Learning more about laser beam welding by applying it to copper and copper alloys

Welding of copper is generally considered to be difficult, particularly due to its high heat conductivity. During welding with high-power lasers the low absorptance of the near and even more the far IR wavelengths means an additional hurdle. Resulting back reflections can be hazardous for optics, beam guidance and laser source. On the other hand copper and its alloys gain in importance e.g. in view of the coming electro-mobility and therefore also related joining methods for well conducting, fatigue-proof, corrosion resistant and sealing connections are sought after. This is a good reason to systematically investigate copper material welding capabilities of the latest generation of fiber-coupled lasers at powers up to 10 kW. Results achieved at Fraunhofer ILT reveal new insights in the physics of laser welding by showing the scaling laws for the influence of parameters such as beam power, intensity and material properties on welding depth versus speed. Consequences for practical copper and copper alloy joints are derived and demonstrate the high potential of laser welding solutions.