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

Résumé fourni par la source

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.

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