Aluminum alloys have the advantages of low density, high strength and good corrosion resistance, so they are widely used in the automotive industry, new energy and construction industries. At present, laser welding machines have been widely used in the production of aluminum alloy products. Compared with traditional welding methods, laser welding technology can provide higher production efficiency, better weld quality, and achieve high-precision welding of complex structures.

 

According to the thermal action mechanism of laser welding, it can be divided into two types: thermal conduction welding and deep penetration welding. Among them, aluminum alloy welding is mainly by deep penetration welding. Laser deep penetration welding is mainly used in the welding of materials that require complete penetration, and is currently the most widely used laser welding method.

 

Due to the inherent physical properties of aluminum alloys, some defects are prone to occur during the laser welding process. Among them, porosity is the most likely problem in the process of laser welding aluminum alloy, which will reduce the mechanical properties and corrosion resistance of the weld. Therefore, in the process of laser welding, effective measures must be taken to prevent the generation of pores and improve the internal quality of the weld. Here are a few ways to inhibit stomata generation.

 

Treating the metal surface before laser welding is an effective method to control the occurrence of porosity in aluminum alloy welding. Usually surface treatment methods include physical mechanical cleaning and chemical cleaning. After the surface treatment of the aluminum alloy material, laser welding should be carried out within 24 hours. When the material stays for a long time, the surface should be wiped with anhydrous alcohol before welding.

 

The formation of welding pores is not only related to the quality of the surface treatment of the welded workpiece, but also related to the parameters of the laser welding process. The influence of welding parameters on weld porosity is mainly reflected in the penetration of the weld, that is, the influence of the back-to-width ratio of the weld on the porosity.

It can be seen from the welding test that the concentration distribution of chain pores in the weld can be effectively improved when the back-to-width ratio of the weld is greater than 0.6. When the back-to-width ratio is greater than 0.8, the existence of large pores in the weld can be effectively improved, and the residual of the pores in the weld can be largely eliminated.

 

During the laser welding process, the correct blowing of the shielding gas can effectively reduce the porosity of the weld. The selection of shielding gas will directly affect the quality, efficiency and cost of laser welding.

The weld surface is protected with Ar (argon) and He (helium). In the process of laser welding aluminum alloy, the ionization degree of argon and helium to the laser is different, resulting in different welding seam formation. The results show that the overall porosity of the weld obtained by selecting argon as the shielding gas is lower than that obtained when helium is selected as the shielding gas.

At the same time, it should be noted that the large amount of plasma generated by welding cannot be blown away when the airflow rate is too small (10L/min), which makes the welding pool unstable and increases the probability of porosity formation. The gas flow is moderate (about 15L/min) and the plasma is effectively controlled, and the protective gas has a good anti-oxidation effect on the molten pool, with the fewest pores. Excessive gas flow is accompanied by excessive gas pressure, so that part of the shielding gas is mixed into the interior of the bath, which increases the porosity.

 

Affected by the performance of the aluminum alloy material itself, the phenomenon of no porosity in welding cannot be completely avoided during the laser welding process, but the porosity can only be reduced. Through the above three methods, I hope to help you better complete the laser welding process of aluminum alloy products.