Breuning Christoph, Pistor Julian, Markl Matthias, Körner Carolin
Chair of Materials Science and Engineering for Metals, Friedrich-Alexander-Universität Erlangen-Nürnberg, Martensstr. 5, 91058 Erlangen, Germany.
Joint Institute of Advanced Materials and Processes, Friedrich-Alexander-Universität Erlangen-Nürnberg, Dr. Mack Str. 81, 90762 Fürth, Germany.
Materials (Basel). 2022 Jul 7;15(14):4754. doi: 10.3390/ma15144754.
This study introduces and verifies a basic mechanism of surface topography evolution in electron beam additive manufacturing (E-PBF). A semi-analytical heat conduction model is used to examine the spatio-temporal evolution of the meltpool and segment the build surface according to the emerging persistent meltpool domains. Each persistent domain is directly compared with the corresponding melt surface, and exhibits a characteristic surface morphology and topography. The proposed underlying mechanism of topography evolution is based on different forms of material transport in each distinct persistent domain, driven by evaporation and thermocapillary convection along the temperature gradient of the emerging meltpool. This effect is shown to be responsible for the upper bound of the standard process window in E-PBF, where surface bulges form. Based on this mechanism, process strategies to prevent the formation of surface bulges for complex geometries are proposed.
本研究介绍并验证了电子束增材制造（E-PBF）中表面形貌演变的基本机制。采用半解析热传导模型来研究熔池的时空演变，并根据出现的持续熔池区域对构建表面进行划分。将每个持续区域直接与相应的熔池表面进行比较，其呈现出独特的表面形态和形貌。所提出的形貌演变潜在机制基于每个不同持续区域中不同形式的材料传输，这是由沿新出现熔池温度梯度的蒸发和热毛细对流驱动的。结果表明，这种效应是E-PBF中标准工艺窗口上限的原因，在此上限处会形成表面凸起。基于这一机制，提出了防止复杂几何形状表面凸起形成的工艺策略。
