Dendritic microstructure and hot cracking of laser additive manufactured Inconel 718 under improved base cooling
Dendritic microstructure and hot cracking of laser additive manufactured Inconel 718 under improved base cooling
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DOI：
10.1016/j.jallcom.2016.01.250
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发表时间：
2016-06-15
影响因子：
6.2
通讯作者：
Li, Zhuguo
中科院分区：
文献类型：
--
作者：
Chen, Yuan;Lu, Fenggui;Li, Zhuguo
在Inconel 718（IN718）的激光增材制造期间，通过在基底的背面施加连续的水流来改善基底冷却效果。利用光学显微镜（OM）、扫描电子显微镜（SEM）和电子背散射衍射（EBSD）技术研究了枝晶组织、晶体取向和热裂行为。结果表明，在沉积过程中，通过增加基底冷却效果，可以提高晶体的取向度。此外，高度有序的柱状枝晶的建立，并在最终的包覆构造单晶织构。结果表明，凝固裂纹只在存款的顶部区域产生，对最终熔覆层性能的影响可以忽略不计，而液化裂纹则产生并保留在热影响区（HAZ），需要小心控制。液化裂纹的敏感性表现出很高的依赖于晶界取向差，这被认为是由于枝晶间液化膜的稳定性，以及在凝固的最后阶段的局部应力集中的大小。(C)© 2016 Elsevier B.V.版权所有。
The base cooling effect was improved by imposing the continuous water flow on the back of the substrate during the laser additive manufacturing of Inconel 718 (IN718). The dendritic microstructure, crystal orientation and hot cracking behavior were studied by using optical microscopy (OM), scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD) techniques. The results showed that the crystal orientation was increased by increasing the base cooling effect during the deposition. Also, highly ordered columnar dendrites were established, and mono-crystalline texture was constructed in the final clad. It was fund that the effect of solidification cracking on the properties of final clad was negligible since it was only generated at the top region of the deposit, while liquation cracking was produced and remained in the heat affected zone (HAZ) and needed to be carefully controlled. The susceptibility to the liquation cracking showed a high dependence on the grain boundary misorientation, which was considered to be attributed to the stability of interdendritic liquation films, as well as the magnitude of local stress concentration in the last stage of solidification. (C) 2016 Elsevier B.V. All rights reserved.