3D non-isothermal phase-field simulation of microstructure evolution during selective laser sintering
3D non-isothermal phase-field simulation of microstructure evolution during selective laser sintering
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DOI：
10.1038/s41524-019-0219-7
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发表时间：
2019-02
影响因子：
9.7
通讯作者：
Yangyiwei Yang;Olav Ragnvaldsen;Yang Bai;M. Yi;Bai-Xiang Xu
中科院分区：
文献类型：
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作者：
Yangyiwei Yang;Olav Ragnvaldsen;Yang Bai;M. Yi;Bai-Xiang Xu
预测选择性激光烧结 (SLS) 过程中的微观结构非常有意义，它可以通过高效的计算设计工具补充当前时间和成本昂贵的试错原则。然而，由于复杂的底层物理现象，模拟 SLS 过程中的微观结构演化仍然是一个巨大的挑战。在这项工作中，我们提出了 SLS 单次扫描的三维有限元相场模拟，并揭示了过程与微观结构的关系。我们使用热力学一致的非等温相场模型，包括各种物理场（即部分熔化、孔隙结构演化、扩散、晶界迁移和耦合传热）以及粉末床和激光功率吸收的相互作用。初始粉末床是通过离散元方法生成的。此外，我们在手稿中提出了一种新颖的算法来模拟最小着色问题，并设法使用低至 8 个非保守序参数来模拟 200 个颗粒的系统，并进行颗粒跟踪。所开发的模型能够捕获传统等温模型无法实现的有趣现象。具体来说，将该模型应用于不锈钢 316L 粉末的 SLS，我们确定了激光功率和扫描速度对微观结构指标的影响，包括孔隙率、表面形貌、温度分布、晶粒几何形状和致密化。我们进一步验证了孔隙度演化过程中的一级动力学，并证明了所开发的模型在预测 SLS 期间致密化因子与特定能量输入之间的联系的适用性。
Predicting the microstructure during selective laser sintering (SLS) is of great interests, which can compliment the current time and cost expensive trial-and-error principle with an efficient computational design tool. However, it still remains a great challenge to simulate the microstructure evolution during SLS due to the complex underlying physical phenomena. In this work, we present a three-dimensional finite element phase-field simulation of the SLS single scan, and revealed the process-microstructure relation. We use a thermodynamically consistent non-isothermal phase-field model including various physics (i.e. partial melting, pore structure evolution, diffusion, grain boundary migration, and coupled heat transfer), and interaction of powder bed and laser power absorption. The initial powder bed is generated by the discrete element method. Moreover, we present in the manuscript a novel algorithm analogy to minimum coloring problem and managed to simulate a system of 200 grains with grain tracking using as low as 8 non-conserved order parameters. The developed model is shown to capture interesting phenomena which are not accessible to the conventional isothermal model. Specifically, applying the model to SLS of the stainless steel 316L powder, we identify the influences of laser power and scanning speed on microstructural indicators, including the porosity, surface morphology, temperature profile, grain geometry, and densification. We further validate the first-order kinetics during the porosity evolution, and demonstrate the applicability of the developed model in predicting the linkage of densification factor to the specific energy input during SLS.