Benchmark Study of Thermal Behavior, Surface Topography, and Dendritic Microstructure in Selective Laser Melting of Inconel 625
Benchmark Study of Thermal Behavior, Surface Topography, and Dendritic Microstructure in Selective Laser Melting of Inconel 625
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DOI：
10.1007/s40192-019-00130-x
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发表时间：
2019-06-01
影响因子：
3.3
通讯作者：
Wagner, Gregory J.
中科院分区：
文献类型：
--
作者：
Gan, Zhengtao;Lian, Yanping;Wagner, Gregory J.
在 NIST 增材制造基准 (AM-Bench) 实验中，激光熔化 Inconel 625 中的熔池几何形状、冷却速率、表面形貌和枝晶微观结构被用来挑战和验证熔化和凝固过程的计算模型。为此，将包含不同物理场的三个热模型与实验数据进行了比较。研究表明，熔池内热毛细管流动增强的热对流和汽化引起的热损失对于保证预测的准确性起着关键作用，因此应在热模型中予以考虑。从结果来看，忽略流体流动和汽化导致凝固过程中的冷却速率相差近100%，而凝固后的冷却速率相差20%。利用最准确的热模型，可以预测并定量分析熔体轨迹的表面形貌。使用 Kurz-Fisher 模型，根据热梯度和凝固速率预测来预测一次枝晶臂间距，同时使用 Scheil-Gulliver 模型和非平衡凝固模型来预测元素偏析。此外，研究表明，增加扫描速度可以抑制元素微观偏析。
In the NIST additive manufacturing benchmark (AM-Bench) experiments, melt pool geometry, cooling rates, surface topography, and dendritic microstructure in laser melted Inconel 625 were used to challenge and validate computational models of the melting and solidification process. To this end, three thermal models incorporating different physics are compared with the experimental data. It is identified that the heat convection enhanced by the thermocapillary flow inside the melt pool and heat loss caused by vaporization play pivotal roles to guarantee the accuracy of the predictions, and thus should be considered in the thermal model. Neglecting fluid flow and vaporization leads to nearly 100% difference in cooling rate during solidification, and 20% difference in cooling rate after solidification from the results. With the most accurate thermal model, surface topographies of the melt tracks are predicted and quantitatively analyzed. Using the Kurz-Fisher model, the primary dendrite arm spacing is predicted based on the thermal gradient and solidification rate predictions, while elemental segregation is predicted using the Scheil-Gulliver model and a non-equilibrium solidification model. Additionally, it is shown that increasing scan speed inhibits elemental microsegregation.