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A novel type of austenite–martensite dual-phase laminate steel with a yield strength of 2.2 GPa, ultimate tensile strength of 2.5 GPa, uniform elongation of 9.4% and total elongation of 12% was produced. Such unexpectable mechanical properties were mainly due to the synergistic strengthening of nanolaminate microstructure, high densities of dislocations and nanoprecipitates. The high uniform elongation at very high stress could be attributed to the strongly enhanced work hardening rate, mainly enabled by transformation-induced plasticity (TRIP) of the austenite reverted by annealing, as well as the cooperative deformation and stress/strain partitioning between the austenite–martensite stacked nanolaminate.

A novel type of austenite–martensite dual-phase laminate steel with a yield strength of 2.2 GPa, ultimate tensile strength of 2.5 GPa, uniform elongation of 9.4% and total elongation of 12% was produced. Such unexpectable mechanical properties were mainly due to the synergistic strengthening of nanolaminate microstructure, high densities of dislocations and nanoprecipitates. The high uniform elongation at very high stress could be attributed to the strongly enhanced work hardening rate, mainly enabled by transformation-induced plasticity (TRIP) of the austenite reverted by annealing, as well as the cooperative deformation and stress/strain partitioning between the austenite–martensite stacked nanolaminate. This work verifies an effective strategy of combining TRIP and maraging to achieve both ultrahigh strength and high ductility of steel. [ABSTRACT FROM AUTHOR]

A new 0.25C2Cr10Ni8Co2Mo2Al steel was designed and fabricated by vacuum induction melting, forging and heat treatments. Excellent mechanical properties with a combination of a 2.4 GPa ultimate tensile strength, a 2.1 GPa yield strength, a 11.4% total elongation and a 37 J/cm2 V-notch impact toughness were obtained. Such a combination of strength–ductility–toughness of the present steel is much superior than any reported conventional ultrahigh strength steel. The excellent mechanical properties of the steel can be well interpreted by synergistic strengthening of high-density dislocations, strong segregations of C, Mo and Cr on dislocations and massive nanosized NiAl precipitations. An extra-high strength steel of 0.25C2Cr10Ni8Co2Mo2Al was designed and the combined properties could be well interpreted by the microstructure featured with high dense precipitation of NiAl particle, high dense dislocations and the co-segregation of Cr, Mo and Co. Image, graphical abstract [ABSTRACT FROM AUTHOR]