Establishment Of Mathematical Model For Hot Rolling Process Of AZ31B Magnesium Alloy Plate

The hot compression tests for cast AZ31B magnesium alloy cylinder were done using Gleeble-1500D thermal simulation machine under a wide range of deformation condition. Rolling test, numerical simulation and organizational performance were carried on under different process parameters.Firstly, the stress strain data of hot compression was fitted, then the thermal processing map was calculated and temperature range to get the thermal deformation constitutive equation of cast AZ31B magnesium alloy was reasonably divided. Peak stress model was established by the introduction of Zener-Hollomon parameters and the peak strain of Sellars model was simplified effectively.Considering curve characteristics of the hot compression deformation,in this research two new deformation resistance mathematical models available for the material were established. Secondly, with the analysis of rolling characteristics of thick magnesium plate, and synthesization of the basic principle of heat transfer and the rolling theory, this research established rolling force prediction mechanism model of magnesium alloy plate for single-pass by the way of a discrete solution reintegration. Based on the simulation analysis data of Deform-3D and considering the initial rolling temperature, rolling speed and pass reduction, strain and strain rate value distribution models, three-dimensional temperature field and stress field mathematical models in rolling deformation zone were established by mathematical analysis method. Finally, rolling experiments of AZ31B magnesium alloy were carried on under different conditions, the reductions are 20% to 40%,the rolling speeds are 0.1m/s to 0.8m/s and the rolling temperatures are 250 to 450℃.After rolling the magnesium alloy sheets, microstructure and mechanical properties were analyzed and studied.The mathematical model of the average grain size of microstructure after rolling AZ31B magnesium alloy was established. Combining the mathematical model of the average grain size of microstructure after rolling AZ31B magnesium alloy, the mathematical model of tensile strength about variable rolling parameters of AZ31B magnesium alloy was established。This study relied on the wide 2300mm magnesium alloy sheet rolling line and laboratory 300mm steckel rolling experiment platform of magnesium alloy construction project and wide magnesium alloy sheet metal CNC rolling theory and technology research project. It has been proven that prediction accuracy was high of each model. The mathematical expression of material mechanistic model not only has a simple form but is easier to produce quote, and could accurately characterize thermal-mechanical coupled deformation mechanism of hot rolling of magnesium plate in hot rolling process. Therefor, they could provide a reliable theoretical basis for the formulation of the reasonable rolling system under different process conditions before rolling, plate shape, plate thickness controlled on-line accurately and in particular, improve defects after the magnesium plate hot rolling.