Cobalt-Chrome Alloy Phynox CW+A
Precip hard · default condition
UNS R30008
CW+A = cold worked and age hardened
Final high-strength spring/stent condition: maximum strength, fatigue life and relaxation resistance after forming.
Values for the CW+A condition
Other Phynox tempers and conditions
Phynox is listed in 4 conditions; see the grade overview at Phynox.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Pick for deep drawing, deep bending or machining before final cold work/ageing. | 450 | 950 | 55 | 26 HRC | — |
1/2 Hard | Compromise temper for parts needing some bending or forming yet moderate spring strength. | 1,250 | 1,450 | 10 | 45 HRC | 1.8 % IACS |
Cold worked | Standard as-supplied strip/wire condition for coiling and stamping springs that will be aged afterwards. | 1,600 | 1,800 | 5 | 52 HRC | — |
CW+ADefaultThis page Cold worked and age hardened | Final high-strength spring/stent condition: maximum strength, fatigue life and relaxation resistance after forming. | 1,850 | 2,050 | 3 | 57 HRC | — |
What is Phynox CW+A?
Phynox CW+A is Phynox in the CW+A condition — final high-strength spring/stent condition: maximum strength, fatigue life and relaxation resistance after forming. Phynox CW+A has a yield strength of 1,850 MPa (268 ksi) and a tensile strength of 2,050 MPa (297 ksi) — stronger than 96% of cobalt-chrome alloy grades. Elongation at break is 3% and the elastic modulus is 220 GPa (31.9 Msi). Phynox CW+A has a density of 8.3 g/cm³ (0.3 lb/in³), lighter than 80% of cobalt-chrome alloy grades. It melts at 1,440°C (2,624 °F).
Advantages
- High strength — 1,850 MPa (268 ksi), better than 96% of cobalt-chrome alloy grades
- Low embodied carbon — 9.5 kg CO₂/kg, better than 87% of cobalt-chrome alloy grades
Limitations
- Limited service temperature — 400°C (752 °F), worse than 96% of cobalt-chrome alloy grades
Phynox CW+A properties
Typical room-temperature values for Phynox CW+A; 16 are specific to this condition. Other listed values are Phynox reference data and may not represent this condition. Bars are the position among cobalt-chrome alloy grades.
Physical3
Phynox CW+A has a density of 8.3 g/cm³ (0.3 lb/in³), lighter than 80% of cobalt-chrome alloy grades. It melts at 1,440°C (2,624 °F).
Mechanical12
Phynox CW+A has a yield strength of 1,850 MPa (268 ksi) and a tensile strength of 2,050 MPa (297 ksi) — stronger than 96% of cobalt-chrome alloy grades. Elongation at break is 3% and the elastic modulus is 220 GPa (31.9 Msi).
Thermal5
Phynox CW+A is rated for continuous service to 400°C (752 °F). It conducts heat at 12.6 W/m·K (7.28 BTU/hr·ft·°F), worse than 71% of cobalt-chrome alloy grades. Thermal expansion is 13.5 µm/m·K (7.5 µin/in·°F).
Electrical3
Phynox CW+A conducts electricity at 1.7 % IACS, worse than 92% of cobalt-chrome alloy grades.
Chemical & Environmental3
Corrosion resistance is excellent (85/100), better than 79% of cobalt-chrome alloy grades.
Sustainability3
Producing a kilogram of Phynox CW+A takes about 130 MJ of energy and emits 9.5 kg of CO₂ — less than 89% of cobalt-chrome alloy grades. Typical recycled content is 20%.
Manufacturability7
Phynox CW+A's machinability is not recommended (10/100, better than 52% of cobalt-chrome alloy grades); weldability poor (30/100); formability poor (15/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Phynox CW+A
Is Phynox easy to machine?
Very difficult and highly work-hardening — machine in the annealed condition with rigid setups, positive-rake carbide or ceramic tooling, low speed, heavy feed and flood coolant; grinding/EDM preferred for aged parts.
Can Phynox be welded?
Resistance, micro-TIG and laser welding are used for medical assemblies; filler-free autogenous joints are best, and any weld locally destroys the cold-work/ageing strengthening, so re-age or design joints out of high-stress zones.
Can Phynox be formed, bent or molded?
Coil, stamp or bend in the annealed or spring temper, then age 500–550 °C for 4–5 h to reach full strength; allow for springback and use generous bend radii on cold-worked stock.
What surface finishes work on Phynox?
Electropolishing and passivation give the bright, low-inclusion medical surface; mechanical polishing to mirror finish is easy, PVD or gold plating is possible, anodising is not applicable.
Phynox 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 |
|---|---|---|
| Co | 39 – 41 | 40 |
| Cr | 19 – 21 | 20 |
| Ni | 14 – 18 | 16 |
| Mo | 6.5 – 7.5 | 7 |
| Mn | 1.5 – 2.5 | 2 |
| C | ≤ 0.15 | 0.1 |
| Beberyllium-free grade (unlike F1058 Grade 1 / Elgiloy) | ≤ 0 | 0 |
| Si | ≤ 1.2 | 0.3 |
| P | ≤ 0.02 | — |
| S | ≤ 0.02 | — |
| Febalance, typically ≈15 % | balance | — |
Phynox CW+A — frequently asked
What is Phynox CW+A used for?
Phynox CW+A is typically used for coronary stents, surgical springs and guidewires. In short: medical-grade cobalt spring alloy; biocompatible fatigue performance; fine wire and strip.
What is the yield strength of Phynox CW+A?
Phynox CW+A has a typical yield strength of 1,850 MPa (268 ksi) and a tensile strength of 2,050 MPa (297 ksi) — stronger than 96% of cobalt-chrome alloy grades. Strength varies by condition: see the 4 listed tempers.
Is Phynox CW+A easy to machine?
Not especially — machinability is rated not recommended (10/100, better than 52% of cobalt-chrome alloy grades). Very difficult and highly work-hardening — machine in the annealed condition with rigid setups, positive-rake carbide or ceramic tooling, low speed, heavy feed and flood coolant; grinding/EDM preferred for aged parts.
Can Phynox CW+A be welded?
Not readily — weldability is rated poor (30/100). Resistance, micro-TIG and laser welding are used for medical assemblies; filler-free autogenous joints are best, and any weld locally destroys the cold-work/ageing strengthening, so re-age or design joints out of high-stress zones.
What surface finishes work on Phynox CW+A?
Electropolishing and passivation give the bright, low-inclusion medical surface; mechanical polishing to mirror finish is easy, PVD or gold plating is possible, anodising is not applicable.
Can Phynox CW+A be formed, bent or molded?
Coil, stamp or bend in the annealed or spring temper, then age 500–550 °C for 4–5 h to reach full strength; allow for springback and use generous bend radii on cold-worked stock.
What is the maximum service temperature of Phynox CW+A?
Phynox CW+A is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between Phynox CW+A and Phynox-A?
CW+A is the default condition — final high-strength spring/stent condition: maximum strength, fatigue life and relaxation resistance after forming. A: pick for deep drawing, deep bending or machining before final cold work/ageing. Yield strength is 1,850 MPa in CW+A versus 450 MPa in A.
Sources
- ASTM F1058 — Wrought 40Co-20Cr-16Fe-15Ni-7Mo Alloy Wire and Strip for Surgical Implants — ASTM International (2016)
- Phynox cobalt alloy technical data — Aubert & Duval (2021)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials — ASM International (1990)
- ASM Handbook Vol. 13B — Corrosion: Materials — ASM International (2005)
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.