Proceedings of the Third International Conference on Metals & Hydrogen K02

Correlating Steel Pipeline Microstructure to Fatigue Crack Growth Rates in High Pressure Hydrogen Gas

Eun Ju Song (1)1 , Yanli Wang (2)2 , Zhili Feng (2)2 , Zhenggang Wu (2)2 , Robert Amaro (3)3 , Andrew Slifka (4)4 , Elizabeth Drexler (4)4 , Joseph A. Ronevich (1)1

  • (1) 1

    Sandia National Laboratories, 7011 East Avenue, Livermore, CA, 94550, USA

  • (2) 2

    Oak Ridge National Laboratory, 1 Bethel Valley Rd, Oak Ridge, TN, 37830, USA

  • (3) 3

    University of Alabama, Tuscaloosa, AL, 35487, USA

  • (4) 4

    National Institute of Standards and Technology, 325 Broadway, Boulder, CO, 80305, USA


Steel pipelines represent one of the lowest cost options to transport large volumes of gaseous hydrogen over long distances. Current codes limit hydrogen pipelines to lower strength grades such as X52, resulting in limitations on operating pressures and pipeline diameters. Higher strength steel pipes with yield strengths up to 551 MPa are permitted, but significant design penalties are required resulting in increased thickness and as a result, negligible cost savings. Steel pipelines exhibit accelerated fatigue crack growth rates in gaseous hydrogen relative to air, however, the degradation does not appear to be correlated to strength as typically presumed. It is conventionally expected that higher strength steels are more susceptible to hydrogen embrittlement than lower strength steels, however, recent testing on a variety of pipeline steel grades has not proven this trend to be true for fatigue crack growth rate. It is thought that microstructure may play a more defining role than strength in determining the hydrogen susceptibility. In this work, fatigue crack growth rates were measured in hydrogen for a variety of high strength steel pipeline microstructures. A detailed microstructural investigation was performed, in an effort to understand the role of microstructure in the materials fatigue crack growth rate performance. Understanding microstructure-mechanical property relationships in pipeline steels is necessary to improve design margins, develop predictive models, and ultimately provide a pathway to enable the implementation of higher strength pipeline steels.


  • microstructure
  • fatigue crack growth rate
  • pipeline steel
  • hydrogen embrittlement