The multi-directional forging process of aluminium alloy 7075 (AA 7075) is studied using Deform 3D Version 11.0 simulation software. This process results in grain refinement in the bulk material. The 7075 aluminium alloy is used widely in the aerospace and automobile industries. Thermomechanical processing affects the mechanical properties of this alloy. This study focuses on optimising process parameters that affect the multi-directional forging using simulation. In the Taguchi design of experiment, four-factors and five levels are selected. The process input parameters considered are temperature, the strain per pass, the plunger speed, and the friction coefficient (μ). From Taguchi’s orthogonal array, forging simulations are undertaken and analysed. The significance of the process output parameters: material damage, stress and strain are analysed by analysis of variance. The results show that the friction coefficient and strain per pass highly affect the stress/strain distribution. Grey relational analysis is adopted to determine the optimum process parameters. The results show that the optimal combination of parameters is: temperature (200 °C), plunger speed (5 mm/s), friction coefficient (0.6), and strain per pass (0.6). Confirmation of simulation is carried out using the optimum input parameters. From the simulation results, the grey relational grade's optimal parameters have the highest maximum effective strain of 5.57, maximum effective stress of 665 MPa, and maximum damage of 0.416 compared to other simulated results.

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In this study, a multi-directional forging process was conducted on AA 7075. Analysis of the evolution of the mechanical properties (tensile and hardness) and the microstructure was done. The effects of the process parameters (temperatures, die speed, and strain per pass) on the process outputs were investigated. The hardness of the MDF processed samples was determined using Brinell hardness tester, the tensile tests were conducted on a universal tensile machine (GT-7001-LS50), while the grains were observed using the Zeiss Axio Zoom V16 microscope and Tescan VEGA3 scanning electron microscope. It was observed that the MDF process leads to grain refinement with increase temperature and strain per pass. However, large strains per pass caused damages to the samples. The hardness and the tensile strength were seen to generally improve with an increase in strain per pass.