The degassing mechanism in the R-H degassing equipment was investigated by analyzing the degassing action by single bubble as a model, and these results were utilized to estimate the rate of the circulation flow and the decarburizatipn curve.
Of the total volume of CO reaction, one-third occurs within the up-leg and two-thirds within the vacuum chamber. This ratio, however, varies depending on the concentrations of carbon and oxygen in the liquid metal. If the concentrations are rather high, more reaction occurs within the up-leg, while higher ratio of the reaction is noted within the vacuum chamber at lower concentrations.
In deoxidizing low carbon steel, it is necessary to inject a substantial amount of argon in order to attain a below 100ppm level without using any deoxidizing agent. Although the inner pressure fo the vacuum chamber generally has much effect upon the degassing, significant effect is no longer shown at a pressure as low as minus 1 torr. In removing the hydrogen from killed steel, care should be taken to obtain much splash in the vacuum chamber.
The rate of the circulation flow is proportional to the 1·5th power of the inner diameter of the circulation legs and to the 0·33rd power of the argon injection rate. The rate of circulation flow in the treatment of undeoxidized steel attains its maximum when a certain rate of argon injection, which depends upon the leg size, is applied.
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