Korean Journal of Metals and Materials (대한금속재료학회지)

The Korean Institute of Metals and Materials (대한금속재료학회)
권호 표지

Effect of Mo, Cr, and V on Tensile and Charpy Impact Properties of API X80 Linepipe Steels Rolled in Single Phase Region

단상영역에서 압연된 API X80 라인파이프강의 인장 및 샤르피 충격 특성에 미치는 Mo, Cr, V의 영향

  • Han, Seung Youb (Center for Advanced Aerospace Materials Pohang University of Science and Technology) ;
  • Shin, Sang Yong (Center for Advanced Aerospace Materials Pohang University of Science and Technology) ;
  • Seo, Chang-hyo (Center for Advanced Aerospace Materials Pohang University of Science and Technology) ;
  • Lee, Hakcheol (Center for Advanced Aerospace Materials Pohang University of Science and Technology) ;
  • Bae, Jin-ho (Sheet Products & Process Research Group Technical Research Laboratories, POSCO) ;
  • Kim, Kisoo (Sheet Products & Process Research Group Technical Research Laboratories, POSCO) ;
  • Lee, Sunghak (Center for Advanced Aerospace Materials Pohang University of Science and Technology) ;
  • Kim, Nack J. (Center for Advanced Aerospace Materials Pohang University of Science and Technology)
  • 한승엽 (포항공과대학교 항공재료연구센터) ;
  • 신상용 (포항공과대학교 항공재료연구센터) ;
  • 서창효 (포항공과대학교 항공재료연구센터) ;
  • 이학철 (포항공과대학교 항공재료연구센터) ;
  • 배진호 (POSCO 기술연구소 박판연구그룹) ;
  • 김기수 (POSCO 기술연구소 박판연구그룹) ;
  • 이성학 (포항공과대학교 항공재료연구센터) ;
  • 김낙준 (포항공과대학교 항공재료연구센터)
  • Received : 2008.07.08
  • Published : 2008.12.25
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Abstract

This study is concerned with the effects of Mo, Cr, and V addition on tensile and Charpy impact properties of API X80 linepipe steels. Four kinds of steels were processed by varying Mo, Cr, and V additions, and their microstructures and tensile and Charpy impact properties were investigated. Since the addition of Mo and V promoted to form fine acicular ferrite and granular bainite, while prohibiting the coarsening of granular bainite, it increased the strength and upper shelf energy, and decreased the energy transition temperature. The Cr addition promoted the formation of coarse granular bainite and secondary phases such as martensite-austenite constituents, thereby leading to the increased effective grain size, energy transition temperature, and strength and to the decreased upper shelf energy. The steel containing 0.3wt.% Mo and 0.06wt.% V without Cr had the highest upper shelf energy and the lowest energy transition temperature because its microstructure was composed of fine acicular ferrite and granular bainite, together with a small amount of hard secondary phases, while its tensile properties maintained excellent.

Keywords

Acknowledgement

Supported by : POSCO, 한국과학재단

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