The effect of grain segmentation by [10•2] mechanical twinning upon the strain-hardening behaviour of textured and random polycrystals was assessed using the Kocks-Mecking method of analysis. Profuse twinning in the first 6-8% strain in textured polycrystals has relatively small strengthening effects despite the large volume fraction of grains undergoing twinning. This was due to the small value of the Hall-Petch constant in textured polycrystals. For random polycrystals, the Hall-Petch constant was much larger but the overall hardening effect was reduced due to the small volume fraction of grains undergoing twinning. Additional hardening effects due to the twinning crystallographic transformation on dislocation mobility were deemed small in cast polycrystals due to their low dislocation density, but could be more important in textured polycrystals with higher dislocation densities. Grain size-independent storage of dislocations accounted for the strain hardening at large strains.

Strain Hardening due to {1012} Twinning in Pure Magnesium. C.H.Cáceres, P.Lukáč, A.Blake: Philosophical Magazine, 2008, 88[7], 991-1003