ANISOTROPIC STRAIN-HARDENING IN POLYCRYSTALLINE COPPER AND ALUMINUM

A new viscoplastic model for the plastic stress-strain behaviour of f. c.c. metals is presented. In this model the strain hardening results f rom increasing dislocation densities. The observed stagnation of strai n hardening after strain reversals is explained by a lowering of the i ncrease in dislocations due to annihilation of dislocations with oppos ite polarity. The model is applied to Bauschinger and x-y tests on com mercial copper and aluminium, and to cyclic tests on copper. The theor etical results are in good agreement with the measurements.