The dissolution of niobium and zirconium in liquid steel

The dissolution rates of niobium and zirconium cylinders in liquid steel have been measured in a 'dynamic way', with the help of a data acquisition and process control facility. Two distinct periods were identified; the steel shell period and the free dissolution period.Lower bath superheats allowed a reaction to take place at the steel shell/niobium interface while higher superheats didn't; the intermetallic compounds Fe$sb 2$Nb and Fe$sb 2$Nb$sb 3$ were identified as the reaction products. Niobium dissolved relatively slowly in liquid steel and its dissolution speed was increased under dynamic conditions (i.e., inductively stirred baths).In the case of zirconium, an exothermic reaction occurred at the steel shell/zirconium interface and the intermetallics Fe$sb 2$Zr and FeZr$sb 2$ were identified as the reaction products. This reaction was triggered at 1220 K by the formation of a liquid Fe-Zr (76 at% Zr) eutectic. For the experimental conditions under which this study was performed, the hydrodynamic conditions of the steel baths did not seem to influence the dissolution rates of zirconium.A simplified mathematical model was used in order to simulate the coupled heat and mass transfer phenomena which take place during the two periods