Bolt for projection welding and method of welding the same

Abstract

Provided are a bolt for projection welding and a method of welding the same in which a portion of large fusion depth is formed in a small region and in which junction to a steel sheet part is secured in other regions, thereby realizing high weld strength and stable junction state. A bolt includes a shaft part, an enlarged diameter part, and a fusion bonding projection, the fusion bonding projection including an initial fusion part having at an end surface thereof a tapered portion and a main fusion part continuous with the initial fusion part. Energization with welding current for fusing the fusion bonding projection only is effected on the fusion bonding projection, and in which through pressurization of the fusion bonding projection against a steel sheet part and subsequent energization thereof, a region of the fusion bonding projection is fusion-bonded to the steel sheet part, and an end surface of the enlarged diameter part on the outer peripheral side thereof is brought into junction with a surface of the steel sheet part. With this structure, it is possible to realize a satisfactory welding in an appropriate fused state.