Host: The Japan Society of Mechanical Engineers
Name : [in Japanese]
Date : September 08, 2019 - September 11, 2019
Creep damage gradually progress during operation especially at weldment parts of 2.25Cr steel boiler pipes. Since the creep strength of welded joints is significantly lower than that of the base metal, it is necessary to develop creep damage assessment method. In this study, in order to clarify influence of a long-term operation on creep strength of a welded joint, creep tests were performed using standard welded joint specimens and miniature welded joint specimens taken from a welded joint in a long-term used boiler header. Creep rupture times of the standard welded joint specimens were similar to those of the new welded joints. Rupture times of the miniature welded joint specimens were within the scatter of the standard welded joint specimens suggesting that creep rupture time of the standard welded joint specimen can be predicted by a rupture time of the miniature welded joint specimen. Different levels of creep damaged welded joint specimens were produced by interrupted creep tests. Creep voids were observed mainly from the coarse grain to the weld metal. From creep test results of the miniature welded joint specimen taken from creep damaged standard welded joint specimen, it was demonstrated that creep damage greater than medium level can be evaluated by the miniature welded joint creep specimen.
