Bieliaiev S. Theoretical justification and development of extrusion technology of bimetallic aluminum-magnesium products with expected layers distribution

The dissertation is devoted to research of regularities of metal forming and power parameters, depending on the technological parameters of extrusion process of aluminum-magnesium bimetallic solid and hollow profiles of simple shape, as well as to elaboration of fabrication technology of profiles. The effect of parameters such as the geometric characteristics of the billet and tool, the deformation and temperature-speed process parameters and material of layers on the forming at extrusion of aluminum-magnesium bimetallic solid and hollow billets have been theoretically researched. Theoretical analysis of the influence of above mentioned technological parameters was carried out with the special software package, designed for calculation of the thermal, stress and strain state of metal during extrusion with utilization of the experimentally obtained data on the rheological properties of magnesium alloy Mg-Al-Zn and friction conditions on contact between the liner and aluminum alloys of next systems Al, Al-Mg-Si and Al-Zn-Mg. These studies allow optimizing the technological parameters of the extrusion technology of aluminum-magnesium bimetallic products. Experimental studies of extrusion of aluminum-magnesium bimetallic profiles of simple shape have been carried out on hydraulic presses using special tools. Extruded bimetallic rods have been investigated on distribution of inner layer and mechanical properties. Obtained data have confirmed the adequacy of the theoretical developments and shown the influence of technology parameters of process on distribution of layers lengthwise. Theoretical definition of power extrusion parameters of bimetallic profiles, including hollow, in view of the heterogeneity of material properties over the cross section of a billet, has been further developed on the basis of experimental studies. The proposed method for the extrusion force determination is different in view of the distribution of yield stress in layers of a billet on the basis of experimental data on the rheological properties of magnesium alloy AZ31 and in view of the values of friction stress of alloys of systems Al, Al-Mg-Si, Al-Zn-Mg, obtained experimentally on industrial equipment. The results of work are used at the plant PC "Dniprovski zavod "ALUMASH", in Metal Forming Department of National Metallurgical Academy of Ukraine and are provided for use to SE "Production Association Yuzhny Machine-Building Plant named after A. Makarov"