Study On High Temperature Properties And Microstructure Simulation Of Continuous Casting Slab

Continuous casting is one of the most active technologies in steel industry, and the high-temperature properties of continuous cast slab are very important for guiding its production process. The high-temperature physical and mechanical properties parameters are also very important during the slab continuous cast process despite improving solidification cooling system, judging cracks in casting slab and establishing parameters of dynamic soft reduction in continuous casting. Paper select steel A and B slab casting in One Iron and Steel Company to test part of mechanical behavior and physical property of steel casting blank under high temperature; on the mathematical model of heat transfer and stress variety in slab continuous casting process.The test and measurement on two steel grades temperature expansion and differential thermal analysis are made according to the actual situation. Through these test and analysis the two steels high temperature physical property of casting slab like temperature expansion, heat capacity, latent heat, solidus curve and liquid line etc are achieved. In different speed of heating, we obtained the heat capacity of casting slab in the heating process and cooling process.Mechanical property variations with the temperature changing from 600 degree centigrade to 1300 degree centigrade are gotten through the Tension test t on the Gleeble-1500D and the steel high temperature brittleness zone especial the third one are determined according to the reduction rate of the cross-section. The second brittle zone of steel B is about between 775 degree centigrade and 950 degree centigrade. The second brittle zone of steel A is about between 725 degree centigrade and 900 degree centigrade.The steel properties have been used to defining suitable bound conditions which are very useful for the casting slab secondary cooling simulation software. Then with the simulation an optimal of the secondary cooling system in the continuous slab casting at No.4 steel making and rolling plant of One Iron and Steel Corp. The practical production shows good results after the optimal, it proved that the steel properties have very important meaning to optimal of the secondary cooling system.Also the steel properties and surface temperature tests of casting slab results are very important basis data of continuous casting slab's microstructure simulation. The Cellular Automaton (CA) is coupled with Finite Difference Method (FDM) here to establish the stochastic nucleation and growth model. The CA is used to simulate the solidification structure, where the FDM is used to calculate the temperature and solute diffusion. Three different casting condition have been simulated by the model, the results show good in agreement with the regulation of microstructure evolvement rule and the stochastic nucleation,preferred growth,competitive growth and random orientation of grain. The effects of processing parameters on the competition growth between columnar and equiaxed grains are analyzed. The results are in agreement with practical process and theoretical analysis.