抄録
Carbon redistribution in the liquid ahead of planar and paraboloid interfaces of flake graphite cast iron unidirectionally solidified was calculated. The fraction of carbon diffusion in the liquid f in eutectic solidification is related to the growth rate R, the intergraphite spacing λ, the diffusion coefficient of carbon in liquid D and undercooling at the solidification front ΔT0, as
fλR=0.0032DΔT0
This equation is approximately valid both for the planar and paraboloid interfaces at different temperature gradients. The calculated f decreases with a decrease in the growth rate. This corresponds to the empirical fact that the paraboloid protrusions become more prominent with a decrease in the growth rate. The fraction of carbon diffusion through austenite sheath (1−f) in eutectic solidification increases with increasing growth rate. The protrusions often appearing on the slowly solidifying interface are attributed to a less undercooling at the interface, where carbon diffuses both in the liquid and the austenite, than that in the liquid.
