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Deterministic Modeling of Solidification Microstructure Formation in Directed Energy Deposition Fabricated Ti6Al4V
Additive Manufacturing ( IF 11.0 ) Pub Date : 2021-07-27 , DOI: 10.1016/j.addma.2021.102182
Jinghao Li 1 , Xianglin Zhou 2 , Qingbo Meng 2 , Mathieu Brochu 3 , Nejib Chekir 3, 4 , J.J. Sixsmith 4 , J.Y. Hascoët 5 , Yaoyao Fiona Zhao 1
Affiliation  

Metal additive manufacturing (MAM) technology is now widely applied in the manufacturing and remanufacturing industry, among which microstructure simulation gradually shows its importance. Traditional solidification microstructure simulation methods all have their merits as well as drawbacks when applied in MAM cases. In this work, a deterministic solidification microstructure model, named “invasion model”, is established to avoid the essential defects of traditional methods. This model focuses on the interaction between the neighboring bi-crystals instead of simulating the growth kinetics of each columnar grain or deriving the field form of variables. Within a bi-crystal system, the grain boundary tilt from thermal gradient direction is understood as a transient invasion behavior of one grain to another, and the competitive grain growth behavior along the buildup process of MAM is a summary of all the invasions in bi-crystal systems. To fill the gaps in the rapid solidification theory, a database recording the anisotropic growth effect under a rapid directional solidification condition was established with the help of an artificial neural network (ANN). Wire feed directed energy deposition (DED) fabricated Ti6Al4V thin-wall samples with full dendritic columnar grains (prior beta) are used as a benchmark to test the validation of the novel simulation model. The grain geometrical structure of reconstructed prior β grains along the build-up direction has a good agreement with the simulation result. The model can also be applied to other cases of MAM or combine with various models to achieve real-time as-solidified crystallographic feature prediction when it meets the scope of application.



中文翻译:

定向能量沉积制造 Ti6Al4V 中凝固显微组织形成的确定性建模

金属增材制造(MAM)技术现已广泛应用于制造和再制造行业,其中微观结构模拟逐渐显示出其重要性。传统的凝固微观结构模拟方法在应用于 MAM 案例时都有其优点和缺点。在这项工作中,为了避免传统方法的本质缺陷,建立了一个确定性的凝固组织模型,称为“入侵模型”。该模型侧重于相邻双晶之间的相互作用,而不是模拟每个柱状晶粒的生长动力学或推导变量的场形式。在双晶系统中,晶界从热梯度方向倾斜被理解为一个晶粒向另一个晶粒的瞬态侵入行为,沿着 MAM 构建过程的竞争性晶粒生长行为是双晶系统中所有入侵的总结。为了填补快速凝固理论的空白,在人工神经网络(ANN)的帮助下建立了一个记录快速定向凝固条件下各向异性生长效应的数据库。送丝定向能量沉积 (DED) 制造的具有完整树枝状柱状晶粒(先前的 beta)的 Ti6Al4V 薄壁样品被用作测试新型模拟模型验证的基准。沿堆积方向重构的先验β晶粒的晶粒几何结构与模拟结果吻合较好。

更新日期:2021-07-27
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