高V-Cr-Ni鋳鉄の疲労挙動に関する基礎的研究

抄録

This paper describes the fatigue behaviour of a high V-Cr-Ni cast iron. Rotating bending fatigue tests have been performed using smooth specimens in laboratory air at ambient temperature. The obtained results were compared with the fatigue behaviour of three types of nodular cast irons, FCD450, FCD700 and ADI, and fracture mechanisms were discussed on the basis of crack initiation behaviour and fracture surface analysis. The high V-Cr-Ni cast iron showed superior fatigue strength to the nodular cast irons and the fatigue strength characterized in terms of fatigue ratio was also significantly higher than that of the nodular cast irons. Fatigue cracks initiated at inclusion, casting defect and cluster of VC carbides, of which cluster of VC carbides was the predominant crack initiation site. In small crack region following the crack initiation, cracks grew avoiding VC carbides, indicating that VC carbides acted as a barrier to the growth of small cracks.