Synchronous multidirectional extrusion based on uniaxial load assembled toggle-arm mechanisms: A case study on 2195 Al-Li alloy

Synchronous extrusion from independent directions for each port is a potential approach for manufacturing multidirectional structural components (MDSCs). However, its universality and flexibility are limited by the need for specific forming devices, and the accuracy constraints of these devices may lead to folding defects and non-uniform microstructures. To address these challenges, this study proposes a synchronous multidirectional extrusion (SMDE) method based on uniaxial load. The uniaxial load is synchronously decomposed and redirected into multiple independent movements by toggle-arm mechanisms. This method allows excellent flexibility in manufacturing MDSCs since almost arbitrary load direction is available by adjusting the angle and size of the toggle-arm. Moreover, the load synchrony will be easier enabled by the rigidity of toolsets rather than the accuracy of the devices. The feasibility of SMDE was demonstrated by manufacturing an MDSC with square ports and orthogonal ribs using 2195 aluminum-lithium alloy. The investigations in material flow and microstructures at different forming stages revealed non-uniform forming mechanisms influenced by the nonlinear kinematic characteristics and multidirectional discrepancies. Results show that the progressive reduction in horizontal velocity, combined with additional compression, reduces inter-directional variations in height of thin-walled ports, improving the dimensional accuracy. Meanwhile, the active control of nonuniform deformation with additional compression promotes uniform dynamic recrystallization and grain refinement, leading to uniform microstructures and near-isotropic properties across the ports. The average yield strength, ultimate tensile strength, and elongation were tested to be 487.4 MPa, 529.4 MPa and 8.2 %, respectively. Moreover, the strength heterogeneity of the tested ports was calculated to below 1.39 %. This work provides theoretical and experimental guidance for optimizing of multidirectional load paths and actively controlling nonuniform deformation, and offers a novel and efficient method for the precision forming of MDSCs with arbitrary orientations.