Cobalt-Chrome Alloy F1537 Alloy 3
ASTM F1537 Alloy 3 · UNS R31539
ASTM F1537 Alloy 3 (UNS R31539) is a wrought Co-Cr-Mo implant alloy strengthened by a fine dispersed oxide phase, supplied annealed, hot worked or warm worked as bar, rod and forging stock.
Reference datasheet — F1537 Alloy 3 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 HW condition
F1537 Alloy 3 tempers and conditions
F1537 Alloy 3 is supplied in 3 conditions, soft to hard. HW is the default FabDigit quotes; the values on this page are for it.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Softest condition — choose for subsequent forging, deep machining or when maximum ductility is needed. | 600 | 1,000 | 32 | 28 HRC | — |
HWDefault Hot Worked | Standard mill supply for forged implant components — balanced strength, ductility and machinability. | 930 | 1,280 | 20 | 36 HRC | — |
Warm Worked | Highest strength and fatigue life — chosen for machined-from-bar hip stems and other high-cycle load-bearing parts. | 1,300 | 1,550 | 18 | 45 HRC | — |
What is F1537 Alloy 3?
ASTM F1537 Alloy 3 (UNS R31539) is a wrought Co-Cr-Mo implant alloy strengthened by a fine dispersed oxide phase, supplied annealed, hot worked or warm worked as bar, rod and forging stock. Engineers choose it for the higher fatigue strength it gives hip and knee stems: 930 MPa yield, 1280 MPa tensile, 20 % elongation and 340 HB (36 HRC), with corrosion resistance rated 90/100. Machinability is rated 12/100 and weldability 30/100, service is limited to about 500 °C, and shaping is restricted to hot or warm work. F1537 Alloy 1 is the alternative when ductility and weldability matter more. F1537 Alloy 3 has a density of 8.3 g/cm³ (0.3 lb/in³), lighter than 80% of cobalt-chrome alloy grades. It melts at 1,330°C (2,426 °F). F1537 Alloy 3 has a yield strength of 930 MPa (135 ksi) and a tensile strength of 1,280 MPa (186 ksi) — stronger than 81% of cobalt-chrome alloy grades. Elongation at break is 20% and the elastic modulus is 230 GPa (33.4 Msi).
What is F1537 Alloy 3 used for?
- Orthopedic implant stems
- Joint replacement components
- Knee femoral components
- Modular hip necks and tapers
- Spinal rods and connectors
- Trauma fixation hardware
- Implant bearing surfaces
Advantages
- Good corrosion resistance — 90/100, better than 95% of cobalt-chrome alloy grades
- Polishes to a fine finish — 92/100, better than 93% of cobalt-chrome alloy grades
- Tough — resists crack growth — 70 MPa·√m (63.7 ksi·√in), better than 82% of cobalt-chrome alloy grades
- Forms and bends easily — 25/100, better than 82% of cobalt-chrome alloy grades
- High strength — 930 MPa (135 ksi), better than 81% of cobalt-chrome alloy grades
Limitations
- Limited service temperature — 500°C (932 °F), worse than 87% of cobalt-chrome alloy grades
F1537 Alloy 3 properties
Typical room-temperature values for F1537 Alloy 3-HW; bars are the position among cobalt-chrome alloy grades.
Physical3
F1537 Alloy 3 has a density of 8.3 g/cm³ (0.3 lb/in³), lighter than 80% of cobalt-chrome alloy grades. It melts at 1,330°C (2,426 °F).
Mechanical14
F1537 Alloy 3 has a yield strength of 930 MPa (135 ksi) and a tensile strength of 1,280 MPa (186 ksi) — stronger than 81% of cobalt-chrome alloy grades. Elongation at break is 20% and the elastic modulus is 230 GPa (33.4 Msi).
Thermal6
F1537 Alloy 3 is rated for continuous service to 500°C (932 °F). It conducts heat at 14 W/m·K (8.09 BTU/hr·ft·°F), worse than 55% of cobalt-chrome alloy grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).
Electrical3
F1537 Alloy 3 conducts electricity at 2 % IACS, better than 79% of cobalt-chrome alloy grades.
Chemical & Environmental3
Corrosion resistance is excellent (90/100), better than 95% of cobalt-chrome alloy grades.
Sustainability4
Producing a kilogram of F1537 Alloy 3 takes about 170 MJ of energy and emits 12 kg of CO₂ — more than 63% of cobalt-chrome alloy grades. Typical recycled content is 20%.
Manufacturability7
F1537 Alloy 3's machinability is not recommended (12/100, better than 61% of cobalt-chrome alloy grades); weldability poor (30/100); formability poor (25/100).
