High frequency beam oscillation keyhole dynamics in laser melting revealed by in-situ x-ray imaging
High frequency beam oscillation keyhole dynamics in laser melting revealed by in-situ x-ray imaging
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DOI：
10.1038/s43246-023-00332-z
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发表时间：
2023-02
影响因子：
7.8
通讯作者：
Ziheng Wu;Guannan Tang;S. Clark;A. Meshkov;S. Roychowdhury;Benjamin J. Gould;V. Ostroverkhov;
中科院分区：
文献类型：
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作者：
Ziheng Wu;Guannan Tang;S. Clark;A. Meshkov;S. Roychowdhury;Benjamin J. Gould;V. Ostroverkhov;
金属增材制造行业正在积极开发工具和策略，以实现更高的生产率，最佳的构建质量和可控的建成微观结构。激光振荡是一种光束控制技术，在激光焊接的所有这些方面都显示出了潜力;然而，很少有人试图了解振荡小孔/熔池的基本物理学，这是这些策略成为基于激光的增材制造工艺的有用工具的先决条件。在这里，为了解决这一差距，我们利用基于同步加速器的X射线操作技术，使用微型粉末床融合装置对Ti-6Al-4V中的动态锁孔振荡进行成像。我们发现实验观察和模拟之间有很好的一致性与验证的格子玻尔兹曼多物理场模型。该研究揭示了特征小孔参数的连续和周期性波动，这些参数是振荡激光束加工所特有的，并且是在凝固时形成人字形图案的原因。特别是，尽管固有的较长范围的波动，振荡技术表现出潜在的减少锁孔不稳定性，减轻孔隙形成，并改变表面拓扑结构。这些见解的振荡锁孔动力学可以是有用的，为未来的发展和应用这项技术。
The metal additive manufacturing industry is actively developing instruments and strategies to enable higher productivity, optimal build quality, and controllable as-built microstructure. A beam controlling technique, laser oscillation has shown potential in all these aspects in laser welding; however, few attempts have been made to understand the underlying physics of the oscillating keyholes/melt pools which are the prerequisites for these strategies to become a useful tool for laser-based additive manufacturing processes. Here, to address this gap, we utilized a synchrotron-based X-ray operando technique to image the dynamic keyhole oscillation in Ti-6Al-4V using a miniature powder bed fusion setup. We found good agreement between the experimental observations and simulations performed with a validated Lattice Boltzmann multiphysics model. The study revealed the continuous and periodic fluctuations in the characteristic keyhole parameters that are unique to the oscillating laser beam processing and responsible for the chevron pattern formation at solidification. In particular, despite the intrinsic longer-range fluctuation, the oscillating technique displayed potential for reducing keyhole instability, mitigating porosity formation, and altering surface topology. These insights on the oscillating keyhole dynamics can be useful for the future development and application of this technique.