基于正交试验的液态模锻Al-Sn-Cu轴套中Sn的宏观偏析

采用正交试验法分析了液态模锻Al-Sn-Cu轴套中Sn的宏观偏析规律。结果表明:液态模锻Al-Sn-Cu轴套不可避免的产生Sn的宏观偏析,铸件中同时存在着正偏析和逆偏析,正偏析出现在浇铸中心的近端,逆偏析主要存在于浇铸中心的远端;铸件凝固后期,低熔点液相被强制挤压至热节位置,形成粗晶区和细晶区相间的双峰组织,细晶区Sn的质量分数明显较高。液态模锻工艺参数对铸件宏观偏析产生较大影响,对Sn偏析影响由大到小依次是浇注温度、模具温度、保压时间及比压;本次实验条件下,当浇注温度为700℃,模具温度为240℃,比压为80 MPa,保压时间为5 s时,轴套铸件中Sn元素分布较均匀,Sn元素的宏观偏析得到减轻。

Macrosegregation of Sn in squeeze-cast Al-Sn-Cu sleeve based on orthogonal experiment

Orthogonal test was used to investigate the macrosegregation of Sn in Al-Sn-Cu sleeve in the squeeze casting.The results show that the macrosegregation of Sn is inevitable in Al-Sn-Cu sleeve in the squeeze casting.In the casting,both positive segregation and inverse segregation exist.The positive segregation appears near the casting center,while the reverse segregation mainly exists at the far end of the casting center.At the later solidification stage,the liquid phase with low melting point is forced to be extruded to the thermal center,which formed bimodal structure of coarse crystal region and fine crystal region,and the Sn mass fraction of fine crystal region was obviously higher.The process parameters have a great influence on the macrosegregation of castings.The influence sequence of squeeze casting parameters on macrosegregation from large to small is pouring temperature,die temperature,dwell time and specific pressure.Under this experiment condition,the distribution of Sn element in shaft sleeve casting is uniform and the macrosegregation of Sn element is reduced,when the pouring temperature is 700℃,mold temperature is 240℃,the pressure is 80 MPa,the holding time is 5 s.