Morphology of impurities in steel after desulfurization and vacuum degassing
2015
Lipinski, T., University of Warmia and Mazury in Olsztyn, Poland
The properties of high-grade steel are influenced by a combination of factors, including the chemical composition, production technology and other factors. The quantity of impurities is also a key determinant of the steels properties. Inclusions may also play a negative important effect, which is dependent on their content, size, shape and distribution. An effective method for complete elimination of non-metallic inclusions has not been developed to date. There are, however, various techniques for reducing the quantity and the size of inclusions and controlling the quality of inclusions to minimize their adverse impact on the mechanical properties of highgrade steel. Steel was melted in a 100 ton converter and treated involved vacuum circulation degassing. The aim of this study was to determine the quantity and dimensional structure of inclusions in carbon steel melted in a converter subjected to desulfurization and vacuum circulation degassing. The results of the tests indicate that the quantity of submicroscopic non-metallic inclusions measuring up to 2 µm is the highest. Larger inclusions occupied greater volume in the alloy, but their number was lower. The dissipation coefficient is a sensitive parameter illustrating the strength of correlations between the oxygen content of steel and the volumetric share of oxide inclusions.
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