Influence of Silicon, Manganese, Nickel and Chromium on the Determination of Oxygen in Iron and Steel by the Ledebur Method

Abstract

Experimental equipment, similar to that adopted by Petersen but somewhat modified, was used for this investigation. The sample was a cylindrical block having about 10 g. As alloying metal, tin or gold was used. The reduction temperature and the temperature of the nickel-thoria catalyst was kept at 1, 200°C and 250°C respectively. The blank value to be reduced from the observed value obtained in the usual analysis was as follows: In the first weighing tube, 0.074 mg. per hour, at 1, 200°C. In the second weighing tube, 0.080 mg. per hour at 250°C. Armco iron was first accurately analyzed for its oxygen to be used as the standard sample for the following experiment. Silicon, manganese, nickel and chromium in the slate of metal or ferro-alloy were then melted together with the standard sample. From the results of this investigation, it was confirmed that nickel has no influence, but silicon, manganese and chromium have a great influence on the results of the Ledebur method adopted here. It was also found that the complete reduction of the deoxidation products such as SiO₂, MnO or Cr₂O₃ by hydrogen in this process is not impossible, although it requires a very prolonged time. This phenomenon was explained theoretically.