鋼塊の凝固偏析におよぼす溶湯流動の影響

概要

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It is possible to show quantitatively the macrosegregation in steel ingot if the flow velocity of bulk liquid during solidification can be obtained. It is found that the flow velocity of bulk liquid is determined by applying the hydrodynamical method known as Taylor's vortex flow to the solidification. Using this method, the following relation is introduced, U/V=7500S_h/(1-S_h) where U is the flow velocity, V the solidification rate, and S_h the fraction of solid depending on the washed depth. The effective distribution coefficient, k_e is theoretically deduced on the basis of the mass transfer with turbulent mixing in the solidifying zone, which is composed of solid and liquid. It is expressed as follows : k_e=1-Bl/L(1-k_o)(1-S_h)U/V where B is an experimental constant of 0.81×10^<-2>, l the primary dendrite arm spacing, L the thickness of the solidifying zone, and k_o the equilibrium distribution coefficient. There is a limit for the degree of washing against the solidifying zone because of the growing dendrite morphology, and the limiting fraction of solid is about 0.67. Furthermore the relation among the deflection angle of dendrite, the solidification rate, and the flow velocity of bulk liquid is obtained.
社団法人日本鉄鋼協会の論文
1975-07-01