The influence of crystal structure on the dynamic behavior of materials at high temperatures

The rate dependent thermomechanical behaviors of OFHC copper, vanadium, and alpha-titanium have been examined using a recently developed experimental technique for the performance of high temperature, high-strain-rate experiments in the compression Kolsky bar. These three materials represent the three most common lattice structures for metals: FCC, BCC and HCP (respectively). Stress-strain curves are obtained for each material at strain rates of 4 x 10(3) s(-1) and at temperatures ranging from 300 to 1100 K. Quasistatic thermal softening behavior is extracted from the literature for these specific materials and is compared with the new high strain rate data. It is observed that the rate of thermal softening is a function of the strain rate, with the strongest effects in BCC vanadium and HCP alpha-titanium. In addition, the differences in the high rate thermal softening behavior of the three different crystal structures are studied. Finally, the experimental data for copper and vanadium are compared to the FCC and BCC formulations of the Zerilli-Armstrong model respectively. (C) 2003 Elsevier Ltd. All rights reserved.