By field emission scanning electron microscope equipped with an EBSD imaging system the structure and properties of ferritic/martensitic dual-phase steel 0. 05C-2. 8Mn-4. 2Ni-2AJ-l. 2Mo-l. 9Cu after rolling deformation and heat treatment are studied. The results show that by rolled with 900 °C. 30% +780 °C 75% deforming and 500 °C. annealed

of F- M steel the grain size 0.97μm

yield tensile strength and elongation are respectively 876 MPa

976 MPa and 15.2%

and by rolled with 900 °C 30% +780 °C 50% deforming and 500 °C annealed

of F-M steel the grain size 1.54 μm

yield、 tensile strength and elongation are respectively 801 MPa

895 MPa and 19. 4%. Hie grain refinement and the increase of small-angle grain boundaries caused by rolling deformation are the main reasons for improving the strength of the experimental steel. However

the large rolling deformation also makes too many small-angle grain boundaries hinder the movement of dislocations

which leads to more difficult deformation arid slightly poorer ductility in the plastic deformation process of the experimental steel.