High strength and ductile low density austenitic FeMnAlC steels: Simplex and alloys strengthened by nanoscale ordered carbides

Abstract

We introduce the alloy design concepts of high performance austenitic FeMnAlC steels, namely, Simplex and alloys strengthened by nanoscale ordered k-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 L912 ordered precipitates (so called k-carbides) resulting in high strength (yield stress ∼ 1.0 GPa) and ductile (elongation to fracture 7sim; 30%) steels. Novel insights into dislocation-particle interactions in a Fe- 30.5Mn-8.0Al-1.2C (wt-%) steel strengthened by nanoscale k-carbides are discussed. © 2014 Institute of Materials, Minerals and Mining.