US Patent 10220885 Different material joining structure and different material joining method

The present invention is provided with a roof side rail, a side outer panel that is formed of a dissimilar metal material having a higher electrical conductivity than the roof side rail, and a metal layer that is formed of the same metal material as the roof side rail and is disposed between the roof side rail and the side outer panel. Forming a nugget, which is a joint portion, between the roof side rail and the metal layer by carrying out resistance welding with the metal coating disposed between the roof side rail and the side outer panel makes it possible to accommodate the enhanced strength of an iron member and to render prepared hole processing unnecessary.