Research On The Formation And Influence Factors Of Surface Transversal Crack During Continuous Casting Of Steel

Surface transversal crack is a kind of common surface quality defect in the castingslab production, and seriously impacts on the hot delivery and directly rolling. At present,there is no uniform conclusion on the formation mechanism of surface transversal crack,so further studying of the formation mechanism of surface transversal crack and puttingforward some measures to reduce or eliminate the crack have great significance forproduction of casting slab without defects and realization of directly rolling.According to the actual production of Ansteel, the mechanism of surface transversalcrack from the generation to the expansion was analysed. The main influence factors thatimpacted the surface transversal crack, such as chemical composition, heat transfer,friction were furtherly studied.The effects of the main chemical compositions on the mechanics properties of hightemperature steel and the relationship between mould powder and the surface crack ofsteel in mould were analysed. The control principle of the main chemical composition andthe selection principle of the mould powder for the crack sensitive steel were summarized.According to the actual conditions of the slab continuous production and on the basisof simplifications and reasonable hypothesis, the thermal physical parameters, basicmechanical parameters and boundary conditions were determined. The three-dimensionalheat transfer and coupled thermo-mechanical finite element models for mould slab wereestablished by finite element analysis software MSC.Marc.Through the simulation and calculation, the rules that solidified shell temperaturedistribution, the thickness of the solidified shell distribution, the friction force distribution,equivalent stress and strain distribution in the process of mould oscillation process werederived. Based on the simulation results, the effects of the temperature field distribution,thermal stress and friction on the slab of primary surface crack in mould were analysed.