Abstract
Two series of experimental studies have been made of uni-directional solidification of iron for the variation of intensity of CO formation at the solidification velocity of 5 mm/min: one was solidification from inductively stirred melts, and the other from quiescent melts. In the latter case a molybdenum tube was used as the susceptor of high frequency induction.
The transitional concentration range for the formation of elongated blowholes was unaffected by the stirring and was found to be [%O] t, l=0.003-0.004 ([%C] L=0.11-0.13) to [%O] t, u=0.010-0.011 ([%C] L=0.14-0.17).
Elongated blowholes observed in the solidified specimens were classified into three types: cylindrical, beads-like, and discrete beads-like. It was found that the formation of blowholes was unaffected by the stirring.
In the case of solidification without CO formation, the effective distribution coefficient k* melts was nearly equal to one, whereas in the presence of stirring it was 0.90-0.95. In contrast to this, in the case of solidification with the formation of CO, the stirring produced no detectable effect on k* With the onset of CO blowhole formation, k* tion, k*
It is shown that the present data give a reasonable explanation to macrosegregation occurring during solidification of a riming steel.
