摘要
To improve the understanding of coupling effect between dynamic recrystallization(DRX)behaviors and flow behaviors of as-cast AlCu4 SiMg, a finite element(FE) simulation equipped with the models of DRX evolution was implemented. A series of isothermal compression tests were performed primarily on a Gleeble-3500 thermo-mechanical simulator in a temperature range of 648-748 K and a strain rate range of 0.01-10 s-1.According to the measured true stress-strain data,the strain hardening rate curves(dσ/dε versus σ) were plotted to identify the critical strains for DRX initiation(εc). By further derivation of the related material constants, the DRX volume fraction equation and the strain for 50% DRX(ε0.5) equation were solved. Accordingly, the aforementioned DRX equations were implanted into the FE model to conduct a series of simulations for the isothermal compression tests. The results show that during the evolution of DRX volume fraction at a fixed strain rate, the strain required for the same amount of DRX volume fraction increases with decreasing temperature. In contrast, at a fixed temperature, it increases with increasing strain rate. Ultimately, the DRX kinetics model of AlCu4 SiMg alloy and the consequence of the FE analysis were validated by microstructure observations.
为了更好地剖析AlCu4SiMg合金的动态再结晶(DRX)行为和流变行为的耦合效应,实施了具有DRX演变模型的有限元模拟。利用Gleeble-3500热模拟试验机,在温度为648~748K,应变速率为0.01~10s^-1的变形条件下对该合金进行等温压缩实验。依据实验所得的真实应力-应变数据,拟合应变硬化率曲线(表征dσ/dε与σ之间的关系),并识别产生动态再结晶时的临界应变值(εc)。通过对材料参数的求解,确定DRX的体积分数方程和DRX达到50%时的应变方程。构建DRX体积分数演变的有限元(FE)模型,对一系列等温压缩实验进行模拟仿真。DRX体积分数演变可视化结果显示:在同一应变速率条件下,达到相同DRX体积分数的应变量随温度的降低而增加;在同一温度条件下,该应变量随应变速率的增加而增加。最后,通过金相分析验证AlCu4SiMg合金的DRX动力学模型及有限元模拟结果的可靠性。
基金
Project(cstc2016jcyjA0335)supported by Chongqing Foundation and Frontier Research,China
Project(P2017-020)supported by Open Fund Project of State Key Laboratory of Materials Processing and Die&Mould Technology,China
