Cobalt-Chrome Alloy Ultimet
UNS R31233
Ultimet (UNS R31233) is a wrought multi-alloyed cobalt-chromium-nickel-molybdenum-tungsten alloy that pairs a passive Cr-Mo film with cobalt-alloy wear and galling resistance in a single material.
Reference datasheet — Ultimet is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the SA condition
Ultimet tempers and conditions
Ultimet is supplied in 4 conditions, soft to hard. SA is the default FabDigit quotes; the values on this page are for it.
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 |
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 |
Supply forms, finishes and certifications
Ways Ultimet is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
PWD | Atomized powder for thermal spray / PTA / laser cladding / AM | Supply form |
SA-BAR | SA | Supply form |
What is Ultimet?
Ultimet (UNS R31233) is a wrought multi-alloyed cobalt-chromium-nickel-molybdenum-tungsten alloy that pairs a passive Cr-Mo film with cobalt-alloy wear and galling resistance in a single material. It is chosen where one part must resist both corrosion and wear: 490 MPa yield, 1000 MPa tensile, 39% elongation, 277 HB (28 HRC), service to 900 °C and a corrosion score of 82, supplied as plate, sheet, bar and weld powder. Unlike S-816 it welds readily (score 75) with matching filler and needs no PWHT, but it work-hardens rapidly in forming (score 60) and machines poorly (score 18). Ultimet 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). Ultimet 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).
What is Ultimet used for?
- oilfield valve seats and trim
- pump shafts
- surgical instruments
- downhole tools
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 properties
Typical room-temperature values for Ultimet-SA; bars are the position among cobalt-chrome alloy grades.
Physical3
Ultimet 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 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 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 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 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'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. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the cobalt-chrome alloy family
Yield strength against density for every cobalt-chrome alloy grade FabDigit runs. Ultimet is highlighted; hover a dot for its name, or open the interactive family chart.
Working with Ultimet
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.
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 |
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.
Equivalent designations
Standards and trade names that resolve to Cobalt-Chrome Alloy Ultimet in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- R31233
How much does Ultimet cost?
Ultimet is a high-cost cobalt-chrome alloy ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Ultimet — frequently asked
What is Ultimet used for?
Ultimet 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?
Ultimet 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 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 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?
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 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?
Ultimet 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.
How much does Ultimet cost?
Ultimet is a high-cost cobalt-chrome alloy ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
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; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.