AZ31镁合金板等应变速率挤压研究

Research on Constant-strain-rate Extrusion of AZ31 Magnesium alloy plate

摘要:

本文设计了等应变速率模具,将等应变速率挤压技术应用于AZ31镁合金板材挤压。采用有限元软件对等应变速率挤压和传统挤压分别进行模拟仿真。对比研究了镁合金挤压过程中,分别使用等应变速率模具和传统模具时,金属流动速度场、等效应变场、模具出口温度场、平均应力场等坯料主要场变量的变化规律。研究结果表明：在本文设定的具体工况下,使用等应变速率模具挤压使金属流动速度场、等效应变场、模具出口温度场和应力场分布的均匀性分别提高了13.5%,43.2%,7.6%和13.4%。两种模具的出口处板材的等效应变均是从中心向边缘逐渐增加,温度场均呈现中心部分基本保持稳定,靠近板材边缘部分逐渐降低趋势,且等应变速率模具出口处板材温增小于传统模具。等应变速率模具减小了模具出口附近板材拉应力出现的范围,且在模具出口处等应变速率挤压板材的平均压应力大于传统挤压。

Abstract:

To extrusion AZ31 magnesium alloy plate by the constant-strain-rate extrusion techniques, a new constant-strain-rate die was designed. Constant-strain-rate and traditional extrusion were investigated by finite element software Deform-3D separately. Key field variables, metal flow velocity, effective strain, exit temperature and mean stress, were studied systematically using the two type’s dies, during the extrusion processing. Results show that the uniformity of metal flow velocity, effective strain, exit temperature and mean stress are increased by 13.5%, 43.2%, 7.6% and 13.4%, respectively, by the constant-strain-rate extrusion.The effective strain of the plates at the exit of two kinds of dies exhibits gradually increasing trend from the center to the edge and the exit temperature field exhibits a trend that the center keeps stable and the edge gradually reduces. Moreover, the plate at the exit of constant-strain-rate die exhibits lower temperature increment than the plate at the exit of the traditional die. The range of tensile stress of the plate near the die exit is reduced by using constant-strain-rate die and the plate at the exit of constant-strain-rate die exhibit large compressive stress than the plate at the exit of the traditional die.