Modeling temperature and strain rate history effects in OFHC Cu

Abstract

Abstract In this paper, we report the modeling of a series of large strain deformation experiments on initially annealed OFHC Cu involving sequences of temperature, and strain rate (varying from quasi-static to dynamic). It is shown that equations-of-state with parameters determined using constant strain rate data from monotonic loading paths, although they employ instantaneous temperature and strain rate dependence, are insufficient to describe mechanical behavior. Macroscale internal state variable (ISV) viscoplasticity models, such as the Mechanical Threshold Stress (Follansbee, P.S., Kocks, U.F., 1988. A constitutive description of the deformation of copper based on the use of the mechanical threshold as an internal state variable. Acta Metall. 36, 81.) and BCJ–SNL (Bammann, D., Chiesa, M.L., Johnson, G.C., 1990a. A strain rate dependent flow surface model of plasticity. Sandia National Laboratory Report, SAND90-8227, Livermore, CA.) models, representative of a broad class of such models, are fit to the quasistatic isothermal and high strain rate (approximately adiabatic) data for compression and then predictions are compared to the experimental results for path sequence experiments. Implications for the representation of path history effects through the hardening, static and dynamic recovery functions are considered. A mesoscale polycrystal plasticity model with one and two slip system hardening variables is also examined in the context of sequence experiments.