| As a good conductive, thermal conductivity, corrosion resistance material, copper is widely used in the every aspect of production and life. The welding of copper is an important part of the application of copper. At present, the tradition welding methods of copper, such as tungsten argon arc welding, friction stir welding, etc, cannot meet the increasing demanding environment. This paper apply fiber laser welding in the welding of copper, choose 2mm thick T2 copper as the research object, carry out laser welding experiment and preheating laser welding of copper, and research the influence of different laser welding parameters and preheating temperature on microstructure and properties.The experimental results show that the laser power, welding speed and defocus amount have significant impacts on the microstructure, microhardness, conductivity and corrosion resistance. The microstructure of weld is fine equiaxed grain, the microstructure of fusion zone is cellular dendrite; the maximum microhardness occurs in weld zone, the microhardness decreases first and then increases from weld zone to base material, and the minimum microhardness occurs in heat affected zone; grain refinement results in the decrease of conductivity of the welded joint, but the impact is not big; the appropriate welding parameters can significantly improve the corrosion resistance of welded joint.The preheating temperature before welding has a direct influence on the microstructure and properties of welded joint. When the temperature are 100℃ and 150℃, the microstructure of weld is fine equiaxed grain, when the temperature is 200℃, the microstructure of weld is α-Cu; when the other welding parameters are constant, preheating reduces the maximum microhardness of welded joint, and reduces the tendency of hardenability; preheating increases the grain size, which improves the conductivity of welded joint; the appropriate preheating temperature before welding can also improve the corrosion resistance of welded joint. |
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