Keyhole fluctuation and pore formation mechanisms during laser powder bed fusion additive manufacturing.
Keyhole fluctuation and pore formation mechanisms during laser powder bed fusion additive manufacturing.
复制标题
DOI：
10.1038/s41467-022-28694-x
复制
发表时间：
2022-03-04
影响因子：
16.6
通讯作者：
Lee PD
中科院分区：
文献类型：
--
作者：
Huang Y;Fleming TG;Clark SJ;Marussi S;Fezzaa K;Thiyagalingam J;Leung CLA;Lee PD
小孔孔隙率是激光粉末床熔合 (LPBF) 中的一个关键问题，可能会影响部件的疲劳寿命。然而，一些小孔孔隙形成机制，例如小孔波动、塌陷以及气泡生长和收缩，仍不清楚。使用同步加速器 X 射线成像，我们揭示了锁孔和气泡的行为，量化了它们的形成动力学。研究结果支持以下假设：（i）小孔孔隙不仅可以在不稳定的情况下产生，而且可以在高激光功率速度条件产生的过渡小孔区域中产生，导致快速的径向小孔波动（2.5-10kHz）； (ii) 过渡制度崩溃往往发生在后墙的部分位置； (iii) 在小孔破裂后，气泡立即由于压力平衡而快速增长，然后由于金属蒸气凝结而收缩。在冷凝的同时，氢气扩散到气泡中减缓了收缩并稳定了气泡尺寸。这里揭示的小孔波动和气泡演化机制可能会指导开发最小化孔隙率的控制系统。了解小孔孔隙的形成对于激光粉末床熔合非常重要。在这里，作者揭示了导致气泡形成的匙孔波动和崩溃的动力学，包括三个主要的演化阶段：生长、收缩以及被凝固前沿捕获。
Keyhole porosity is a key concern in laser powder-bed fusion (LPBF), potentially impacting component fatigue life. However, some keyhole porosity formation mechanisms, e.g., keyhole fluctuation, collapse and bubble growth and shrinkage, remain unclear. Using synchrotron X-ray imaging we reveal keyhole and bubble behaviour, quantifying their formation dynamics. The findings support the hypotheses that: (i) keyhole porosity can initiate not only in unstable, but also in the transition keyhole regimes created by high laser power-velocity conditions, causing fast radial keyhole fluctuations (2.5–10 kHz); (ii) transition regime collapse tends to occur part way up the rear-wall; and (iii) immediately after keyhole collapse, bubbles undergo rapid growth due to pressure equilibration, then shrink due to metal-vapour condensation. Concurrent with condensation, hydrogen diffusion into the bubble slows the shrinkage and stabilises the bubble size. The keyhole fluctuation and bubble evolution mechanisms revealed here may guide the development of control systems for minimising porosity. Understanding the keyhole porosity formation is important in laser powder bed fusion. Here the authors reveal the dynamics of keyhole fluctuation, and collapse that induces bubble formation with three main stages of evolution; growth, shrinkage, and being captured by the solidification front.
登录
查看更多内容
影响因子：
8.3
作者：
Chen, Yunhui;Clark, Samuel J.;Lee, Peter D.
通讯作者：
Lee, Peter D.
影响因子：
3.4
作者：
Fabbro, R;Slimani, S;Briand, F
通讯作者：
Briand, F
影响因子：
2.1
作者：
Farson, D;Hillsley, K;Young, R
通讯作者：
Young, R
影响因子：
11
作者：
Bayat, Mohamad;Thanki, Aditi;Hattel, Jesper Henri
通讯作者：
Hattel, Jesper Henri
通过高激光吸收 Co 相修饰实现 Al 粉末的高性能 3D 打印
影响因子：
11
作者：
Geng, Kang;Yang, Yafeng;Zhu, Qingshan
通讯作者：
Zhu, Qingshan