Effect of hydrogen and strain rate on nanoindentation creep of austenitic stainless steel

The effect of hydrogen and strain rate on nanoindentation creep of austenitic stainless steel was investigated by nanoindentation loading and creep tests. The loading segment mainly reflects dislocation nucleation, but creep mainly indicates dislocation movement. The strain rate significantly influences dislocation nucleation, resulting in increased creep displacement with strain rate. The interaction between hydrogen and dislocation is responsible for the increased creep displacement in 310S steel. Hydrogen greatly enhances the displacement burst after small strain rate due to increased dislocation nucleation rate. Hydrogen slightly enhances creep of 304 steel as hydrogen diffuses through strain-induced alpha' martensite to accumulate under the indenter before creep and enhances dislocation movement. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.