Effect of Hydrogen on Experimental Pipeline Steels (C2026-00262)

Lucas Teeter, Zineb Belarbi, Kyle Rozman, Richard Oleksak, David Alman

Hydrogen can negatively impact pipeline steels due to the transporting fluid containing hydrogen gas or hydrogen produced during corrosion. Minor additions of rare earth elements, such as Cerium (Ce), have been shown to improve a variety of steel properties by eliminating elongated inclusions which have been proposed as crack nucleation sites during the hydrogen embrittlement process. Ce also exhibits a relatively high affinity for hydrogen, raising the possibility of limiting hydrogen diffusion in the steel to inhibit the embrittlement process. Four experimental pipeline steels with varying levels of Ce additions: 0, 57, 164, and 263 ppm were developed and were compared to three commercial API 5L steels: X56, X65, and X100. For hydrogen embrittlement tensile testing, the Ce steels were compared with both in-situ and ex-situ hydrogen charging techniques. Additionally, thermal desorption mass spectroscopy was utilized to measure the hydrogen concentration these materials contained during testing.
This study found that adding Ce to the steel had no significant effect on the hydrogen embrittlement of the steels; however, Ce had a pronounced effect on hydrogen uptake and absorption into the surface.