金属热处理 ›› 2025, Vol. 50 ›› Issue (7): 81-88.DOI: 10.13251/j.issn.0254-6051.2025.07.012

• 组织与性能 • 上一篇    下一篇

焊后冷却速度对X80管线钢组织与性能的影响

付立武1, 燕冰川1, 张舒展2, 刘庚2, 刘世博2, 史显波2, 严伟2   

  1. 1.国家管网集团储运技术发展有限公司, 天津 300457;
    2.中国科学院金属研究所, 辽宁 沈阳 110016
  • 收稿日期:2025-02-17 修回日期:2025-05-22 出版日期:2025-07-25 发布日期:2025-07-28
  • 通讯作者: 史显波,研究员,博士,E-mail:xbshi@imr.ac.cn
  • 作者简介:付立武(1975—),男,高级工程师,硕士,主要研究方向为管道维护抢修与完整性管理,E-mail:fulw@pipechina.com.cn。
  • 基金资助:
    国家管网集团揭榜挂帅课题-高钢级管道环焊缝失效机理研究(WZXGL202105);辽宁省自然科学基金(2023-MS-019)

Effect of post-welding cooling rate on microstructure and properties of X80 pipeline steel

Fu Liwu1, Yan Bingchuan1, Zhang Shuzhan2, Liu Geng2, Liu Shibo2, Shi Xianbo2, Yan Wei2   

  1. 1. Pipe China Pipeline Technology Development Co., Ltd., Tianjin 300457, China;
    2. Institute of Metal Research, Chinese Academy of Sciences, Shenyang Liaoning 110016, China
  • Received:2025-02-17 Revised:2025-05-22 Online:2025-07-25 Published:2025-07-28

摘要: 采用Gleeble-3800热模拟试验机对X80管线钢进行焊接模拟,研究不同焊后冷却速度(对应t8/5为10、30、60、150 s)下的组织和性能变化。结果表明:当焊后冷速较快,t8/5为10~30 s时,X80管线钢焊接热影响区的组织主要为细密的板条贝氏体和沿板条界分布的纳米级碳化物;当冷速较慢,t8/5为60 s时,组织转变为板条状铁素体和相邻板条间细小的岛状M/A组元;当冷速继续降低、t8/5为150 s时,组织由多边形铁素体和大尺寸、形状不规则的M/A组元形成。EBSD结果表明,当焊后冷速慢、t8/5为150 s时,大角度晶界占比较低;当焊后冷速快、t8/5为10 s时,基体局部应变和位错密度略有提高。此外,当焊后冷速慢、t8/5为150 s时,因粗大M/A组元形成,冲击性能大幅降低。焊后冷速控制t8/5在60 s以内时,X80管线钢焊接热影响区可获得优异的强韧性。

关键词: 管线钢, 焊接热模拟, 显微组织, M/A岛, 力学性能

Abstract: Welding simulation experiments were conducted on X80 pipeline steel by using Gleeble-3800 thermal simulator to investigate microstructure and properties evolution under different post-weld cooling rates (corresponding t8/5 of 10, 30, 60, 150 s). The results indicate that at faster cooling rates with t8/5 of 10-30 s, the heat affected zone (HAZ) microstructure consists of fine lath bainite with nano-sized carbides distributed along lath boundaries. When the cooling rate decreases to corresponding t8/5 of 60 s, the microstructure transforms to lath ferrite with fine island-shaped M/A constituents between adjacent laths. Further decreasing the cooling rate to corresponding t8/5 of 150 s results in the formation of polygonal ferrite and large irregularly-shaped M/A constituents. The EBSD analysis reveals that slower cooling (t8/5=150 s) leads to a lower proportion of high-angle grain boundaries, while faster cooling (t8/5=10 s) induces slight increasing in local strain and dislocation density within the matrix. Furthermore, the impact property significantly deteriorates at t8/5=150 s due to the formation of coarse M/A constituents. Optimal strength-toughness balance in HAZ of the X80 pipeline steel can be achieved when the post-weld cooling rate is controlled as t8/5 within 60 s.

Key words: pipeline steel, welding thermal simulation, microstructure, M/A island, mechanical properties

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