  Austenitic stainless steels with low carbon have exceptional mechanical
properties and are capable to reduce embrittlement, due to high chromium and
nickel alloying, thus they are very attractive for efficient energy production
in extreme environments. It is key to perform nanomechanical investigations of
the role of chromium and the form of the particular alloy composition that give
rise to the excellent mechanical properties of steel. We perform
nanoindentation experiments and molecular dynamics (MD) simulations of FCC
austenitic stainless steel 310S, using established interatomic potentials, and
we use a comparison to the plastic behavior of NiFe solid solutions under
similar conditions for the elucidation of key dislocation mechanisms. We
combine EBSD images to connect crystalline orientations to nanoindentation
results, and provide input data to MD simulations for modeling mechanisms of
defects nucleation and interactions. The maps of impressions after
nanoindentation indicate that the Ni-Fe-Cr composition in 310S steel leads to
strain localization and hardening. A detailed analysis of the dislocation
dynamics at different depths leads to the development of an experimentally
consistent Kocks-Mecking-based continuum multiscale model. Furthermore, the
analysis of geometrically necessary dislocations (GND) shows to be responsible
for exceptional hardness at low depths, predicted by the Ma-Clarke's
constitutive model.
