高温合金真空感应电极凝固过程数值模拟研究

Numerical simulation study of solidification process during superalloy vacuum induction electrode casting

通过数值模拟,对使用保温冒口和未使用保温冒口时,不同浇注速度下∅430 mm规格GH4169高温合金真空感应电极凝固过程进行了研究,结果表明:感应电极凝固顺序为首先径向凝固然后纵向凝固,浇注速度越大越易在电极中部形成孤立未凝固的中心圆柱区域,浇注速度越小越易形成从底部向顶部的顺序凝固而不形成孤立隔断区域。保温冒口可以提高电极中缩孔位置使其集中于电极头部的保温冒口处,有效减小高温合金感应电极的缩孔尺寸,而且能有效增加电极头部的凝固时间,促进气体和夹杂物上浮于电极头部的保温冒口处,头部切除后增加电极纯净度和致密性。

The solidification processes of GH4169 superalloy vacuum induction electrode in 430 mm diameter were studied by numerical simulation,which was with and without hot cap in different pouring rates.The simulation results show that the solidification sequence is first radial solidification and then longitudinal solidification.Moreover,the larger the pouring rate,the easier the formation of an isolated non-solidified central cylindrical region in the middle of the electrode.Conversely,the lower the pouring rate,the easier the sequence solidification from the bottom to the top of the electrode forms without the isolated non-solidified central cylindrical region.The hot cap can raise the positions of the shrinkage holes in the electrode and promote them to gather in the electrode top surrounded by the hot cap,which may effectively reduce the size of the shrinkage holes.What’s more,the hot cap can effectively increase the solidification time of the electrode top.Therefore,it may promote the gas and inclusions to the section.Once the electrode top surrounded by the hot top is cut off,the purity and compactness of the electrode are improved.