Effect of Hydrogen Sulfide Corrosion on Fracture Toughness of X80 Pipeline Steel

Abstract: Fracture toughness of X80 pipeline steel in a simulated petrochemical environment is studied in this paper. Original specimens and saturated H2S pre-corroded specimens were tested respectively and δ-Δa resistance curves were obtained, while the influence of hydrogen sulfide corrosive environment on the resistance curve, fracture toughness and plastic work of X80 pipeline steel was analyzed. It follows that the lower limit of KIC of the pre-corroded X80 steel is 75.43 MPa·m½, and the hydrogen sulfide corrosion affect significantly on the fracture toughness of X80 steel: the crack growth resistance curve obtained from original specimens is much higher than that of the pre-corroded specimens; the fracture toughness of stable crack propagation δ0.2BL is 0.740 mm and 0.365 mm respectively, and the former is 2.02 times of the latter. In case for a given amount of crack propagation Δa, the plastic work of the original specimen is about 2.29 times of the pre-corroded specimen. Hydrogen sulfide corrosion reduced the fracture toughness of the X80 steel remarkablely. Thus, in the course of natural gas pipeline, hydrogen sulfide corrosive environment should be avoided to keep the steel a proper high toughness to prevent damage.