Study And Application Of On-line Solidification And Heat Transfer Model For 360mm×450mm Bloom Continuous Casting

As one of the core models of dynamic soft reduction control system for bloom continuous casting, the on-line solidification and heat transfer model provides the solidification process parameters for the other two core models, such as secondary cooling dynamic control model and dynamic soft reduction model. The computation precise of the on-line solidification and heat transfer model is directly related to the rationality of reduction position and the effectiveness of dynamic soft reduction. On the basis of the actual conditions of 360mm×450m bloom continuous casting machine in someone steelworks, a on-line sodification and heat transfer model was established, that provided processing parameters for the dynamic soft reduction control system. The main research performed and the correspondent results obtained are as follows:(1) The establishment of on-line solidification and heat transfer model for bloom continuous casting. The on-line solidification and heat transfer model was established by idea of tracing element, which assumed that the tracing element was born at meniscus in mould and died out at the final withdrawal and strengthening machine. The whole strand consisted of many tracing elements hand by hand and the attribution of each tracing element was related to practice.(2) The development of on-line solidification and heat transfer model for bloom continuous casting. The on-line solidification and heat transfer model was programmed and created dynamic link library, using the MFC appwizard(dll) in VC++6.0 development environment. The dynamic link library of on-line solidification and heat transfer model was transplantable and accessed simultaneously by multiple application, so that repeating meaningless development work was avoided and multiple strand on-line computation is carried out simultaneously.(3) The development of solidification and heat transfer simulation system for bloom continuous casting. The simulation system for 360mm×450mm bloom continuous casting was programmed by VC++6.0 development language, convenient for debugging and optimizing, and the development time of model was reduced.(4) The validation and industrial application of solidification and heat transfer model for bloom continuous casting. The optimized solidification and heat transfer model was integrated into dynamic soft reduction control system and applied to industrial production. The model was validated by the measured data obtained by infrared thermoscope, and the difference between the bloom surface measured temperature and calculation temperature is less than 1%.(5) The effect of operating parameters on the solidification of typical steel grades. The solidification processes of typical steel grades as YQ450NQR1,37Mn2 and 42CrMo, were analyzed under different continuous casting practice. The computation results show that the solidification process was impacted by casting speed obviously, and the effect of casting speed on crater end became significant with high carbon content in steel grade. As the casting speed increased by O.lm/min, the forward movement of final solidification points for YQ450NQR1,37Mn2 and 42CrMo are 4.7m,5.2 and 4.96m respectively, and the increment length of mushzone are 2.4m,2.75m and 2.55m respectively. Although the solidification process was impacted by super heat gently, it has a great effect on shell thickness at the exit of mould. When super heat increased 10℃, the surface temperature increased 5℃around, but the shell thickness at exit of mould reduced 2.7%.