Investigation of the Effect of Backpressure and Friction on Material Flow in the Twist Extrusion Process of 6063 Aluminum Alloy

In this paper, the severe plastic deformation by twist extrusion (TE) process is investigated. In this process, the workpiece is forced through a twist channel, which develops shear strains in the material. These shear strains result in a fine-grained structure in the material. For investigating the material deformation, the TE process was simulated in the Abaqus finite element (FE) software. The effects of backpressure and friction between the sample and channel were investigated. In the FE model, a sample of AA6063 aluminum alloy was formed in a twist channel with an angle of 45 degrees and a length of 16 mm. The FE simulation results were validated by conducting experimental tests. When the backpressure of 50 MPa was used, the sample was distorted, which improved by increasing the backpressure to 70 MPa. The highest strains occurred in the corners of the sample, which was about twice of the plastic strains obtained at the side edges of the sample. Furthermore, the calculated plastic strains in the central areas of the sample were very low (0.042) in comparison to the strains developed in the corners and side edges of the sample.