Laser pressure welding of copper

Industrial application of copper often requires a joining. Unfortunately, a commercial laser welding of this material is challenging due to extremely high reflectivity of copper at the near-infrared wavelength. In this work, the sound copper joints were produced at relatively high welding speed of 15 m/min by using a pressure-assisted fiber-laser welding. It was theoretically shown that the material melting arisen from a convergence of multiple reflections of the laser beam. By using electron backscatter diffraction (EBSD), it was found that microstructural changes were induced by a laser-induced thermal effect as well as a roller-induced pressure. It was deduced that the molten material solidified before feeding to the pressure rolls and thus it experienced a notable plastic strain during the welding process. The present work provides an effective method for commercial joining of high-reflective metals by using the near-infrared fiber laser.