J0310304 ASME T92材厚肉継手から採取した大型クリープ試験片の破断時および途中止め時損傷評価

Abstract

Large sized creep rupture and interruption tests were performed for specimens made from ASME T92 thick plate weld joint. For one specimen, creep test was continued till rupture. For another specimen, creep test was interrupted at 60% and 70% of estimated creep life time, 10,000 hours. Rupture time was almost comparable to that of published creep data acquired by standard size specimens. Type IV damage was observed for both, ruptured and interrupted specimens. SEM observations revealed that a number of micro-voids were nucleated at grain boundary of FGHAZ. On the same specimen, growth and cross-linking of micro-voids, heavily damaged and almost separated grain boundaries and grain-sized voids were also observed. These microstructural features were considered to show Type IV damage evolution. An importance was indicated to detect and consider early stage damage, i.e. micro-voids, grain boundary separation, to evaluate residual life of actual component from the earlier stage of usage.