Influence of the carbon content on the strain rate sensitivity of nanocrystalline steels

The strain rate sensitivity of three steels with carbon contents ranging from 0.05 to 0.55 wt.% has been determined by nanoindentation and compression tests in the nanocrystalline and ultrafine-grained ranges. Samples were obtained by warm consolidation from milled powders. In the nanocrystalline range the steel with higher carbon content was found to be slightly rate sensitive, which means that the presence of carbon involves a change in the deformation mechanism of body-centered cubic iron, resulting in grain boundaries contributing to the plasticity.