The aluminum alloy laser welding process is a new technology. Compared with the traditional welding process, it has the characteristics of strong function, high reliability, no vacuum conditions and high efficiency. It has the advantages of large power density, low total heat input, large penetration depth of the same heat input, small heat affected zone, small welding deformation, fast speed, and easy industrial automation. It has a large application advantage especially for heat-treated aluminum alloy.
It can increase its processing speed and greatly reduce heat input, which can improve production efficiency and improve welding quality. When welding high-strength and large-thickness aluminum alloys, single-pass welding is impossible at all by traditional welding methods, and a keyhole with a large depth is formed during laser deep welding, and the keyhole effect can be achieved.
Advantages of laser welding aluminum alloy
1. High energy density, low heat input, small amount of heat deformation, narrow melting zone and heat affected zone and large melting depth;
2. The high cooling rate results in a micro-welded structure and good joint performance;
3. Compared with contact welding, laser welding does not use electrodes, so it reduces man-hours and costs;
4. The vacuum atmosphere during electron beam welding is not required, and the shielding gas and pressure can be selected. The shape of the workpiece to be welded is not affected by electromagnetics and does not produce X-rays;
5. Welding of metal materials inside closed transparent objects;
6. The laser can use optical fiber for long-distance transmission, so that the process is adaptable, and with the computer and manipulator, it can realize the automation and precision control of the welding process.
Laser welding aluminum alloys need to pay attention to the following issues
1. Due to the small absorption rate and high thermal conductivity, in the actual aluminum alloy welding process, it is necessary to ensure good beam focusing, and at the same time, high-energy laser beams with high power density should be used for irradiation.
2. During laser welding of aluminum alloys, deep penetration welding occurs, and the laser function must reach a specific threshold, which imposes certain requirements on the laser and is also a difficult point of laser welding. The ionization energy of aluminum alloy is low, and the photo-induced plasma is easy to overheat and diffuse during welding of some brands, and the welding stability is poor.
3. Welding aluminum alloys must require high energy density of the laser beam and good beam focusing performance. Aluminum alloys are typical eutectic alloys. The rapid solidification S in laser welding, or the small holes are blown out of the molten pool by the plasma sprayed out before the small holes are formed to form the so-called spray holes.
4. The liquid aluminum alloy has good fluidity and low surface tension. The instability during the welding process causes the welding pool to oscillate violently, which is prone to undercutting and molding discontinuity. A process hole with a larger diameter is generated in the weld, or a small hole is blown out of the molten pool by the plasma sprayed out before the hole is closed to form a so-called spray hole.
