Gradient ultrafine ferrite and martensite structure and its tensile properties by asymmetric rolling in low carbon microalloyed steel

Asymmetric rolling (AsR) was carried out to achieve a gradient ultrafine ferrite and martensite duplex structure in a commercial low-carbon microalloyed steel and compared with symmetric rolling. Two specific fiber textures 〈110〉//RD and 〈111〉//ND were developed through the thickness when imposing shear strains by AsR. In hibition of plastic instability in the ultrafine ferrite was closely associated with the gradient grain-size distribution, beneficial shear fiber textures and the dispersed martensite, resulting in high strength (~905 MPa) with good ductility (~17%).