新型镁合金大变形技术的研究与验证

Research and Validation of a New Severe Plastic Deformation Technology for Magnesium Alloys

研究了一种正挤压与等通道挤压相结合的新的Extrusion-Shearing(ES)变形方法。应用有限元法对ES变形过程进行了计算机模拟,表明ES技术可以大大提高累积应变和动态再结晶晶粒的体积分数。在Gleeble1500热模拟机上安装ES成形模具,对ES成形挤出的棒料进行微观组织观察,并对热模拟的数据进行处理。结果表明,ES成形可以细化晶粒并提高成形的均匀性。计算机模拟和热模拟实验表明,ES成形是一种新型的镁合金大塑性变形方法,可以有效细化晶粒、提高组织的均匀性。

A new severe plastic deformation (SPD) K has been explored which includes two consecutive processes, i.e. initial forward extrusion and subsequent shearing process. The process can be shortened as Extrusion-Shearing (ES). The geometrical and numerical models for the structures of ES forming die have been built. Initial and boundary conditions were exerted and FEM molding has been simulated. The structures of ES forming die have been manufactured and installed to Gleeble1500D thermo-mechanical simulator. Physical modeling of ES forming has been done by instituted procedures. Microstructure observations have been carried out on the extruded rods (as-received) and ES formed rod from simulator. From the research results, the ES forming can produce the severe plastic deformation and improve the volume fraction of dynamic recrystallization. The ES simple shear process can produce intense deformation by the combination of forward extrusion and provides a convenient procedure for introducing an ultra fine grain size into a material. The results show that the ES forming process affected both the microstructure of AZ31 Mg alloy. These results can be explained by the effects of the process on microstructure of AZ31 Mg alloy such as grain size and dislocation density caused by the change in recrystallization behavior.