Abstract
The irregularity of shapes of fractured units with various lengths in a creep crack path on creep crack growth resistance were characterized based on the concept of the fractal and scaling effect. Furthermore, the general validity of this characterization for subcritical crack growth was proposed by comparing the obtained results with those in rock fracture. As a result, both the fracture unit length denoted as FA of creep cracking in metals and the characteristic scale of rock fracture were found to have fractal dimensions that show both have the same scale effect. These results will promote that the possibility of a unified scientific description of the effect of geometrical morphology of various subcritical crack growth patterns will be possible on the basis of the concept of the fractal and characteristic scale effect.