同轴送粉激光熔覆气泡逃逸行为及分布研究  

Analysis of Bubble Escape Behavior and Distribution of the Coaxial Powder Feeding Laser Cladding

作　　者：徐磊 王匀[1] 许桢英[1] 倪旺 闫金金 XU Lei;WANG Yun;XU Zhen-ying;NI Wang;YAN Jin-jin(School of Mechanical Engineering,Jiangsu University,Jiangsu Zhenjiang 212013,China)

机构地区：[1]江苏大学机械工程学院,江苏镇江212013

出　　处：《精密成形工程》2023年第1期137-145,共9页Journal of Netshape Forming Engineering

基　　金：国家自然科学基金面上项目(51679112);扬州市广陵区科技计划(GL202016)。

摘　　要：目的获取Inconel 718合金在同轴送粉激光熔覆过程中,熔池内气泡的动态行为及熔覆层中气孔缺陷的分布规律。方法建立熔池内部气泡力学模型和方程,考虑气泡浮力、重力、气泡和熔液相对运动产生的黏滞力,以及熔液对流带来的拖曳力等力的综合作用,着重研究浮力、拖曳力对气泡逃逸行为的影响,并计算不同条件下的气泡逃逸时间;搭建“三明治”观测平台,原位观测在熔覆过程中熔池内气泡的动态行为,获取熔池寿命;进行单因素Inconel718合金同轴送粉激光熔覆实验,探究熔覆层气孔缺陷的分布规律。结果熔池寿命通常在0.2~0.4 s;熔池内气泡直径临界值约为60μm,当熔池内气泡直径大于60μm时更容易通过自身浮力逸出,与单因素实验获得的熔覆层中96.94%的气孔缺陷直径小于60μm具有较好的一致性;对熔覆层气孔缺陷表征发现,浮力对临界直径以下气泡运动状态的影响一般小于拖曳力。结论Inconel718合金在激光熔覆过程中,熔池内气泡大小存在临界值,且主要受浮力向上运动及受拖曳力随熔池对流运动的影响,熔覆层中气孔缺陷倾向于分布在对流路径上。The work aims to obtain the dynamic behavior of bubbles inside the melt pool and the distribution law of porosity defects in the cladding layer during the coaxial powder feeding laser cladding of Inconel 718 alloy.Mechanics model and equation were established for bubbles in melt pool to study the effect of buoyancy and drag force on the bubble escape behavior and calculate the bubble escape time under different conditions by considering the combined effects of bubble buoyancy,gravity,viscous force and drag force.A"sandwich"observation platform was built to observe the dynamic behavior of bubbles in the melt pool in situ and obtain the service life of the melt pool.Single-factor experiment was carried out on coaxial powder feeding laser cladding of Inconel 718 alloy to investigate the distribution law of porosity defects in the cladding layer.The service life of the melt pool was usually 0.2~0.4 s,and the critical value of bubble diameter in the melt pool was about 60μm.When the diameter was larger than 60μm,the bubble was easier to escape through its own buoyancy,and 96.94%of the porosity defects in the cladding layer obtained from the single-factor experiments were smaller than 60μm in diameter,which showed good consistency with the calculation results.From the characterization of porosity defects in cladding layer,buoyancy generally had smaller effect than drag force on movement of bubbles with diameter below critical value.During the laser cladding of Inconel 718 alloy,there is a critical value for bubble size in the melt pool.Bubbles mainly move upward by buoyancy and drag force with the convection of the melt pool and porosity defects in the cladding layer tend to be distributed in the convection path.

关 键 词：同轴送粉激光熔覆 Inconel 718 气泡逃逸 受力分析 气孔分布 

分 类 号：TN249[电子电信—物理电子学]