Simulating hydrogen in fcc materials with discrete dislocation plasticity
Professor Edmund Tarleton, with colleagues from the Department of Engineering, recently performed discrete dislocation plasticity simulations of hydrogen charged micocantilever bend tests on fcc materials at realistic hydrogen concentrations. Their paper is published in Vol 45 Issue 28 of the International Journal of Hydrogen Energy.
After observing dislocation pile-ups at the neutral mid plane of the cantilever, it was noted hydrogen was increasing the number of dislocations within the pile-ups. Meanwhile, hydrogen was also observed to decrease the flow stress due to the reduced dislocation core force, which was in contrast to the first-order hydrogen elastic shielding mechanism, which was found to be negligible at realistic concentrations.
Local stress elevation was observed in the presence of hydrogen in simulations which included an obstacle close to the free surface of the microcantilever, indicating how hydrogen might induce premature stress controlled failture.