In a powder bed fusion additive manufacturing process, the balling effect has a significant impact on the surface quality of the printing parts. Surface wetting helps the bonding between powder and substrate and the inter-particle fusion, whereas the balling effect forms large spheroidal beads around the laser beam and causes voids, discontinuities, and poor surface roughness during the printing process. To better understand the transient dynamics, a theoretical model with a simplified 2D configuration is developed to investigate the underlying fluid flow and heat transfer, phase transition, and interfacial instability along with the laser heating. We demonstrate that the degree of wetting and fast solidification counter-balance the balling effect, and the Rayleigh–Plateau flow instability plays an important role for cases with relatively low substrate wettability and high scanning rate.

中文翻译：

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粉末床熔合过程中润湿和球化动力学的相场建模

在粉末床熔融添加剂制造过程中，滚珠作用对印刷零件的表面质量有重大影响。表面润湿有助于粉末与基材之间的粘合以及粒子间的融合，而滚珠效应会在激光束周围形成大的球形珠，并在打印过程中导致空隙，不连续和不良的表面粗糙度。为了更好地了解瞬态动力学，开发了具有简化2D配置的理论模型，以研究潜在的流体流动和传热，相变以及界面不稳定性以及激光加热。我们证明润湿和快速凝固的程度抵消了起球作用，