Evaluation of the Chemical Vacuum Effect in Decarburization Treatment by Argon-injected Steel under Normal Atmosphere

For the mass production of ultra-low-carbon steel, application of the chemical vacuum method was examined in depth. In the present study, based on the results of 600-kg-scale experiments and theoretical analysis of them, the possibility of innovative creation producing ultra-low-carbon products without using a vacuum degasser was obtained. To confirm the effect, a 60-t-scale AOD plant test was carried out. As a result, by using the chemical vacuum effect, the carbon content is reduced to 9 ppm in normal steel because of its much higher CO partial pressure than that of stainless steel. The results of the examination show that, theoretically, the reaction rate can be further enhanced. However, it is necessary to construct a dispersion condition in a large-scale metal vessel with small argon bubbles because applying the current technique of small bubble production cannot produce a sufficiently high argon injection flow rate. For the construction of an innovative secondary refining process in the future steelmaking process, the gas dispersion technique is strongly preferred.