Determination of Oxygen in Special Steels by the Argon Carrier Coulometric Method with Tin Flux

Abstract

The analytical method for the oxygen in special steels has been studied by the argon carrier-coulometry with the addition of Sn metal drops as the bath or flux.
Since the analytical results often decrease in the order of sample dropping though the temperature and other conditions are held constant, the effects of the properties of graphite crucible and powder on the oxygen values are studied. More accurate and precise values are given by maintaining the, wholeiheating part containing the molten sample at an even high temperature during the operation. When the crucible shape and its position in an induction coil are suitable, the use of graphite material with a large bulk density (d>1.70) and coarse grain is effective to obtain a high temperature. The application to the samples with a large amount of harmful element (Al, Mn, S) gives no interuption under the concentration of 1.6% Al, 3-2% Mn, and 0.5% S, respectively. The determinations of oxygen in the most kind of special steels in volving Ni base high alloys are performed with a good precision [ex:σ=0.7 ppm for JIS-SKS2 (x=8 ppm), σ=3.6 ppm for JIS-SUS 304 (x=71.7 ppm)] and the values obtained agree with those by the vacuum fusion method.