抄録
Ultrasonic fatigue tests were carried out for high carbon chromium bearing steel, SUJ2, under two-step variable amplitude loading at a frequency of 20 kHz in order to investigate the growth of an interior crack. Since it is important to clarify the damage mechanisms under variable amplitude loading for practical applications, fatigue tests are conducted under repeated two-step variable amplitude loading. Cumulative damage values calculated by Miner's rule are relevant to the size of inclusions under repeated two-step variable amplitude loading. Characteristics of interior fatigue crack growth were determined by the fracture surface observations for beach marks and the ODA sizes.
