Strain hardening in single crystals of Hadfield steel

Orientation dependence of the mechanism of deformation, i.e., slip and twinning, was studied at 300 K on single crystals of Hadfield steel. It was shown that mechanical twinning in [111], [144], and [011] crystals is developed upon tension from the very early deformation stages. The high values of Θ in [ 111 ] crystals are related to the development of twinning on several twinning systems; in the [144] and [011] crystals, the early stages of deformation are connected with twinning in a single system a/6[211](111), and the passage to the operation of several twinning systems is accompanied by an increase in Θ. In [012], [123], and [113) orientations, the early stages of deformation are determined by slip; later, a change of the mechanism of deformation from slip to twinning occurs. For the first time, we revealed mechanical twinning upon tension of [001] crystals and showed that there is an orientational dependence of resolved shear stresses related to the orientational dependence of the mechanisms of deformation by slip and twinning. Dislocation mechanisms of twin nucleation in Hadfield steel are suggested.