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Peiqing La1 Yu Shi1 Keliang Wang1 Yi Song1

1, State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals, Lanzhou University of Technology, Lanzhou, , China

Strength and ductility are mutually trade off usually in steels and alloys. Grain refinement to nanoscale can make the conventional steels several times stronger, but invariably leads to poor ductility. Here we demonstrate a micro/nanostructured lamellar phases in 2205 stainless steel prepared by aluminothermic reaction and followed hot rolling that produced a superior yield strength of 780MPa, ultimate tensile strength of 979 MPa and elongation of 54%. The elongation is the highest in the reported steels with that level of strength. The product of tensile strength and elongation exceeds 50 GPa% and is the highest value that was reported in the literatures. The steel consists of micro/nanostructured lamellar ferrite phase and micro/nanostructured lamellar austenitic phase in which the dislocation free hard nano grains dispersed in soft coarse grains. The high strength is attributed to strengthening of dislocation free nano grains and interface between the two phases. The unusual high ductility originates from cracks propagation resistance by the nano grains and the two phase interfaces.

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