Effect of Tempering Temperature on Microstructure and Properties of E690 Offshore Plate Steel

• Published in: Journal of iron and steel research, international international, 2012-03, Vol.19 (3), p.67-72
• Main Authors: ZHANG, Jie, CAI, Qing-wu, WU, Hui-bin, ZHANG, Kun, WU, Bo
• Format: Article
• Language: English
• Subjects: Applied and Technical Physics; Bainite; EBSD; Electron microscopes; Engineering; Iron and steel industry; low carbon bainitic steel; Machines; Manufacturing; Materials Engineering; Materials Science; Metallic Materials; Microstructure; Offshore; offshore plate; Physical Chemistry; Processes; Steel making; Steels; Tempering; TMCP工艺; toughness; 回火温度; 扫描电子显微镜; 热机械控制工艺; 电子背散射衍射; 组织和性能; 透射电子显微镜; 钢板
• ISSN: 1006-706X; 2210-3988
• DOI: 10.1016/S1006-706X(12)60076-4

A new kind of Mn Mo Nb Cu B bainite steel which satisfied mechanical demands of E690 offshore plate steel was designed. The effect of two processes thermomechanical control process （TMCP）＋ tempering （T） and thermomechanical control process （TMCP） ＋ reheating and quenching （RQ） ＋ tempering （T） on microstructure and mechanical properties were studied by means of scan electron microscope （SEM）, transmission electron micro- scope （TEM） and electron back scatter diffraction （EBSD）. The results showed that optimal mechanical properties were available when tempering at 550 ℃ for both processes. The microstructure of the TMCP＋T treated sample tempering in the range of 450 to 550 ℃ for 1 h did not change dramatically yet the lath in the TMCP＋RQ＋T trea- ted sample merged together and transformed into polygonal ferrite. At the same time, the sub-structure of grain bainite transformed from lath to cell shape to refine grains with tempering temperature mounting. Lots of sub-grain boundaries were located within bainite and adjacent bainite grain boundaries were high angle.