Korean Journal of Metals and Materials (대한금속재료학회지)

The Korean Institute of Metals and Materials (대한금속재료학회)
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Effects of Tempering Temperature and Heat-Treatment Path on the Microstructural and Mechanical Properties of ASTM Gr.92 Steel

ASTM Gr.92강의 미세조직 및 기계적 성질에 미치는 템퍼링 온도 및 열처리경로의 영향

  • Kim, Yeon-Keun (Energy Functional Material Laboratory, Chungnam National Universty) ;
  • Han, Chang-Hee (FR Fuel Development, Korea Atomic Energy Research institute) ;
  • Baek, Jong-Hyuk (FR Fuel Development, Korea Atomic Energy Research institute) ;
  • Kim, Sung-Ho (FR Fuel Development, Korea Atomic Energy Research institute) ;
  • Lee, Chan-Bock (FR Fuel Development, Korea Atomic Energy Research institute) ;
  • Hong, Sun-Ig (Energy Functional Material Laboratory, Chungnam National Universty)
  • 김연근 (충남대학교/응용소재공학과) ;
  • 한창희 (한국원자력연구원/SFR핵연료개발) ;
  • 백종혁 (한국원자력연구원/SFR핵연료개발) ;
  • 김성호 (한국원자력연구원/SFR핵연료개발) ;
  • 이찬복 (한국원자력연구원/SFR핵연료개발) ;
  • 홍순익 (충남대학교/응용소재공학과)
  • Received : 2009.08.20
  • Published : 2010.01.20
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Abstract

In order to investigate the effects of tempering temperature and heat-treatment path on the microstructural and mechanical properties of ASTM Gr.92 steels, four samples with different tempering temperatures and heat-treatment paths wer prepared. THeree experimental steels showed tempered martensitic microstructures, but the sample tempered at $810^{\circ}C$ was presumed to retain partially untempered martensitic microstructures due to a lower ${\alpha}$+${\gamma}$ phase regime. $M_{23}C_6$, V(C,N), and Nb(C,N) precipitates were observed in all samples. In addition $Cr_2N$ was observed to be precipitated finely and uniformly by isothermal heat-treatment. The lath width and precipitate size in the isothermal heat-treated samples were much smaller than those of the tempered-only specimens. Because of a fine and uniform precipitate, a reduction of lath width would enhance precipitation hardeing, and it was shown that mechanical propertiesincluding the hardness and tensile properties of the steels were improved by isothermal heat-treatment.

Keywords

Acknowledgement

Grant : 소듐냉각고속로(SFR) 핵연료핵심기반기술개발

Supported by : 교육과학기술부

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