METHOD FOR WELDING TUBE BODY TO HEADER AND WELDED STRUCTURE OF HEADER WITH TUBE BODY WELDED THERETO

PROBLEM TO BE SOLVED: To provide a welding method and a welding structure that hardly cause cracks due to creep damage in a weld heat affected zone by long time use even if a main steam temperature exceeds 560°C and facilitate control of welding and heat treatment.SOLUTION: A welding method includes the steps of: laminating a welding metal layer 10 of a predetermined build-up height using a Ni-based alloy welding material at the position for attaching a heat transfer tube, on an outer diameter surface of a header 1 comprising a ferrite-based steel; working a tube hole 1a substantially in the center of the welding metal layer 10; forming one side of a groove on a height-direction end surface of the welding metal layer 10; and welding the heat transfer tube 4 to the header 1 by butt welding, the heat transfer tube 4 having the other side of butt groove formed on the end surface and comprising an austenitic stainless steel or Ni-based alloy, to the header 1 . Also, a welded structure is obtained by the method.