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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。对如何解决杆形件疏松分布不对称性提出了一些建议
Through the casting of TiAl alloy rod size and microstructure studies found that TiAl alloy pouring temperature in the range of 1595 ~ 1685 ℃, the melt solidification shrinkage s = (74.2 0 96-0 .0 945 8t +3 .0 65 75 × 10 -5t2), and the microscopic loose serious. The effects of three kinds of casting process on the internal loose distribution of TiAl alloy rod were studied. The results show that the gravity casting is loosely distributed on the central axis of the rod, while the centrifugal casting, the loose amount decreases, but the loose distribution deviates from the central axis , This loose distribution will lead to the bar after the hot isostatic pressing bending and scrapped. Paraffin wax was used to simulate the filling process of the centrifugal casting rod. The results show that when the arbitrary section of the rod-shaped material is melted, the flow-in surface is filled first and the back-flow surface is filled by back flow, so that the melt solidification process in the same cross-section is not axisymmetric Distribution, the final solidification area away from the central axis of the backflow surface, this deviation at the entrance of the rod-shaped pieces the most serious, corresponding to the parts of this part of the largest hot isostatic pressing deformation. Some suggestions are put forward on how to solve the loose distribution asymmetry of the bar