挤压铸造铝合金弹粘塑性本构模型

AN ELASTIC-VISCOPLASTIC CONSTITUTIVE MODEL FOR SQUEEZE CASTING ALUMINUM ALLOY

针对挤压铸造铝合金材料,在Gleeble-1500D热-力模拟试验机上进行3种不同挤压压力(25,50和75 MPa)下制备的挤压铸造试样的力学行为测试,获得温度范围为300—500℃、应变速率范围为0.001—0.1 s^(-1)的条件下一系列真应力-真应变曲线.基于所获实验结果,建立了一种弹粘塑性本构模型,其主要特点是能够描述材料在进入稳态流变前及稳态流变时的应力-应变关系,而且对模型中与温度和应变速率密切相关的主要参数给出了定量函数关系式.模型预测的真应力-真应变曲线与实验结果吻合良好.

The elevated temperature mechanical behaviors of aluminum alloys produced by squeeze casting process were studied using the physical simulation system Gleeble-1500D. A series of true stress-strain curves under temperatures ranging from 300 to 500 ℃ and strain rates ranging from 0.001 to 0.1 s^-1 were obtained for the materials produced under different squeeze pressures （25, 50 and 75 MPa）. Based on the experimental results, an elastic-viscoplastic constitutive model for describing the stress-strain relationship before and in the steady flow state was developed, and the mathematic expressions of several key model parameters were given are in good agreement with the experimental data. It is shown that the predictions by the model