抄録
The fracture modes, i.e., brittle fracture and ductile fracture are studied comparing the criteria in macroscopic and microscopic aspects. As the macroscopic criterion, the critical stress intensity factor is used. As the microscopic criterion, the idea of fractal is applied to the profile of fracture surfaces. In this study, the three points bending fracture tests of cracked specimens were carried out using S45C, S55C and FC20. The relationship between the fracture modes and the fractal dimension of the fracture surfaces is discussed.
