Effect of Quenchant Temperature on the Surface Residual Stress in Gas Carburized AISI 8620 Steel

가스침탄 처리한 AISI 8620 강에서 급냉제가 표면잔류응력에 미치는 영향

  • Jang, C.G. (Department of Mechanical Engineering, Sung Kyun Kwan Univ.) ;
  • Hahn, J.H. (Materials Properties Lab., Korea Standards Research Institute) ;
  • Hwang, N.M. (Materials Properties Lab., Korea Standards Research Institute) ;
  • Kim, J.J. (Materials Properties Lab., Korea Standards Research Institute) ;
  • Lim, B.S. (Department of Mechanical Engineering, Sung Kyun Kwan Univ.)
  • 장충길 (성균관대학교 기계공학과) ;
  • 한준희 (한국표준연구소 재료연구실) ;
  • 황농문 (한국표준연구소 재료연구실) ;
  • 김종집 (한국표준연구소 재료연구실) ;
  • 임병수 (성균관대학교 기계공학과)
  • Published : 1989.06.30

Abstract

The effect of quenchant temperature on the surface residual stress was studied for AISI 8620 steel. Specimens were carburized at $900^{\circ}C$ in all case type furnace using a gas-base atmosphere of methanol cracked and liquefied petroleum gas, and then subjected to single reheat quenchant in oil or salt bath in the temperature range of $60^{\circ}C$ to $300^{\circ}C$. After carburizing and reheat Quenching, residual stress was measured by the hole drilling method. Experimental results showed that the surface residual stress was increased as the quenchant temperature was raised. This is in contrast to the fact that the formation of phase of low transformation strain such as bainite results in lower surface compressive stress. The greater compressive stress observed in specimens Quenched at higher temperature may be attributed to the shifting of the transformation start point farther from the surface, as was reported in other carburizing steels.

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