金属热处理 ›› 2020, Vol. 45 ›› Issue (10): 79-84.DOI: 10.13251/j.issn.0254-6051.2020.10.016

• 工艺研究 • 上一篇    下一篇

热处理对极寒服役条件下弯管用X80钢焊缝组织性能的影响

毕宗岳1,2, 韦奉1,2, 张万鹏1,2, 李洁3, 张敏3   

  1. 1.国家石油天然气管材工程技术研究中心, 陕西 宝鸡 721008;
    2.宝鸡石油钢管有限责任公司, 陕西 宝鸡 721008;
    3.西安理工大学 材料科学与工程学院, 陕西 西安 710048
  • 收稿日期:2020-03-28 出版日期:2020-10-25 发布日期:2020-12-29
  • 作者简介:毕宗岳(1962—),男,教授级高级工程师,主要研究方向为管材开发及焊接技术,E-mail:bsgbzy@cnpc.com.cn
  • 基金资助:
    国家重点研发计划(2018YFC0310300)

Effect of heat treatment on microstructure and properties of welded joints of X80 steel used for bent pipe under extremely cold service conditions

Bi Zongyue1,2, Wei Feng1,2, Zhang Wanpeng1,2, Li Jie3, Zhang Min3   

  1. 1. Chinese National Engineering Research Center for Petroleum and Natural Gas Tubular Goods, Baoji Shaanxi 721008, China;
    2. Baoji Petroleum Steel Pipe Co., Ltd., Baoji Shaanxi 721008, China;
    3. School of Materials Science and Engineering, Xi’an University of Technology, Xi’an Shaanxi 710048, China
  • Received:2020-03-28 Online:2020-10-25 Published:2020-12-29

摘要: 利用显微组织分析、低温冲击试验、断口分析等手段,研究了不同热处理工艺对弯管用X80钢焊缝显微组织与低温冲击性能的影响。结果表明,在890~980 ℃范围内正火,随着正火温度升高,焊缝组织逐渐粗化,M-A组元和碳化物数量增多且聚集程度逐渐增加,低温冲击性能下降。在620~680 ℃范围内回火,随着回火温度的升高,焊缝中贝氏体及针状铁素体的混合组织发生回复与再结晶,碳化物析出和先共析铁素体含量增加,硬脆M-A组元逐渐分解,低温冲击吸收能量则先升后降,显微硬度逐渐降低。热处理后焊缝组织主要以针状铁素体(AF)和粒状贝氏体(GB)为主,同时存在少量的先共析铁素体(PF)和弥散分布的M-A组元。采用920 ℃正火+660 ℃高温回火时,焊缝低温冲击吸收能量最优,为148 J,同时显微硬度波动较小,冲击断口放射区为准解理断裂,无大尺寸裂纹且出现部分韧窝,表明该热处理工艺下处理的弯管可以满足在-45 ℃极寒条件下的服役要求。

关键词: X80管线钢, 焊缝组织, 热处理, 低温韧性

Abstract: Effects of different heat treatment processes on the microstructure and low-temperature impact property of the welded joints of X80 steel used for bent pipe were studied by means of microstructure analysis, low-temperature impact test, and fracture analysis. The results show that, when normalized in the range of 890-980 ℃, the microstructure of welded joints gradually coarsens with the increase of normalizing temperature, and the number of M-A components and carbides rises, the aggregation extent increases gradually, and the low-temperature impact property decreases. When tempered in the range of 620-680 ℃, with the increase of tempering temperature, the mixed microstructure of bainite and acicular ferrite in the welded joints undergoes recovery and recrystallization, the content of carbide precipitates and proeutectoid ferrite increases, and the hard and brittle M-A components decompose gradually, the impact absorbed energy at low temperature increases first and then decreases, and the microhardness decreases gradually. The microstructure of the welded joints after heat treatment is mainly composed of acicular ferrite (AF) and granular bainite (GB), while a small amount of proeutectoid ferrite (PF) and dispersed M-A components are present. When normalized at 920 ℃ and then tempered at 660 ℃, the impact absorbed energy at low temperature of the welded joints is the best (148 J), while the microhardness is fluctuated slightly, and the radiation zone of the impact fracture is quasi-cleavage fracture, without large-scale cracks and with partial dimples, showing that the bent pipe treated by this heat treatment process can meet the service requirements under the extreme cold condition of -45 ℃.

Key words: X80 pipeline steel, microstructure of welded joints, heat treatment, low temperature toughness

中图分类号: