Statistical models for cyclic strain hardening of copper single crystals

Models based on testing of copper single crystals and on the statistical theories of flow and cyclic work hardening are developed to explain the measurements of plastic strain amplitude as a function of acting shear stress amplitude, flow strength and number of cycles. The penetration probability of mobile dislocations through the microstructural obstacle distribution is analogous to the Weibull distribution depending on the ratio of stress amplitude to flow strength and other physical parameters. For the easy glide orientation crystals the results support the strain hardening model where new obstacles are stored as Orowan type loops and for multiple slip orientation crystals the forest cutting and the long range stress field theories seem probable.