Fractal Analysis of Fracture Surfaces in Materials Crept at High Temperatures or Fatigued by Repeated Bending

摘要

Fracture processes of materials can be known to some extent by detecting characteristic patterns such as striations or river patterns on the fracture surface with a scanning electron microscope (SEM). However, such characteristic patterns are not visible on the fatigue fracture surfaces of high-strength materials such as SUS631 steel! as well as on the creep fracture surfaces of heat-resistant alloys.” Frac- ture surface topography analysis (FRASTA), which relies on the matching of paired fracture surfaces on a computer monitor, is known to be useful for reproducing the fracture process in materials.*’ Unfortunately, it is difficult to apply FRASTA to fatigue fracture surfaces when their morphol- ogy changes by cyclic compressive loading! or to creep fracture surfaces that are severely oxidized at high tempera- tures.” Therefore, it is necessary to develop a new fractog- raphy that is applicable to any fracture surface in materials.