钛合金冷坩埚连续熔铸过程定向凝固

水冷铜坩埚存在很强的侧向散热,而定向凝固则必须保证单向热流,分别从电磁力、温度场及传热3方面来分析冷坩埚定向凝固的可行性.结果表明:在三相点焦耳热最大,感应焦耳热弥补了侧向散热,保证在下驼峰与坩埚接触点Z0附近区域等温线近乎平直,能够利用冷坩埚实现钛合金的定向生长.增大电磁压力,提高熔体过热度,可以减小坩埚壁的侧向散热,有利于冷坩埚实现定向凝固.

Directional Solidification of Titanium Alloys during Continuous Casting with a Cold Crucible

Unidirectional heat flow is required during directional solidification, so it is very difficult to solidify directionally because of strong side radiation around a water-cold copper crucible. The feasibility of directional solidification with the cold crucible was analyzed by mathematic analysis from electromagnetism, temperature field and heat transfer. Results show that Joule heat is strongest at triple point, and it can counterweigh the side heat dissipation; therefore isotherms approach level near the contact point between the hump and the crucible. Increasing of the electromagnetic force and the degree of superheat of the melt can decrease side radiation of the crucible wall. Consequently it is possible to realize directional solidification with the cold crucible.