A Review of the Factors That Can Increase the Risk of Sulfide Stress Cracking in Thermomechanical Controlled Processed Pipeline Steels

This review aims to improve our understanding of the important factors which influence the susceptibility of thermomechanical controlled processed (TMCP) steels to sulfide stress cracking (SSC). Mechanisms involved in hydrogen embrittlement (HE) from three perspectives are focused on: the microstructure constituents of TMCP steels; environmental factors; and fracture mechanism of SSC. Microstructures are reviewed as they affect the diffusion and trapping of hydrogen that can reduce the resistance to fracture. Environmental factors discussed highlight that when exposed to an aqueous H₂S environment, a sulfide layer can form and influence the ingress of hydrogen, and this is affected by pH, temperature, and H₂S partial pressure. Fracture is influenced by the nature of the crack tip and the crack tip plastic zone during crack propagation, and hydrogen can significantly affect crack tip growth. This review provides a critical assessment of the interplay between these three factors and aims to provide understanding to enhance our engineering approaches to manage and mitigate against fracture of TMCP steels.