A Combined Applied Mechanics/Materials Science Approach Toward Quantifying the Role of Hydrogen on Material Degradation

Development and validation of a lifetime prediction methodology for failure of materials used for hydrogen containment components is of paramount importance to the planned hydrogen economy. In the case of low strength steel pipelines, we outline a hydrogen transport methodology for the calculation of hydrogen accumulation ahead of the tip of an axial crack on the inner surface. For all practical purposes, we find that the stress, deformation, and hydrogen fields exhibit a small scale character which allows for the use of the standard modified boundary layer approach to the study of the fracture behavior of steel pipelines. Arguably the most devastating mode of hydrogen-induced degradation is the hydrogen embrittlement of high-strength steels. We present an approach to quantify the effect of hydrogen on the fracture strength and toughness of a low alloy martensitic steel through the use of a statistically-based micromechanical model for the critical local fracture event.