METHOD FOR POST-HEAT TREATMENT FOR REDUCING PRIMARY WATER STRESS CORROSION CRACKING IN DISSIMILAR WELD SO AS TO IMPROVE MICROSTRUCTURE OF MATERIAL

摘要

The present invention relates to a method for post-heat treatment for reducing PWSCC in a dissimilar weld so as to improve the microstructure of a material, the method comprising: a step of heating the external surface of a dissimilar weld of a pipe to a temperature of 570℃ to 620℃; a step of maintaining the temperature of the heated state for 4 to 10 hours; and a step of having the inner surface of the dissimilar weld remain cool (at room temperature) by using cooling water or a sprinkler while the temperature of the outer surface of the weld is maintained at 570℃ to 620℃. The method produces a PWSCC resistance-increasing precipitate in the microstructure of the dissimilar weld and can prevent cracking therein and does not cause stainless steel sensitization.