Journal of the Korean Society for Heat Treatment (열처리공학회지)

The Korean Society for Heat Treatment (한국열처리공학회)
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Effect of Retained Austenite on Rolling Contact Fatigue of Nitrocarburized High-Carbon Chromium Bearing Steel

침질탄화처리한 고탄소 크롬 베어링강의 회전접촉 피로거동에 미치는 잔류오스테나이트의 영향

  • Choi, Byung Young (School of Advanced Materials Engineering, Research Institute of Advanced Materials Development, Chonbuk National University) ;
  • Kim, Dong Keon (School of Advanced Materials Engineering, Research Institute of Advanced Materials Development, Chonbuk National University) ;
  • Kim, Chang Seok (Kia Steel Co.) ;
  • Jin, Jai Koan (Hanwha Machinary Co.)
  • 최병영 (전북대학교 공과대학 신소재공학부) ;
  • 김동건 (전북대학교 공과대학 신소재공학부) ;
  • 김창석 (기아특수강(주)) ;
  • 진재관 (한화기계(주))
  • Published : 1996.09.30
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Abstract

Effect of retained austenite on rolling contact fatigue of nitrocarburized high-carbon chromium bearing steel has been investigated to develop surface-hardened bearing steel with imprved resistance to rolling contact fatigue. Fatigue tests were conducted in elesto-hydrodynamic lubricating conditions at a shaft speed of 5,000rpm, under max, hertzian stress of $492kg/mm^2$. Volume fraction of retained austenite in austenitic nitrocarburized STB2 steel was controlled by tempering at various temperature, $200{\sim}250^{\circ}C$. It was observed using TEM that decomposition of retained austenite during tempering at $250^{\circ}C$ was the highest in quantity, resulted in formation of lower bainite. Rolling contact fatigue life of the specimens with lower bainite, formed by decomposition of retained austenite, was improved in comparison with there of specimens with more amount of retained austenite.

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Acknowledgement

Supported by : 전북대학교 자동차신기술연구소