Study of the microstructure and mechanical properties of Al6061 aluminum alloys rheo-forged by vacuum pump

Rheo-forging of metal offers not only superior mechanical strength but also requires significantly lower machine loads than solid forming processes. In order to produce semi-solid materials that have the desired microstructure, a stirring process is applied during solidification from molten state. During this process, air indraft can occasionally result in degradation of the mechanical properties of the semi-solid materials. As an attempt to offer a solution to this problem, this paper presents the results obtained from controlling the air during the stirring and forging stages of the rheo-forging process. Al6061 aluminum alloys were prepared by the process of electromagnetic stirring under vacuum in order to prevent the indraft of air. Samples of metal parts were subsequently fabricated with hydraulic press machinery. In order to compare the influence of air control, two types of samples were fabricated: (1) samples fabricated under vacuum and (2) samples fabricated while open to the atmosphere.