单轴线挤压铸造凝固组织形态和塑性变形缺陷分析

Solidification Structure of Single Axial Squeezing Castings and Its Plastic Deformation Defects

分析了单轴线挤压铸造凝固体内部正向和径向压力存在的差异。结果表明,正向压力沿轴线分布同样不均匀,压力差异使得界面传热系数、结晶前沿熔体温度梯度、晶体生长速度以及塑性变形出现差异,产生单轴线挤压铸造件凝固组织形态不一致、致密度不均匀等缺陷。提出了一种满足组织性能均匀、高致密等要求的高性能铸件的多向挤压铸造工艺方法。

Difference of positive and radial pressure in internal solidification structure in single axial squeezing castings was analyzed,and there exists uneven pressure along axial direction for positive pressure.Pressure difference results in the change of interfacial heat transfer coefficient,melt temperature gradient of solidification front and grain growth rate as well as plastic deformation,which are responsible for the defects,such as heterogeneous solidification structure and density in single axial squeezing castings.Multi-direction squeezing method was presented to realize the requirements of homogeneous structure and desirable properties as well as high density of squeezing castings.