焊前预热对T2紫铜激光焊接接头组织和性能的影响

Effects of Preheating before Welding on Microstructure and Properties of Laser Welded T2 Copper Joint

对2mm厚T2紫铜板进行了未预热和不同温度预热(100,150,200℃)的光纤激光焊接,研究了焊前预热对该焊接接头组织和性能的影响。结果表明:与未预热的相比,150℃预热激光焊接接头的熔深和熔宽较大,焊缝的等轴晶和熔合区的胞状晶粒均较粗大;预热激光焊接接头焊缝的电阻率与未预热的相比有所降低,焊前预热改善了焊接接头的导电性能;150℃预热激光焊接接头的显微硬度总体上高于100,200℃预热的,显微硬度均随距焊缝中心距离的增大先减后增,焊缝中心的最大;随着预热温度的升高,焊缝的自腐蚀电流密度先增大后减小,耐腐蚀性能虽先减小后增大,但相差较小。

The 2 mm thick T2 copper was first non-preheated and preheated at different temperatures （100, 150,200 ~C） then welded by fiber laser. The influences of preheating before welding on the microstructures and properties of the welded joint were investigated.The results show that the fusion depth and width of the welded joint with preheating at 150 ~C were larger than those of without preheating and the equiaxed crystals in weld and cellular grains in fusion zone were coarser. The weld resistivity of the welded joint with preheating decreased comparing to those without preheating, indicating that the preheating improved the conductivity of the welded joint. The micro- hardness of the welded joint with preheating at 150 ~C was higher than that of at 100, 200 ~C. The micro-hardness first decreased then increased with the increasing distance from the weld center and that of weld center was the largest. With the preheating temperature increasing, the free corrosion current density of the weld first increased then decreased. The corrosion resistance first decreased then increased while the difference was very small.