The Analysis Of Active Laser Welding Plasma And Molten Pool

Active laser welding technology,compared to the traditional laser welding technology,can effectively increase the weld penetration and reduce the weld width.The active laser welding technology can reduce the power and heat input needed in the welding process,while maintaining the advantages of the traditional laser welding technology.In this way,the active laser welding technology can effectively reduce the cost,improve the production efficiency and the welding quality.As a result of the advantages,the active laser welding technology has gained great interest from researchers.In order to study the mechanism of the influence of active flux on laser welding,this paper conducted an in-depth analysis from the perspective of arc shape.As the laser arc is difficult to be observed directly,the research was conducted from two approaches,i.e.the impact of the active flux on the plasma and the effect of active flux on the shape of the molten pool.For the first approach,304 stainless steel was used as the research material.High-power semiconductor laser welding was used for surfacing plate.High-speed photographic technique was used to capture and analyze the influence of active flux on laser welding arc shape.For the second approach,a H13 hot work die steel was used as the research material in order to prevent the plasma from blocking the molten pool shape.A low-power pulsed laser welding was used for flat surfacing.The influence of active flux on laser welding pool was captured by CCD monitoring system.The mechanism of active laser welding was discussed and analyzed.To analyze the plasma shape captured by the high speed camera,the collected image information was processed by image gray-scale processing,image filtering denoising,image binarization,image edge extraction and feature extraction.The experimental results showed that the active flux can effectively suppress the plasma generation,compress the height of the plasma along the direction of the optical path,reduce the volume of the photo-induced plasma,and effectively reduce the shielding effect of the photo-induced plasma on the incident laser.The effect of active flux on the morphology of laser welding pool was observed by CCD monitoring system,and the change in weld shape was observed in low power pulsed laser welding.The experimental results showed that the active flux can change the shape of weld pool,increase the amount of molten metal,increase the weld penetration,as well as improve the weld strength.The variations in the laser welding parameters affected the effects generated by the active flux.The effect of the active flux decreased with the increase in the defocusing amount.The results showed that the active flux can reduce the absorption of laser arc energy,change the flow direction of molten metal and increase the absorption of laser energy.The study showed that the active laser welding technology can play an important role in increasing the welding penetration and reducing the weld width.