Ram speed profile design for isothermal extrusion of AZ31 magnesium alloy by using FEM simulation

In the conventional hot extrusion of metallic materials, the temperature of the workpiece varies during the whole extrusion process, leading to the non-uniformity of the product dimension, microstructure and properties. In the present research, a simulation model based on the principle of PID control was developed to establish ram speed profiles that can suppress the temperature evolution during the process to allow for isothermal extrusion. With this simulation model, the real-time extrusion ram speed was adjusted according to the simulated exit temperature. The results show that temperature homogeneity is significantly improved not only along the extrudate length but also on its cross section in the case of extrusion in the isothermal mode with a designed ram speed profile in the extrusion process of AZ31 magnesium. In addition, die temperature varies over a more narrow range in comparison with extrusion in the conventional iso-speed mode.