The dependence of polycrystal work hardening on grain size

Existing rationales for the effect of grain size on work hardening do not explain the behavior of copper and aluminum. A new analytical approach to polycrystal work hardening was devised to understand and describe these data, together with data on 70-30 brass. The physical model was novel in its emphasis on the importance of regions of the grains in which either statistically stored or geometrically necessary dislocations are accumulated. One prediction of the model, that large-strain cell size in copper ought to depend on grain size, was verified by direct measurement. A number of other details computed from the model, including slip lengths and dislocation density variation with strain, were consistent with the results of other workers.