回転曲げを受けるFCD60の中高温における微小き裂の発生と進展の両挙動

概要

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Rotating bending fatigue tests of a spheroidal graphite cast iron with a pearlite matrix were performed in the rage from room temperature to 450℃. The behavior of both the nucleation and the propagation of a small surface cracks were observed. The fatigue limits were verified to be the critical stress required to propagate the microcracks nucleated in the material faults of the graphites and shrinkage pores. Because of the retardation effect in crack propagation stage due to cyclic strain aging, the maximum value of the fatigue limits and the maximum length of nonpropagating cracks observed in unbroken specimens were seen at about 350℃. At all testing temperatures, the values of threshold stress intensity factor range calculated by incorporating the values of fatigue limits and the length of nonpropagating cracks were decreased down to about 0.38 when compared to the values of CT specimens with a long crack represented by the effective stress intensity factor range.
一般社団法人日本機械学会の論文
1987-08-25