An Experimental Study On Hot Deformation Behaviors And Parameter Identification For Magnesium Alloys

It is significant for a successful forming process design and the production quality control to predict numerically microstructure evolution in magnesium alloys during the hot forming. However, at present, the prediction has a difficulty, which is an absence of the systemic exact material parameters for calculation of constitutive relation equation. So an experimental study on thermal deformation behaviors and parameter identification for magnesium alloys AZ31D is carried out in this paper.Firstly, the thermal visco-plastic constitutive model considering dynamic recrystallization is derived theoretically and the constitutive parameters to be identified are determined. Then both objective function and optimization algorithms, as the theoretical foundation of the inverse analysis for parameter identification, are discussed. An objective function based on the root-mean-square error criterion and a mixed global optimization algorithm including the advantages of the genetic algorithm, the Gauss-Newton model and other algorithms are developed.Through hot compress test and metallographic observation, a study on hot deformation behaviors and microstructure evolution rule is carried out in this paper. All characteristic variables of dynamic recrystallization with the parameter Z are described punitively. It is found out that a criterion of the shear fracture of a compressed specimen is the parameter Z> 2. 61E+6. It is also found out that the hot deformation and the grain refinement of magnesium alloys AZ31D, under the presented conditions in this paper, will obey the basic rule of the single peak dynamic recrystallization. The recrystallized grain size for the material used in this study is not over 10μm.All kinds of data for parameter identification are constructed in basis of...