Experimental Study On The Interfacial Heat Transfer Coefficient Between Roll Surface And Molten Pool And The Verification Of The Result

The twin-roll casting is a kind of near net shape forming process, with the advantage of short process, low energy consumption and high economic benefits, it has been widely studied by researches and companies in recent years. As the core part of the whole process, the casting roller is used as not only a roll but also a crystallizer. The interface heat transfer coefficient between roller surface and molten pool is one of the most important factors affecting the whole roll casting process, which finally decided the performance and quality of the strip by influencing the solidification rate of liquid metal. However there are some limitations in the study of the heat transfer coefficient at present. The conclusions are usually some qualitative rules, which only apply to specific conditions.In this paper, firstly, the contact of the metal melt and the roller surface is analyzed, and a set of simulation experiment device is designed according to the solidification characteristics of the metal melt in the roll surface and whether to bear rolling force. Using this device can measure the temperature of liquid metal and roller surface between the process from the initial contact to early stage of solidification, based on the measured experimental data, the distribution of heat transfer coefficient along the surface of the roller is obtained by using the inverse analysis method of heat conduction and the reasonable modification. The conclusion is that the heat transfer coefficient get its maximum value in the initial stage and began to decrease rapidly, but the rate of decrease is more and more slow, then it increases rapidly because of the rolling force when reaching the KISS point, the growth rate is about 70%. The influence of pouring temperature on the interfacial heat transfer coefficient can also be obtained by changing the initial temperature of the molten metal, that is, the interfacial heat transfer coefficient will increase slightly with the increase of the pouring temperature.Secondly, in order to verify the accuracy of the interfacial heat transfer coefficient, a mathematical model coupled with the flow, heat transfer and solidification of molten pool in the casting process was established, the obtained interfacial heat transfer coefficient is used as the boundary condition to carry on the numerical simulation, and compared with the actual twin roll casting process with the same parameters, the results show that the temperature of the outlet zone has a high degree of anastomosis at different pouring temperatures. Besides, also compared the simulation results of temperature field and solidification conditions with other types heat transfer coefficient, the results show that the interfacial heat transfer coefficient obtained from this peper can make the temperature field more in line with the actual situation and the solidification process is also more reasonable.