Research on the Mechanical Behavior of Commonly Used Steels for Pressure Vessels and Pipelines in China Under Ambient Temperature and High-Pressure Hydrogen Environment

Hydrogen gas is one of the most important long-term energy storage methods for renewable energy, and hydrogen utilization is also considered as an important means of achieving carbon reduction. At present, hydrogen storage and transportation under ambient-temperature and high-pressure is an important method for hydrogen energy storage and transportation. However, due to the threat of hydrogen embrittlement under high-temperature and high-pressure environment, there is a common concern over the hydrogen embrittlement of the steel pressure vessels and pipelines caused by hydrogen, which may result in unsafe consequences. In the present paper, the hydrogen charging tests, the conventional slow strain rate tensile (SSRT) tests, modified slow strain rate tensile (MSSRT) tests, and the hydrogen-induced cracking tests with the wedge-open loading (WOL) samples under ambient-temperature and high-pressure gaseous hydrogen environments were carried out for the commonly used pressure vessel steels Q345R, 30CrMo and X80 pipeline steel in China. The experimental results show that hydrogen hardly penetrates into Q345R, 30CrMo and X80 steels under ambient-temperature and 35 MPa gaseous hydrogen environment. When increasing the hydrogen pressure to 70 MPa, it is also difficult for hydrogen to penetrate the above three kinds of steels, and the maximum increase in hydrogen concentration is only about 0.1 ppm. When increasing the hydrogen pressure to 110 MPa, a small amount of hydrogen can penetrate into 30CrMo steel (the increase in hydrogen concentration is 0.38 ppm), but it is still difficult for hydrogen to penetrate into Q345R and X80 steels (the increase in hydrogen concentration is less than 0.0645 ppm). The MSSRT tests under the ambient-temperature and 35 MPa gaseous hydrogen environment show that the elongation (EL) and reduction of area (RA) of the above three kinds of steels does not decrease significantly. Compared with the MSSRT results under the ambient-temperature and 35 MPa gaseous nitrogen environment, the ELs of Q345R, 30CrMo and X80 steels decrease by 0.2%, 4.3%, and 3.2%, respectively, and the RAs of Q345R, 30CrMo and X80 steels decrease by 0.4%, 1.1%, and 1.5%, respectively. In addition, the results of the hydrogen-induced cracking tests with WOL samples show that, even if the applied stress intensity factor reaches 103 MPa·m1/2, the pre-crack of 30CrMo steel does not propagate under the ambient-temperature and 110 MPa gaseous hydrogen environment. In summary, hydrogen has almost no effect on Q345R, 30CrMo and X80 steels under the ambient-temperature and medium/high-pressure (below 35 MPa) gaseous hydrogen environment. When hydrogen pressure reaches 70 MPa, there is little difference in hydrogen permeation compared to the 35 MPa condition, thereby the influence of hydrogen on the mechanical properties of the above steels could be slight as well. When the hydrogen pressure reaches 110 MPa, the 30CrMo steel with the highest hydrogen permeation also exhibits good resistance to hydrogen induced cracking, indicating that hydrogen has limited influence on the mechanical properties of the steels.