타이어 보강용 고 탄소강 미세 강선의 굽힘 피로 성질에 미치는 미세 조직의 영향

The Effects of Microstrucutral Parameters on Bending Fatigue Properties of Heavily Drawn Pearlitic Steel Filaments used for Automotive Tires

  • 양요셉 (포항공과대학교 신소재공학과) ;
  • 임승호 (고려강선(주) 기술연구소) ;
  • 반덕영 (고려강선(주) 기술연구소) ;
  • 박찬경 (포항공과대학교 신소재공학과)
  • 발행 : 2005.10.01

초록

Influences of microstructure on high-cycle fatigue (HCF) limit of high carbon $(>0.7wt.\;\%)$ steel filaments used for tires have been investigated. A series of the fatigue tests was carried out depending on carbon content by using Hunter-type tester at a frequency of 60 Hz at a tension/compression stress of 900 to 1500 MPa. Microstructural changes of the filaments were identified in the lateral direction by using transmission electron microscopy (TEM). It was found that the mechanical properties, such as fatigue limit and tensile strength, were improved with increasing carbon content, which was mainly attributed to decreased lamellar spacing and cementite thickness. However, the fatigue ratio, which is defined as the ratio of the fatigue limit to the tensile strength, was reduced in a higher carbon range of 0.8 to $0.9\;wt.\%$, while the fatigue ratio was nearly constant in a lower carbon range of 0.7 to $0.8\;wt.\%$. Overall mechanical properties of the filaments, depending on carbon content, have been discussed in terms of the microstructural parameter change of lamellar spacing and cementite thickness. In addition, the variation of cementite morphology on the fatigue crack propagation of high carbon $(0.9wt.\;\%)$ filaments will be discussed.

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