Application of fuzzy theory to predict deformation behaviors of magnesium alloy sheets under hot extrusion

The study predicts forming behaviors and tensile strength of the magnesium alloy sheet under extrusion in converging dies using fuzzy theory. The variable speed method was used to extrude perfect magnesium alloy sheets with a high extrusion ratio. However, the selection of adjustment timing would affects the success of sheet forming. Therefore, if fuzzy theory can be applied to predict the adjustment timing, then the experimental effectiveness of the trial and error method for adjustment timing will definitely increase. The billets used in this study were AZ31 and AZ61 magnesium alloys, and the two corresponding sets of converging dies had semi-die angles of 20° and 40°, respectively. The process parameters are set using orthogonal arrays (OA), which are used in the experiments. The experimental results are then used to establish the predictive model based on fuzzy theory. The variable speed timing and the tensile strength of the final product are then predicted at semi-die angles of 20°, 30° and 40°, and at heating temperatures of the billet between 320 °C and 360 °C. Further experiments are performed to verify the accuracy of the approach.