Korean Journal of Metals and Materials (대한금속재료학회지)

The Korean Institute of Metals and Materials (대한금속재료학회)
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Effect of Austenitizing Temperature on Secondary Hardening and Impact Toughness in P/M High Speed Vanadium Steel

바나듐 분말 고속도공구강의 이차경화 및 충격인성에 미치는 오스테니타이징 온도의 영향

  • Moon, H.K. (Human Resources Development Service of Korea) ;
  • Yang, H.R. (Department of Mechanical Engineering, Incheon City College) ;
  • Cho, K.S. (School of Advanced Materials Engineering, Kookmin University) ;
  • Lee, K.B. (School of Advanced Materials Engineering, Kookmin University) ;
  • Kwon, H. (School of Advanced Materials Engineering, Kookmin University)
  • 문희권 (한국산업인력공단) ;
  • 양형렬 (시립인천전문대학 기계공학과) ;
  • 조기섭 (국민대학교 신소재공학부) ;
  • 이건배 (국민대학교 신소재공학부) ;
  • 권훈 (국민대학교 신소재공학부)
  • Received : 2008.12.20
  • Published : 2008.08.25
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Abstract

The secondary hardening and fracture behavior in P/M high speed steels bearing V content of 9 to 10 wt% have been investigated in terms of austenitizing temperature and precipitation behavior. Austenitizing was conducted at 1,100 and $1,175^{\circ}C$ of relatively low and high temperatures. Coarse primary carbides retained after austenitization were mainly V-rich MC type. They give a significant influence on hardeness and toughness, as well as wear resistance. Tempering was performed in the range of $500{\sim}600^{\circ}C$. The peak hardness resulting from the precipitation of the fine MC secondary carbides was observed near 520, irrespective of austenitizing temperature. Aging acceleration(or deceleration) did not occur with increasing austenitizing temperature because it mainly influences contents of V and C of matrix through the dissloution of coarse primary MC containing lots of V and C. The precipitation of secondary MC carbides, which also contain V and C, did not change the aging kinetics itself. In the 10V alloy containing much higher C content, the impact toughness was lower than 9V alloy, because of the larger amount of primary carbide and high hardness.

Keywords

Acknowledgement

Supported by : 과학재단

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