Let's explain how to improve the welding process of aluminum alloy.

How to improve the welding process of aluminum alloy

Aluminum alloy has good corrosion resistance, electrical conductivity, thermal conductivity and high strength characteristics. It is a widely used non-ferrous metal structural material in industry, and is widely used in aviation, aerospace, automobile, machinery manufacturing, shipbuilding and chemical industries.

With the rapid development of science and technology and industrial economy in recent years, the demand for aluminum alloy welded structures is increasing, and the research on weldability of aluminum alloy is becoming more and more in-depth. The wide application of aluminum alloy promotes the development of aluminum alloy welding technology, and the development of laser welding technology expands the application field of aluminum alloy.

1. Physical and chemical properties of aluminum alloy material itself

Aluminum alloy material has high reflectivity and high thermal conductivity. From the perspective of microelectronic structure, aluminum alloy has many free electrons, and the density is not high. When laser acts on this kind of electrons, it will produce strong vibration and secondary electromagnetic wave, which will produce strong reflection wave and weak transmission wave. Therefore, the strong reflectivity of aluminum alloy surface to laser will affect the absorption rate of laser, At the same time, due to the violent Brownian motion of electrons, the thermal conductivity of aluminum alloy material will be significantly improved.

a lot of research on laser welding of aluminum alloy materials has been carried out in china, and the results show that the welding of aluminum alloy materials requires surface pretreatment such as sandblasting, sandpaper treatment, surface chemical etching, surface electroplating, carbon black addition, oxidation and so on. in addition, considering the design of welding structure, the v-shaped wave port is opened by manually opening holes on the surface of aluminum alloy or using joints in the form of light collectors, or use the method of welding (the connection gap is equivalent to manual opening), so as to manufacture aluminum. In addition, the laser energy absorption of the aluminum alloy surface can also be increased by using a reasonably designed welding gap.

2. Effect of orifice effect and plasma on laser welding of aluminum alloy

In the process of laser welding of aluminum alloy, the appearance of small holes can greatly improve the absorption rate of the material to the laser, and the welding can obtain more energy, while the aluminum element and the Mg, Zn, and Li in the aluminum alloy have low boiling points, easy evaporation, and vapor pressure Large, although this helps the formation of small holes, however, the cooling effect of the plasma (plasma shielding and absorbing energy, laser energy input to the base metal is reduced) will make the plasma itself "overheat", but because it hinders the continuous existence of small holes, it is easy to produce welding defects such as pores, which affects the mechanical properties of welding forming and joints. Therefore, the induction and stability of small holes become the key to ensure the quality of laser welding.

Due to the high reflectivity and high thermal conductivity of aluminum alloy, the formation of induced holes requires a higher energy density of the laser. Since the energy density threshold is essentially controlled by the alloy composition, the laser power is determined by controlling the process parameters to ensure appropriate input heat, and a stable welding process can be obtained. In addition, the energy density threshold is also affected by the type of protective gas to some extent.

I 'd like to introduce you to the welding process of high aluminum alloy. I wish you a happy life!