Numerical Simulation Of Solidification Heat Transfer In Continuous Casting Billet And Study On The Rising Temperature Of Billet

In recent years,China's steel production has been on a steady rise.In 2019,the output value reached nearly 1.205 billion tons,accounting for 53% of the world's total output,and the import volume of mineral resources exceeded 60%,providing a strong support for China's economic development.However,at the same time,it is also faced with the problems of energy,resources,environment,overcapacity and so on.How to effectively save energy,reduce emissions and reduce production costs has become a problem to be solved.In this form,relevant scholars put forward the technology of direct rod and wire rolling without heat.On the premise of ensuring no steel leakage,it is one of the key technologies to improve the billet temperature as much as possible.In view of the current demand of continuous casting section for billet temperature improvement of the technology,as well as the current problems that restrict the improvement of billet temperature(at present,the domestic casting machine drawing speed is slow,the secondary cooling water distribution is not uniform,the process parameters are set,etc.).In this paper,taking the continuous casting section of the 120 t production line of chenggang continuous casting straight rolling line as a reference,based on the theoretical knowledge of heat transfer,using the large-scale dynamic software ANSYS and material performance software Jmatpro,the thermal physical parameters were set dynamically,and the two-dimensional unsteady heat transfer mathematical model of billet in the continuous casting process was established:(1)considering the predecessors to ignore the mold Angle of air gap on the temperature of slab effect,on the basis of the influence of the small billet through field testing in mold and secondary cooling zone for export,export of air cooling zone temperature and shell thickness value,the transient thermal analysis with ANSYS simulation of small billet in continuous casting process by real-time temperature compared with shell thickness values,to explore suitable for the actual thermal physical property parameters of the optimal treatment,found that the calculated JMat Pro thermal physical parameters of the temperature of solidification heat transfer model is established and the actual error within 5% and more truly reflect the development process of slab temperature.(2)the section temperature distribution and shell thickness distribution of the casting billet at the outlet of the mold,the outlet of the secondary cooling zone and the outlet of the air cooling zone were analyzed in detail under the current process.At the same time,the influence of technological parameters such as superheat,drawing speed and secondary cold water on the cross section temperature of casting billet was analyzed.The results show that with the solidification process,the influence of superheat of molten steel on the surface temperature decreases gradually,and the superheat of 10? increases the length of liquid core by 0.15 m,which is easy to leak and segregation.When the casting temperature is increased by changing the cooling intensity of the secondary cooling zone,changing the cooling intensity of only one section of the secondary cooling zone cannot effectively improve the casting temperature at the outlet of the secondary cooling zone,so it is necessary to adjust the cooling intensity of all sections of the secondary cooling zone.Based on the theory of heat transfer,the numerical model of solidification and heat transfer of billet was constructed in this paper,which can predict the billet temperature and shell thickness at a certain point during the continuous casting process,and can reasonably identify whether the billet meets the DROF process requirements.At the same time,the effect of the process parameters on the heating process of billet in continuous casting section was investigated,which satisfied the basic demand of the application of continuous casting direct rolling technology.It provides the basis for determining the process parameters of billet temperature raising and the basis for optimizing the quality of billet under direct rolling without heating.