1989 Volume 75 Issue 8 Pages 1308-1315
18-8 stainless steel ingots which are added with surface active elements, Bi, Sn, Te are cast with the water cooled copper mold at the pouring speed of 10 mm/s. Transverse and longitudinal microstructures in the vicinity of the surface of ingots are observed. The solidification microstructures become fine and the effect of rapid quenching increases with increasing the amount of the surface active element. Primary dendrite arm spacing is about 50μm at the 50μm from the surface of ingot which is not added with the surface, active element, but arm spacing is about 10μm in the case of 0.0055 mass %Bi addition. Corresponding cooling rate are 1×102 and 3×103K/s, respectively.From temperature distribution in the water cooled copper mold, heat flux are calculated. The maximum value of heat flux in the mold increases and appears soon, when the surface active element is added.It is seemed that by the addition of the surface active element wettability increases, therefore heat transfer coefficient between molten steel and mold increases. Furthermore, the surface active element seems to have the effect of increase of nucleation rate.