Copper-Beryllium
UNS C17500 · CuCo2Be · ASTM B441‐ B534‐ B870 · RWMA Class 3
Copper-beryllium alloys for parts that need mechanical strength and electrical or thermal conductivity at the same time.
Alloy family
What this family is good at
Strength and conductivity in one alloy
A small addition of beryllium gives copper high mechanical properties while keeping most of its conductivity. In CB4, cobalt joins beryllium, which places the grade on the conductive side of the family. The part carries current and heat well and still holds a load.
Where CB4 works
CB4 serves as plungers for die casting and as electrodes for the resistance welding of thick plates or stainless steel. It also goes into heads of pistons for diesel engines. These uses combine heat, pressure and friction, which is where its anti-friction behaviour counts.
CB4 in figures
CB4 (CuCo2Be, UNS C17500) is the one copper-beryllium grade in our catalogue today, supplied as bars in the TR temper. Its guaranteed minimum tensile strength is 690 MPa, with a hardness of 220 HB and an electrical conductivity of 43 % IACS. It is compliant with ASTM B441‐ B534‐ B870, classed RWMA Class 3, and lead-free.
Beryllium-free alternatives when the application allows
Because the use of beryllium is increasingly restricted for health and environmental reasons, we also produce beryllium-free grades. Hardiall®, a copper-nickel-tin alloy, covers strength and friction, and our copper-nickel-silicon grades cover thermal conductivity or high-temperature service. Our engineers tell you which route fits your part, and where CB4 remains the right answer.
Guaranteed minimum tensile strength of 690 MPa with an electrical conductivity of 43 % IACS.
Good anti-friction properties, used on die-casting plungers and resistance-welding electrodes.
Compliant with ASTM B441‐ B534‐ B870, classed RWMA Class 3 and lead-free.
Beryllium-free alternatives in copper-nickel-tin and copper-nickel-silicon when your application allows it.
Range at a glance
The extent of this family's measured properties across its active variants — a range, never a single figure.
1 – 965 MPa
23/24 measured
1 – 760 MPa
24/24 measured
2 – 35 %
24/24 measured
120 – 360 HB
19/24 measured
28 – 45 %IACS
24/24 measured
8.3 – 8.9 g/cm³
24/24 measured
110 – 230 W/m·K
24/24 measured
All Copper-Beryllium references
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Used in
- automotive
- industry
Specify it with an engineer
Check CB4 against your part
Send us the drawing and the strength and conductivity your part needs. Our engineers confirm whether CB4 fits, or which beryllium-free grade to consider.