CoCrMo

metal

cobalt-chromium alloy (biomedical and aerospace grade)

Cobalt-Chromium-MolybdenumUNS R30075ASTM F75 (casting equiv.)ISO 5832-12 (wrought equiv.)EOS Cobalt Chrome MP1Co-28Cr-6Mo

Density

8.29 g/cm³

YS (LPBF as-built (XY))

980–1200 MPa

UTS (LPBF as-built (XY))

1200–1420 MPa

Elongation (LPBF as-built (XY))

2.0–6.0 %

Elastic modulus

195–220 GPa

Thermal conductivity

14.3 W/m·K

Composition — UNS R30075 / ASTM F3213-17

Element	Min %	Max %	Notes
Co	bal.		balance
Cr	26.00	30.000	Passivation layer (Cr₂O₃) — drives corrosion and oxidation resistance. Key for biocompatibility.
Mo	5.00	7.000	Solid solution strengthening and pitting corrosion resistance in chloride (body fluids)
Ni	—	1.000
Fe	—	0.750
C

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Mechanical & thermal properties — 3 conditions

Property	LPBF as-built (XY)	LPBF as-built (Z)	LPBF solution-annealed (XY)
Elastic modulus	195–220 GPa	—	—
Yield strength (0.2%)	980–1200 MPa	840–1080 MPa	630–780 MPa
Ultimate tensile strength	1200–1420 MPa	1050–1270 MPa	880–1080 MPa
Elongation at break	2.0–6.0 %	1.0–4.0 %	8.0–18.0 %
Hardness (HV)	380–480 HV10	—	270–340 HV10
Fatigue strength	430–580 MPa	—	—
Density	8.29 g/cm³	—	—
Thermal conductivity	14.3 W/m·K	—	—
CTE	12.8–14.0 µm/m·K	—	—
As-built surface Ra	8.0–16.0 µm	—	—

Values shown as min–max where a spread is reported, otherwise as typical ± unit. Ranges reflect inter-source variation, not single-sample scatter. All values are for AM-processed specimens unless noted.

Engineering considerations

Biocompatibility testing: ASTM F3213 covers mechanical and compositional requirements but NOT biocompatibility. ISO 10993-1 cytotoxicity, sensitisation, and genotoxicity testing required for implantable devices.
Wear debris: metal-on-metal bearing surfaces (CoCrMo-on-CoCrMo) are under increasing regulatory scrutiny (FDA 2016 guidance). Ceramic-on-CoCrMo or UHMWPE-on-CoCrMo reduces ion release.
Surface finish for implants: Ra <0.8 µm for bone cement interfaces; Ra <0.05 µm (mirror polish) for articulating bearing surfaces. Electropolishing achieves Ra ~0.05 µm from as-built Ra ~12 µm.
Lattice structures: CoCrMo LPBF lattices (300–600 µm pore size) achieve stiffness matching to trabecular bone (~0.5–3 GPa) — used for spinal cages and metaphyseal sleeves. Strut diameter minimum ~200 µm.
Stress relief before part removal: minimum 1000°C/1h (vacuum) recommended to prevent distortion. Parts are highly susceptible to distortion if removed without stress relief.
Post-heat-treatment decision: as-built provides optimal wear resistance (hardness 430 HV). Solution anneal (1150°C) improves ductility but sacrifices wear resistance. Choose based on application.
Powder safety: cobalt powder is designated as a possible human carcinogen (IARC Group 2B). Vacuum or glove-box powder handling required. Mandatory COSHH assessment before any CoCrMo LPBF operation.
Regulatory pathway (EU): Class III medical devices (joint replacements) require CE marking under EU MDR 2017/745 with Notified Body review. AM-specific process validation per ASTM F3407 or equivalent required.

Advantages

Highest hardness of any standard AM biomedical metal — superior wear resistance for articulating surfaces
Excellent corrosion resistance in physiological environments (body fluids, PBS, Ringer's solution)
Biocompatible — ISO 10993 compliant; long clinical track record in cobalt alloy implants
High fatigue strength (~500 MPa) — critical for cyclic-loaded implants (hip stems: ~3 million cycles/year)
Strong high-temperature properties: retains significant strength to 900°C — aerospace turbine component use
Outstanding creep resistance at moderate temperatures
Excellent osseointegration potential when surface-roughened (Ra 1–3 µm for bone contact)
Non-magnetic — MRI compatible implants possible

Limitations

Very low as-built ductility (2.5–6%) — barely meets ASTM F3213 minimum; fatigue-critical implants need rigorous process control
Ion release concern: Co²⁺ and Cr³⁺/Cr⁶⁺ ions released from wear debris — regulatory and clinical concern for metal-on-metal bearings
Extremely high hardness makes post-machining difficult — hard turning tools, CBN inserts, slow cutting speeds required
Dense (8.29 g/cm³) — heaviest common biomedical AM metal; hip implant weight matters for elderly patients
Limited LPBF machine compatibility — requires high-power laser (≥400 W) and careful atmosphere control
High residual tensile stress in as-built state — mandatory stress relief for fatigue-critical implants
Powder handling: Co is classified as a potentially carcinogenic metal — strict COSHH/OSHA inhalation controls mandatory
High cost: raw powder 4–6× more expensive than SS316L per kg

Typical applications

Orthopaedic implants — hip femoral heads, knee bearing tibial insertsDental frameworks, crowns, and bridges (metal-ceramic restorations)Spinal fusion cages and interbody devicesPatient-specific maxillofacial reconstruction platesSurgical instruments requiring high wear resistanceTurbine blades for industrial gas turbines (high-temperature aerospace grade)Rotary instruments (dental drills, cutting burs)Articulating joint surfaces requiring Ra <0.1 µmCustom orthopaedic implants with trabecular lattice structures

Standards & certifications

ASTM-F3213established

CoCrMo (Co-28Cr-6Mo) parts produced by powder bed fusion — composition, powder, and minimum mechanical property requirements

medicaldentalaerospace

YS ≥827 MPa, UTS ≥1172 MPa, El ≥2.5% minimum. Implant parts additionally require ISO 10993 biocompatibility testing.

ISO-5832-12established

Wrought CoCrMo baseline for comparison with LPBF-produced implants

medical

Regulatory bodies (FDA, CE) require LPBF CoCrMo implants to meet or exceed ISO 5832-12 properties.

ASTM-E8established

Tensile test method for acceptance testing

medicaldentalaerospace

ISO-52904established

Process quality assurance for safety-critical PBF parts

medicalaerospace

CoCrMo

Composition — UNS R30075 / ASTM F3213-17

Mechanical & thermal properties — 3 conditions

Engineering considerations

Advantages

Limitations

Typical applications

Industries

Standards & certifications

Compatible AM processes (4)

Other metal materials

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