Ebeling, T: Plastic Deformation Modeling of Magnesium Alloys

Magnesium wrought alloys have attained an increasing interest in research during the last years in order to improve mechanical properties oflight-weight structural parts. However, the use ofsemi-finished components like sheets is stilllimited due to the insufficient formability at room-temperature, which can be traced back to the lack ofadequate activation ofslip modes. As a consequence, a high plastic anisotropy appears during deformation ofmagnesium, and slight asymmetries in the texture can have significant effects on their mechanical properties. For this reason, it is of fundamental interest for the processing ofthe magnesium alloys to gain more detailed insight into the deformation behavior of magnesium alloys. In addition, modeling ofdeformation behavior is essential for magnesium alloys in order to be utilized in structural applications, such as car frames. However, the insight into hcp plasticity is restrained by the fact that the deformation ofhcp materials consists ofthree or more deformation modes, which complicates micromechanical modeling.In this work it is demonstrated in case ofmagnesium alloys that an inverse parameter calculation of plasticity parameters can be significantly improved by a simulation strategy which is based on an appropriately chosen set ofexperiments. Simulation methods and strategies were developed based on the model system AZ31. Therefore, room temperature deformation tests were performed. The results were simulated by using a viscoplastic self-consistent model. It is concluded that the resuIts ofsimple tensile testing ofrolled sheets are not sufficient, by contrast the results oftensile and compression tests of extruded bars are a firm basis for model calculations. In order to obtain further experimental information from the tensile tests ofrolled sheets, the two-axial strain in transverse and longitudinal was additionally measured. The additional information was included into the model scheme improving the modeling quality.