Ratio of Δ σ HDI to Δ σ T (top) and that of Θ HDI to Θ T (bottom). Here σ HDI and Θ HDI denote the HDI stress and HDI-stress-induced hardening rate, respectively, and σ T and Θ T denote the true stress and global work-hardening rate, respectively. The mean values ± standard error of the mean are presented on the basis of three unload–reload tensile tests.
