Journal of the Korean Society for Heat Treatment (열처리공학회지)

The Korean Society for Heat Treatment (한국열처리공학회)
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Effects of Rolling and Cooling Conditions on Microstructures and Mechanical Properties of High-Deformable Pipeline Steels

고변형능 라인파이프강의 미세조직과 기계적 특성에 미치는 압연 및 냉각 조건의 영향

  • Lee, S.I. (Department of Materials Science and Engineering, Seoul National University of Science and Technology) ;
  • Hwang, B. (Department of Materials Science and Engineering, Seoul National University of Science and Technology)
  • 이상인 (서울과학기술대학교 신소재공학과) ;
  • 황병철 (서울과학기술대학교 신소재공학과)
  • Received : 2014.08.08
  • Accepted : 2014.08.28
  • Published : 2014.09.30
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Abstract

Effects of rolling and cooling conditions on microstructures and mechanical properties of high-deformable pipeline steels were investigated in this study. Six kinds of pipeline steels were fabricated by varying rolling and cooling conditions, and their microstructures were analyzed by scanning electron microscopy, electron back-scattered diffraction, and transmission electron microscopy. Tensile and Charpy impact tests were conducted on the steels in order to examine the mechanical properties. The steels rolled in the two-phase region showed better low-temperature toughness than those in the single-phase region due to the larger amount of ferrites having high-angle boundaries, although they have lower strength and absorbed energy. The steel rolled in single-phase and finish-cooled at higher temperature showed a good combination of high strength and good low-temperature toughness as well as excellent deformability of the lowest yield ratio and the highest uniform elongation because of the presence of fine ferrite and a mixture of various low-temperature transformation phases.

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