Effect of steep reduction in strain rate on the dynamic flow stress of copper at very high strain rates

In the previous work, strain rate change tests were conducted for high-purity polycrystalline aluminum at very high strain rates. Here we present the results of reduction tests carried out for copper. The experimental apparatus devised in the previous work is used to attain a sufficiently steep reduction in the strain rate. The flow stress obtained from the reduction tests is analyzed by means of the deconvolution method. The results indicate that the instantaneous strain rate plays a more important role than the strain rate history for the dynamic flow stress at very high strain rates where a steep increase in the strain rate sensitivity of the flow stress is observed. The above-mentioned results are the same as those found in the previous work.