01 Thick plate laser-arc hybrid welding
Thick plate (thickness ≥ 20mm) welding plays a key role in the manufacturing of large equipment in important fields such as aerospace, navigation and shipbuilding, rail transportation, etc. These components are usually characterized by large thickness, complex joint forms, and complex service environments. Welding quality has a direct impact on the performance and life of the equipment. Due to the slow welding speed and serious spatter problems, the traditional gas shielded welding method faces challenges such as low welding efficiency, high energy consumption, and large residual stress, making it difficult to meet the ever-increasing manufacturing requirements. However, laser-arc hybrid welding technology is different from traditional welding technology. It successfully combines the advantages of laser welding and arc welding, and has the characteristics of large penetration depth, fast welding speed, high efficiency and better weld quality, as shown in Figure 1 Show. Therefore, this technology has attracted widespread attention and has begun to be applied in some key areas.
Figure 1 Principle of laser-arc hybrid welding
02Research on laser-arc hybrid welding of thick plates
The Norwegian Institute of Industrial Technology and Lule University of Technology in Sweden studied the structural uniformity of composite welded joints under 15kW for 45mm thick micro-alloyed high-strength low-alloy steel. Osaka University and Egypt’s Central Metallurgical Research Institute used a 20kW fiber laser to conduct research on the single-pass laser-arc hybrid welding process of thick plates (25mm), using a bottom liner to solve the bottom hump problem. The Danish Force Technology Company used two 16 kW disk lasers in series to conduct research on the hybrid welding of 40mm thick steel plates at 32 kW, indicating that high-power laser-arc welding is expected to be used in offshore wind power tower base welding, as shown in Figure 2. Harbin Welding Co., Ltd. is the first in the country to master the core technology and equipment integration technology of high-power solid laser-melting electrode arc hybrid heat source welding. It is the first time to successfully apply high-power solid laser-dual-wire melting electrode arc hybrid welding technology and equipment to high-end equipment in my country. manufacturing.
Figure 2. Laser installation layout diagram
According to the current research status of laser-arc hybrid welding of thick plates at home and abroad, it can be seen that the combination of laser-arc hybrid welding method and narrow gap groove can achieve the welding of thick plates. When the laser power increases to more than 10,000 watts, under the irradiation of high-energy laser, the vaporization behavior of the material, the interaction process between laser and plasma, the stable state of the molten pool flow, the heat transfer mechanism, and the metallurgical behavior of the weld Changes will occur to varying degrees. As the power increases to more than 10,000 watts, the increase in power density will intensify the degree of vaporization in the area near the small hole, and the recoil force will directly affect the stability of the small hole and the flow of the molten pool, thereby affecting the welding process. The changes have a non-negligible impact on the implementation of laser and its composite welding processes. These characteristic phenomena in the welding process directly or indirectly reflect the stability of the welding process to some extent, and can even determine the quality of the weld. The coupling effect of the two heat sources of laser and arc can make the two heat sources give full play to their own characteristics and obtain better welding effects than single laser welding and arc welding. Compared with the laser autogenous welding method, this welding method has the advantages of strong gap adaptability and large weldable thickness. Compared with the narrow gap laser wire filling welding method of thick plates, it has the advantages of high wire melting efficiency and good groove fusion effect. . In addition, the attraction of the laser to the arc enhances the stability of the arc, making laser-arc hybrid welding faster than traditional arc welding and laser filler wire welding, with relatively high welding efficiency.
03 High-power laser-arc hybrid welding application
High-power laser-arc hybrid welding technology is widely used in the shipbuilding industry. Meyer Shipyard in Germany has established a 12kW CO2 laser-arc hybrid welding production line for welding hull flat plates and stiffeners to achieve the formation of 20m long fillet welds in one go and reduce the degree of deformation by 2/3. GE developed a fiber laser-arc hybrid welding system with a maximum output power of 20kW to weld the USS Saratoga aircraft carrier, saving 800 tons of weld metal and reducing man-hours by 80%, as shown in Figure 3. CSSC 725 adopts a 20kW fiber laser high-power laser-arc hybrid welding system, which can reduce welding deformation by 60% and increase welding efficiency by 300%. Shanghai Waigaoqiao Shipyard uses a 16kW fiber laser high-power laser-arc hybrid welding system. The production line adopts a new process technology of laser hybrid welding + MAG welding to achieve single-sided single-pass welding and double-sided forming of 4-25mm thick steel plates. High-power laser-arc hybrid welding technology is widely used in armored vehicles. Its welding characteristics are: welding of large-thickness complex metal structures, low cost, and high-efficiency manufacturing.
Figure 3. USS Sara Toga aircraft carrier
High-power laser-arc hybrid welding technology has been initially applied in some industrial fields and will become an important means for efficient manufacturing of large structures with medium and large wall thicknesses. At present, there is a lack of research on the mechanism of high-power laser-arc hybrid welding, which needs to be further strengthened, such as the interaction between photoplasma and arc and the interaction between arc and molten pool. There are still many unresolved problems in the high-power laser-arc hybrid welding process, such as a narrow process window, uneven mechanical properties of the weld structure, and complicated welding quality control. As the output power of industrial-grade lasers gradually increases, high-power laser-arc hybrid welding technology will develop rapidly, and a variety of new laser hybrid welding technologies will continue to emerge. Localization, large-scale and intelligentization will be important trends in the development of high-power laser welding equipment in the future.
Post time: Apr-24-2024
