Research Of Surface Crack For Productions Of Direct Hot Charging Rolling

With the development of steel industry, continuous casting- hot charge rolling and hot send direct rolling technology have become the new target level to measure level of iron and steel production technologies, billet hot charging has increased productivity, reduced energy consumption and reduce the role of oxidation loss slab production .Practice indicates that the temperature in hot charge of 600℃, hot charge than 50%, hot rolling heating furnace productivity increased by about 30%, reduce energy consumption by about 20%. However, because of the shortage knowledge of steel properties, with the rate increased in continuous casting-hot charge rolling, product defect gradually increased including serious or even scrapped problem, causing huge economic losses.In this paper, The CC-DHCR process of The second hot rolling plant WISCO was studied through different steels in high temperature thermoplastic, in particular Nb microalloyed steel with brittle zone in thermoplasticⅢ, analysis of the correction in the continuous casting direct the course of the plastic case of steel, Nb-containing steel and high temperature thermoplastic non-Nb steel were compared and analyzed the impact of Nb steel thermoplastic. Through different kinds of phase transition in the determination of the critical points obtained in the continuous casting process of steel straightening austenite and ferrite mixed grain structure, in which the lower intensity of ferrite along the austenite distribution of grain boundary cracks in the slab by the force of the important reasons.Through different steels thermoplastic experiments, the steel sectionⅢbrittle zone temperature range, made for Q345B, Q345C, X70 billet straightening temperature range, by avoiding the firstⅢbrittle zone temperature range effective in reducing the coercivity straight cracks, reducing the appearance of surface defects, after rolling.