A new kinetics model of dynamic recrystallization for magnesium alloy AZ31B

The classical kinetics models of dynamic recrystallization (DRX) in the form of Avrami function describe the development of DRX process to a large extent; however, because of the characteristics of exponent function, the conventional models cannot exactly exhibit the development speed of DRX process. Based on this analysis, a new kinetics model of DRX was proposed, which represents the ‘slow–rapid–slow’ property of DRX development. According to the new model, the development process of DRX can be divided into three phases: slow-beginning phase, rapid-increasing phase and slow-rising-to-balance phase. Because the turning point between the second phase and the third one corresponds to the inflexion from the faster velocity of DRX development to the slower one, the strain at this moment can be considered as the most appropriate and economic strain that guarantees fine grains and saves energy consumption. Take a typical metal characterized by DRX magnesium alloy AZ31B for instance, the Gleeble-1500 thermomechanical simulation compression tests were conducted together with microscopic examination, according to which the model parameters were determined. Statistics shows that the experimental results are in good agreement with the predicted values, which validates the accuracy of the new kinetics model.