【摘要】 采用离心精密铸造方法,初步研究了铸造大尺寸薄壁钛合金筒体(直径660 mm,高750 mm,壁厚4 mm)的可行性。结果表明:离心转速较小时,Ti-6Al-4V筒体无法完整充型,而较大的转速可实现完整充型。对于完整充型的筒体,其内部疏松缺陷数量随转速提高而减少。对于给定转速和具有均匀温度场的型壳,筒体中疏松缺陷数量随熔液路径增长而增加。采用Y2O3面层型壳可获得无α壳层的表面质量良好的精密铸件,其内部疏松可通过热等静压消除。铸件的晶粒度随铸件截面厚度变化改变较大,需通过微合金化和后续热处理等措施加以调整。更多还原

【Abstract】 Centrifugal investment casting of large thin-wall titanium alloy cylinders(with diameter of 660 mm,height of 750 mm and thickness of 4 mm) has been studied.The results show that small centrifugal force(or low rotation speed) leads to incomplete fill of the cylinder mould by Ti-6Al-4V melt,while complete fill of the mould cavity is achieved at large centrifugal force.For properly filled cylinders,the quantity of internal pores decreases with increasing centrifugal force.For a given rotation speed and shell mould with uniform temperature field,the density of porocity increases with the length of melt path.By using shell moulds with an yttria face coat,precision cast parts with high surface quality free of α case can be obtained,and the internal porosity can be eliminated by HIPing.Grain size of the castings tends to vary significantly with cross-section thickness,and needs to be adjusted through measures such as post-casting heat treatment and composition modification.更多还原