Precious Metal CuCr50 PM-S
Other
GB CuCr50
PM-S = press and solid-state sintered
Pick when chopping-current level and dielectric withstand matter more than conductivity; blended powder pressed and solid-state sintered gives fine, uniform chromium at 37% IACS.
Values for the PM-S condition
Other CuCr50 tempers and conditions
CuCr50 is listed in 4 conditions; see the grade overview at CuCr50.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
PM-SThis page Press and solid-state sintered | Pick when chopping-current level and dielectric withstand matter more than conductivity; blended powder pressed and solid-state sintered gives fine, uniform chromium at 37% IACS. | 220 | 300 | 5 | 105 HB | 37 % IACS |
PM-IDefault Chromium skeleton infiltrated with copper | Choose as the default contact blank: a pre-sintered chromium skeleton vacuum-infiltrated with pure copper gives high density, 43% IACS conductivity and moderate cost. | 245 | 350 | 8 | 95 HB | 43 % IACS |
Sintered plus repress/resinter or hot pressing | Use for large-diameter contacts breaking high currents; repressing and resintering or hot pressing after solid-state sintering cuts porosity and lifts strength to 380 MPa and 41% IACS. | 270 | 380 | 8 | 110 HB | 41 % IACS |
Hot isostatic pressed | Choose for high-end vacuum interrupter contacts needing high dielectric withstand, low chopping current and long electrical life; hot isostatic pressing gives near-full density, minimal gas content. | 290 | 410 | 10 | 112 HB | 42 % IACS |
What is CuCr50 PM-S?
CuCr50 PM-S is CuCr50 in the PM-S condition — pick when chopping-current level and dielectric withstand matter more than conductivity; blended powder pressed and solid-state sintered gives fine, uniform chromium at 37% IACS. CuCr50 PM-S has a yield strength of 220 MPa (31.9 ksi) and a tensile strength of 300 MPa (43.5 ksi) — stronger than 67% of precious metal grades. Elongation at break is 5% and the elastic modulus is 150 GPa (21.8 Msi). CuCr50 PM-S has a density of 7.7 g/cm³ (0.278 lb/in³), lighter than 99% of precious metal grades. It melts at 1,076°C (1,969 °F). PM-I is the default condition FabDigit quotes; PM-S is available on request or by drawing note.
Advantages
- Low embodied carbon — 6.5 kg CO₂/kg, better than 100% of precious metal grades
- Lightweight — 7.7 g/cm³ (0.278 lb/in³), better than 99% of precious metal grades
- Stiff — 150 GPa (21.8 Msi), better than 87% of precious metal grades
Limitations
- Hard to polish — 55/100, worse than 97% of precious metal grades
- Limited formability — 20/100, worse than 96% of precious metal grades
- Needs corrosion protection — 55/100, worse than 94% of precious metal grades
- Limited ductility — 5%, worse than 93% of precious metal grades
- Difficult to machine — 28/100, worse than 91% of precious metal grades
CuCr50 PM-S properties
Typical room-temperature values for CuCr50 PM-S; 10 are specific to this condition. Other listed values are CuCr50 reference data and may not represent this condition. Bars are the position among precious metal grades.
Physical3
CuCr50 PM-S has a density of 7.7 g/cm³ (0.278 lb/in³), lighter than 99% of precious metal grades. It melts at 1,076°C (1,969 °F).
Mechanical10
CuCr50 PM-S has a yield strength of 220 MPa (31.9 ksi) and a tensile strength of 300 MPa (43.5 ksi) — stronger than 67% of precious metal grades. Elongation at break is 5% and the elastic modulus is 150 GPa (21.8 Msi).
Thermal6
CuCr50 PM-S is rated for continuous service to 300°C (572 °F). It conducts heat at 165 W/m·K (95.3 BTU/hr·ft·°F), better than 67% of precious metal grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical3
CuCr50 PM-S conducts electricity at 37 % IACS, better than 68% of precious metal grades.
Chemical & Environmental3
Corrosion resistance is good (55/100), worse than 94% of precious metal grades.
Sustainability4
Producing a kilogram of CuCr50 PM-S takes about 95 MJ of energy and emits 6.5 kg of CO₂ — less than 100% of precious metal grades. Typical recycled content is 15%.
