Abstract: By combination of rolling in (α+γ) dual-phase region and short-time heat preservation treatment in the dual-phase region,a high-strength high-toughness low-carbon low-alloy ferrite/martensite dual phase steel was prepared.The effect of different rolling processes on the microstructure and mechanical properties of the ferrite/martensite dual-phase steel were investigated by scanning electron microscopy (SEM),tensile test at room temperature and Vickers hardness test.The results show that,compared with the common continuous rolling process,the combination of the isothermal rolling with the short-time heat preservation treatment between passes has an important influence on the phase ratio,morphology and size of the ferrite/martensite dual phase steel.The microstructure of the dual-phase steel after isothermal rolling and short-time heat preservation treatment is obviously refined.The martensite phase ratio is increased,and the structure uniformity is significantly improved.The yield strength is increased by 34% to 1229 MPa,and the yield ratio is as high as 0.78.The fracture surface is ductile fracture type characterized by small dimples and showing good comprehensive mechanical properties.

Key words: rolling process, ferrite/martensite dual-phase steel, microstructure, mechanical properties, refined microstructure