Qiu Yang, Li Xintao, Liu Mingyang, Zhou Nan, Zheng Kaihong
Institute of New Materials, Guangdong Academy of Sciences, Guangzhou 510630, China.
Guangdong Provincial Key Laboratory of Metal Toughening Technology and Application, Guangzhou 510630, China.
Materials (Basel). 2022 Feb 28;15(5):1809. doi: 10.3390/ma15051809.
Internal electromagnetic stirring is an advanced melt treatment method, which can be used in direct chill casting to prepare large-scale Al alloy billets. Intercooling intensity is a primary parameter of internal electromagnetic stirring; its effects on temperature fields and microstructures have been investigated via numerical simulations and industrial experiments, respectively. The simulated results show an increase in the intercooling affected area and a decrease in sump depth with an increase in the intercooling heat transfer coefficient. The heat transfer coefficient should not exceed 500 W/(m °C) because the solid fraction of the intercooling end bottom may exceed 50%. The experiment's results demonstrate that the average grain sizes in the edge, 1/2 radius, and center are 151 ± 13 μm, 159 ± 14 μm, and 149 ± 16 μm, respectively, under a liquid nitrogen flow rate of 160 L/min, which is much finer than that of 80 L/min and more homogeneous than that of 240 L/min. Furthermore, an experimental liquid nitrogen flow rate of 80 L/min, 160 L/min, and 240 L/min approximately correspond to the simulated heat transfer coefficient of 200 W/(m °C), 300 W/(m °C), and 400 W/(m °C), respectively.
内电磁搅拌是一种先进的熔体处理方法，可用于直接水冷铸造制备大型铝合金坯料。中间冷却强度是内电磁搅拌的一个主要参数；分别通过数值模拟和工业实验研究了其对温度场和微观组织的影响。模拟结果表明，随着中间冷却传热系数的增加，中间冷却影响区域增大，熔池深度减小。传热系数不应超过500W/(m·°C)，因为中间冷却端底部的固相分数可能超过50%。实验结果表明，在液氮流速为160L/min时，边缘、1/2半径和中心处的平均晶粒尺寸分别为151±13μm、159±14μm和149±16μm，比80L/min时的晶粒细得多，且比240L/min时的更均匀。此外，实验中的液氮流速80L/min、160L/min和240L/min分别大致对应于模拟的传热系数200W/(m·°C)、300W/(m·°C)和400W/(m·°C)。
