At present, the consumption of non-ferrous metals in industrial manufacturing, red copper ranks second, second only to aluminum.
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Red copper is widely used in the construction industry, electrical, machinery manufacturing and other industries.
Red copper has good conductivity and thermal conductivity, excellent plasticity, and is easy to be processed by hot pressing and cold pressing.
With the continuous improvement of production demand, the application of red copper has been gradually expanded.
Laser welding has the advantages of high energy density, less molten metal, narrow heat-affected zone, high welding quality and high production efficiency.
It can effectively improve the production efficiency when applied to red copper welding and is gradually selected by more and more industries.
However, due to the low absorptivity of high anti-material to fiber laser, it is also difficult to process, which also has more requirements for laser source.
Common problems in red copper welding
(1) Difficult fusion and variability
Due to the large thermal conductivity of red copper, the heat transfer speed during welding is very fast, and the overall heat-affected zone of the weldment is also large, so it is difficult to fuse the materials together;
Due to the large linear expansion coefficient of red copper, the improper clamping force of the fixture will deform the material when welding is heated.
(2) Prone to porosity
Another important problem in red copper welding is porosity, especially in deep penetration welding.
The formation of pores is mainly caused by two conditions: one is the diffusive pores directly generated by the dissolution of hydrogen in red copper, and the other is the reactive pores caused by redox reaction.
At room temperature, the absorptivity of red copper to the infrared laser is about 5%, and when heated near the melting point, the absorptivity can reach about 20%.
In order to realize laser deep penetration welding of red copper, it is necessary to improve the laser power density.
Using high-power laser combined with swing welding joint, stir the molten pool and expand the keyhole with light beam during deep penetration welding, which is conducive to gas overflow, more stable welding process, less spatter and fewer micro pores after welding.
(1) During welding, the angle of the welded joint is inclined to prevent long-term retroreflection from damaging the laser.
(2) The laser power must reach the absorption value of red copper to prevent light from being reflected.
(3) The absorption value of red copper can be easily reached by the concentration of energy density ratio with a small core diameter.
(4) Swing welding can improve the surface quality of welding.