Evaluation of hydrogen related degradation of API X42 pipeline under hydrogen/natural gas mixture conditions using small punch test

This study investigates the effect of a hydrogen/natural gas mixture on the mechanical properties of API X42 pipeline steel using small punch (SP) test. The hydrogen-assisted fracture behavior demonstrated a transition from ductile to brittle failure, similar to the temperature-assisted brittle fracture mode. The preferential sites for hydrogen-assisted crack initiation in the X42 pipeline steel were located at the ferrite/pearlite interface, where hydrogen diffusion is enhanced by localized stress/strain conditions. The feasibility of the hydrogen environment embrittlement susceptibility obtained in the SP test and the correlation to the conventional test method is also discussed.

Automated summary

The study investigates the impact of a hydrogen/natural gas mixture on the mechanical properties of API X42 pipeline steel. It found that hydrogen can lead to a transition from ductile to brittle fracture behavior, with preferential crack initiation sites at the ferrite/pearlite interface. The feasibility of hydrogen environment embrittlement susceptibility obtained in the SP test and its correlation to traditional testing methods were also discussed.