Abstract
The fatigue limit did not appear within the range of 10^8 cycles at temperatures higher than 500℃ as a result of the high temperature rotary bending test of modified 9Cr-1Mo steel. It was clarified that fatigue cracks always started at the surface of the samples regardless of the existence of inclusions. Therefore, in order to discuss the mechanism of the crack initiation, the change of the micro texture of the alloy under the fatigue loading at elevated temperature was evaluated quantitatively by applying an EBSD method. As a result, both the reduction of the misorientation and change in the martensite structure were observed at the surface of the damaged specimens.
