Cobalt-Chrome Alloy Hiperco 50-SR (Stress relieved)
Heat-treated state
UNS K92650 · ASTM A801 · also 2V-Permendur, Permendur
Intermediate treatment that removes forming stresses and partly restores magnetics while keeping more strength than a full magnetic anneal.
Values for the SR condition
Other Hiperco 50 tempers and conditions
Hiperco 50 is listed in 7 conditions; see the grade overview at Hiperco 50.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Rapid-cooled / ductilized | Order the strip or bar in this soft, disordered state when you must stamp, deep-draw, bend or machine before the final magnetic anneal. | 290 | 590 | 28 | 160 HB | 3.8 % IACS |
AnnealedDefault magnetic (final) anneal, 843–885 °C in dry hydrogen, controlled slow cool | Standard finished condition for laminations and magnetic cores — best permeability and lowest coercivity, but the ordered structure is relatively brittle. | 380 | 655 | 8 | 190 HB | — |
Hiperco 50A | Choose when thin gauge strip with finer grain, better punchability and slightly higher strength is needed at essentially the same saturation. | 430 | 700 | 8 | 200 HB | 4.3 % IACS |
Hot rolled | Bar, billet and forging stock condition for machined pole pieces that will be magnetically annealed afterwards. | 480 | 720 | 6 | 20 HRC | 4.1 % IACS |
SRThis page Stress relieved | Intermediate treatment that removes forming stresses and partly restores magnetics while keeping more strength than a full magnetic anneal. | 520 | 760 | 6 | 22 HRC | 4.2 % IACS |
Hiperco 50HS | Specified for high-speed rotor laminations where centrifugal stress governs: roughly double the yield strength of annealed Hiperco 50 with a modest magnetic penalty. | 720 | 1,000 | 5 | 30 HRC | 4.1 % IACS |
Cold rolled | As-supplied hard strip from the rolling mill — use only as feedstock; magnetic properties are poor until annealed. | 830 | 1,000 | 3 | 30 HRC | 3.8 % IACS |
What is Hiperco 50-SR?
Hiperco 50-SR is Hiperco 50 heat treated to SR — intermediate treatment that removes forming stresses and partly restores magnetics while keeping more strength than a full magnetic anneal. Hiperco 50-SR has a yield strength of 520 MPa (75.4 ksi) and a tensile strength of 760 MPa (110 ksi) — weaker than 54% of cobalt-chrome alloy grades. Elongation at break is 6% and the elastic modulus is 207 GPa (30 Msi). Hiperco 50-SR has a density of 8.12 g/cm³ (0.293 lb/in³), lighter than 100% of cobalt-chrome alloy grades. It melts at 1,440°C (2,624 °F). Annealed is the default condition FabDigit quotes; SR is available on request or by drawing note.
Advantages
- Easy to machine — 27/100, better than 104% of cobalt-chrome alloy grades
- Conducts heat well — 29.5 W/m·K (17 BTU/hr·ft·°F), better than 100% of cobalt-chrome alloy grades
- High electrical conductivity — 4.2 % IACS, better than 100% of cobalt-chrome alloy grades
- Low embodied carbon — 6.5 kg CO₂/kg, better than 96% of cobalt-chrome alloy grades
- Forms and bends easily — 25/100, better than 82% of cobalt-chrome alloy grades
Limitations
- Needs corrosion protection — 20/100, worse than 100% of cobalt-chrome alloy grades
- Hard to polish — 70/100, worse than 91% of cobalt-chrome alloy grades
- Limited service temperature — 500°C (932 °F), worse than 87% of cobalt-chrome alloy grades
Hiperco 50-SR properties
Typical room-temperature values for Hiperco 50-SR; 19 are specific to this condition. Other listed values are Hiperco 50 reference data and may not represent this condition. Bars are the position among cobalt-chrome alloy grades.
Physical3
Hiperco 50-SR has a density of 8.12 g/cm³ (0.293 lb/in³), lighter than 100% of cobalt-chrome alloy grades. It melts at 1,440°C (2,624 °F).
Mechanical13
Hiperco 50-SR has a yield strength of 520 MPa (75.4 ksi) and a tensile strength of 760 MPa (110 ksi) — weaker than 54% of cobalt-chrome alloy grades. Elongation at break is 6% and the elastic modulus is 207 GPa (30 Msi).
Thermal6
Hiperco 50-SR is rated for continuous service to 500°C (932 °F). It conducts heat at 29.5 W/m·K (17 BTU/hr·ft·°F), better than 100% of cobalt-chrome alloy grades. Thermal expansion is 9.4 µm/m·K (5.22 µin/in·°F).
Electrical3
Hiperco 50-SR conducts electricity at 4.2 % IACS, better than 100% of cobalt-chrome alloy grades.
