Tungsten Alloy W70Cu30
also CuW70
W70Cu30 (CuW70, GB/T 8320) is an infiltrated tungsten-copper pseudo-alloy in which a sintered tungsten skeleton is filled with copper, combining tungsten arc-erosion resistance with copper conductivity.
Reference datasheet — W70Cu30 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 INF condition
W70Cu30 tempers and conditions
W70Cu30 is supplied in 3 conditions, soft to hard. INF 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 |
|---|---|---|---|---|---|---|
Mixed-powder press & liquid-phase sintered | Lower-cost route for simple contact shapes; slightly lower density and conductivity because of residual closed porosity. | 400 | 550 | 3 | 175 HB | 38 % IACS |
INFDefault Copper-infiltrated | Standard commercial condition for EDM electrodes, switchgear contacts and heat spreaders — highest density and conductivity for a given W content. | 620 | 5 | 185 HB | 42 % IACS | |
HIP/vacuum-degassed high-density electronic grade | Choose for microwave packages, vacuum interrupters and hermetic heat sinks where closed porosity, outgassing and plating quality matter. | 660 | 6 | 190 HB | 45 % IACS |
Supply forms, finishes and certifications
Ways W70Cu30 is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
B702-CL11 | B702 Class 11 | Certification |
GB8320-CuW70 | GB/T 8320 CuW70 | Certification |
What is W70Cu30?
W70Cu30 (CuW70, GB/T 8320) is an infiltrated tungsten-copper pseudo-alloy in which a sintered tungsten skeleton is filled with copper, combining tungsten arc-erosion resistance with copper conductivity. Engineers use it as a workhorse EDM electrode and switchgear contact material because it holds 42% IACS electrical and 200 W/m·K thermal conductivity at 185 HB (95 HRB) with 620 MPa tensile strength and 5% elongation; stock forms are plate, rod, bar and pressed preforms. Density is 14 g/cm3, maximum service temperature 600 °C, and machinability rates 35, so it is not fusion weldable and cannot be formed. W80Cu20 is the alternative when erosion resistance matters more than conductivity. W70Cu30 has a density of 14 g/cm³ (0.506 lb/in³), lighter than 100% of tungsten alloy grades. It melts at 1,083°C (1,981 °F). W70Cu30 has a yield strength of 450 MPa (65.3 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 100% of tungsten alloy grades. Elongation at break is 5% and the elastic modulus is 230 GPa (33.4 Msi).
What is W70Cu30 used for?
- EDM electrodes
- High-voltage switch contacts
- Heat sinks
- Resistance welding electrodes
Advantages
- Lightweight — 14 g/cm³ (0.506 lb/in³), better than 100% of tungsten alloy grades
- Conducts heat well — 200 W/m·K (115.6 BTU/hr·ft·°F), better than 100% of tungsten alloy grades
- High electrical conductivity — 42 % IACS, better than 100% of tungsten alloy grades
- Easy to machine — 35/100, better than 90% of tungsten alloy grades
- Low embodied carbon — 19 kg CO₂/kg, better than 90% of tungsten alloy grades
Limitations
- Low strength — 450 MPa (65.3 ksi), worse than 100% of tungsten alloy grades
- Low stiffness — 230 GPa (33.4 Msi), worse than 100% of tungsten alloy grades
W70Cu30 properties
Typical room-temperature values for W70Cu30-INF; bars are the position among tungsten alloy grades.
Physical2
W70Cu30 has a density of 14 g/cm³ (0.506 lb/in³), lighter than 100% of tungsten alloy grades. It melts at 1,083°C (1,981 °F).
Mechanical13
W70Cu30 has a yield strength of 450 MPa (65.3 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 100% of tungsten alloy grades. Elongation at break is 5% and the elastic modulus is 230 GPa (33.4 Msi).
Thermal5
W70Cu30 is rated for continuous service to 600°C (1,112 °F). It conducts heat at 200 W/m·K (115.6 BTU/hr·ft·°F), better than 100% of tungsten alloy grades. Thermal expansion is 9.4 µm/m·K (5.22 µin/in·°F).
Electrical3
W70Cu30 conducts electricity at 42 % IACS, better than 100% of tungsten alloy grades.
Chemical & Environmental3
Corrosion resistance is fair (50/100), worse than 69% of tungsten alloy grades.
Sustainability4
Producing a kilogram of W70Cu30 takes about 300 MJ of energy and emits 19 kg of CO₂ — less than 88% of tungsten alloy grades. Typical recycled content is 25%.
