镁合金汽车轮毂半固态触变成形的刚-粘塑性有限元分析

镁及镁合金由于具有比重低、较高的比强度和比刚度、优良的电磁屏蔽性和阻尼性能等优点,日益受到人们的关注,作为结构和功能元件已越来越多的应用于汽车、电子等行业。采用半固态方法生产的镁及镁合金零部件,可以大大降低或消除通常压铸方法产生的气孔或疏松。采用Gleeble-1500热模拟机,对半固态AZ91D镁合金进行大量、系统的单向压缩试验,以此研究AZ91D镁合金在半固态温度区间的变形力学行为,建立AZ91D合金不同温度、应变和应变速率下的粘塑性本构关系,在此基础上采用DEFORM-3D商用软件模拟镁合金轮毂触变成形过程,得到触变成形过程流动和应力-应变场以及他们之间的关系。上述工作为镁合金半固态触变成形过程的实际应用和零件质量的提高打下基础。

Rigid-viscoplastic finite element analysis on semi-solid thixoforming automobile wheel of AZ91D magnesium alloy

Magnesium and magnesium alloy are being increasingly used as functional and structural components in the automobile and electronic industries due to their low density, high strength/stiffness to weight ratio and electromagnetic interference shielding capabilities, good damping capacity, etc. It is desirable to used semi-solid processing technology to produce components free of gas hole and porosity which usually found in those produced by the method of die casting. In this paper, in order to study the deformation behavior of AZ91D magnesium alloy in semi-solid state and obtain the constitutive relationship necessary for numerical simulation, the compression tests are carried out systematically on the Gleeble-1500 material thermo-simulation machine. The temperature' s range of test is 510℃-570℃ and strain rate' s range is 0.1~20s-1. Based on the theory of rigid-viscoplastic finite element and experiment data, the constitutive equation (σ=AεBT+c·eeeeeeeDT+E·eF/T+Gεt) has been established by regression method. The commercial software DEFORM-3D is employed to simulate the process of thixoforming a practical automobile wheel of minimized size. Thus the flow and stress-strain field of thixoforming process have been set up and the relationship among stress, strain rate and temperature has been also analyzed. The above works will lay a foundation for magnesium components to improve quality and further practical used in future industry.