Enhanced hydrogen embrittlement of low-carbon steel to natural gas/hydrogen mixtures

Abstract

Fatigue crack growth rate (FCGR) tests were used to investigate the fatigue property of low-carbon steel in actual natural gas/hydrogen mixtures and carbon dioxide/hydrogen/nitrogen mixtures. It is found for the first time that the acceleration of FCGRs in the mixtures are much faster than that in hydrogen or natural gas. Natural gas/hydrogen mixtures changed the fracture mode from ductile fatigue striation to brittle cleavage fracture , and restricted the deformation activities around the crack. Synergy effect of carbon dioxide and hydrogen on the material is proposed to be the major reason for the abnormal performance of steel in the mixtures.