EXPERIMENTAL INVESTIGATION AND ANALYSIS OF MICROSTRUCTURE AND MECHANICAL PROPERTIES ON TWIST EXTRUSI

The objective of this study is to investigate the twist extrusion forming behaviour of AA 7075-T6 Aluminium alloy. Samples of 28x18x70 mm cross sections were subjected to twist extrusion forming with the aim to decrease the grain size and improve the mechanical properties. Four different temperatures and three passes were employed to conduct the experiments. The mechanical and microstructure properties of the as received and twist extruded samples at different temperatures and passes were examined. The results reveal that Twist Extrusion (TE) can refine the grain structure, with increasing number of passes, the hardness increase with structure homogeneity improvement but with decrease in the tensile strength at high temperatures. SEM micrographs show that the twist extrusion passes reduces the sizes of the second phase particles which enhance the improvement in mechanical properties