Simulation Study On Solidification And Heat Transfer Of Square Billet Continuous Casting In High Speed Continuous Casting

Currently,Endless strip processing has became the advanced technology in the field of steel rolling.High-quality,high-speed continuous casting technology is the key to achieve Endless strip processing.In this research,combined with the need of wire and rod Endless strip processing,the solidification and heat transfer process in square billet high-speed continuous casting process was studied,and some research progress was obtained.The main research contents and results are as follows:(1)The typical square billet continuous casting machine for field application was selected,and heat conduction control equation of two-dimensional solidification heat transfer during billet continuous casting was established.Meanwhile,the explicit finite difference method was used to simulate and calculate the temperature field of square billet under the continuous casting speed of 2.32m/mim.The heat transfer coefficient of each cooling section in the model was corrected according to shell thickness at the specific position of the second cooling section measured by the Nail-shooting method,so that reasonable boundary conditions for the solidification process of the square billet were obtained.(2)The heat transfer control process of high-speed billet was simulated by establishing heat conduction control equation.The results showed that when the continuous casting speed was too high,the thickness of solidified shell at the exit of crystallizer was too small.The surface temperature rise of speed square billet in each section of second cooling zone was too large,which made it easy for the square billet to generate internal cracks and other defects.The core liquid ratio and surface center temperature at the straightening point also could not meet actual production requirements.(3)According to the heat transfer simulation calculation results of the high-speed square billet solidification process,the suitable crystallizer structure and mold fluxes for high-speed continuous casting machine was proposed.The size of the casting machine was adjusted appropriately.Meanwhile,the type of suitable nozzle,pouring temperature and water distribution coefficient of the second cooling zone were determined.(4)After optimization and adjustment,when the high speed continuous casting reached 3.5m/min,4.5m/min and 5m/min,the thickness of solidified shell at the exit of crystallizer were 14.6mm,13.1mm and 13.0mm,respectively,which reached the safe thickness of solidified shell required for normal production.Besides,the surface center temperature at the straightening point was about 994?,1031? and 1043? and the temperature rise of each section was less than 110?.