Abstract: The 2507 duplex stainless steel with nano/micro-crystalline structure prepared by the aluminothermic reaction was subjected to a rolling treatment at 1 000 ℃ with 40%, 60% and 80% deformation. The microstructure of the as-rolled state was investigated by X-ray diffraction (XRD), optical microscopy (OM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The mechanical properties were measured by using a universal tensile testing machine and a Brook field optical hardness measuring instrument respectively. All measured results show that the rolling process makes austenite and ferrite phases elongated along the rolling direction and the transformation of austenite to ferrite happens in the steel as a result. With increase of rolling deformation, the nanocrystalline size does not change too much, while volume fraction of the nanocrystalline decreases. The yield strength of the steel is about 232, 284, 456 MPa, tensile strength is about 533, 577, 582 MPa, hardness is 325, 330, 337 HV, elongation takes 12.5%, 11.1% and 11.5% when the steel was rolled at 1 000 ℃ with 40%, 60% and 80% deformation, respectively.

Key words: 2507 duplex stainless steel, micro/nano-crystalline structure, rolling, strength