Some studies on twist extrusion forming of aa7075 t6 alloy with different annealing conditions

Abstract

Grain refining is one of the approaches for the improvement of the mechanical properties of polycrystalline materials. Since the 1990s, many SPD approaches have been employed for processing massive quantities of UFG metals. Ultra-fine grain (UFG) materials produced by SPD methods show increased strength connected with both the Hall-Petch connection with remarkable mechanical properties identified with coarse-grained products, the substantial reduction in unvaried elongation, strain-rate flexibility, flow stress and enhanced low-temperature toughness. Twist extrusion (TE) is a recently advanced technique that uses extensive pressure to enforce very heavy loads on solid materials, achieving excellent grain refinement without causing any major change in the overall sample dimensions. The general concept is to press a billet through a designed die with a model based on two prism ways by a twisted segment to press out a prismatic sample. It initiates severe plastic deformation as the sample is processed, while keeping its original cross-sectional shape.In this research work, twist extrusion of AA7075-T6 aluminum alloy was performed experimentally and numerically for investigation of the influences of the process parameters such as annealing temperature, forming velocity and a number of passes on the mechanical and microstructural behavior of the AA7075-T6 aluminum alloy. L27 orthogonal array design was developed in the planning of the experiments. The TOPSIS method was used for the development of experimental models to find the optimal process parameters. Mechanical properties, namely, tensile strength, microhardness and elongation were examined. Annealed and the twist extruded billet surfaces were examined by using a scanning electron microscope. Various precipitates were identified using the energy dispersive X-Ray analysis (EDX) and XRD peak analysis newline newline newline