Modelling the effect of hydrogen on crack growth in zirconium

Via molecular dynamics simulations, the effects of hydrogen on stress evolution of -zirconium and crack propagation in monocrystalline and multiple grained zirconium systems are investigated. Diffusion barriers are shown to reduce when strain is applied, which then causes hydrogen to accumulate at surfaces and grain boundaries. Crack growth is considered for a range of -zirconium systems, both with and without hydrogen, strained in multiple directions. The effects of crystal orientation are shown to be of high influence on the stress evolution of -zirconium irrespective of hydrogen content. Crack growth velocity is increased the most by hydrogen for -zirconium when uniaxial strain is applied in the [0 0 0 1] direction. Simulations are conducted investigating the effects of single grain boundaries in normal and parallel orientations to crack growth showing a high importance on the location of interstitial hydrogen in crack growth behaviour. In addition, larger scale simulations show the effects of multiple grain boundaries and hydrogen content in the evolution of cracks.