Numerical simulation of multi-component evaporation during selective electron beam melting of TiAl
Numerical simulation of multi-component evaporation during selective electron beam melting of TiAl
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DOI：
10.1016/j.jmatprotec.2017.04.016
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发表时间：
2017-09-01
影响因子：
6.3
通讯作者：
Koerner, Carolin
中科院分区：
文献类型：
--
作者：
Klassen, Alexander;Forster, Vera E.;Koerner, Carolin
基于粉末的增材制造技术，如选择性激光熔化（SLM）和选择性电子束熔化（SEBM），为生产具有定制几何形状的高价值金属部件提供了巨大的希望。因此，扫描策略的发展和最佳工艺参数的预测仍然是制造高质量产品的关键因素，而不是合金成分或孔隙率的局部不均匀。本文对Ti-48A1-2Cr-2Nb钛合金的能量输入、蒸发和残余孔隙率之间的关系进行了数值研究。数值模型基于晶格玻尔兹曼方法，包括流体力学、热力学和多组分蒸发。结果表明：合金元素在成形件内的空间分布受表面张力和蒸发后坐力驱动的熔体平流控制，并受粉末颗粒随机排列的影响。关于蒸发损失，线能量似乎是至关重要的，因为它强烈影响加工过程中的峰值温度。对于给定的熔体策略，在孔隙度和铝因蒸发而损失之间存在权衡。结果表明，采用合适的波束扫描策略可以显著降低蒸发损失。数值计算结果与实验数据吻合较好。
Powder-based additive manufacturing technologies such as selective laser melting (SLM) and selective electron beam melting (SEBM) hold great promise for producing high-value metal components with customized geometries. Development of scanning strategies and prediction of optimal process parameters thereby remain key factors for the fabrication of high-quality products without local inhomogeneities in alloy composition or porosity.In this contribution, the relation between energy input, evaporation and residual porosity is numerically investigated on the titanium aluminide alloy Ti-48A1-2Cr-2Nb. The numerical model is based on a lattice Boltzmann method and includes hydrodynamics, thermodynamics and multi-component evaporation. Simulation results show that the spatial distribution of alloying elements within the final part is dominated by the advection of melt which is driven by surface tension and evaporative recoil and influenced by the random arrangement of powder particles. Regarding evaporation losses, the line energy appears to be of central importance, as it strongly affects peak temperatures during processing. For a given melt strategy there is a trade-off between porosity and loss of aluminum due to evaporation. It is demonstrated that significant reductions in evaporation losses can be achieved by application of a suitable beam scanning strategy. The presented numerical findings are consistent with experimental data.