Aluminum and aluminum alloy with its light weight, high strength, corrosion resistance and other characteristics, is widely used in construction, transportation, automotive, electronics, packaging and aerospace and other fields. With the development of technology, aluminum alloy welding process has been improved. Laser welding is a widely used welding technology in the market, which has the advantages of high power heat source concentration, small heat affected zone, less deformation, energy saving and consumption reduction.
In the daily welding process, due to the special properties of aluminum, laser welding aluminum and aluminum alloy will be difficult to control the laser focus and weld pool. When the welder sets the process parameters improperly or lacks rich experience, there may be problems such as porosity, cracking deformation, black weld and non-fusion of the edge, which seriously affect the welding quality and performance. Next, we will introduce the difficulties and solutions encountered by welding aluminum.
Pores
The main problem encountered when using laser welding aluminum is porosity. During the welding process, the laser beam causes the metal in the molten pool to fluctuate, and when the gas trapped in the metal expands and overflows, the porosity will appear. In addition, alumina films will hinder the bonding between metals, absorb water and easily produce impurities, and promote the formation of pores.
The formation of pores will lead to weak weld strength, reduced corrosion resistance, and unattractive welds. In general, the following measures are recommended:
Adjust the appropriate laser power to ensure uniform heat input.
When welding thin sheets, it is recommended to increase the speed to reduce the time of gas expansion in the metal;
When welding thick plates, in the case of material preheating, the welding speed can be reduced to ensure the performance of the weld.
The weld surface is chemically or mechanically cleaned to reduce the impact of impurities on the welding quality.
Control the use of protective gases or fluxes to reduce oxidation and reduce the amount of gas formed.
Hot cracks
Due to the high temperature generated during the welding process, the aluminum will rapidly expand and contract, and produce stress points. If the weld solidification interval is too short, the stress point is not released, they will lead to aluminum cracking and then hot cracks. In addition, when the protection effect of the weld is not good, it will be easy to oxidize and appear hot cracks.
In order to avoid this situation, we need to control the heat during the welding process, fully preheat the welding parts before welding, and adjust the protective gas.
Weld blackening
Laser welding aluminum blackening is mainly caused by insufficient laser power, the defocusing amount is not adjusted to the appropriate value, or the laser lens is damaged. In this case, the energy of the laser fails to reach the melting threshold of the oxide layer on the surface of the aluminum, causing the aluminum to mix with air and impurities, resulting in blackening of the welding site.
In order to better obtain the quality and beauty of welding, it is recommended to first select the appropriate power and set the correct defocusing amount in the process of aluminum welding. Secondly, you can also check whether the protective lens is damaged.
The edge of the bite is not fused
When laser welding of aluminum, the weld path is discontinuous, rough and uneven, and uneven corrugating is a typical phenomenon. The main reasons are too large weld assembly gap, laser spot offset, laser power shortage and too large defocus.
First, we can reduce the root gap of the welding workpiece. Secondly, the laser beam focus is adjusted to determine the correct spot position. In addition, we can also ensure the welding quality of aluminum after melting by increasing the laser power and adjusting the focus position of the defocus amount.
Due to the particularity of aluminum, the process of laser welding will also encounter other problems. Before welding aluminum and aluminum alloys, we must not only consider the stability of welding quality, but also consider the appearance of welding. With the improvement of laser technology and aluminum manufacturing technology, the process of laser welding aluminum has also been greatly improved, providing a solid foundation for creating lightweight metal structural components in automotive, aerospace and other fields.
Xi'an Guosheng Laser Technology Co., Ltd. is a high-tech enterprise specializing in R&D, manufacturing and sales of automatic laser cladding machine, high-speed laser cladding machine, laser quenching machine, laser welding machine and laser 3D printing equipment. Our products are cost-effective and sold domestically and abroad. If you're interested in our products, please contact us at bob@gshenglaser.com.