TiAl基合金杆形件铸造缺陷与铸造方法的关系  

Influence of Casting Processes on Shrinkage Distribution in TiAl Based Alloy Shaft Castings

作　　者：苏彦庆[1] 刘畅[1] 毕维升[1] 郭景杰[1] 贾均[1] 

机构地区：[1]哈尔滨工业大学

出　　处：《特种铸造及有色合金》2002年第5期11-12,共2页Special Casting & Nonferrous Alloys

基　　金：中南大学粉未冶金国家重点实验室高校访问学者基金资助项目

摘　　要：通过对铸造TiAl合金杆形件的尺寸及微观组织研究发现 ,TiAl合金浇注温度在 15 95～ 1685℃范围内 ,熔体凝固收缩率s =(74.2 0 96-0 .0 945 8t + 3 .0 65 75× 10 -5t2 ) ,而且微观疏松严重。研究了 3种铸造工艺对TiAl合金杆形件内部疏松分布的影响 ,结果表明重力铸造时疏松分布在杆形件的中轴线上 ,而离心铸造时 ,疏松量减少 ,但疏松分布位置偏离中轴线 ,这种分布的疏松会导致杆形件在热等静压后发生弯曲而报废。利用石蜡模拟了杆形件离心浇注充型过程 ,结果表明 ,杆形件的任意截面熔体充填时先充填迎流面 ,通过回流充填背流面 ,致使同一截面内熔体凝固进程不是轴对称分布 ,最后凝固区域远离中轴线偏向背流面 ,这种偏离在杆形件的入口处最严重 ,对应杆形件该部位热等静压后的变形量最大。Macro shrinkage and microstructure of TiAl alloy shaft casting were studied. The results showed that the solidification macro shrinkage rate varied as a function of with melt temperature s(%)=74.209 6-0.09 458 t +3.06 575×10 -5 t 2 and there are noticeable micro shrinkage in casting structure with pouring temperature ranging from 1 595 to 1 685 ℃ for TiAl alloy. Influence of three varities of casting processes on shrinkage distribution in TiAl alloy shaft castings was examined. The results showed that shrinkage porosity was distributed along axial line in gravity casting while volume shrinkage value decreased and porosity distribution deviated from the axial line in centrifugal casting, resulting in bending and rejecting the shaft casting during heat isotropic pressing(HIP). The filling process of the shaft casting in centrifugal casting was simulated with wax. The results showed that at begining the front, and then the bact were filled through refluence in arbitrary cross section of the shaft casting during filling, resulting in axially asymmetrical distribution during solidification process in a cross section. The finally solidified part would be far from the axial line with deviation of the back. The serious deviation and the maximum deformation at intake place after HIP. It is proposed to alleviate asymmetrical distribution of the porosity for the shaft casting.

关 键 词：铸造缺陷 铸造方法 TIAL合金 杆形件 离心铸造 疏松 

分 类 号：TG292[金属学及工艺—铸造] TG249.4