Direct observation of bubble generation processes inside a molten pool during laser cladding
Direct observation of bubble generation processes inside a molten pool during laser cladding
复制标题
DOI：
10.1016/j.surfcoat.2022.128831
复制
发表时间：
2022-08
影响因子：
5.4
通讯作者：
Keigo Tanaka;Takuto Yamaguchi
中科院分区：
文献类型：
--
作者：
Keigo Tanaka;Takuto Yamaguchi
使用石英玻璃的直接观察技术使得在激光熔覆期间在熔池内部发生的气泡生成过程可视化。该技术揭示了在Inconel 625和WC-12wt%Co粉末的激光熔覆期间气泡产生过程不同。对于Inconel 625粉末，粉末颗粒冲入熔池。在粒子后面形成的空腔。随后，颗粒在熔池内消失，并被气泡取代。气泡被认为是分离并留在颗粒后面的空腔。为了减少Inconel 625激光熔覆过程中气泡的产生，最好通过降低粉末颗粒的动能来实现空腔形成抑制。而WC-12wt%Co粉末中的气泡主要产生于熔池内部。结果表明，气体产生的熔池内。随着时间的推移，气泡因为生长和合并而膨胀。一些气泡打开了熔池表面，另一些则被困在凝固的熔池中，形成孔隙或凹坑。结果表明，要降低WC-12wt%Co的气孔率，熔池中必须存在抑制气体生成的条件。将直接观察技术广泛应用于各种激光熔覆工艺，有望在不久的将来实现无气孔熔覆珠的制造。
A direct observation technique using quartz glass enabled visualization of the bubble generation processes occurring inside a molten pool during laser cladding. This technique revealed that bubble generation processes during laser cladding of Inconel 625 and WC-12 wt% Co powder differed. For the Inconel 625 powder, the powder particles rushed into the molten pool. A cavity formed behind the particles. Subsequently, the particles disappeared inside the molten pool, and were replaced with bubbles. Bubbles were regarded as cavities that separated and remained behind the particle. To reduce bubble generation during laser cladding of Inconel 625, cavity formation suppression is best achieved by reducing the kinetic energy of the powder particles. However, the bubbles in WC-12 wt% Co powder were generated mainly from inside of the molten pool. Results suggest that gas was generated inside of the molten pool. The bubbles expanded because of growth and coalescence as time passed. Some bubbles opened the molten pool surface; others were trapped in the solidified molten pool as a porosity or a pit. Results indicate that gas-formation suppressing conditions must exist in the molten pool to reduce the WC-12 wt% Co porosity. Applying the direct observation technique to widely various laser cladding processes is expected to enable the fabrication of porosity-free clad beads in the near future.