Study on Mechanical Properties and Formability of Ti Type 550NH High Strength Weather Resistant Steel Strip

In order to comprehensively study the mechanical properties and formability of Ti type 550NH weather resistant steel strip, three kinds of weather resistant steel were designed by changing the content of Ti element in the test steels.Combined with the smelting process and rolling process, the trial production of steel was carried out. The microstructure and impact fracture of the steel after rolling were analyzed by optical microscope and scanning electron microscope, and tensile and impact tests were carried out. The results show that at high coiling temperature, the structure of the test steel is ferrite matrix + part of pearlite. Extending the insulation time for the heating and appropriately reducing the final rolling temperature can effectively reduce or even eliminate the pearlite band structure. In terms of mechanical properties, Ti element plays a dual role of grain refinement strengthening and precipitation strengthening during hot rolling, but too much Ti element content will reduce the toughness and plasticity of the material. In terms of formability, the test steel without band structure has better cold bending performance because of the uniform distribution of F+P structure; the test steel with banded structure has obvious cold bending cracks, and the plastic deformation ability of the material decreases.