摘要
To predict hot tearing susceptibility(HTS)during solidification and improve the quality of Al alloy castings,constitutive equations for AA6111 alloys were developed using a direct finite element(FE)method.A hot tearing model was established for direct chill(DC)casting of industrial AA6111 alloys via coupling FE model and hot tearing criterion.By applying this model to real manufacture processes,the effects of casting speed,bottom cooling,secondary cooling,and geometric variations on the HTS were revealed.The results show that the HTS of the billet increases as the speed and billet radius increase,while it reduces as the interfacial heat transfer coefficient at the bottom or secondary water-cooling rate increases.This model shows the capabilities of incorporating maximum pore fraction in simulating hot tearing initiation,which will have a significant impact on optimizing casting conditions and chemistry for minimizing HTS and thus controlling the casting quality.
为了预测凝固过程中的热裂敏感性(HTS)并提高铝合金铸件的质量,采用直接有限元(FE)方法建立AA6111的本构方程。通过有限元模型和热撕裂准则的耦合,建立用于工业AA6111合金半连续铸造的热撕裂模型。将此模型应用于实际制造过程,表征铸造速度、底部冷却、二次冷却以及几何形状变化对HTS的影响。结果表明,铸坯的HTS随着速度和铸坯半径的增大而增加,而随着底部界面传热系数或二次水冷却速率的增大而降低。该模型展示出在模拟热裂引发时结合最大孔隙率的能力,这将对优化铸造条件和化学成分以达到HTS最小化从而控制铸造质量产生重大影响。
