Hydrogen Embrittlement Behavior of X42 Pipeline Steel in Gaseous Hydrogen with Different Pressures

This work explored the effect of pressure on the hydrogen embrittlement behavior of X42 pipeline steel by using tensile test. Fracture mode changes from ductile fracture when exposed to nitrogen to coexistence of ductile and brittle fracture in the presence of hydrogen. Furthermore, it has been observed that raising the hydrogen pressure can significantly increase the susceptibility to hydrogen embrittlement. This is supported by the presence of a greater proportion of brittle characteristic area on the cross section at fracture. The hydrogen embrittlement susceptibility index reaches 13.05% at pressure of 4 MPa, approximately 1.7 times higher than that at the pressure of 2 MPa.