Controlling Hydrogen Cottrell Atmospheres Around Dislocations in Austenitic Stainless Steels Through Alloying Using a Combined MD-DFT Pipeline

The growing need for hydrogen energy has led to an increased demand for structural materials with resistance to hydrogen embrittlement. The performance of these materials is governed by how dislocations move through the system under external loading. The Hydrogen-Enhanced Localized Plasticity model casts the segregation of hydrogen towards dislocations as one possible mechanism of hydrogen embrittlement. Therefore, we performed a combined Molecular Dynamics – Density Functional Theory study of alloying effects on an austenitic stainless steel and find large changes in hydrogen concentration near dislocations when we modulate the amount of added chromium. We explore the basis for the observed impact of chromium on the segregation behavior and find that the interaction between hydrogen and chromium is highly dependent on the lattice strain from the dislocation. We propose how these finding can be integrated into a materials design context, using the power of machine learning to aid in designing materials that are more resistant to hydrogen embrittlement.<br/><b><i>Acknowledgement</i></b><i>- SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525. We gratefully acknowledge research support from the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Hydrogen and Fuel Cell Technologies Office through the H-Mat program.</i>