Abstract
Two kinds of C-Si-Mn-Cr-Mo-Nb tested steels with different C content were disigned, and controlled rolling and controlled cooling experiment of tested steels have been carried out in lab to analyze the effect of C on microstructure and mechanical property of high strength hot rolled dual phase steel. It is shown that two kinds of tested steels obtained ferrite and martensite microstructure under controlled rolling and step cooling process. With the increase of C content from 0.032wt% to 0.064wt%, ferrite grain size refines from 9.8μm to 5.0μm, width of martensite colony reduces from 10μm to 5.8μm, and martensite volume fraction increases from 11% to 25%. Yielding strength of high C tested steel is higher than that of low C steel by 55MPa, and amplification of tensile strength is about 155MPa. Elongation ratio decreases about 6.4%. Increasing of yielding strength is determined by strengthening of ferrite grain refining. The amplification of tensile strength is effect by volume fraction and refining of strengthening phase.
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