The Significance of the Isotropic Hardening Rule in Relation to the Stress-Strain Curves of a Pre-Strained Metal

Defining yield in different ways leads to different shapes of yield surface. This is shown in connection with tests on commercially pure aluminium. Attention is drawn to a flow surface associated with the isotropic hardening rule. Experimental results suggest that, beyond this surface, the stress-strain curves of a pre-deformed specimen are parallel to similar curves for an annealed metal.