Cyclic strain hardening in polycrystalline copper

Polycrystals of pure copper were cyclically deformed, at room temperature under symmetric tension-compression fatigue at constant total strain amplitude control with an approximate constant plastic strain rate of 10−4. The relationship between the saturation stress amplitude and strain amplitude over a range of plastic strain from 2 × 10−7 to 10−2 reveals three regions of cyclic hardening. A quasi-plateau, where the stresses show a slow …