Successive Determination of Oxygen in Stainless Steels Containing High Manganese or High Aluminium by the Argon Carrier Coulo-matic Counting Method

Abstract

A study was made of the successive method of correct determination of O in stainless steels containing high Mn (9-10%) or high Al (2-3%) by Ar carrier coulomatic counting method. The analytical values decreased in the order of specimens dropping. The accurate values were obtained when the concentration of Mn or Al in bathes were less than 3% and 1.2% respectively. Allowable evaporation concentration of Mn was under 0.5% in order to determine oxygen content accurately. The effect of evaporated Al was not confirmed because of its small amounts. According to the above results, it was confirmed that correct determination of O could be made by limiting in number of specimens thrown into a bath or by controlling the concentration of Mn and Al to be less than 3.5% and 1.2% respectively by dilution of specimen with carbon steel. The concentration of Mn or Al was calculated by the following equation; Mn or Al (%) amounts of Mn (or Al) in a bath (g) + [concn. of Mn (or Al) in specimen (%) ×wt. of specimen (g) ×0.01] /total wt. of metals thrown into a bath (g) ×100
Total wt. of metals (g) =wt. of carbon steel (g) +wt. of specimen (g) +wt. of Sn×0.81.