Texture and large-strain deformation microstructure

Large-strain plastic deformation at low homologous temperature implies, among other things, severe work hardening, strong crystallographic texturing, microstructural refining, and some degree of macroscopic redundant strain. In most cases, the development of texture does not seem to particularly increase grain interactions above their initial level, which is at the origin of the Ball-Fetch effect. Continued strain then leads asymptotically towards an absolute maximum of the tensile flow stress below G/50, where G represents the elastic shear modulus. However, it is well known that some simple deformation textures promote an extraordinary enhancement of the plastic grain interactions that need to be accommodated by monotonically increasing mesoscopic (grain-size range) strain gradients. Such behaviour is accompanied by a concomitant high work-hardening rate and by a remarkable extension of the strengthening limit. The [110] body-centred-cubic or [0001] hexagonal close-packed wire drawing textures constitute the paradigmatic case, for which the flow stress limit reaches up to G/20. A quantitative explanation of the phenomenon is given here with the help of a geometrical model of microstructural development.