formability poor (25/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Ultimet-CW
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-CW — frequently asked
What is Ultimet-CW used for?
Ultimet-CW 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-CW?
Ultimet-CW has a typical yield strength of 1,200 MPa (174 ksi) and a tensile strength of 1,400 MPa (203 ksi) — stronger than 88% of cobalt-chrome alloy grades. Strength varies by condition: see the 4 listed tempers.
Is Ultimet-CW easy to machine?
Not especially — machinability is rated not recommended (14/100, better than 71% 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-CW be welded?
Yes — weldability is rated good (65/100). 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-CW?
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-CW 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-CW?
Ultimet-CW is rated for continuous use to about 500°C (932 °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.