Critical Oxygen Concentration for the Ceasing of CO Macroblowhole Growth during Solidification of Iron

Abstract

The iron containing about 0.1% C was solidified unidirectionally to obtain the basic information on the ceasing of growth of CO macroblowholes. Experiments were done for the two solidification rates of 5 and 10 mm/min. Blowhole growth was examined by X-ray radiography.
The critical oxygen concentration for the ceasing of blowhole growth at the solidification rate of 5 and 10 mm/min were 0.00280.0045% (C 0.100.11%) and 0.00340.0050% (C 0.110.12%), respeclively. These critical concentrations agree with those obtained from the calculation on the basis of the model of steady growth of cylindrical blowholes.