Work-Hardening of Iron Single Crystals between 25°C and 900°C

Tensile tests of iron single crystals in [100], [110], or the intermediate between these directions were carried out between 25°C and 900°C. The yield stress above 300°C was found to be determined by the work-hardening characteristics at the beginning of deformation. The work-hardening in the later stage of deformation decreased linearly with temperature. The density of cell boundaries or sub-boundaries was revealed by etch-pitting at dislocations on the (001) and (11̄0) surfaces of the [110] crystals; it decreased with increasing temperature and was nearly proportional to applied stress. It was concluded that cell boundaries play an essential role for the work-hardening of the high-temperature type deformation of iron single crystals.