Chemical & Environmental3
Corrosion resistance is poor (20/100), worse than 100% of cobalt-chrome alloy grades.
Sustainability4
Producing a kilogram of Hiperco 50-SR takes about 85 MJ of energy and emits 6.5 kg of CO₂ — less than 100% of cobalt-chrome alloy grades. Typical recycled content is 10%.
Manufacturability7
Hiperco 50-SR's machinability is poor (27/100, better than 104% of cobalt-chrome alloy grades); weldability fair (40/100); formability poor (25/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Hiperco 50-SR
Is Hiperco 50 easy to machine?
Machine in the rapid-cooled (disordered) condition with sharp carbide tools, rigid setups, moderate speed (~30–50 m/min) and generous coolant; ordered annealed material chips brittlely and grinding is often preferred for finish cuts.
Can Hiperco 50 be welded?
EB, laser and GTAW joints are made in vacuum or high-purity argon with matching or Fe-Co filler; always follow with the full magnetic anneal, since the weld and HAZ otherwise have high coercivity.
Can Hiperco 50 be formed, bent or molded?
Stamp, bend and draw only in the quenched disordered state — laminations are punched at 0.1–0.35 mm gauge, then stress-free stacked and given the 843–885 °C hydrogen anneal with a slow controlled cool.
What surface finishes work on Hiperco 50?
No natural corrosion resistance: apply C-5/oxide interlaminar coating, epoxy varnish, electroless nickel or passivation-type plating; handle annealed parts gently as any mechanical stress degrades permeability.
Hiperco 50 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 |
|---|---|---|
| CoASTM A801 Type 1 | 48 – 50 | 49 |
| Vraises resistivity and ductility | 1.8 – 2.2 | 2 |
| Nbup to ~0.3 % in the 50A/50HS variants | ≤ 0.05 | 0.02 |
| Mn | ≤ 0.05 | 0.02 |
| Si | ≤ 0.05 | 0.02 |
| Clow C essential for soft magnetics | ≤ 0.01 | 0.01 |
| Niresidual | ≤ 0.05 | — |
| Sresidual | ≤ 0.01 | — |
| Presidual | ≤ 0.01 | — |
| Febalance, ≈49 % | balance | — |
Hiperco 50-SR — frequently asked
What is Hiperco 50-SR used for?
Hiperco 50-SR is typically used for aircraft generator/motor laminations, transformer cores, magnetic pole pieces and solenoid actuators. In short: highest saturation flux density; cobalt-priced lamination alloy; brittle after magnetic anneal.
What is the yield strength of Hiperco 50-SR?
Hiperco 50-SR has a typical yield strength of 520 MPa (75.4 ksi) and a tensile strength of 760 MPa (110 ksi) — weaker than 54% of cobalt-chrome alloy grades. Strength varies by condition: see the 7 listed tempers.
Is Hiperco 50-SR easy to machine?
Not especially — machinability is rated poor (27/100, better than 104% of cobalt-chrome alloy grades). Machine in the rapid-cooled (disordered) condition with sharp carbide tools, rigid setups, moderate speed (~30–50 m/min) and generous coolant; ordered annealed material chips brittlely and grinding is often preferred for finish cuts.
Can Hiperco 50-SR be welded?
With care — weldability is rated fair (40/100). EB, laser and GTAW joints are made in vacuum or high-purity argon with matching or Fe-Co filler; always follow with the full magnetic anneal, since the weld and HAZ otherwise have high coercivity.
What surface finishes work on Hiperco 50-SR?
No natural corrosion resistance: apply C-5/oxide interlaminar coating, epoxy varnish, electroless nickel or passivation-type plating; handle annealed parts gently as any mechanical stress degrades permeability.
Can Hiperco 50-SR be formed, bent or molded?
Stamp, bend and draw only in the quenched disordered state — laminations are punched at 0.1–0.35 mm gauge, then stress-free stacked and given the 843–885 °C hydrogen anneal with a slow controlled cool.
What is the maximum service temperature of Hiperco 50-SR?
Hiperco 50-SR 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 Hiperco 50 Annealed and Hiperco 50-CR?
Annealed is the default condition — standard finished condition for laminations and magnetic cores — best permeability and lowest coercivity, but the ordered structure is relatively brittle. CR: as-supplied hard strip from the rolling mill — use only as feedstock; magnetic properties are poor until annealed. Yield strength is 380 MPa in Annealed versus 830 MPa in CR.
Sources
- ASTM A801 — Standard Specification for Wrought Iron-Cobalt High Magnetic Saturation Alloys (UNS K92650) — ASTM International (2021)
- Hiperco 50 / 50A / 50HS Alloy Technical Datasheets — Carpenter Technology (2020)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials (soft magnetic alloys) — ASM International (1990)
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.