Abstract This study focuses on the characterization of the
microstructures of an FeCrMoVC alloy in two states (an
as-cast and a heat-treated state) as well as the compressive
strain rate-dependent material and fracture toughness
behavior. Both microstructures consist of martensite,
retained austenite and complex carbides. Tempering results
in a transformation of retained austenite into martensite, the
precipitation of fine alloy carbides, and diffusion processes.
High yield stresses, flow and ultimate compressive strength
values at a relatively good deformability were measured.
The yield and flow stresses at the onset of deformation are
higher for the heat-treated state due to higher martensitic
phase fractions and fine precipitations of alloy carbides
respectively. Compressive deformation causes a straininduced
transformation of retained austenite to a0
-martensite.
Hence, both high-strength alloys are TRIP-assisted
steels (TRansformation-Induced Plasticity). However, the
martensitic transformation is more pronounced in the as-cast
state due to higher phase fractions of retained austenite
already in the initial state. Examinations of strained
microstructures showed decreased crystallite sizes with
increasing deformation. It is assumed that, during plastic
deformation, the amount of low angle grain boundaries
increases while the incremental formation of a0
-martensite
leads to decreased crystallite size. In general, lower microstrains
were determined in the heat-treated state as a
consequence of stress relaxation during tempering. In
comparison to commercially available tool steels, the
determined fracture toughness KIc of both variants revealed
relatively high fracture toughness values. It was found that
the lower shelf of KIc is already reached at room temperature.
Higher loading rates K_ resulted in lower dynamic
fracture toughness KId values. Notch fracture toughness KA
measurements indicate that the critical notch tip radii of the
examined materials are slightly smaller than 0.09 mm.
Int