Effect of Grain Size on Adiabatic Shear Susceptibility of Copper.

The effect of grain size on adiabatic shear susceptibility of copper was investigated in this paper. Moreover, the results show that the critical time and critical strain corresponding to the stress collapse point decrease with the increase of grain size at the same strain rate, while the widths of adiabatic shear bands (ASBs) increase as grain size increases, indicating that the adiabatic shear susceptibility of copper increases with the increase of grain size. The electron backscatter diffraction (EBSD) experiment shows that the fraction of twin boundaries in large-grain copper is higher than that in small-grain copper before loading. Furthermore, the larger the grain size is, the easier twin will be produced in large-grain copper during deformation, which leads to the twin boundary ratio of large-grain copper will be further higher than that of small-grain copper. The higher fraction of twin boundaries makes large-grain copper have a stronger strain rate hardening effect and thermal softening effect than small-grain copper. Considering that their strain hardening effects are similar, the enhancement of thermal softening caused by the increase of twin boundary ratio exceeds the enhancement of strain hardening effect and strain rate hardening effect, indicating that large-grain copper has a higher adiabatic shear susceptibility. [ABSTRACT FROM AUTHOR]