A Proposal on Creep Damage Analysis of Welded Joint of Low-Alloy Steel Considering Microscopic Damage Progress

摘要

Creep damage analysis method of welded joint on the basis of the random fracture resistance model was proposed and was applied to the creep damage evaluation of welded joint of low alloy steel. Firstly a random fracture resistance of grain boundaries, an initiation and a growth driving forces of small defects, which were necessary in the above model, were determined considering the stress-dependent damage progress of the fine-grain HAZ material of 21/4Cr-1Mo steel. Secondly a procedure combining both the stress distribution in the welded joint and the random fracture resistance model was concretely proposed and was applied to the creep damage evaluation of the model test and the actual power piping. Experimental results of both the time history and the distribution of the number density of small defects in the welded joint were successfully reproduced by the proposed method.