抄録
In order to improve creep-fatigue life prediction technology based on the crack growth of 2¼Cr-Mo steel casting, an investigation was carried out to predict the cycle-to-failure of smooth specimens with the fatigue-crack-growth-rate data obtained with CT specimens, as well as to comprehend the crack growth behavior with fatigue tests and creep-fatigue tests.
The results obtained are as follows:
(1) The micro-crack-growth-rate property of the casting material can be evaluated with the growth-rate data obtained by the macro-crack-growth tests with CT specimens.
(2) There is good correlation between the behavior of the main crack growth and the life ratio for the surface crack growth behavior. In addition, the crack initiates at a relatively early stage of N/Nf=0.15 and the most part of the life is occupied by crack growth.
(3) The calculated growth curves of the micro-surface-cracks correspond comparatively well with the observed crack growth behavior. Thus, even when the crack propagation life is considered to govern the total life, the cycles-to-failure of the specimen level can be predicted accurately within a factor of 2.
