Abstract: CAFE model was applied to investigate grain distribution in 12Cr2Mo1R steel water-cooled ingot along Z-direction, and cooling intensity and heterogeneous nucleation parameters were specially considered. The results showed that with the increase of cooling intensity, the width of columnar crystal was enlarged when the cooling intensity was between 50 and 800 W/(m2K). In contrast, the degree of the width increase of columnar crystal by raising cooling intensity was weakened, when cooling intensity was greater than 800 W/(m2K). However, the cooling intensity has little effect on grain distribution in central equiaxed zone. The growth of columnar crystal was restrained and the grain in central equiaxed zone was refined by adding nucleating agent.

Key words: grain distribution, CAFE model, Z-direction, cooling intensity, heterogeneous nucleation