Analysis of the Multi-Directional Forging of Aluminium Alloy 7075 Process parameters: Numerical and Experimental Analysis

The multi-directional forging (MDF) process is one of the most promising severe plastic deformation methods used to refine microstructures. The MDF process has been used to improve superplasticity and other mechanical properties in metals and their alloys at the industrial levels because it is less complicated and can process large samples; some with complex geometries. In this study, the MDF 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 (temperature, die speed and strain per pass) on the microstructure, hardness and tensile strength were investigated. The hardness of the MDF processed samples was determined using a Brinell hardness tester. The tensile tests were conducted on a universal tensile testing machine (GT-7001-LS50). The evolution of the microstructure was observed using the Zeiss Axio Zoom V16 microscope and Tescan VEGA3 scanning electron microscope. After MDF processing, it was observed that the process led to grain refinement as temperature and strain per pass were increased. The grain refinement results in the development of materials with high strength, hardness and better ductility. The AA 7075 grains were refined to approximately 4.95 μm when a strain per pass of 0.6, a die speed of 5 mm/s and a temperature of 400°C were used. The tensile strength improved from 537.52 MPa to 606.65 MPa, a 12.85% improvement. The hardness also improved by 3.16% while the ductility improved by 2%, when the process was done at 200°C, 5 mm/s die speed and 0.6 strains per pass.