Journal of the Korean Society for Heat Treatment (열처리공학회지)

The Korean Society for Heat Treatment (한국열처리공학회)
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Effect of Quenching Temperature Change on Hardenability of AISI 51B20 Boron Steel

AISI 51B20 보론첨가강의 경화능에 미치는 오스테나이트화 온도의 영향

  • Kim, Heon-Joo (Dept. of Metallurgical Engineering, Pukyong National University) ;
  • Park, Moo-Yong (Dept. of Metallurgical Engineering, Pukyong National Graduate School)
  • 김헌주 (부경대학교 공과대학 금속공학과) ;
  • 박무용 (부경대학교 대학원 금속공학과)
  • Received : 2010.09.10
  • Accepted : 2010.11.02
  • Published : 2010.11.30
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Abstract

Effect of hardenability, grain size and microstructural change according to the change of austenitizing temperature was analyzed in Jominy hardenability test of AISI 51B20 steel. Grain growth was small, 7 ${\mu}m$ and 12 ${\mu}m$ austenite grain sizes at austenitizing temperature of $900^{\circ}C$ and $1000^{\circ}C$, respectively, while rapid grain growth was observed up to 30 ${\mu}m$ austenite grain size at austenitizing temperature of $1100^{\circ}C$. As austenitizing temperature increased from $900^{\circ}C$ to $1100^{\circ}C$, hardenability in the region within 15 mm from end-quenched surface decreased due to the grains growth of bainite and martensite mixture, on the other hand the hardenability in the region exceeding 15 mm from end-quenched surface increased. Increased hardenability was attributed to different microstructures; pearlite, fine pearlite and bainite, and bainite and martensite structures at austenitizing temperature of $900^{\circ}C$, $1000^{\circ}C$ and $1100^{\circ}C$, respectively.

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References

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