Collaborative Research: Evolution of Strain and Microstructures in the Presence of Solute Hydrogen - a Mulitscale Experimental Investigation

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Hydrogen embrittlement, a sudden and catastrophic failure, of metallic structures, accounts for losses equal to 3 percent of the gross domestic product. This enhanced failure mechanism presents a significant challenge to transitioning from a fossil fuel powered transportation system to one powered by hydrogen. For this to occur, the mechanisms by which hydrogen enhances the failure must be discovered. This advance will enable design of alloys for use in hydrogen environments as well as development of models to predict component lifetime. This experimental collaborative effort between UW-Madison and Cornell University seeks to identify the fundamental mechanisms driving the hydrogen-enhanced failure. Students educated in this effort will gain international experience through collaboration with faculty at Kyushu University in Japan and their International Institute for Carbon Neutral Energy Research. In addition, the PIs will develop and distribute engineering based in-class activities that emphasize mechanical properties of metallic systems.The deleterious impact of a hydrogen environment on the mechanical properties of metallic structures is well-documented and yet the fundamental mechanisms driving the enhanced sudden failure remain elusive. This collaborative effort will employ a multi-scale experimental approach designed to test the premise that solute hydrogen can accelerate the evolution of the microstructure (strain) and it, along with attendant high hydrogen concentration, establishes the local conditions that determine the fracture path and mechanism. The influence of hydrogen on the evolution of microscale lattice strains and orientations will be probed dynamically using high energy x-ray diffraction and in-situ mechanical loading at Cornell High-energy Synchrotron Source (CHESS). This effort will be coupled with post-loading microstructure characterization in the TEM of materials loaded to varying degrees of strain under different conditions, including those used in the in-situ testing. Confirmation of the premise will provide a basis for design of hydrogen tolerant microstructures as well as for physically-based predictive models.