Yu Hao a, Nannan Chen a,b, Hui-Ping Wang c,*, Blair E. Carlson c, Fenggui Lu a,*
a Shanghai Key Laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai,
200240, PR China b Department of Industrial and Manufacturing Eng
A three-dimensional thermal-fluid numerical model considering zinc vapor interaction with the molten pool was developed to study the occurrence of zinc vapor-induced spatter in partial penetration laser overlap welding of zinc-coated steels. The zinc vapor effect was represented by two forces: a jet pressure force acting on the keyhole rear wall as the vapor bursts into the keyhole and a drag force on the upper keyhole wall as the vapor escapes upwards. The numerical model was calibrated by comparing the predicted keyhole shape with the keyhole shape observed by high-speed X-ray imaging and applied for various weld schedules. The study showed that large jet pressure forces induced violent fluctuations of the keyhole rear wall, resulting in an unstable keyhole and turbulent melt flow. A large drag force pushed the melt adjacent to the keyhole surface upward and accelerated the movement of the melt whose velocities reached 1 m/s or even higher, potentially inducing spatter. Increased heat input facilitated the occurrence of large droplets of spatter, which agreed with experimental observations captured by high-speed camera.
아연도금강의 부분용입 레이저 겹침용접에서 아연증기유도 스패터의 발생을 연구하기 위하여 용융풀과의 아연증기 상호작용을 고려한 3차원 열유체 수치모델을 개발하였습니다.
아연 증기 효과는 증기가 열쇠 구멍으로 폭발할 때 키홀 뒤쪽 벽에 작용하는 제트 압력력과 증기가 위쪽으로 빠져나갈 때 위쪽 키홀 벽에 작용하는 항력의 두 가지 힘으로 표시됩니다.
수치 모델은 예측된 열쇠 구멍 모양과 고속 X선 영상으로 관찰된 키홀 모양을 비교하여 보정하고 다양한 용접 일정에 적용했습니다.
이 연구는 큰 제트 압력이 키홀 뒷벽의 격렬한 변동을 유발하여 불안정한 열쇠 구멍과 난류 용융 흐름을 초래한다는 것을 보여주었습니다. 큰 항력은 키홀 표면에 인접한 용융물을 위로 밀어올리고 속도가 1m/s 이상에 도달한 용융물의 이동을 가속화하여 잠재적으로 스패터를 유발할 수 있습니다.
증가된 열 입력은 고속 카메라로 포착한 실험적 관찰과 일치하는 큰 방울의 스패터 발생을 촉진했습니다.
Ai, Y., Jiang, P., Wang, C., et al., 2018. Experimental and numerical analysis of molten
pool and keyhole profile during high-power deep-penetration laser welding. Int. J.
Heat Mass Transf. 126 (part-A), 779–789.
Chen, Z., Yang, S., Wang, C., et al., 2014. A study of fiber laser welding of galvanized
steel using a suction method. J. Mater. Process. Technol. 214 (7), 1456–1465.
Cho, W.I., Na, S.J., Thomy, C., et al., 2012. Numerical simulation of molten pool
dynamics in high power disk laser welding. J. Mater. Process. Technol. 212 (1),
Deng, S., Wang, H.P., Lu, F., et al., 2019. Investigation of spatter occurrence in remote
laser spiral welding of zinc-coated steels. Int. J. Heat Mass Transf. 140 (9), 269–280.
Fabbro, R., Coste, F., Goebels, D., et al., 2006. Study of CW Nd-Yag laser welding of Zncoated steel sheets. J. Phys. D Appl. Phys. 39 (2), 401.
Gao, Z., Wu, Y., Huang, J., 2009. Analysis of weld pool dynamic during stationary
laser–MIG hybrid welding. Int. J. Adv. Manuf. Technol. 44 (9), 870–879.
Kaplan, A., 1994. A model of deep penetration laser welding based on calculation of the
keyhole profile. J. Phys. D Appl. Phys. 27 (9), 1805.
Kim, J., Oh, S., Ki, H., 2015. A study of keyhole geometry in laser welding of zinc-coated
and uncoated steels using a coaxial observation method. J. Mater. Process. Technol.
Kim, J., Oh, S., Ki, H., 2016. Effect of keyhole geometry and dynamics in zero-gap laser
welding of zinc-coated steel sheets. J. Mater. Process. Technol. 232, 131–141.
Koch, H., KaGeler, C., Otto, A., et al., 2011. Analysis of welding zinc coated steel sheets
in zero gap configuration by 3D simulations and high-speed imaging. Phys. Procedia
12 (part-B), 428–436.
Kouraytem, N., Li, X., Cunningham, R., et al., 2019. Effect of laser-matter interaction on
molten pool flow and keyhole dynamics. Phys. Rev. Appl. 11 (6), 54–64.
Li, S., Chen, G., Katayama, S., et al., 2014. Relationship between spatter formation and
dynamic molten pool during high-power deep-penetration laser welding. Appl. Surf.
Sci. 303 (6), 481–488.
Ma, J., 2013. Experimental and Numerical Studies on the Issues in Laser Welding of
Galvanized High-Strength Dual-Phase Steels in a Zero-Gap Lap Joint Configuration,
PhD Thesis. Southern Methodist University.
Pan, Y., 2011. Laser Welding of Zinc Coated Steel Without a Pre-Set Gap, PhD Thesis.
Delft University of Technology.
Schmidt, M., Otto, A., 2008. Analysis of YAG laser lap-welding of zinc coated steel sheets.
CIRP Ann. Manuf. Technol. 57, 213–216.
Semak, V., Matsunawa, A., 1999. The role of recoil pressure in energy balance during
laser materials processing. J. Phys. D Appl. Phys. 30 (18), 2541.
Wu, S., Zhao, H., Wang, Y., Zhang, X., 2004. A new heat source model in numerical
simulation of high energy beam welding. Trans. China Weld. 21, 99–102.
Yaws, C.L., 2015. The Yaws Handbook of Vapor Pressure: Antoine Coefficients.
Zhou, J., Tsai, H.L., 2008. Modeling of transport phenomena in hybrid laser-MIG keyhole
welding. Int. J. Heat Mass Transf. 51 (17–18), 4353–4366.