Purpose: This work presents the influence of chemical composition and plastic deformation
temperature of CuCoNi and CuCoNiB as well as CuCo2 and CuCo2B alloys on the structure,
mechanical properties and, especially on the inter-crystalline brittleness phenomenon and
ductility minimum temperature effect in tensile testing with strain rate of 1.2·10-3 s-1 in the
range from 20°C to 800°C.
Design/methodology/approach: The tensile test of the investigated copper alloys
was realized in the temperature range of 20-800°C with a strain rate of 1.2·10-3 s–1 on the
universal testing machine. Metallographic observations of the structure were carried out on
a light microscope and the fractographic investigation of fracture on an electron scanning
microscope.
Findings: Low-alloy copper alloys such as CuCo2 and CuCo2B as well as CuCoNi and
CuCoNiB show a phenomenon of minimum plasticity at tensile testing in plastic deforming
temperature respectively from 500°C to 700°C for CuCo2, from 450°C to 600°C for CuCo2B
and from 450°C to 600°C for CuCo2B and from 500°C to 600°C for CuCoNiB.
Practical implications: In result of tensile tests of copper alloys it has been found that
the ductility minimum temperature of the alloys equals to about 500°C. At the temperature
of stretching of about 450°C the investigated copper alloys show maximum strength values.
Originality/value: Based on the test results the temperature range for decreased plasticity
of CuCoNi and CuCoNiB as well as CuCo2 and CuCo2B alloys was specified. This brittleness
is a result of decreasing plasticity in a determined range of temperatures of deforming called
the ductility minimum temperature.
Specimen Inertia in high strain rate tensile testing
