双频电磁约束成形过程的温度场研究

Study on Temperature Field in Dual-Frequency Electromagnetic Shaping Process

以耐热不锈钢为实验材料 ,利用自制的真空电磁约束成形定向凝固实验设备 ,测试并分析了双频电磁成形过程中样件的温度场及其影响因素 ,结果表明 :合理的预热感应圈结构使送入固态料棒的温度分布合理 ;在预热感应圈不影响成形感应圈的磁场分布的情况下 ,预热感应圈能调整熔体的温度分布 ,提高熔体的过热度 ;屏蔽罩能够调节成形感应圈内熔体的温度分布 ,使熔体的下固 /液界面上移 ,使成形感应圈内的熔体处于理想状态 ,侧表面垂直 ,位于电磁压力最大作用范围内 ;在其他条件一定时 ,抽拉速度和电源功率必须良好匹配 ,才能实现使金属熔化和凝固的动态平衡。

Dual-frequency electromagnetic shaping is a novel directional solidification technique with no mould(crucible), no contamination during melting and solidification. It is considered to be suitable for pure metals, superalloy and other alloys with active elements. In this paper, the temperature field of melt in dual-frequency electromagnetic shaping for stainless steel parts with small cross section rod feeding was studied. The dual-frequency electromagnetic shaping for stainless steel parts with small cross section rod feeding was carried out by using self-made electromagnetic shaping and directional solidification experiment apparatus. The temperature field of the part was measured with electric thermo-couple. We found that the following factors affect the temperature field of the part in dual-frequency electromagnetic shaping: (1) the reasonable structure of preheating inductor can result in good distribution of temperature in rod;(2) preheating inductor can regulate the temperature distribution of melt in shaping inductor and increase overheat degree of melt; (3) a certain distance between two inductors must be maintained so that the magnetic field in the preheating inductor has no effect on the magnetic field in shaping inductor for steady shaping; (4) a screen can regulate the melt temperature distribution and raise the S/L(Soilid/Liquid) interface into a proper position in shaping inductor, which causes melt in an ideal state with vertical side face in shaping inductor and makes melt shaping by maximal electromagnetic pressure; (5) when other conditions are constant, there is a rational drawing velocity to match electrical power in order to reach a balance of melting and solidification.