A critical perspective on pipeline processing and failure risks in hydrogen service conditions

The development of high-strength pipeline steels with low susceptibility to hydrogen embrittlement (HE) is essential in the energy industry. Studies focusing on the HE of steels often results in contradicting findings due to the complex connection between hydrogen behavior and other material characteristics such as microstructure, chemical composition, and mechanical properties. Moreover, hydrogen trapping is strongly influenced by the properties created during steel processing. Hydrogen traps are broadly categorized as structural defects, microstructural phases, inclusions, and precipitates. The mechanisms associated with embrittlement by these traps are discussed in this work. Notably, the effect of hydrogen on mechanical properties was found to be inconsistent across different steels. A recent theoretical model was introduced to quantitatively analyze hydrogen accumulation and the critical conditions for crack initiation at inclusion-matrix interfaces. This review gives a clearer insight into the state of knowledge concerning HE in steels. It also provides an in-depth understanding on the effects of selected metallurgical factors towards hydrogen-induced degradation of mechanical properties.