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Abstract:
We introduce the alloy design concepts of high performance austenitic
FeMnAlC steels, namely, Simplex and alloys strengthened by nanoscale
ordered kappa-carbides. Simplex steels are characterised by an
outstanding strain hardening capacity at room temperature. This is
attributed to the multiple stage strain hardening behaviour associated
to dislocation substructure refinement and subsequent activation of
deformation twinning, which leads to a steadily increase of the strain
hardening. Al additions higher that 5 wt-% promote the precipitation of
nanoscale L'1(2) ordered precipitates (so called kappa-carbides)
resulting in high strength (yield stress similar to 1.0 GPa) and ductile
(elongation to fracture similar to 30%) steels. Novel insights into
dislocation-particle interactions in a Fe-30.5Mn-8.0Al-1.2C (wt-%) steel
strengthened by nanoscale kappa-carbides are discussed.
