Abstract :
Large plastic strains between 1 and 15 can be
imposed in chips formed by plane-strain (2-D) machining
of metals and alloys. This approach has been used to
examine microstructure changes induced by large strain
deformation in model systems—copper and its alloys,
precipitation-hardenable aluminum alloys, highstrength
materials such as titanium, Inconel 718 and
52100 steel, and an amorphous alloy. It is shown that
materials with average grain sizes in the range of
60 nm–1 lm can be created by varying the parameters
of machining, which in turn affects the deformation
processes. Furthermore, a switch-over from an elongated
subgrain microstructure to an equi-axed nanocrystalline
microstructure, with a preponderance of
large-angle grain boundaries, has been demonstrated at
the higher levels of strain in several of these materials.
This switch-over can be readily controlled by varying
the deformation conditions. Dynamic recrystallization
has been demonstrated in select material systems under
particular conditions of strain and temperature. This
study may be seen as providing an important bridge
between furthering the understanding of microstructural
refinement by large strain deformation and the
practical utilization of nanostructured materials in
structural and mechanical applications. Conventional
plane-strain machining has been shown to be a viable
SPD method for examining the underlying processes of
very large strain deformation
