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测试X80管线钢分别在未腐蚀状态下及饱和H2S预腐蚀后的δ-Δa阻力曲线;分析了H2S腐蚀对其裂纹扩展阻力曲线、断裂韧性、塑性功等方面影响。结果表明,H2S腐蚀后X80材料KIC下限为75.43 MPa·m?。对比分析H2S腐蚀前后测试结果,发现H2S腐蚀会对X80钢的断裂韧性产生显著影响:未腐蚀试样的裂纹扩展阻力曲线明显高于H2S腐蚀后的;H2S腐蚀前后材料的稳定裂纹扩展下的启裂韧度δ0.2BL分别为0.740 mm和0.365 mm,前者是后者的2.02倍;扩展量Δa相近的情况下,未腐蚀试样的裂纹扩展过程所需塑性功是H2S预腐蚀后的2.29倍左右,H2S腐蚀明显会降低X80材料的断裂韧度。因此,管道在输送天然气过程中应尽量避免H2S的腐蚀,保证材料的韧性不受破坏。
The δ-Δa resistance curves of X80 pipeline steel under unetched condition and saturated H2S pre-corrosion respectively were tested. The influence of H2S corrosion on crack growth resistance, fracture toughness and plastic work were analyzed. The results show that the lower limit of KIC of X80 material after H2S corrosion is 75.43 MPa · m ~. The results of H2S corrosion test before and after comparison show that H2S corrosion has a significant effect on the fracture toughness of X80 steel: the crack growth resistance curve of non-corrosive sample is obviously higher than that of H2S corrosion; The fracture toughness δ0.2BL is 0.740 mm and 0.365 mm respectively, the former is 2.02 times of that of the latter. The plastic work required for the crack propagation of the un-corroded specimen is 2.29 times H2S corrosion will obviously reduce the fracture toughness of X80 material. Therefore, the pipeline in the process of transporting natural gas should be avoided H2S corrosion, to ensure the toughness of the material from damage.