Revealing melt flow instabilities in laser powder bed fusion additive manufacturing of aluminum alloy via in-situ high-speed X-ray imaging
Revealing melt flow instabilities in laser powder bed fusion additive manufacturing of aluminum alloy via in-situ high-speed X-ray imaging
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DOI：
10.1016/j.ijmachtools.2022.103861
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发表时间：
2022-02-28
影响因子：
14
通讯作者：
Chen, Lianyi
中科院分区：
文献类型：
--
作者：
Guo, Qilin;Qu, Minglei;Chen, Lianyi
激光金属增材制造技术能够制造传统制造方法无法实现的几何和成分复杂的零件。然而，增材制造零件的认证和鉴定受到该过程固有的随机熔体流动不稳定性的极大阻碍，这一点尚未通过直接观察明确揭示。在这里，我们报告了通过原位高速高分辨率同步加速器 X 射线成像揭示的激光粉末床熔融增材制造过程中熔体流动不稳定性的机制。我们确定粉末/液滴冲击、显着的小孔振荡和熔化模式切换是导致熔体流动不稳定的三个主要机制。我们证明了这些不稳定性给过程带来的有害后果，并对熔体流动演变和小孔振荡提出了新的理解。这项工作为激光金属增材制造过程中的工艺不稳定性提供了重要的见解，这可能会指导不稳定缓解方法的开发。这里报告的结果对于高保真计算模型的开发和验证也很重要。
Laser metal additive manufacturing technologies enable the fabrication of geometrically and compositionally complex parts unachievable by conventional manufacturing methods. However, the certification and qualification of additively manufactured parts are greatly hindered by the stochastic melt flow instabilities intrinsic to the process, which has not been explicitly revealed by direct observation. Here, we report the mechanisms of the melt flow instabilities in laser powder bed fusion additive manufacturing process revealed by in-situ high-speed high-resolution synchrotron X-ray imaging. We identified powder/droplet impact, significant keyhole oscillation, and melting-mode switching as three major mechanisms for causing melt flow instabilities. We demonstrated the detrimental consequences of these instabilities brought to the process, and presented new understanding on the melt flow evolution and keyhole oscillation. This work provides critical insights into process instabilities during laser metal additive manufacturing, which may guide the development of instability mitigation approaches. The results reported here are also important for the development and validation of high-fidelity computational models.