Welding structure of press formed part, structural part for automotive body including the welding structure, and method for manufacturing welding part (as amended)

A method for manufacturing a welding part that is made by combining and joining two parts that are formed by press-forming and that each have an opening portion on at least one side of a cross-section, while the opening portions face each other, the method comprising:

• a bent-projection-forming step of providing a step portion by forming a bent projection at a location corresponding to a tip end portion of a side wall portion on a blank sheet in one part;
• a first press-forming step of manufacturing one part having an opening portion by forming the side wall portion of the blank sheet on which the bent projection is formed;
• a second press-forming step of manufacturing another part having an opening portion by forming a side wall portion on a blank sheet;
• and
• a joining step of linearly joining the step portion of the one part and a tip end of the side wall portion of the other part, by fitting a tip end side of the step portion of the one part into the opening portion of the other part, by arc welding.