Numerical analysis and experimental validation in determining optimum multi-angular twist channel extrusion die geometries

Recently, researchers have shown interest in developing integrated severe plastic deformation (SPD) processes to produce ultra-fine grained (UFG) metal in a single pass. This article proposes a new integrated severe plastic technique named Multi-angular twist channel extrusion (MATE). The method was devised to impose a large strain in a single pass with better strain homogeneity and lower punch load. The effects of MATE die geometries on the effective strain, strain inhomogeneity, and punch load were analyzed by performing finite element analysis (FEA) to understand the mechanism of the process. The developed artificial neural network (ANN) model was used to optimize the die geometries by genetic algorithm (GA) to attain the desired output characteristics. The twist slope angle (β) = 43°, channel angle (Ø) = 108°, and outer corner angle (ψ) = 50° were determined as the optimum die geometries. With the optimized MATE die, an average effective strain of 2.703 was achieved with good strain homogeneity. Based on the simulation results MATE die was fabricated with the optimum die geometries and experiments were conducted using pure copper. The experimental studies reveal that the ultimate tensile strength and hardness of pure copper was increased by 65.6% and 102%, respectively. The electron back scatter diffraction (EBSD) analysis reveals that the average grain size was 3.1 µm in the extruded copper. The simulated and experimental results corroborate the EBSD findings.