Journal of the Korean Society for Nondestructive Testing (비파괴검사학회지)

The Korean Society for Nondestructive Testing (한국비파괴검사학회)
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Feasibility Study on Ultrasonic Velocity for Evaluation of Microstructure and Quality of Cast Iron

초음파 속도 측정에 의한 주철의 미세구조 및 품질평가 가능성 검토

  • Choi, C.Y. (Department of Materials Science & Engineering, Seoul National University of Science & Technology) ;
  • Hyun, C.Y. (Department of Materials Science & Engineering, Seoul National University of Science & Technology) ;
  • Byeon, Jai-Won (Department of Materials Science & Engineering, Seoul National University of Science & Technology)
  • 최찬양 (서울과학기술대학교 신소재공학과) ;
  • 현창용 (서울과학기술대학교 신소재공학과) ;
  • 변재원 (서울과학기술대학교 신소재공학과)
  • Received : 2012.02.10
  • Accepted : 2012.04.13
  • Published : 2012.04.30
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Abstract

It was attempted to evaluate the microstructure and quality of various types of cast iron by ultrasonic velocity measurement. Three types of commercial gray cast iron and ductile cast iron were used for this investigation, respectively. One type of the ductile cast iron was heat-treated as a function of annealing time to produce different microstructure. Ultrasonic velocity measurement, microstructural analysis (pearlite area fraction, graphite length and nodularity), and hardness measurement were performed to find empirical correlations among these parameters. Ultrasonic velocity of ductile cast iron was markedly faster than that of gray cast iron. Ultrasonic velocity decreased with the decrease of fraction of pearlite structure. As a quality monitoring parameter of cast iron, potential of ultrasonic velocity was suggested.

초음파 속도를 이용하여 다양한 종류의 주철에 대해 미세구조와 품질 특성을 평가하였다. 상용으로 사용되는 3종의 회주철 및 3종의 구상흑연주철을 준비하였으며, 열처리 미세구조의 영향을 평가하기 위해 구상흑연주철을 어닐링 열처리를 다르게 하여 시편을 준비하였다. 초음파 전파 속도 측정, 미세구조(펄라이트 분율, 흑연의 길이 및 구상화율) 정량화, 경도 측정을 행하여 이들 파라미터 사이의 경험적 상관관계를 확인하였다. 구상흑연주철의 초음파 전파 속도가 회주철에서의 속도보다 크게 나타났다. 구상흑연주철에서 펄라이트 미세조직의 분율이 감소할수록 경도 및 초음파 속도는 감소하였다. 초음파 속도를 주철 소재의 품질관리를 위한 비파괴평가 파라미터로서 사용할 수 있는 가능성을 보여주었다.

Keywords

References

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