Manufacturability7
CuCr50 PM-S's machinability is poor (28/100, worse than 91% of precious metal grades); weldability poor (25/100); formability poor (20/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with CuCr50 PM-S
Is CuCr50 easy to machine?
The hard chromium particles are strongly abrasive: use fine-grain carbide or PCD tooling with large rake angles, low feed and full coolant. After finish turning the contact face, vacuum degas the part to secure dielectric withstand.
Can CuCr50 be welded?
Fusion welding is generally not used because of porosity and chromium segregation. Contacts are brazed to copper conductor stems with BAg or BCu filler in a vacuum or hydrogen furnace.
Can CuCr50 be formed, bent or molded?
Standard routes are powder pressing plus sintering, chromium-skeleton infiltration, or vacuum melting; dense blanks can be hot forged or hot rolled into cup or axial-magnetic-field slotted contacts. Cold forming capability is very poor and cracking is likely.
What surface finishes work on CuCr50?
After finish turning or grinding, clean, degrease and vacuum degas. Conductive joint faces can be silver- or nickel-plated, while arcing faces are left as bare metal with no coating.
CuCr50 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 |
|---|---|---|
| Crchromium powder or Cr skeleton, typically 40–150 µm particle size | 48 – 52 | 50 |
| Ototal oxygen; vacuum-melted parts can reach ≤0.03% | ≤ 0.06 | 0.04 |
| Fe | ≤ 0.05 | 0.02 |
| Si | ≤ 0.03 | 0.01 |
| C | ≤ 0.02 | 0.01 |
| Ngas content directly affects dielectric withstand level | ≤ 0.02 | 0.01 |
| Al | ≤ 0.02 | 0.01 |
| S | ≤ 0.01 | 0 |
| Cuoxygen-free or electrolytic copper | ≥ 48 (balance) | — |
CuCr50 PM-S — frequently asked
What is CuCr50 PM-S used for?
CuCr50 PM-S is typically used for vacuum circuit breakers, vacuum contactors and medium-voltage switchgear interrupters. In short: standard vacuum interrupter material; low chopping current; poor cold formability.
What is the yield strength of CuCr50 PM-S?
CuCr50 PM-S has a typical yield strength of 220 MPa (31.9 ksi) and a tensile strength of 300 MPa (43.5 ksi) — stronger than 67% of precious metal grades. Strength varies by condition: see the 4 listed tempers.
Is CuCr50 PM-S easy to machine?
Not especially — machinability is rated poor (28/100, worse than 91% of precious metal grades). The hard chromium particles are strongly abrasive: use fine-grain carbide or PCD tooling with large rake angles, low feed and full coolant. After finish turning the contact face, vacuum degas the part to secure dielectric withstand.
Can CuCr50 PM-S be welded?
Not readily — weldability is rated poor (25/100). Fusion welding is generally not used because of porosity and chromium segregation. Contacts are brazed to copper conductor stems with BAg or BCu filler in a vacuum or hydrogen furnace.
What surface finishes work on CuCr50 PM-S?
After finish turning or grinding, clean, degrease and vacuum degas. Conductive joint faces can be silver- or nickel-plated, while arcing faces are left as bare metal with no coating.
Can CuCr50 PM-S be formed, bent or molded?
Standard routes are powder pressing plus sintering, chromium-skeleton infiltration, or vacuum melting; dense blanks can be hot forged or hot rolled into cup or axial-magnetic-field slotted contacts. Cold forming capability is very poor and cracking is likely.
What is the maximum service temperature of CuCr50 PM-S?
CuCr50 PM-S is rated for continuous use to about 300°C (572 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between CuCr50 PM-I and CuCr50-HIP?
PM-I is the default condition — choose as the default contact blank: a pre-sintered chromium skeleton vacuum-infiltrated with pure copper gives high density, 43% IACS conductivity and moderate cost. HIP: choose for high-end vacuum interrupter contacts needing high dielectric withstand, low chopping current and long electrical life; hot isostatic pressing gives near-full density, minimal gas content. Yield strength is 245 MPa in PM-I versus 290 MPa in HIP.
Sources
- ASM Handbook Vol. 7 — Powder Metallurgy (electrical contact materials) — ASM International (2015)
- ASM Alloy Phase Diagrams — Cu-Cr system — ASM International (2016)
- CuCr (CuCr25/CuCr40/CuCr50) (2023)
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.