AZ80镁合金变形特性及管材挤压数值模拟研究

Study on Hot Deformation Behaviors of AZ80 Alloy and Numerical Simulation of Tube Extrusion Process

利用Gleeble热模拟机研究了AZ80合金的高温变形特性。结果表明,流变应力取决于变形温度和变形速率。当应变速率一定时,流变应力随变形温度的升高而降低;当温度一定时,流变应力随着应变速率的升高而增大。根据AZ80镁合金真应力-真应变曲线,建立了其流变应力模型。采用刚塑性有限元法对AZ80镁合金管材挤压过程进行热力耦合数值模拟,并分析了高温挤压成形过程中变形力及金属流动规律,着重探讨了变形温度和挤压速度等挤压工艺参数对挤压力、应变场以及应力场的分布及变化情况的影响。模拟的结果为AZ80镁合金管材挤压工艺参数的制定、优化提供了科学依据。

The hot deformation behaviors of AZ80 alloy were studied by Gleeble-1500 thermal simulation test machine. It is found that flow stress is dependent on deformation temperature and strain rates. When strain rate is constant, flow stress decreases with the increase of deformation temperature. When deformation temperature is constant, flow stress increases with the increase of strain rate. According to true stress-true strain curves of AZ80 magnesium alloy, the constitutive equation of AZ80 alloy for hot deformation was established, the rigid plastic finite element method was used for the couple thermal-mechanical numerical simulation of the tube extrusion process of AZ80 alloy. The deformation force and metal flow law were analyzed during the isothermal extrusion process. The effects of the extrusion process parameters, such as deformation temperature and extrusion velocity, on the distribution and variety of the stress field, strain field and temperature field were discussed. On the basis of the simulation results, scientific evidences are provided to build and optimize the process parameters of tube extrusion of AZ80 alloy.