Difficulties In Applying Laser Welding Technology To Copper Welding

Common problems when copper welding:

(1) Difficulty in fusion and variability: Due to the relatively large thermal conductivity of red copper, the heat transfer rate is very fast during welding, and the overall heat-affected zone of the weldment is also large, making it difficult to fuse the materials together; and due to the linear expansion coefficient of red copper It is very large. When welding is heated, improper clamping force of the clamp will cause the material to deform.

(2) Porosity is prone to occur: Another important problem that occurs during copper welding is pores, especially when deep penetration welding is more serious. The generation of pores is mainly caused by two situations. One is the diffusive pores directly produced by the dissolution of hydrogen in the copper, and the other is the reaction pores caused by the redox reaction.

Solution:

The absorption rate of infrared laser by red copper at room temperature is about 5%. After heating to near the melting point, the absorption rate can reach about 20%. To achieve laser deep penetration welding of red copper, the laser power density must be increased.

Using a high-power laser coupled with a swing welding head, the beam is used to stir the molten pool and expand the keyhole during deep penetration welding, which is beneficial to gas overflow, making the welding process more stable, with less spatter, and fewer micropores after welding.