Numerical Simulation Of Q345 Steel Solidification Microstructure In Continous Cating With Matlab

With the development of the continuous casting technology, how to improve the billet quality is the main direction that are studied on continuous casting technology. The formation of solidification microstructure has an important influence on the processing performance and mechanical properties of steel. Therefore, it is very meaningful to have a simulation of solidification structure of continuous casting billet.Based on the 250 mm section diameter of continuous casting round billet in a steelworks, this paper established the macro-temperature field model by using the finite difference method and the solidification microstructure formation model by using cellular automaton method. The Q345 steel microstructure of the continuous casting billet was simulated by Matlab software.This paper modified the physical parameters and nucleation parameters according to some literature. Solidification structure was obtained clearly by calculating relevant parameters. The sample of continuous casting round billet of Q345 steel was get from the steelworks. The samples were corroded after polishing, and then were observed and taken photos using optical microscope. Comparing the samples and the numerical simulation results, we find that they were similar mostly. So the model can represent the grain morphology and the grain size preferably.The simulation results show the distribution of the equiaxed grains and columnar grains clearly. It also shows the chang rules of the equiaxed grains ratio in the different average nucleation undercooling. We also analyze the effect of the pouring temperature, the cooling intensity and the casting speed on the equiaxed grains ratio.The research results shows that the occupancy of the equal axial grain becomes larger with the decrease of the average nucleation undercooling. The grain size decreases with the decrease of the average nucleation undercooling. The grain size decreases with the decrease of the pouring temperature, and decreases with the decrease of the cooling intensity. When the cooling intensity get stronger, the equiaxed grains ratio will decrease, the grain size will get larger. In actual production, when the continous casting speed get faster, the cooling intensity will increase correspondingly. That will decrease the equiaxed grains ratio, and increase the grain size. To sum up, the effective way to increase the equiaxed grains ratio is lower temperature pouring, the weaker cooling intensity and the lower continous casting speed. Therefore, to improve the speed of casting, it must take other appropriate measures,such as electromagnetic stirring.