Experimental and numerical investigation of the effect of laser input energy on the mechanical behavior of stainless steel and polyamide joint in the LAMP joining method

The present study investigated the effect of laser input energy on the quality and mechanical behavior of a 304 stainless steel–polyamide 6 joint in the laser-assisted metal and polymer direct joining (LAMP) method experimentally and numerically. After the proposed heat transfer model was validated, it was determined whether there was an optimal amount of laser input energy that could produce a joint with favorable quality and mechanical behavior. Among different laser input energies used in this study, 28-J/mm energy can provide more uniform and extensive wetting of the metal surface by the polymer, while excessive polymer degradation in the joint zone was prevented. As a result, an optimal combination of strength and toughness of the joint would be achieved. Further, it was found that the crystallinity of the polymer in the joint zone had a significant effect on the joint toughness so that the maximum toughness of the joint was recorded for the laser input energy of 50 J/mm, despite the reduced effective joint area due to excessive thermal degradation of the polymer in the joint zone.