Numerical Simulation of Solidification Structures of Ag–28Cu–1Ni Alloy through Continuous Casting Based on Three-Dimensional CAFE Method

Abstract

Microstructure evolution of Ag28Cu1Ni alloy during the continuous casting process was simulated based on 3D-CAFE method, and the effect of the mean nucleation undercooling and the distance from the bottom of the ingot to the cross section on the solidification structure were studied. Furthermore, the effects of pouring temperature, heat transfer coefficient and pulling speed on solidification structure were also investigated. The results show that the simulated results are in agreement with the experimental results. The solidification structure consists of four parts, including region of surface fine grain, zone of columnar grain, transition zone of CET (columnar to equiaxed grain transition) and region of center equiaxed grain. The higher the mean undercooling, the larger the columnar dendrite zone. The ¦T v,max = 5 K is determined as an important simulation parameter to simulate the microstructure evolution. As the cross-section increases from the bottom of the ingot, the columnar crystal regions gradually expand. Moreover, lowering the pouring temperature, increasing the heat transfer coefficient or improving the pulling speed have the beneficial effect on grain refinement. Under the optimal process conditions, the largest proportion of equiaxed grains and the finer grain size is present in the solidified structure.

Numerical simulation of solidification structures in continuous casting of a thin slab at high casting speed

“…The three-dimensional slice moving method is used to simulate the solidification heat transfer process in the thin slab model [7], as shown in Figure 1. Quadrilateral grids were used to divide the regions.…”

“…The solidification microstructure has been related to the casting speed, pouring temperature, cooling conditions, and alloying elements [3][4][5][6]. The casting speed increases with shorter residence time in the mould, thereby promoting the growth of columnar crystals [7]. The superheat of molten steel directly changes the area of central equiaxed crystal zone and then changes the columnar to equiaxed ratio of the casting slab [8,9].…”