3. Laser welding

3.1 Laser planing

In laser butt welding, gaseous or liquid residues resulting from coating degradation are easily evacuated to either side of the assembly, and do not induce defects in the weld. On the other hand, the presence of the coating modifies the laser/material coupling, notably via surface reflectivity. Zinc is brighter than bare steel, so more of the beam's energy is reflected. Welding speeds must therefore be reduced, and/or energies increased, in the presence of a metallic coating. Organic coatings, on the other hand, generally have a matt...