Research On Weld Profile Controlling Technology Of Laser Welding Complex Internal Flow Passage Component

Complex internal flow passage component is a thin-walled sandwich structure with complex dense channels. Laser welding is the mostly used technology to manufacture this kind of structure. Weld strength and deformation control are the main technical indicators of the process. In this paper, the method of weld profile controlling is researched. The “vase” shape welds with large effective weld width?the weld width on the junction section of overlap joint? and small cross-section area are obtained. The joints have the advantages of small distortion and excellent mechanical properties. Therefore, this method is suitable for laser welding manufacturing of complex internal flow passage component.Influence of the welding parameters and focusing parameters on weld appearance, microstructure and mechanical properties are studied using a DC035 Slab CO₂ laser. The research has shown that the “vase” shape weld can be obtained when using 100 mm focal length lens, and the welding speed is no less than 6 m/min. This shows that the different focal length of the focusing lens affect the divergence angle of the laser beam, therefore changing the energy density distribution on the focusing beam cross section, and ultimately change the weld profile. During high speed welding?v ? 6 m/min?, the laser power density distribution is better reflected by weld profile. Simulating the complex internal flow passage component mechanics characteristic after laser welding manufacturing, comparing microstructure and mechanical properties of different weld profile with T-joint. The result has shown that in when “vase” shape and “nail head” shape weld cross-section T-joints have the same effective weld width, the cross sections area of the “vase” shape weld was reduced 34.79%, the laser input energy density was reduced 54.83%, the microstructure was refined, the micro hardness of both welds were slightly higher than the base metal. The "Vase" shape weld joint tensile performance is better and the fracture morphology is ductile fracture, the “nail head” shape weld joint with ductile fracture and quasi cleavage fracture.Due to the application prospects of fiber laser to welding manufacturing complex internal flow passage component, IPG YLS-6000 fiber laser and YLS-3000-SM fiber laser are used to study the weld formation under different welding parameters and focusing parameters. The result indicates that, in addition to the divergence angle and welding speed, the beam quality is also an important factor in obtaining a "vase" shape weld. YLS-6000 fiber laser beam quality factor M2 = 23, it cannot obtain “vase” shape weld in the short focal length and high welding speed. When the focal length is 200 mm, the welding speed is no less than 6 m/min, a "cylindrical" shape weld can be obtained. When the focal length is 100 mm, the weld profile showing a trend of "vase" shape weld in the YLS-3000-SM fiber laser.The complex internal flow passage component is a three-dimensional structure, complex structure, it is not suitable for using paraxial welding technology weld manufacture. According to coaxial welding work head weld manufacturing processing requirements of complex internal flow passage component, researched the influence of nozzle size, shielding gas flow rate, laser incident angle, laser power and other process parameters on weld profile, obtained optimum process window of complex internal flow passage component of coaxial laser welding manufacturing.