2%氢气含量对X80管线钢断裂韧性和缺陷容限的影响

氢气的存在会劣化金属材料的力学性能，导致材料发生氢脆断裂，严重影响含氢天然气输送管线的安全输送，为此本文开展X80 管线钢在含氢环境中的断裂韧性试验，通过对比无氢环境，评定氢气的存在对X80管线钢断裂韧性和缺陷容限的影响规律，利用扫描电镜对断口进行观察分析，判断其在不同条件下的断裂模式。结果表明，在12 MPa的输送压力环境中掺入2% H₂，X80管线钢的断裂韧性比氮气环境有一定程度的下降，X80管线钢在氮气中的裂纹尖端张开位移 (crack tip opening displacement, CTOD)值为0.42 mm，在氢气中的值为0.33 mm，2% H₂使X80的断裂韧性下降21.42%，相应地氢气降低了管线钢允许的缺陷尺寸。从断口的形貌来看，氢气并没有改变材料的断裂模式，仍表现出明显的韧性断裂的特征，但局部有少量微裂纹存在。

STUDY ON FRACTURE TOUGHNESS AND DEFECT TOLERANCE OF X80 PIPELINE STEEL IN SIMULATED NATURAL GAS ENVIRONMENT CONTAINING 2%H2

Hydrogen will degrade the mechanical properties and lead to the hydrogen embrittlement of pipeline steel, which has an important impact on its safe transportation. Therefore, the fracture toughness experiment of X80 pipeline steel in hydrogen-containing environment was carried out in this paper, and the influence of hydrogen on fracture toughness of X80 pipeline steel was evaluated. The scanning electron microscopy (SEM) was used to observe and analyze the fracture surface to determine its fracture mode under different conditions. The results show that the fracture toughness of X80 pipeline steel in H2 environment is lower than that in nitrogen environment. The fracture toughness CTOD value of X80 pipeline steel in nitrogen is 0.42 mm, and the fracture toughness CTOD value in 2% hydrogen is 0.33 mm. H2 reduces the fracture toughness of X80 pipeline steel by 21.42%. From the fracture morphology, hydrogen does not change the fracture mode of the material. X80 pipeline steel still shows obvious characteristics of ductile fracture, but there are a few local micro-cracks.