TC4合金变截面构件熔模铸造工艺优化及缺陷控制

Optimization of the investment casting process and defect control for variable cross−section components of TC4 alloy

以TC4合金变截面构件为研究对象,基于正交试验设计,采用ProCAST软件对铸件的离心熔模铸造工艺进行了优化。同时,对铸件的充型与凝固行为进行了数值分析,并对铸件质量及力学性能进行了表征。结果表明,缩松缩孔集中分布在铸件顶部,少量缩松缩孔离散分布在铸件中部或底部,孤立液相区是导致缩松缩孔形成的主要原因,熔体流动停止表现出窄结晶温度范围合金特征;应力集中主要发生在内浇道与铸件连接处,较大的结构变化是诱使应力集中产生的主要原因。对铸件内部质量及尺寸进行表征分析,发现铸件内部无缩松缩孔存在,铸件尺寸可以较好地满足设计要求,未发生明显变形。热等静压态铸件的室温抗拉强度为953.5 MPa、屈服强度为835.0 MPa、断后伸长率为10.0%,可以较好地满足实际服役要求。

In this study,the centrifugal investment casting process was optimized using ProCAST software based on an orthogonal experiment for TC4 alloy variable cross−section components.Simultaneously,the mold filling and solidification behaviors of the castings were investigated in detail,and the quality and mechanical properties of the castings were characterized.The results show that a small amount of shrinkage porosity is discretely distributed in the middle and bottom of the casting,while a large concentration is discretely distributed at the top.The formation of isolated liquid phase zones is the main reason for the shrinkage porosity,and the termination of melt metal flow exhibits the characteristics of a narrow crystallization temperature range.At the same time,the stress concentration mainly occurs at the connection between the inner sprue and the casting,and the major cause of it is the large structural change.The internal quality and dimensions of the casting were characterized,and it was discovered that there is no shrinkage porosity,the casting dimensions better satisfy the design requirements,and there is no visible deformation.The room-temperature tensile strength(UTS)of the hot isostatic pressing(HIPed)castings is 953.5 MPa,the yield strength(YS)is 835.0 MPa,and the elongation(EL)is 10.0%,which can better meet the actual service demands.