Laser marginal lap microwelding for ultrathin sheet metal

Butt welding is practically difficult for sheet metals as thin as 50–100 μm. A new concept called marginal lap welding is developed in this study to produce continuous and distortion-free welds for such thin sheets. The energy loss due to heat conduction into the clamps becomes significant under this situation, and therefore, the input laser power to produce an effective weld increases. This article investigates the effects of heat loss during marginal lap welding of ultrathin stainless-steel (SS316L) sheets experimentally and theoretically. A mathematical model is developed to calculate the amount of conduction heat loss and the weld geometry. The results show that a smaller clamp gap causes more heat loss into the clamps and generates a narrow heat-affected zone, which is found to be beneficial to the corrosion resistance of the weldment.