Manufacturing of fine-grained structures by multilevel kinking mechanism through a novel periodic undulating compression method: An example 7075 aluminum alloy

Abstract

Combining the advantages of high strength and excellent plasticity, fine-grained bulk materials have gained superiority and potential to manufacture lightweight components. However, the efficient preparation of large-sized fine-grained materials remains a challenge, which further hinders their industrial applications. In this study, a novel approach named periodic undulating compression (PUC) and a multilevel kinking mechanism based on this approach were proposed for the fabrication of large-sized fine-grained materials. Compared with conventional severe plastic deformation (SPD) approaches, PUC can realize multi-pass deformation of large-sized materials without changing the dies and can homogeneously accumulate relatively high strain in a single pass deformation. Furthermore, large amounts of kinking band are generated at 350 °C, which improves the conversion of dislocations to grain boundaries, and effectively promotes grain refinement. Due to the complex flow trajectories of materials, and matrix refinement during PUC deformation, the texture intensity can be effectively inhibited with increasing deformation passes. Experimental results indicate that multilevel kinking bands are more efficient at inhibiting the texture intensity than continuous dynamic recrystallization (CDRX). Therefore, the production of ultrafine grained materials for industrial applications is possible with PUC.