MnS夹杂和氢分压耦合作用对X80管线钢氢脆敏感性影响研究

Effect of MnS Inclusion and Hydrogen Partial Pressure Coupling on Hydrogen Embrittlement Sensitivity of X80 Pipeline Steel

为了研究含有较多夹杂物的X80管线钢在空气介质和不同氢分压条件下的氢脆敏感性,采用慢拉伸试验机分别在空气和不同压力氢气环境中进行缺口慢拉伸试验,采用金相显微镜和扫描电子显微镜对断口形貌和成分进行表征分析。结果表明,包含较多夹杂物的X80管线钢在空气介质中的缺口慢拉伸断裂方式为韧性断裂;管线钢在0.6 MPa、1 MPa、3 MPa和6 MPa氢分压条件下的断面收缩率损失率分别为32.4%、74.2%、84.6%和86.6%,即在氢分压增加到1 MPa时发生了氢脆,这是夹杂物和氢分压共同作用的结果;条带状MnS与基体的界面位置在氢的作用下形成微裂纹,并进一步扩展形成环向裂纹;同时,成串的MnS夹杂促进了微孔洞的形核,并在氢分压的作用下扩展连接形成大尺寸裂纹,导致塑性急剧降低。通过分析夹杂物与氢分压对X80管线钢氢脆敏感性的影响,为输氢管线的建设提供技术参考。

In order to study the hydrogen embrittlement sensitivity of X80 pipeline steel with more inclusions under air medium and different hydrogen partial pressure conditions,slow tensile testing machines were used to conduct notch slow tensile tests in air and hydrogen environments at different pressures.The fracture morphology and composition were characterized and analyzed using metallographic microscopy and scanning electron microscopy.The results show that the fracture mode of notch slow tensile of the X80 steel containing more inclusions in air medium was ductile fracture.Under the conditions of 0.6 MPa,1 MPa,3 MPa and 6 MPa,hydrogen partial pressure,the loss rates of the reduction of area were 32.4%,74.2%,84.6%and 86.6%respectively.In other words,hydrogen embrittlement occurred when the hydrogen partial pressure increases to 1 MPa,which was the result of the joint action of inclusions and hydrogen partial pressure.Microcracks were formed at the interface between banded MnS and matrix under the action of hydrogen,and then further propagated to form the circumferential cracks.Meanwhile,the series of MnS inclusions promoted the nucleation of micropores,and expand to form a large size crack by the action of hydrogen partial pressure,resulting in a sharp reduction of plasticity.By analyzing the effects of inclusions and hydrogen partial pressure on the hydrogen embrittlement sensitivity of X80 pipeline steel,technical reference is provided for the construction of hydrogen transmission pipelines.