Tension/compression anisotropy in yield stress and Bauschinger effect in ultrafine-grained metals

Tsuru, Tomohito   ; Aoyagi, Yoshiteru*; Kaji, Yoshiyuki  ; Shimokawa, Tomotsugu*

The plastic deformation characteristics of ultrafine-grained metals were investigated by huge scale atomistic simulations. Some polycrystalline models were constructed and the uniaxial tension and compression were applied to the polycrystalline aluminum and copper models. It is found that yield stress is strongly influenced by the number of intragranular dislocation sources, i.e., dislocation density. The Bauschinger effect of UFG metals is caused by the change in dislocation density in the process of forwarding and backwarding deformation. Additionally, the yield stresses of tensile and compressive deformation have some sort of plastic anisotropy. UFG aluminum shows more significant anisotropy than UFG copper.