东北大学学报(自然科学版) ›› 2022, Vol. 43 ›› Issue (2): 188-196.DOI: 10.12068/j.issn.1005-3026.2022.02.006

• 材料与冶金 • 上一篇    下一篇

690MPa级海洋平台用特厚齿条钢的回火稳定性

刘庚, 李慧杰, 王庆海, 叶其斌   

  1. (东北大学 轧制技术及连轧自动化国家重点实验室, 辽宁 沈阳110819)
  • 修回日期:2021-05-11 接受日期:2021-05-11 发布日期:2022-02-28
  • 通讯作者: 刘庚
  • 作者简介:刘庚(1997-),男,辽宁朝阳人,东北大学硕士研究生; 叶其斌(1977-),男,福建南平人,东北大学副研究员, 硕士生导师.
  • 基金资助:
    辽宁省科技重大专项(2020JH1/10100001); 鞍山钢铁集团有限公司国家重点实验室开放课题(SKLMEA-K202003).

Tempering Stability of a 690MPa Grade Ultra-heavy Rack Steel for Offshore Platform

LIU Geng, LI Hui-jie, WANG Qing-hai, YE Qi-bin   

  1. State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819, China.
  • Revised:2021-05-11 Accepted:2021-05-11 Published:2022-02-28
  • Contact: YE Qi-bin
  • About author:-
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摘要: 研究了长时间回火(2,4和8h)对海洋平台用齿条钢A514 GrQ显微组织及力学性能的影响.结果表明,回火过程中,淬火态马氏体板条组织发生回复,C,Cr,Mo和V等元素扩散,析出MC,M2C和M23C6型碳化物,回火2h后碳化物类型趋于稳定,并发生Ostwald熟化现象;随着回火时间的增加,实验钢的抗拉强度由淬火态的1100MPa逐渐降低到回火8h时的813MPa,屈服强度由淬火态的931MPa逐渐降低至回火8h时的725MPa;淬火态实验钢回火2h后,-60℃冲击功由淬火态的187J增加至238J,继续增加回火时间,冲击功趋于稳定,约为245J;延伸率由淬火态的15.2%增加至回火2h时的16.7%,并且随着回火时间的增加,升高至回火8h时的19.5%.实验钢在600℃回火2~8h过程中,具有良好的回火稳定性和强韧性匹配,最佳回火时间为2h.

关键词: 特厚齿条钢;回火时间;碳化物;强韧性;马氏体

Abstract: The effects of long-term tempering (2h,4h and 8h) on microstructure and mechanical property of rack steel A514 GrQ for offshore platforms were studied. It is found that during the tempering process, the quenched martensite lath structure recovered, C, Cr, Mo and V elements diffused, and MC, M2C, and M23C6 type carbides were precipitated in the martensite matrix. After tempering for 2h, the carbides tended to be stable and the Ostwald ripening occurred. With the increase of tempering time from 0h to 8h, tensile strength of the tested steel decreased from 1100MPa to 813MPa and yield strength decreased from 931MPa to 725MPa. The impact energy at -60℃ increased from 187J of the as-quenched steel to 238J after 2h tempering and then it tended to be stable with a value about 245J for further tempering. The elongation increased from 15.2% of the as-quenched steel to 16.7% after 2h tempering and further increased up to 19.5% for 8h tempering. These results indicate that in the process of tempering at 600℃ for 2-8h, the experimental steel A514 GrQ can perform the good tempering stability and the excellent combination of strength and toughness, associated with the best tempering time of 2h.

Key words: ultra-heavy rack steel; tempering time; carbides; strength and toughness; martensite

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