| 摘要 |
PURPOSE:To execute satisfactorily lap welding without removing a low boiling point substance layer which has covered a base metal, by providing a projecting part on at least one of each base metal to be welded, forming a gap in the periphery of a weld zone, and thereafter, executing arc welding. CONSTITUTION:A galvanized steel sheet 12 has a roughly OMEGA-shaped section, and projecting parts 18, 20 which have been protruded in the lower direction are formed in a slightly inner part than each side end. This galvanized steel sheet 12 is superposed on a plate-shaped galvanized steel sheet 10 and welded by supplying a welding wire 30 from a welding torch 28, and weld zones 22, 24 are formed. In this case, a galvanized layer which has covered both steel plates 10, 12 is boiled and vaporized by welding heat, but vaporized zinc is diffused into the air from a gap 26, therefore, it can be prevented that it is left in the weld zone and becomes the cause for generating a blowhole.
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