INFLUENCE OF Ce ON CRYSTAL MORPHOLOGY OF AUSTENITE AND DENDRITIC SEGREGATION OF Mn IN HIGH-Mn STEEL

Samples of casting high-Mn steel with structure of stable austenitic cells were prepared by strictly controlled directional solidification. With the increasing of the Ce content, the cell structure changes gradually in the front of crystals into dendrites and then into separate crystals, so as to narrow the columnar crystal region. An EPMA was performed quantitatively on the influence of Ce upon the Mn segregation in cellcrystals, columnar and Equiaxial dendrites of high-Mn steel. Considering the solute diffusion in solid state together with the previous works, an expression of Mn distribution in high-Mn steel was approached. After quite a few theoretical analysis on the experimental data, it seems to be indicated that the solute equilibrium partition coefficient, K_0, is the determinant factor of influence on dendritic segregation.