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Numerical Analysis of the Morphological Characteristics of the Powder Stream in Laser Welding with Coaxial Filler Powder
Y. Zhang, B-S. Li, X. Yang and H-Y. Wei

Analyses of powder streams can facilitate better coupling of laser and powders and improve the efficiency of energy and powder in laser welding with filler powder. This paper presents a theoretical and experimental study to develop a gas-solid two phase stream powder injection model for laser welding with filler powder. The model was compared to the shape of the powder injection stream that was experimentally measured from images; the simulation results are in excellent agreement with the experimental ones. The results show that the tangent of the injection angle of the powder nozzle is linearly correlated with the focal length of the powder stream. When the flow rates of the carrier gas and shielding gas were both 8 l/min and the injection angle of the powder nozzle was 70°, a powder stream spot size that matches the width of the welding pool and excellent powder stream focus can be obtained. Experiments of laser welding with coaxial filler powder show that excellent laser-powder coupling can improve the quality of the laser weld. The investigation of the powder stream provides a basis for the development of coaxial powder injection and high-quality laser welding with filler powder.

Keywords: Laser welding, powder filler, gas flow rate, injection angle, powder stream characteristics, simulation, coaxial powder injection

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