铸造工艺参数对7075/6009铸锭外层合金厚度的影响

采用双流浇注半连续铸造技术制备了7075/6009梯度复合铝合金铸锭，分析了内、外熔体温度、铸造速度、节流片孔径大小、内导管插入深度等工艺参数对铸锭外层厚度的影响，结果表明：内熔体温度的升高、内导管插入深度的增加及节流片孔径的增大都将显著减小铸锭外层厚度，当内熔体温度从680 ℃升高到780 ℃，内导管插入深度从0 mm增大到15 mm，节流孔径从1.6 mm增大到1.8 mm时，7075/6009复合铸锭的外层合金厚度分别可减小38.8 %、30 %和42.2 %；而外熔体温度的升高及铸造速度的增大对减薄铸锭外层厚度不明显；同时探讨了铸造工艺参数对凝固液穴形成和铸锭外层厚度的影响机制。

EFFECT OF PROCESSING PARAMETERS ON THE THICKNESS OF OUTSIDE LAYER OF 7075/6009 ALUMINUM ALLOY INGOTS

The 7075/6009 composite ingots with diameter of 65 mm were prepared by double-stream-pouring continuous casting. The effect of processing parameters on the thickness of outside layer of 7075/6009 composite ingot was analyzed. The results show that temperature of the melt in the inside ladle, depth of the embedded nozzle in the mold and diameter of the throttle bore remarkably affect the thickness of outside layer of the composites. When the melt temperature in the inside ladle increases from 680 ℃ to 780 ℃, depth of the embedded nozzle in the mold increases from 0 mm to 15 mm and the throttle bore diameter increases from 1.6 mm to 1.8 mm, the thickness of the outside layer of the composites decreases about 38.8 %, 30 % and 42.2 %, respectively. However, the parameters, such as the melt temperature in the outside ladle and casting speed, have little effect on the thickness of outside layer. The role of the processing parameters in double-stream-pouring continuous casting was analyzed based on the shape variation of liquid pool.