Research On Longitudinal Crack Control Of DP700 Dual Phase Steel Billet

In recent years,the consumption and output of domestic automobiles have increased substantially,and the demand for high-strength automotive steel has increased,and higher requirements have been placed on its forming properties.Duplex steel is used in the automotive industry for its high strength and high formability.However,the longitudinal crack of DP700 duplex steel will seriously affect the quality of the slab,which brings great inconvenience to the production.Therefore,this paper mainly studies the longitudinal crack morphology and its genesis of dual-phase steel slab and the physicochemical properties of dual-phase steel slag.According to the actual production process parameters and steel composition of Shougang Jingtang,the data analysis of the defect slab is carried out.After analysis,the lower limit of carbon content is reduced,the sulfur content in the steel is reduced,the physical and chemical properties of the slag are optimized,and the crystallizer is adjusted.Measures such as process parameters improve the cracking of the duplex slab.The longitudinal crack defects of the slab were investigated,and the macroscopic characteristics of the longitudinal crack of the slab were analyzed.The longitudinal crack was subjected to SEM analysis to detect the existence characteristics of precipitated particles in and around the crack.The research on the double-phase steel protective slag has determined that the melting point of the protective slag is 1004°C,the melting rate is 27 s,and the viscosity at 1300°C is 0.31 Pa.S.In the simulation range of 1050?1500°C,with the alkalinity of the protective slag From 0.6%to 1.4%,the slag viscosity showed a downward trend.In the simulation range of 1050?1500°C,with the Mg O from 2%to 6%,the viscosity of the protective slag first decreases,then rises and then decreases.In the simulation range of1050?1500°C,with the Al₂O₃ from 2%to 6%,the viscosity of the protective slag is increasing.In the range of 1050?1500°C,when Ca F₂ is from 4%to 8%.Figure44;Table10;Reference 54.