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. F1537 Alloy 3 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with F1537 Alloy 3
Is F1537 Alloy 3 easy to machine?
Very difficult: use rigid setups, sharp coated carbide or ceramic inserts, low speed / heavy positive feed and flood coolant to avoid the severe work-hardened skin; grinding and EDM are common alternatives.
Can F1537 Alloy 3 be welded?
Not recommended for load-bearing joints — high carbon promotes carbide precipitation and hot cracking; if unavoidable use low-heat-input laser or electron-beam welding with matched filler and post-weld solution anneal.
Can F1537 Alloy 3 be formed, bent or molded?
Shape by hot forging (≈1100–1180 °C) or warm working; cold forming is impractical because of the extremely high work-hardening rate.
F1537 Alloy 3 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 | 26 – 30 | 28 |
| Mo | 5 – 7 | 6 |
| Chigh-carbon type, forms M23C6 carbides | 0.15 – 0.35 | 0.25 |
| Larare-earth addition producing the dispersed oxide phase | 0.03 – 0.14 | 0.08 |
| Ni | ≤ 1 | — |
| Fe | ≤ 0.75 | — |
| Si | ≤ 1 | — |
| Mn | ≤ 1 | — |
| N | ≤ 0.25 | — |
| Co | balance | — |
What surface finishes work on F1537 Alloy 3?
Not anodizable — finish by grinding, mirror polishing of bearing surfaces (Ra < 0.02 µm), electropolishing, then passivation per ASTM F86; porous coatings applied by plasma spray or sintered beads.
Equivalent designations
Standards and trade names that resolve to Cobalt-Chrome Alloy F1537 Alloy 3 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- R31539
How much does F1537 Alloy 3 cost?
F1537 Alloy 3 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.
F1537 Alloy 3 — frequently asked
What is F1537 Alloy 3 used for?
F1537 Alloy 3 is typically used for orthopedic implant stems, joint replacement components, knee femoral components, modular hip necks and tapers, spinal rods and connectors and trauma fixation hardware. In short: dispersion-strengthened implant grade; improved implant fatigue strength; very low machinability rating.
What is the yield strength of F1537 Alloy 3?
F1537 Alloy 3 has a typical yield strength of 930 MPa (135 ksi) and a tensile strength of 1,280 MPa (186 ksi) — stronger than 81% of cobalt-chrome alloy grades. Strength varies by condition: see the 3 listed tempers.
Is F1537 Alloy 3 easy to machine?
Not especially — machinability is rated not recommended (12/100, better than 61% of cobalt-chrome alloy grades). Very difficult: use rigid setups, sharp coated carbide or ceramic inserts, low speed / heavy positive feed and flood coolant to avoid the severe work-hardened skin; grinding and EDM are common alternatives.
Can F1537 Alloy 3 be welded?
Not readily — weldability is rated poor (30/100). Not recommended for load-bearing joints — high carbon promotes carbide precipitation and hot cracking; if unavoidable use low-heat-input laser or electron-beam welding with matched filler and post-weld solution anneal.
What surface finishes work on F1537 Alloy 3?
Not anodizable — finish by grinding, mirror polishing of bearing surfaces (Ra < 0.02 µm), electropolishing, then passivation per ASTM F86; porous coatings applied by plasma spray or sintered beads.
Can F1537 Alloy 3 be formed, bent or molded?
Shape by hot forging (≈1100–1180 °C) or warm working; cold forming is impractical because of the extremely high work-hardening rate.
What is the maximum service temperature of F1537 Alloy 3?
F1537 Alloy 3 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 F1537 Alloy 3-HW and F1537 Alloy 3-WW?
HW is the default condition — standard mill supply for forged implant components — balanced strength, ductility and machinability. WW: highest strength and fatigue life — chosen for machined-from-bar hip stems and other high-cycle load-bearing parts. Yield strength is 930 MPa in HW versus 1,300 MPa in WW.
How much does F1537 Alloy 3 cost?
F1537 Alloy 3 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
- ASTM F1537 Standard Specification for Wrought Cobalt-28Chromium-6Molybdenum Alloys for Surgical Implants (UNS R31537, R31538, R31539) — ASTM International (2020)
- ASTM F86 Standard Practice for Surface Preparation and Marking of Metallic Surgical Implants — ASTM International (2021)
- ASM Handbook Vol.23: Materials for Medical Devices — ASM International (2012)
- ASM Handbook Vol.2: Properties and Selection — Nonferrous Alloys and Special-Purpose Materials (Cobalt alloys) — ASM International (1990)
- Wrought Co-28Cr-6Mo medical bar datasheets (Carpenter/Sandvik/Villares type) — various mills (2023)
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.