Aluminum and aluminum alloys are widely used in construction, transportation, automobiles, electronics, packaging, aerospace and other fields due to their light weight, high strength and corrosion resistance. With the development of technology, aluminum alloy welding processes have been improved. Laser welding is a commonly used welding technology in the market. It has the advantages of concentrated high-power heat source, 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 of aluminum and aluminum alloys will be difficult to control the laser focus and molten pool; when the welder sets the process parameters improperly or lacks rich experience, pores, cracking deformation, and weld seam development may occur. Problems such as black spots and undercuts that do not blend have seriously affected the welding quality and performance. Next, we will introduce to you the difficulties encountered in welding aluminum materials and their solutions.
The main problem encountered when laser welding aluminum is porosity. During the welding process, the laser beam causes metal fluctuations in the molten pool. When the gas trapped in the metal expands and overflows, pores will appear; in addition, the aluminum oxide film will hinder the bonding between metals, absorb moisture and easily produce impurities, prompting Form pores.
The occurrence of pores will cause the weld strength to weaken, reduce corrosion resistance, and make the weld unsightly. In general, the following measures are recommended:
1. Adjust appropriate laser power to ensure uniform heat input.
2. When welding thin plates, it is recommended to increase the speed to reduce the time for gas to expand in the metal; when welding thick plates, when the material is preheated, the welding speed can be reduced to ensure weld performance.
3. Clean the weld surface chemically or mechanically to reduce the impact of impurities on welding quality.
4. Control the use of shielding gas or flux to reduce oxidation and reduce the amount of gas formed.
Due to the high temperatures generated during the welding process, aluminum can rapidly expand and contract, creating stress points. If the solidification interval of the weld is too short and the stress points are not released, they will cause the aluminum to crack and cause hot cracks. In addition, if the weld protection effect is not good, it will also be prone to oxidation and hot cracks.
To avoid this situation, we need to control the heat during the welding process, fully preheat the weldment before welding, and adjust the shielding gas.
Weld seam turns black
Blackening of aluminum during laser welding is mainly caused by insufficient laser power, failure to adjust the defocus to an appropriate value, or damage to the laser lens. In this case, the energy of the laser fails to reach the melting threshold of the oxide layer on the surface of the aluminum material, causing the aluminum to mix with air and impurities, causing the welding part to turn black.
In order to better obtain the quality and beauty of welding, during the aluminum welding process, Maxron Electromechanical recommends first choosing the appropriate power and setting the correct defocus amount; secondly, you can also check whether the protective lens is damaged.
Undercut not fused
When laser welding aluminum materials, discontinuous, rough and uneven weld beads are typical phenomena. The main reasons include excessive assembly gap of welding parts, laser spot deviation, insufficient laser power and excessive defocus.
First, we can reduce the root gap of the welded workpiece; secondly, adjust the laser beam focus to determine the correct spot position; in addition, we can also increase the laser power and adjust the defocus amount to ensure the welding after the aluminum is melted quality.
Due to the particularity of aluminum, other problems will also be encountered during laser welding. Before welding aluminum and aluminum alloys, we must not only consider the stability of the welding quality, but also the appearance of the 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 the automotive, aerospace and other fields.