Directional solidification of titanium alloys by electromagnetic confinement in cold crucible
Directional solidification of titanium alloys by electromagnetic confinement in cold crucible
复制标题
DOI：
10.1016/j.matlet.2004.11.053
复制
发表时间：
2005-03
影响因子：
3
通讯作者：
H. Ding;Ruirun Chen;Jingjie Guo;Weisheng Bi;Daming Xu;H. Fu
中科院分区：
文献类型：
--
作者：
H. Ding;Ruirun Chen;Jingjie Guo;Weisheng Bi;Daming Xu;H. Fu
为了抑制钛合金的反应活性，改变其组织的方向性，基于冷坩埚技术，提出了一种连续感应熔炼、电磁约束和推进冷却作用的定向铸造Ti-6Al-4V合金的新型凝固方法。由于电磁约束的结果，钛熔体与冷坩埚内壁的接触不完全，因此通过熔体/坩埚界面的传热系数变得比传统铸造方法低。通过定义重合度kc，考虑到有电磁效应和无电磁效应的冷坩埚内传热现象的比较，在一定程度上理解实验结果。结果表明，在试样的外围区域，凝固前沿总是向上凸出，而在内部生长区，随着退缩速度的增加，凝固前沿的轮廓会从向上的凸面下降到向下的凹面。因此，随着生长速度减慢，晶粒数量会小幅减少，如本实验所示，当速度达到0.5 mm/min时，就获得了单个晶粒。拉伸试验表明，定向凝固铸锭比无定向凝固铸锭具有更高的拉伸强度和伸长率。
In order to suppress the reactivity of titanium alloys and modify their structures into directionality, a new solidification method in which its process is continuity of induction melting, electromagnetic confinement and propelling cooling effect is proposed for casting Ti–6Al–4V alloy directionally based on the cold crucible technology. Due to an incomplete contact of the titanium melt with the inner wall of cold crucible with respect to the results of electromagnetic confinement, heat transfer coefficient becomes lower through the melt/crucible interface than that in the conventional casting method. By defining a contact ratio of kc, the comparison of the heat transfer phenomena in cold crucible with or without electromagnetic effect is taken into account to understand the experimental results to some extent. It is revealed that the solidified front is always convex upward in the periphery areas of the specimens and, in the inner growing zones, the contours of the front will descend from convexity upward to concavity downward with the withdrawal velocities increased. Thus, with slowing down the growth rate, the grain numbers will decrease to a small extent and as shown in this experimental, a single grain has been obtained when the velocity attains 0.5 mm/min. Tensile test shows that directional solidifying ingots have a higher tensile strength and elongation than that without directional structures.