STP393: Studies on the Determination of Stable Oxides in Low-Alloy Steels Using a Combination of Chemical Separations

    McKaveney, J. P.
    Manager of analytical chemistry, staff chemist, staff chemist, and staff metallurgist, Crucible Steel Co. of Am., Pittsburgh, Pa.

    Raber, W. J.
    Manager of analytical chemistry, staff chemist, staff chemist, and staff metallurgist, Crucible Steel Co. of Am., Pittsburgh, Pa.

    Vassilaros, G. L.
    Manager of analytical chemistry, staff chemist, staff chemist, and staff metallurgist, Crucible Steel Co. of Am., Pittsburgh, Pa.

    Snook, J. M.
    Manager of analytical chemistry, staff chemist, staff chemist, and staff metallurgist, Crucible Steel Co. of Am., Pittsburgh, Pa.

    Pages: 28    Published: Jan 1966


    Abstract

    A chemical process was developed for treating inclusions electrolytically separated from silicon or aluminum deoxidized steels, so that stable oxides were isolated for analysis. The electrolysis, a Klinger and Koch type modified by substituting ammonium salts for the sodium salts in the electrolyte, was followed by methanolic bromination of the centrifuged residue. Use of ammonium salts prevented sodium oxide chemisorption. If the residue contained carbides, nitrides, or sulfides, which are stable to bromine, the residue from the methanolic bromination was treated with a dilute mixture of nitric and hydrochloric acid. The residue from the acid treatment was then ignited and fused with Na2B4O7. The melt was leached with 10 per cent citric acid, which contained cobalt as an internal standard, and analyzed spectrochemically using a rotating disk solution technique. Proper specimen preparation is required. Argon atmosphere austenitizing is recommended rather than salt bath austenitizing as the latter can lead to considerable spinel formation. Data are presented for analyses of low-alloy steels ranging from 0.03 to 0.34 carbon, and up to 0.78 manganese, 0.20 silicon, and 0.05 aluminum as well as for medium alloy steels ranging from 0.20 to 0.40 carbon, and up to 0.75 manganese, 0.30 silicon, 1.75 nickel, 1.60 chromium, and 1.15 aluminum. A refractory type of aluminum nitride has been found in high-aluminum (1.15 aluminum) steels, which can lead to errors in alumina values. Contrary to a previous German report, this nitride is completely unaffected by metallurgical treatment of the specimen.

    Keywords:

    isolation, separation, oxides, steels, aluminum oxide, silicon dioxide, electrolysis, spectrochemical analysis, methyl alcohol, bromine


    Paper ID: STP44621S

    Committee/Subcommittee: E03.16

    DOI: 10.1520/STP44621S


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