Bauschinger effect in ultrafine-grained metallic sheets subjected to high-pressure compressive reverse shearing process

Understanding the deformation history of sheet metals is essential for evaluating stress states in forming and structural applications, as both yielding and strain-hardening behavior are strongly influenced by prior plastic deformation. A reversal in the strain path typically leads to a reduction in yield strength, a phenomenon known as the Bauschinger effect. In the present study, commercially pure aluminum sheets were subjected to severe plastic deformation using a novel technique termed High-Pressure Compressive Reverse Shearing (HPCRS). This process produced an ultrafine-grained microstructure with an average grain size of approximately 0.8 μm and resulted in the development of a pronounced shear texture dominated by B and Bb components. The inherent periodic reversal of loading during HPCRS induced a significant Bauschinger effect, highlighting the critical role of microstructural evolution and crystallographic texture in governing the mechanical response, even at high strain levels. Beyond the conventional back-stress-based interpretation, the observed behavior is further rationalized using a crystal plasticity framework, wherein the evolution of the stress state on the single-crystal yield surface during shear reversal naturally leads to asymmetric yielding without explicitly invoking back stresses. These findings demonstrate that the Bauschinger effect in SPD-processed sheet metals arises from the combined influence of dislocation structure evolution, texture development, and the elastoplastic response of constituent grains, providing a unified microstructure–mechanics interpretation of reverse-loading behavior at large strains.