焊管2026，Vol.49Issue(6)：39-49,11.DOI:10.19291/j.cnki.1001-3938.2026.06.005
基于8年氢气输送服役条件的L245NS冷弯管与母管氢脆敏感性对比
Comparative Analysis of Hydrogen Embrittlement Susceptibility in Cold-bent Pipes and Straight Pipes of L245NS Pipeline Steel under Eight-year Hydrogen Transportation Service Conditions
摘要
Abstract
To evaluate the long-term reliability of hydrogen transportation pipelines,the hydrogen embrittlement behavior of cold-bent pipes and straight pipes for L245NS pipeline steel after eight years of service was investigated.A comparative analysis was conducted using slow strain rate testing,metallography,transmission electron microscopy,and electron backscatter diffraction.Results show no significant difference in strength between the two;however,the cold-bent pipe exhibits a higher hydrogen embrittlement susceptibility index(HEI=6.1%),indicating greater hydrogen embrittlement risk.Microstructural analysis reveals that the straight pipe has a rolled ferrite-pearlite structure with an equiaxed grain size of 18 μm,low dislocation density,small-angle grain boundaries(2～5°)totaling 1 960 μm in length,and abundant low-energy coincidence site lattice(CSL)boundaries such as Σ13 and Σ15,resulting in fewer hydrogen traps and suppressed hydrogen aggregation.In contrast,after plastic deformation,the cold-bent pipe shows elongated grains with the minor-axis grain diameter of 15 μm,increased dislocation density forming tangles and networks,small-angle grain boundary length increased to 3 000 μm,and reduced fraction of low-energy Σ boundaries—generating numerous hydrogen trapping sites and promoting hydrogen enrichment.Fractography shows the straight pipe has large,deep dimples and a relatively flat fracture surface,while the cold-bent pipe exhibits fine,shallow dimples and pronounced necking due to strain hardening-induced ductility loss,indicating increased brittleness.The research results demonstrates that cold working significantly amplifies the hydrogen embrittlement susceptibility of L245NS steel,providing quantitative guidance for process optimization and in-service monitoring of cold-bent pipeline sections.关键词
L245NS管线钢/氢脆/冷弯管/慢拉伸/8年氢输服役/低能Σ晶界/位错增殖Key words
L245NS pipeline steel/hydrogen embrittlement/cold-bent pipe/slow strain rate testing/eight-year hydrogen transportation service/low-energy Σ grain boundaries/dislocation multiplication分类
矿业与冶金引用本文复制引用
王旭,赵立前,李硕,李国辉,陈祥,霍玉香..基于8年氢气输送服役条件的L245NS冷弯管与母管氢脆敏感性对比[J].焊管,2026,49(6):39-49,11.基金项目
中国石油管道工程有限公司项目"纯氢管线钢、环焊缝等相关性能氢损伤影响分析及评价研究"(项目编号2024-22) （项目编号2024-22）
内蒙古自治区科技重大专项"中低压纯氢与掺氢燃气管道输送及应用关键技术研发"(项目编号2021SZD0082). （项目编号2021SZD0082）
