Determination and structural analysis of process parameters for combined rolling and extrusion of rods from magnesium ingots

In this work, research was carried out to assess the possibility of producing rods from magnesium ingots and to study their structure and properties under various geometric and technological parameters of the combined rolling-extrusion (CRE) process. The values of the energy-power parameters of the process were determined. Data were obtained on the forces acting on the rolls and on the die, as well as torques on the rolls with a closed box gauge. The patterns of their changes have been established depending on the heating temperature of the workpiece, drawing ratio during extrusion and various sizes of calibers used on the existing combined processing units CRE-200 and CRE-400. Tools and equipment were selected to carry out experimental research by determining the required power of the drive electric motors of these units. A model has been designed to simulate the CRE process for producing Mg rods of a given chemical composition. Calculation of energy-force parameters using the model using the calculated processing mode showed that the obtained values of forces and moments during the implementation of the CRE process correlate with the results obtained during its analytical assessment. Corresponding experimental studies showed the adequacy of the model and analytical calculations. Pilot batches of rods with a diameter of 5 and 9 mm from cast magnesium ingots are produced. The physical and mechanical properties and structure of the resulting semi-finished products were investigated. Recommendations were given on the choice of metal processing temperature to reduce the size of recrystallized grains obtained at relatively large strain. Based on the research results, it was concluded that it is possible to obtain high-quality deformed semi-finished products from cast magnesium billets with a high level of strength properties and sufficient plastic properties.