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2019 Vol.29, Issue 8 Preview Page
Effect of Carbon Equivalent and Cooling Rate on Microstructure in A516 Steels for Pressure Vessel

압력용기용 A516 강의 미세조직에 미치는 탄소 당량과 냉각 속도의 영향

Hyun Wook Lee1
,
Ui Gu Kang2
,
Min Soo Kim2
,
Sang Yong Shin1†
이 현욱1
,
강 의구2
,
김 민수2
,
신 상용1†
1School of Materials Science and Engineering, University of Ulsan, Ulsan 44610, Republic of Korea
2Technical Research Center, Hyundai Steel Company, Dangjin 31719, Republic of Korea
1울산대학교 첨단소재공학과
2현대제철 R&D Center
†Corresponding author E-Mail : sshin@ulsan.ac.kr (S. Y. Shin, Univ. of Ulsan)
August 2019. pp. 511-518
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Abstract

In this study, the effect of carbon equivalent and cooling rate on microstructure and hardness of A516 steels for pressure vessel is investigated. Six kinds of specimens are fabricated by varying carbon equivalent and cooling rate, and their microstructures and hardness levels are analyzed. Specimens with low carbon equivalent consist of ferrite and pearlite. As the cooling rate increases, the size of pearlite decreases slightly. The specimens with high carbon equivalent and rapid cooling rates of 10 and 20 °C/s consist of not only ferrite and pearlite but also bainite structure, such as granular bainite, acicular ferrite, and bainite ferrite. As the cooling rate increases, the volume fractions of bainite structure increase and the effective grain size decreases. The effective grain sizes of granular bainite, acicular ferrite, and bainitic ferrite are ~20, ~5, and ~10 μm, respectively. In the specimens with bainite structure, the volume fractions of acicular ferrite and bainitic ferrite, with small effective grains, increase as cooling rate increases, and so the hardness increases significantly.

Keywords
A516 steel
carbon equivalent
cooling rate
microstructure
bainite
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Information
  • Publisher :Materials Research Society of Korea
  • Publisher(Ko) :한국재료학회
  • Journal Title :Korean Journal of Materials Research
  • Journal Title(Ko) :한국재료학회지
  • Volume : 29
  • No :8
  • Pages :511-518
  • Received Date : 2019-04-22
  • Revised Date : 2019-08-05
  • Accepted Date : 2019-08-13
  • DOI :https://doi.org/10.3740/MRSK.2019.29.8.511
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