Laser welding of zinc coated steels in an edge lap configuration

Ever increasing amounts of zinc coated sheet steel are being applied in the automotive industry. At present, the main joining method used for this application is resistance spot welding. In many automotive applications there are opportunities for replacing this technique by laser welding. During the assembly of these sheets major problems arise when welding in overlap configuration as result of the low boiling temperature of zinc in comparison to the melting temperature of steel. This results in pores and/or blowholes in the weld due to instabilities during welding. In this article research is presented which shows the possibilities of welding these zinc coated steel sheets in an edge lap configuration without present gap. In this configuration the zinc vapor between the sheets has an alternative escape route other than through the weld pool and it is shown that the amount of spatter can be controlled when using such a joint configuration.