Manufacturability7
W70Cu30's machinability is fair (35/100, better than 90% of tungsten alloy grades); weldability poor (15/100); formability not recommended (5/100).
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 tungsten alloy family
Yield strength against density for every tungsten alloy grade FabDigit runs. W70Cu30 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with W70Cu30
Is W70Cu30 easy to machine?
Turn/mill with sharp micrograin-carbide or CBN tooling, light feeds, flood coolant and rigid setups; wire- and sinker-EDM, surface grinding and lapping are the preferred finishing routes.
Can W70Cu30 be welded?
Not fusion weldable — join by silver brazing (BAg-series) or Cu/Ag interlayer diffusion bonding to copper shanks and steel holders; keep braze cycles below ~900 °C to avoid copper sweat-out.
Can W70Cu30 be formed, bent or molded?
No cold or hot forming; net shape comes from powder pressing/infiltration plus machining, with sintered blanks in plate, rod, bar and custom preform forms.
W70Cu30 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 |
|---|---|---|
| Wtungsten skeleton, 68–72 wt% typical trade tolerance ±2 % | 68 – 72 | 70 |
| Nioptional sintering activator in press-sintered variants only | 0 – 0.5 | |
| Other impurities (Fe, Mo, C, O)total, per GB/T 8320 / producer specs | ≤ 0.5 | |
| Cuinfiltrant / matrix | ≥ 28 (balance) |
What surface finishes work on W70Cu30?
Electroless/electrolytic Ni (2–5 µm) followed by Au or Ag plating for solderability and oxidation resistance; degas and bake before plating to avoid blistering from residual porosity.
Equivalent designations
Standards and trade names that resolve to Tungsten Alloy W70Cu30 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Trade names
- CuW70
- Similar grades
- GB/T 8320
How much does W70Cu30 cost?
W70Cu30 is a high-cost tungsten 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.
W70Cu30 — frequently asked
What is W70Cu30 used for?
W70Cu30 is typically used for EDM electrodes, high-voltage switch contacts, heat sinks and resistance welding electrodes. In short: best-conducting W-Cu grade; workhorse EDM electrode; balanced erosion and conductivity.
What is the yield strength of W70Cu30?
W70Cu30 has a typical yield strength of 450 MPa (65.3 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 100% of tungsten alloy grades. Strength varies by condition: see the 3 listed tempers.
Is W70Cu30 easy to machine?
Not especially — machinability is rated fair (35/100, better than 90% of tungsten alloy grades). Turn/mill with sharp micrograin-carbide or CBN tooling, light feeds, flood coolant and rigid setups; wire- and sinker-EDM, surface grinding and lapping are the preferred finishing routes.
Can W70Cu30 be welded?
Not readily — weldability is rated poor (15/100). Not fusion weldable — join by silver brazing (BAg-series) or Cu/Ag interlayer diffusion bonding to copper shanks and steel holders; keep braze cycles below ~900 °C to avoid copper sweat-out.
What surface finishes work on W70Cu30?
Electroless/electrolytic Ni (2–5 µm) followed by Au or Ag plating for solderability and oxidation resistance; degas and bake before plating to avoid blistering from residual porosity.
Can W70Cu30 be formed, bent or molded?
No cold or hot forming; net shape comes from powder pressing/infiltration plus machining, with sintered blanks in plate, rod, bar and custom preform forms.
What is the maximum service temperature of W70Cu30?
W70Cu30 is rated for continuous use to about 600°C (1,112 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between W70Cu30-INF and W70Cu30-PS?
INF is the default condition — standard commercial condition for EDM electrodes, switchgear contacts and heat spreaders — highest density and conductivity for a given W content. PS: lower-cost route for simple contact shapes; slightly lower density and conductivity because of residual closed porosity. Yield strength is 450 MPa in INF versus 400 MPa in PS.
How much does W70Cu30 cost?
W70Cu30 is a high-cost tungsten 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 B702 Standard Specification for Copper-Tungsten Electrical Contact Material — ASTM (2017)
- ASM Handbook Vol. 7: Powder Metallurgy (infiltrated W-Cu composites) — ASM International (2015)
- ASM Handbook Vol. 2: Properties and Selection — Refractory Metals and Alloys — ASM International (1990)
- Tungsten-copper WCu70/30 material data — Plansee / Mi-Tech Tungsten Metals (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.