Laser surface patterning for increased joining strength in laser fusion bonding of CFRP and metal

In this study, we present increased fusion bonding strength between thermoplastic CFRP and zinc-coated steel through laser surface patterning. Optimization of the clamping pressure in addition to the laser processing parameters including output power, focal position, weld pitch, scan path was done prior to introducing the laser patterns. It was found that for the welded samples, after applying rectangular grid surface patterns on the zinc-coated steel sheets, the tensile shear strength increased by up to 100 % compared to that of the samples without surface structures. It was also found that the number of scan passes, the laser power and the pitch of the grid are the key parameters in determining the fusion bonding strength.