Effects Of Multi-directional Forging Process And The Rare Earth Elements On Microstructure And Properties Of The Wrought Aluminum Alloy

Grain refinement is an important way to improve the overall performance of aluminum and aluminum alloys, which can not only improve the strength but also the plastic and toughness of the material. The microalloying and the severe plastic deformation as two effective methods of grain refinement have been widely used in the field of preparation of materials. The multi-directional forging as a strong representation of the process of severe plastic deformation method has been successfully applied to a variety of materials to prepare a large piece of dense material with its low cost and simple process. With the increasing high demand for the material properties, the preparation of aluminum and aluminum alloy materials with high strength and high plastic has become research concentration. The paper was aimed at studying the influence of the forging process and the rare earth elements on the microstructure and properties of the deformed aluminum alloy. For this reason, the effect of the forging process on the microstructure and properties of 7075 aluminum alloy was studied by the use of numerical simulation. Based on the above, the experimental study of the multi-directional forging process and the rare Earth elements on the microstructure and properties of the Al-Mg-Si-Cu alloy was carried out. The research contents can be conducted as follows:(1) taking 7075 high strength aluminum alloy for the study, based on the conventional multi-directional forging process, a multi-directional forging process with the mould was designed. The metal flow, pressing load and the effective strain distribution were comparatively analyzed, and the microstructure and uniformity of 7075 aluminum alloy after deformation were predicted in two kinds of process by simulation method.(2) In order to research the effects of the multi-directional forging process and the rare earth elements Er and Sc on the microstructure and properties of Al-Mg-Si-Cu alloy, three steps were carried out. Firstly, based on the 6061 alloy, five Al-Mg-Si-Cu alloy components were designed, namely:Al-Mg-Si-Cu, Al-Mg-Si-Cu-0.15ErAl-Mg-Si-Cu-0.30Er,Al-Mg-Si-Cu-0.45Er,Al-Mg-Si-Cu-0.15Sc. Secondly, the water-cooled copper mould and the multi-directional forging die were designed and manufactured, which provided the conditions for smoothly conducting experiments. Finally, Combining with DTA and the microstructure, the reasonable homogenization system was determined.(3) The effects of adding Er and Sc on the organizations of the homogenization alloys were comparatively analyzed. The hardness of the center and edge of the alloys after each pass deformation was measured and comparatively analyzed. The results showed that the alloy with adding 0.3wt% Er after three times deformation obtained the best overall performance.