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基于挤压铸造过程微观孔洞的形成机理,建立了模拟铝合金挤压铸造过程微观孔洞的数学模型.该模型考虑了传热、凝固收缩、补缩流动、压力传递、氢(H)的再分配等因素,通过计算凝固收缩导致的补缩流动与压力降低,以及挤压过程的压力传递,获得挤压铸造过程糊状区的压力分布,结合微观孔洞形成条件及H的守恒方程,计算微观孔洞的体积分数.对不同工艺条件下铝合金挤压铸造微观孔洞进行了模拟计算,计算结果与实验结果基本吻合.计算结果还表明,适当提高模具温度和挤压压力有利于减少微观孔洞缺陷.
Based on the formation mechanism of microscopic holes in squeeze casting process, a mathematical model for simulating microscopic holes in aluminum alloy extrusion die casting process is established.The model considers the heat transfer, solidification shrinkage, flow of recombination, pressure transfer, redistribution of hydrogen (H) And other factors, the pressure distribution in the squeeze casting process was obtained by calculating the shrinkage flow and pressure drop caused by the solidification shrinkage and the pressure transmission in the extrusion process. Combined with the formation conditions of microcavities and the conservation equation of H, the microscopic pores Of the volume fraction.The microscopic pores of aluminum alloy extrusion die casting under different technological conditions are simulated and the calculated results are basically consistent with the experimental results.The calculation results also show that the appropriate increase of the die temperature and extrusion pressure is conducive to reduce the micro-hole defects.