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The mechanical characteristics of polycrystalline metallic materials are influenced significantly by various microstructural parameters, one of which is the grain size. Specifically, the strength and the toughness of polycrystalline metals exhibit enhancement as the grain size is reduced. Applying severe plastic deformations (SPDs) has a noticeable result in obtaining metallic materials with ultrafine-grained (UFG) microstructure. SPD, executed through conventional shaping methods like extrusion, plays a pivotal role in the evolution of the texture, which is closely related to the plastic behavior and ductility. A number of SPD processes have been developed to generate ultrafine-grained materials, each having a different shear deformation mechanism. Among these methods, linear twist extrusion (LTE) presents a non-uniform and non-monotonic form of severe plastic deformation, leading to significant shifts in the microstructure. Prior research demonstrates the capability of the LTE process to yield consistent, weak textures in pre-textured copper. However, limitations in production efficiency and the uneven distribution of grain refinement have curbed the widespread use of LTE in industrial settings. This has facilitated the development of an improved novel method, that surpasses the traditional approach, known as the nonlinear twist extrusion procedure (NLTE). The NLTE method innovatively adjusts the channel design of the mold within the twist section to mitigate strain reversal and the rotational movement of the workpiece, both of which have been identified as shortcomings of twist extrusion. Accurate anticipation of texture changes in SPD processes is essential for mold design and process parameter optimization. The performance of the proposed extrusion technique should still be studied. In this context, here, a single crystal (SC) of copper in billet form, passing through both LTE and NLTE, is analyzed, employing a rate-dependent crystal plasticity finite element (CPFE) framework. CPFE simulations were performed for both LTE and NLTE of SC copper specimens having <100> or <111> directions parallel to the extrusion direction initially. The texture evolution as well as the cross-sectional distribution of the stress and strain is studied in detail, and the performance of both processes is compared. Full article

Severe plastic deformation (SPD) can produce ultrafine grained (UFG) and nanocrystalline (NC) materials by imposing intense plastic strain. One of the many options for inducing large plastic strains is to pass the material through a torsional/twist extrusion. The high-strength materials fabricated by SPD has no limit in dimension, and they can even be applied to load-carrying structural materials. Even though the method is quite successful, the industrial transfer has been limited so far because of low production efficiency and high cost. To remedy such difficulties, a new torsional extrusion process called nonlinear twist extrusion (NLTE) is introduced in this study, which has been designed based on two principles; (1) linear arrangement of the production line and (2) effective die geometry resulting in higher and more homogeneous plastic strain evolution which would give better grain refinement. The initial computational study of the designed geometry for the new extrusion process is addressed in the current study. The obtained results are discussed in detail with respect to conventional extrusion process, which is referred to as linear twist extrusion (LTE). The method is expected to offer a great potential for industrial use. Full article