Effect of Hydrogen on Experimental Pipeline Steels

Abstract Hydrogen is known to cause negative effects on the behavior of pipeline steels proposed for transport. This can be due to the transporting fluid containing hydrogen or when hydrogen is produced during corrosion. Rare earth element additions have been shown to offer potential improvements in various steel properties; however, their impact on steel performance in hydrogen is not well understood. The National Energy Technology Laboratory (NETL) developed four exploratory steels with targeted compositions based on X100 steel with and without cerium (Ce). The focus of this research is to evaluate the effect of hydrogen on the mechanical performance of pipeline steels with Ce additions. Four steels with varying levels of Ce additions: 0, 57, 164, and 263 ppm were made and compared to three API 5L steels: X56, X65, and X100. For hydrogen embrittlement testing, the Ce steels were compared with in-situ hydrogen embrittlement. Additionally, duplicate thermal desorption mass spectroscopy was utilized to measure the hydrogen concentration of tested materials. Exploring these developed steels helps to further the understanding of the influence of these microalloying elements and evaluate the potential of Ce as a microalloying addition for improving pipeline steels. It was found that adding Ce to the steel had no significant effect on the hydrogen embrittlement of the steels; however, Ce had an effect on hydrogen uptake and absorption into the surface, increasing with increasing Ce content.