Effect of Process Parameters of Backward Extrusion by Servo Press on Purification of A7075 Alloy under the Semisolid Condition

The aggregation of tramp elements in repeated recycling processes is a growing problem and an effective technology for the separation of tramp elements from aluminium alloy scrap is necessary to produce new alloy products from old scrap. In this study, backward extrusion was conducted under the semisolid condition using a servo press (Komatsu-H1F110) to investigate the industrial-scale purification of A7075 wrought aluminium alloy. and, process parameters such as the semisolid temperature, backward extrusion ratio and initial extrusion speed were investigated. From optical microscopic images and the results of scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS), it was confirmed that the aluminium was significantly purified and distributed homogeneously in the unextruded part for suitable combinations of the specific extrusion temperature, extrusion ratio and initial extrusion speed.