Strain Hardening Behavior of Ultrafine-Grained Cu by Analyzing the Tensile Stress-Strain Curve

UFG Cu was found to experience two stages of strain hardening processes under uniaxial tensile stress, which was similar to the Stage IV and V of CG Cu after large plastic deformation. The storage of dislocations in small grains and dynamic recovery caused by annihilation of dislocations and GB-mediated processes were responsible for the different stages of strain hardening behavior. Improvement of strain hardening capability for UFG metals should be based on the mechanisms of strain hardening.