Microstructure, mechanical properties and electrical conductivity of industrial Cu–0.5%Cr alloy processed by severe plastic deformation

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Microstructure, mechanical properties and electrical conductivity of industrial Cu–0.5% alloy subjected to equal channel angular pressing (ECAP) by route A and cold rolling with and without aging treatment were investigated. The lamellar grains in thickness of 100nm were obtained after eight ECAP passes. They were not further pancake shaped, but fragmentary and obtained less sharp boundaries with more dislocations in addition to cold rolling. After aging at 450°C for 1h, high density of dislocations and some coarse grains were observable after ECAP and the additional cold rolling, respectively. The tensile tests show that tensile strength arrived at 460MPa and 484MPa after four and eight passes of ECAP, respectively, the corresponding tensile strength increased to 570MPa and 579MPa after the additional cold rolling. However, the electrical conductivity was not more than 35% IACS. It was proved that four passes of ECAP followed by 90% cold rolling and aging at 450°C for 1h offered a short process for Cu–0.5%Cr alloy to balance the paradox of high strength and electrical conductivity, under which the tensile strength 554MPa, elongation to failure 22% and electrical conductivity 84% of IACS could be obtained. The high strength was explained by precipitation strengthening and fine grain strengthening.