2008 Volume 48 Issue 3 Pages 286-293
The microstructure control through the refinement of solidification structure has been studied in an Fe–0.05~0.30%C–1.0%Mn–1.0%Ni alloy as functions of particle characteristics of TiOX, Al2O3, ZrO2, Ce2O3 and MgO and solidification mode. The numbers of δ and γ grains per unit area have been measured in the samples quenched at the start temperatures of γ single phase (1673 K at 0.05% C, 1743 K at 0.15% C and 1733 K at 0.30% C). The nucleation event of γ phase per one δ grain per unit area increases with decreasing the lattice misfit parameter between oxide and γ-Fe at 0.15 and 0.30% C, not 0.05% C. The results for γ grain density whose inverse value corresponds to the γ grain size can be explained by the grain-growth-inhibition effect. The γ grain size decreases with increasing the Zener pinning force at 0.15 and 0.30% C, not 0.05% C. The γ grain size obtained by quenching at the start temperatures of γ single phase for 0.05% C is considerably higher than that for 0.15 and 0.30% C.
