Development of Control Technology of Austempered Ductile Iron with High Strength and High Toughness for Gear Parts.

고강도 ADI의 기어부품 개발에 관한 연구

  • Kim, Won-Yong (Department of Metallurgical Engineering, In-ha University) ;
  • Kim, Kwang-Bae (Department of Mechanical Engineering, Hang-gong University) ;
  • Kang, In-Chan (Department of Metallurgical Engineering, In-ha University) ;
  • An, Sang-Uk (Department of Mechanical Engineering, In-ha University)
  • 김원용 (인하대학교 공과대학 금속공학과) ;
  • 김광배 (항공대학교 재료공학과) ;
  • 강인찬 (인하대학교 공과대학 금속공학과) ;
  • 안상욱 (인하대학교 공과대학 기계공학과)
  • Published : 1993.04.20

Abstract

In this study, it was examined the relationship between the microstructure, fatigue properties, mechanical properties and retained austenite volume of Mo-Ni ADI corresponding to various austempering temperatures. When the austempering temperature is increased to $370^{\circ}C$, acicular bainite structure was found to be transformed to feathery bainite structure. But at the austempering temperature of $420^{\circ}C$, the dissolved bainite lath was showned. Up to the austempering temperature of $370^{\circ}C$, the volume of retained austenite was increased. However at the austempering temperature of $420^{\circ}C$ a large amount of retained austenite was decreased. In this study, the retained austenite volume was determined by XRD(X-ray diffraction). It was observed that the optimum fatigue properties can be obtained at the condition of austempering temperature $370^{\circ}C$. Under the such conditions, fatigue limit determined as the value of 290 MPa, tensile strength 877MPa elongation 6%, hardness 285(BHN), impact values(CVN) 9.2J and retained austenite volume 30.3%, respectively.

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