Hot deformation behavior of an antibacterial Co–29Cr–6Mo–1.8Cu alloy and its effect on mechanical property and corrosion resistance

Abstract

In order to optimize the deformation processing, the hot deformation behavior of Co–Cr–Mo–Cu (hereafter named as Co–Cu) alloy was studied in this paper at a deformation temperature range of 950–1150°C and a strain rate range of 0.008–5s−1. Based on the true stress–true strain curves, a constitutive equation in hyperbolic sin function was established and a hot processing map was drawn. It was found that the flow stress of the Co–Cu alloy increased with the increase of the strain rate and decreased with the increase of the deforming temperature. The hot processing map indicated that there were two unstable regions and one well-processing region. The microstructure, the hardness distribution and the electrochemical properties of the hot deformed sample were investigated in order to reveal the influence of the hot deformation. Microstructure observation indicated that the grain size increased with the increase of the deformation temperature but decreased with the increase of the strain rate. High temperature and low strain rate promoted the crystallization process but increased the grain size, which results in a reduction in the hardness. The hot deformation at high temperature (1100–1150°C) would reduce the corrosion resistance slightly. The final optimized deformation process was: a deformation temperature from 1050to 1100°C, and a strain rate from 0.008 to 0.2s−1, where a completely recrystallized and homogeneously distributed microstructure would be obtained.