抄録
Creep void number density is one of the most important parameters to evaluate life of steel. As it is difficult to observe all the area of steel's section, there is arbitrariness in the decision of observation area when measuring creep void number density. In this research, we investigated the effect of the arbitrariness. Firstly, using scanning electron microscope, we made two-dimensional distribution of creep void number density by observing heat affected zone, where it is known to have a lot of creep voids, of three internal creep test specimens which are made of modified 9Cr-1Mo steel. In addition, we modeled people's decision of observation area and applied it to the creep void number density distributions of the specimens, and calculated the minimum value of observation value in older to evaluate accuracy of people's creep evaluation. Finally, using its result, we evaluated the effect of the choice of observation area and the uncertainty of observer's decision.
