Quantitative Evaluation for the Internal Defect Size Governing the Fatigue Life in Ductile Irons

구상흑연주철의 피로수명을 지배하는 내재결함부 크기는 정량적 평가

  • 김진학 (목포대학교, 기계공학부) ;
  • 김민건 (강원대학교, 메카트로닉스공학부)
  • Published : 2000.11.01


In this study, the quantitative evaluation was performed by examination for gatigue crack origin in two prepared ductile irons specimens which have different microstructures using rotary bending fatigue tester, Series A has mixed microstructure. ferrite plus pearlite, and series B has bainitic microstructure. Obtained main results are as follows. The scatterings of fatigue strength were observed on σ(sub)α-Ν diagram of both specimen series, and it is observed that scatterings of series A were more serious. It is reasonable to evaluate the size of mesocrack range by means of √A(원문참조), where A means the area of mesocrack range including globular graphite nodule. As a result of reconsideration for the fatigue data by introduction of K(sub)α-Ν diagram, the scattrings of fatigue life were, remarkably. reduced. Therefore, it is more reasonable to evaluate of mesocrack range on fatigue life by parameter K(sub)α rather than σ(sub)α.


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