东北大学学报（自然科学版）

东北大学学报:自然科学版 ›› 2017, Vol. 38 ›› Issue (6): 809-813.DOI: 10.12068/j.issn.1005-3026.2017.06.010

• 材料与冶金 • 上一篇    下一篇

超高强钢Q1100的SH-CCT曲线及粗晶热影响区组织和性能

温长飞， 邓想涛， 王昭东， 王国栋   

  1. (东北大学 轧制技术与连轧自动化国家重点实验室， 辽宁 沈阳110819)
  • 收稿日期:2016-01-16 修回日期:2016-01-16 出版日期:2017-06-15 发布日期:2017-06-11
  • 通讯作者: 温长飞
  • 作者简介:温长飞(1986-)，男，安徽滁州人，东北大学博士研究生; 王昭东(1968-)，男，安徽怀宁人，东北大学教授，博士生导师； 王国栋(1942-)，男，辽宁大连人， 东北大学教授，博士生导师，中国工程院院士.
  • 基金资助:

    国家自然科学基金资助项目(51234002，51474064，51504064).

SH-CCT Diagram， Microstructure and Properties of Coarse Grain Heat-Affected Zone in Q1100 Ultra-high Strength Steel

WEN Chang-fei， DENG Xiang-tao， WANG Zhao-dong， WANG Guo-dong   

  1. The State Key Laboratory of Rolling and Automation， Northeastern University， Shenyang 110819， China.
  • Received:2016-01-16 Revised:2016-01-16 Online:2017-06-15 Published:2017-06-11
  • Contact: WANG Zhao-dong
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摘要：

利用焊接热模拟试验，采用热膨胀法研究了屈服强度1100MPa级超高强钢在平衡条件和焊接条件下的奥氏体化相变温度，结合OM，SEM观察和硬度检测结果，绘制出实验钢焊接条件下奥氏体连续冷却转变曲线(SH-CCT)，研究了不同冷却速率下粗晶热影响区(CGHAZ)显微组织和硬度的变化规律.采用TEM观察和Lepera腐蚀，研究不同冷速下M-A组元数量、形貌和分布情况.研究结果表明，在焊接条件下，实验钢的奥氏体化温度明显高于平衡条件下的奥氏体化相变温度；随着冷却速率增大，相继发生B，B+M和M相变，硬度逐渐上升，当冷却速率达到60℃/s时，其维氏硬度最高可达HV464.当冷却速率小于10℃/s时，开始出现M-A组元，并且随冷却速率降低，M-A组元数量增加，尺寸增大.

关键词: 超高强钢, SH-CCT曲线, 粗晶热影响区, 组织, M-A组元

Abstract:

It is generally believed that coarse grain heat-affected zone (CGHAZ) in welded region is the weakest part in the welding joint of low alloy ultra-high strength steel. The thermomechanical simulator was employed to simulate the welding thermal cycle processes of CGHAZ in Q1100 ultra-high strength steel. By using thermal expansion measurement combined with OM，SEM observations and hardness test， the critical phase transformation points at the equilibrium state and welding conditions were determined and SH-CCT diagram at different cooling rates was plotted. TEM observation and Lepera reagent were used to reveal the morphology of M-A constituent. The results showed that the austenitizing temperature of this steel in the welding condition was significantly higher than that in equilibrium state. The microstructure of CGHAZ mainly consisted of bainite， bainite and martensite， and martensite accompany with the increase of cooling rate. The hardness increased gradually with the increase of cooling rates， the maximum hardness was HV464. The M-A constituent occurred when the cooling rate was lower than 10℃/s， and the lower cooling rate， the more M-A constituent.

Key words: ultra-high strength steel, SH-CCT diagram, coarse grain heat-affected zone(CGHAZ), microstructure, M-A constituent

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