In this study, AISI 1010 was rapidly cooling to get the lath martensite completely. After cold rolling, it was developed ultra-high strength steel. The mechanical properties of the experimental steels after cold rolling deformation were investigated. Using optical microscopy and scanning electron microscopy, microstructural evolution and tensile fracture morphology were observed. The experimental results show that the AISI 1010 steel with lath martensite structure can still maintain good plasticity(the elongation about 15%) when its tensile strength exceeds 1.3 GPa. With the increase of cold rolling deformation, the strength and hardness of the material increase significantly, while the plasticity gradually decreases. When the cold rolling deformation is greater than 30%, the elongation after fracture is less than 10%. When the cold rolling reduction reach 80%, the hardness of lath martensite steel is increased to 532HV (80%) from 440HV (undeformed). The tensile strength of the experimental steel exceeds 2.0 GPa (80%). With the increase of cold rolling deformation, the spacing of cold-deformed martensite decreases. The deformation microstructures tend to parallel with the rolling direction and gradually change to the layered structure. With the increase of cold rolling deformation, the dimples and voids reduce at the center of the fracture. The size and depth of the dimples are decreased. The voids are connected to each other and the crack initiation occurs. The obvious layered cracks and tearing structure appear in the fracture. When the deformation reaches 80%, the layered structure and tear-like crack are very obvious. © 2020, Materials Review Magazine. All right reserved.
