Grain Selection during Initial Solidification for SUS304 and S45C

Abstract

In order to understand the initial solidification of the continuous casting process, the drop tests have been performed using SUS304 and S45C. The grain is defined as the group of dendrites that grow in the same direction. The grain size of SUS304 quickly increases from surface as solidification proceeds. On the other hand, the grain size of S45C remains constant in the range of experiment. This is due to the difference in the distribution of the growth direction of dendrites.The grain selection model has been modified by taking the distribution of growth direction into consideration. Then the change in number of grains with distance can be explained quantitatively. In order to clarify the difference in the growth direction of dendrites, the influence of the superheat has been evaluated. It has been found that the dendrites incline heavily and radially with increasing the superheat. This may be due to the melting of heterogeneous nuclei and enlarging the high-undercooling region near the chill plate.