气相杂质对临氢环境中L245管线钢氢脆敏感性的影响研究

STUDY ON THE INFLUENCE OF GAS PHASE IMPURITIES ON HYDROGEN EMBRITTLEMENT SENSITIVITY OF L245 PIPELINE STEEL IN HYDROGEN ENVIRONMENT

  • 摘要: 为研究天然气掺氢输送环境中气相杂质对管线钢的氢脆敏感性影响,本文通过缺口圆棒试样慢拉伸测试对比研究了正火态无缝钢管L245在空气和4 MPa氢气环境中的材料力学性能,对比研究4 MPa氢气环境中含H2O,O2,CO2等气相杂质时L245管线钢氢脆敏感性的变化,结合扫描电子显微镜对断口形貌进行了系统分析。结果表明:1)相较于空气环境,4 MPa H2环境下L245管线钢塑性有所降低,缺口试样的断裂方式为缺口边缘准解理断裂和中心部位韧断相结合,具有一定的氢脆敏感性;2)H2O的影响与其浓度有关,100 ppm及以下H2O的加入对L245管线钢的氢脆敏感性影响较小,但H2O浓度增大到1000 ppm,L245氢脆敏感性明显增大;3)4 MPa H2+100 ppm H2O环境下,100 ppm O2的添加使得L245钢的氢脆敏感性程度明显降低;而100 ppm CO2的添加使得L245钢的氢脆敏感性大幅增大。

     

    Abstract: In order to investigate the influence of gaseous impurities in natural gas-hydrogen mixtures on the hydrogen embrittlement susceptibility of pipeline steels. The mechanical properties of L245 pipeline steel under air and 4 MPa hydrogen environments were analyzed using slow tensile testing on notched round bar specimens in the present work. Furthermore, the changes in hydrogen embrittlement susceptibility of L245 pipeline steel were studied when exposed to 4 MPa hydrogen environment with various gaseous impurities such as H2O, O2, CO2, etc., and the fracture surfaces were systematically analyzed using Scanning Electron Microscopy. The results were as follows: 1) Compared to air environment, L245 pipeline steel exhibited reduced plasticity under 4 MPa H2 environment, with a fracture mode characterized by a combination of quasi-cleavage fracture at the edge of the notch and ductile fracture at the center of sample, indicating certain degree of hydrogen embrittlement susceptibility; 2) The effect of H2O varied depending on its concentration. Addition of H2O at or below 100 ppm had minimal impact on the hydrogen embrittlement susceptibility of L245 pipeline steel. However, when H2O concentration increased to 1000 ppm, the sensitivity to hydrogen embrittlement significantly increased; 3) Under an environment consisting of 4 MPa H2+100 ppm H2O, addition of O2 at a concentration level of 100 ppm resulted in significant reduction in hydrogen embrittlement susceptibility for L245 steel. While addition of CO2 at a concentration level also at around 100 ppm led to considerable increase in sensitivity to hydrogen embrittlement for L245 steel.

     

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