STRUCTURAL STEELS MICROSTRUCTURAL HOMOGENEITY EFFECT ON FATIGUE PERFORMANCE IN AIR AND HYDROGEN ENVIRONMENTS
Andrew Slifka, Enrico Lucon, Douglas G. Stalheim
Mechanical properties of low carbon structural steel are predominately driven by both the average grain size and through-thickness microstructural homogeneity in the final product. Fatigue performance is critical to the end-use design for applications such as wind towers, bridges, or high-rise buildings, and in environments of high-pressure gaseous hydrogen for pipelines. To isolate and study through-thickness grain size and homogeneity effects on fatigue performance, laboratory-developed samples were produced of a low carbon API X60 Sour Service steel, characterized by a predominately polygonal ferritic microstructure with excellent "cleanliness", i.e. low levels of impurities, and no microstructural banding. Two sets of steels were made with the only difference being variations in grain size and homogeneity of grain size. It was found that refined grain size and increased homogeneity of grain size across the through-thickness provided resistance to fatigue in pressurized hydrogen gas at 21 MPa. Fatigue testing in air and 21 MPa hydrogen pressure showed that the "Optimized" steel had improved fatigue performance compared to that of the "Non- optimized" and additionally to that of some previously-tested API X70.
, Lucon, E.
and Stalheim, D.
STRUCTURAL STEELS MICROSTRUCTURAL HOMOGENEITY EFFECT ON FATIGUE PERFORMANCE IN AIR AND HYDROGEN ENVIRONMENTS, Proceedings of the AISTech 2020 Conference, Cleveland, OH, US
(Accessed February 21, 2024)