Hot working behavior of a super high strength Cu–Ni–Si alloy

Abstract

Hot working behavior of a novel super high strength Cu–6.0Ni–1.0Si–0.5Al–0.15Mg–0.1Cr alloy has been studied systematically. Experiment of hot compression deformation with temperature ranging from 750°C to 900°C and strain rate from 0.001s−1 to 1s−1 indicated that both strain rate and deforming temperature affect the flow stress. Flow stress increased to a peak value, and then decreased with increase of deformation time, showing continuous dynamic recrystallization behavior. In the deformation temperature zone of 750–800°C, nucleation of the recrystallization grains occurred in the interior grains at special locations such as deformation bands and shear bands. At the high temperature zone (850–900°C), nucleation of the recrystallization grains occurred both at the grain boundaries and inside the grains of the matrix. Three typical textures appeared after hot compressive deformation and the order of the texture intensity from largest to smallest was: Copper texture of {112}〈111〉, S texture of {123}〈634〉, Gauss texture of {011}〈100〉. On the basis of established processing map, appropriate hot working temperature range was 850–875°C. With the optimised hot working parameters and appropriate thermal mechanical treatment, the designed alloy has achieved excellent properties: hardness 341HV, tensile strength 1090MPa, yield strength 940MPa, elongation 3.5%, electrical conductivity 26.5% IACS, and the stress relaxation rate 8.52% as tested at 150°C for 100h.