Estimation of Effective and Specific Permeability in the Mushy Zone of Steel Ingot by the Method of Seepage into Cylindrical Hole

Abstract

The fluidity of the liquid in the solid-liquid coexisting zone of carbon steel was measured by the seepage of interdendritic liquid into a cylindrical hole formed in that zone. The effective permeability K has been determined in relation to the fraction of solid fS and cooling rate R, and the speciffc permeability k which depends on the dendrite morphology has been deduced from the effective permeability to give, log K=log 0.10 R0.81+19.6 R0.33 log (1-fS)……(2)log k=log 1.5×10-6 R+20.3 R0.35 log (1-fS)……(11)The fraction of solid at which dendrites begin to form networks is 0.290.30 depending on the cooling rate. The effective permeability is 6.3×10-4 cm/s and the specific permeability is 6.0×10-9cm2. On the other hand, the fraction of solid above which the liquid cannot flow through the dendrites decreases from 0.73 to 0.60 as the cooling rate increases from 0.033 to 0.15°C/s. The values of effective and specific permeability become constant, 1.6×10-6 cm/s and 2.1×10-11 cm2, respectively, although the fraction of solid is changed by the cooling rate. It has been shown that the effective permeability is mainly controlled by the specific permeability. The fluidity of silicen-free steel which contains 1% molybdenum is smaller than that of carbon steel.