Study on ductile fracture behavior of hydrogen-charged API pipeline steel

Abstract

With the increasing focus on reducing carbon emissions, hydrogen hasemerged as a promising alternative energy source. However, the safetransportation of hydrogen poses challenges due to its potential impacton the integrity of pipeline materials. This study aims to investigate theeffect of hydrogen charging time on the plastic behavior and ductile frac-ture characteristics of API 5L X42 pipelines, which are commonly used fortransporting hydrocarbons. Tensile tests were conducted on various typesof hydrogen-charged specimens at room temperature to assess differentfracture modes. Hydrogen was introduced into the specimens using a cath-odic electrolytic method, and 24-h charging time durations were consid-ered. Finite element analyses were performed on standard dog-bone andnotched tension specimens to evaluate the plastic behavior, employing theSwift hardening law to model the flow stress. Numerical analyses wereconducted to determine the loading path leading to fracture initiation. Adamage framework based on the Hosford？Coulomb model was utilized topredict ductile fracture under non-proportional loading conditions. Thefindings of this study provide insights into the fracture behavior of pipe-lines under hydrogen exposure, aiding in the design and assessment ofsafe and reliable hydrogen transport systems.