Study on the Effects of Partial Pressure on X52M Pipeline Hydrogen Embrittlement Properties in High-Pressure Hydrogen Environments

In pure hydrogen pipeline systems， the transmission pressure is critical for ensuring both efficient operation and safety performance. Through the slow tensile and fatigue life tests under high pressure gas phase environment， the influence law of plasticity and fatigue life properties under different hydrogen partial pressure on X52M pipeline steel （mass fraction /%： 0.04C，0.98Mn，0.010P，0.001S，0.033Nb，0.033V，0.16Cr，0.014Ti） were contrastive studied， Various characterization techniques， including metallographic microscopy and scanning electron microscopy （SEM）， were utilized to examine the microstructural evolution and fracture mechanisms. The results indicated that the loss rate of slow tensile section shrinkage increased significantly with the increasing of hydrogen partial pressure， the ductility loss was measured to be 10.5%， 17.5%， and 28.5% under 4 ， 6 ，10 MPa hydrogen pressure， respectively. Furthermore， hydrogen partial pressure significantly impacted the fatigue life of the material. A substantial increase in fatigue life reduction from 37.1% to 63.1% was observed when the hydrogen pressure was raised from 6 MPa to 10 MPa， indicating a heightened susceptibility to hydrogen embrittlement. The increase in the partial pressure of hydrogen leads to more hydrogen-induced cracks， which are difficult to crack in the hydrogen environment， and eventually leads to more serious hydrogen brittlement of the material. The test results can be used as an important reference basis for hydrogen transmission pipeline design and safe operation.