Unprecedented combination of specific tensile strength and ductility achieved in a novel duplex low-density steel

Abstract

By annealing a cold rolled 30Mn-13Al-1.3C-5Cr steel at 1000 °C, we successfully developed a novel lightweight steel having the tensile strength of 1250 MPa and total elongation of 41.4 % at the measured ultralow density of 6.36 g·cm^-3. Such an unprecedented strength-ductility-density synergy results from the new designed austenite-ferrite duplex microstructures, where the granular α ferrite grains can restrain the austenite grain growth, δ ferrite bands capture and deflect the propagating cracks, and high contents of Mn/Al/C in recrystallized austenite result in the extensive precipitation of κ-carbide nanoparticles for strengthening.