Method of manufacturing welded structure of ferritic heat-resistant steel and welded structure of ferritic heat-resistant steel

摘要

A method of manufacturing a welded structure of a ferritic heat-resistant steel is provided that prevents Type IV damage and that has good on-site operability without adding a high B concentration. The method includes: the step of preparing a base material including 1.0 to 7.0% Cr, less than 0.005% B and other elements; the step of forming an edge on the base material; a pre-weld heat treatment step in which a region located between a surface of the edge and a position distant from the surface of the edge by a pre-weld heat treatment depth of 10 to 50 mm is heated to a temperature of 950 to 1050° C. and is held at this temperature for 10 to 30 minutes; a welding step in which the edge is welded to form the weld metal; and a post-weld heat treatment step in which a region located between the surface of the edge and a position distant therefrom by a distance not smaller than the pre-weld heat treatment depth and not greater than 100 mm is heated to a temperature of 680 to 750° C. and is held at this temperature for a time period not shorter than 30 minutes and satisfying the following formula, (1):(Log(t)+10)·(T+273)<10539  (1).