间接挤压铸造工艺参数对铝合金中Si偏析的影响

摘要

The effects of pouring temperature, squeeze pressure, squeeze speed and cooling type on Si segregation in 6066 alloy were studied in indirect squeeze casting. Taking the difference between the silicon content of the hot spot zone after solidification and the initial silicon content of the alloy as the segregation degree, the Si segregation was analyzed according to orthogonal design which considers two levels, four factors and partial first-class interactions. The results show that pouring temperature, squeeze pressure, squeeze speed and cooling type all have effect on the Si segregation, but pouring temperature is the most significant factor. With the increase of pouring temperature, the segregation degree of Si decreases. Squeeze pressure and squeeze speed have less influence on the Si segregation than pouring temperature, but their influence trends are opposite. The influence degree of mold cooling is similar to that of the partial first class interaction of squeeze pressure and speed. The Si segregation in a copper sleeve ( high cooling speed) is lighter than that in a steel sleeve ( low cooling speed) . Negative Si segregation was found in the hot spot zone of indirect squeeze cast work-pieces.%研究间接挤压铸造工艺条件下,浇注温度、挤压压力、挤压速度、冷却速度及参数间的交互作用对6066铝合金中Si元素的偏析影响规律. 以凝固后零件热节位置硅的质量分数与合金初始硅的质量分数的差值定量表征偏析程度,采用考虑一级交互作用的四因素两水平正交设计,研究间接挤压条件下硅的偏析现象. 结果发现:浇注温度、挤压压力、挤压速度和冷却速度对硅偏析都有影响,其中浇注温度是影响最显著的因素. 随着浇注温度的升高,铝合金中Si偏析程度减小. 挤压压力和挤压速度对硅偏析的影响次之,但两者的影响趋势相反;模具冷却能力的影响程度与挤压压力和挤压速度的交互作用的影响程度相似,铜模套(高冷速)比钢模套(低冷速)的硅偏析程度要轻. 间接挤压铸造条件下,工件热节位置可以出现硅的负偏析.