Hot Deformation Behavior And Extrusion Process Of ZACM8100Magnesium Alloy

Magnesium alloys are becoming widely recognized as playing an increasingly important role in automotive and electronic consumer products due to their low density, high specific strength and specific stiffness, excellent machinability, good electromagnetic shielding. Compared with casting magnesium alloys, wrought magnesium alloys have better mechanical properties, which allows them to be used in a wide application. Mg-Zn system wrought alloys, such as ZK60, have higher strength than Mg-Al system wrought alloys. However, ZK60magnesium alloy is expensive due to the addition of Zr. ZACM8100magnesium alloy is a new wrought magnesium alloy developed by our group recently, the alloy does not consist of expensive elements. In this dissertation, firstly, the hot deformation behavior of the alloy was investigated. Secondly, the extrusion process of the alloy also was studied.The hot deformation behavior of the ZACM8100magnesium alloy was studied by thermal mechanical simulation experiments in the temperature range of200℃-350℃and strain rate range of0.001s-1-ls-1. The true stress-strain curves of ZACM8100magnesium alloy reflect the typical characteristic of dynamic recrystallization. The deformation behavior of the alloy was described by the constitutive equation:In addition, the strain-dependent constitutive model was established by using regression model, and the predicted results agreed well with the experimental data. The processing-map shows the reasonable processing parameters of the cast alloy. The instability phenomenon can be found located in low temperature and high strain rate region. The ZACM8100magnesium alloy was extruded to rods at230℃,260℃and290℃. The extruded rods had almost completely dynamic recrystallization. The extrusion temperature had unobvious influence on the microstructure of the rods. The ZACM8100alloy extruded at290℃showed better mechanical properties, which yield strength, tensile strength and elongation reached227MPa,322MPa and23%,respectively. At the same time, the weak texture and small grains reduce the tension-compression yield asymmetry, the R value of the extruded alloy was about1. The optimal treatment process of the alloy was solution treatment+double aging. After the optimal treatment process the much finer and far more homogeneously distributed precipitates were precilitated and the alloy showed the optimal mechanical properties, the yield strength, tensile strength and elongation reached298MPa,348MPa and18%,, respectively.