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Thermodynamic conditions for inclusions modification in calcium treated steel
Author(s) -
Prešern Vasilij,
Koroušić Blaženko,
Hastie John W.
Publication year - 1991
Publication title -
steel research
Language(s) - English
Resource type - Journals
eISSN - 1869-344X
pISSN - 0177-4832
DOI - 10.1002/srin.199101297
Subject(s) - calcium , aluminate , aluminium , metallurgy , chemistry , phase (matter) , materials science , organic chemistry , cement
The presented paper discussed the fundamental or common thermodynamical relations between calcium‐treated aluminium‐killed molten steel and non‐metallic inclusions. The phase and chemical analyses of inclusions have proven that the correctness of calcium addition can be confirmed and that the analysis of those phenomena can show the effects of previous calcium treatment of aluminium‐killed steel. To make the process of manufacturing quality steel successful the factor affecting the necessary calcium addition should be taken into consideration already during the process. Steel, containing too much calcium could have CaS inclusions with a high melting point, while too low contents of calcium cause unsatisfactory modification of solid alumina inclusions to complex liquid calcium‐aluminate inclusions. This research included the examination of thermodynamic relations in calcium addition and its reactions with solid Al 2 O 3 inclusions. A detailed analysis of the CaO–Al 2 O 3 binary system established the modification of solid alumina inclusions via the following intermediate phases: CaO · 6Al 2 O 3 , CaO · 2Al 2 O 3 , CaO · Al 2 O 3 and liquid phase 12CaO · 7Al 2 O 3 and finally again solid CaO, at 1873 K (1600°C). The investigation discusses the further research engaged in consideration of CaO‐ and Al 2 O 3 ‐activities change in each of the quoted intermediate phases. The system as a whole includes details of oxygen activities.