Crystallization behavior and visualization of fluorine-free CaO-Al2O3-TiO2 based mold flux for high titanium steel
The steel-slag interface reaction often occurs in the mold when casting the high titanium steel,resulting in cracks and defects on the surface of the billet,and even the steel breakout will happen in the serious cases.The CaO-Al2O3-TiO2 based mold flux for high titanium steel was exploited for solving the phenomenon of the steel-slag inter-face reaction,which could inhibit the occurrence of the reaction.But the main component of CaO-Al2O3-TiO2 based mold flux and CaO-Al2O3 based mold flux are CaO and Al2O3,it means that the mold flux may have a strong crystal-lization ability and easy to result in difficultly casting the high titanium steel.Thus,the crystallization behavior of CaO-Al2O3-TiO2 based mold flux was deeply explored.The DHTT equipment was used to simulate the tempera-ture filed of slag films in the mold for realizing the visualization,and the SEM-EDS was used to analyze the micro-structure of slag films,the theoretical guidance for the application of CaO-Al2O3-TiO2 based mold flux was pro-vided.The results showed that the critical cooling rate is 10℃/s,the start crystallization temperature is 1 350℃,incubation time is 345s.The large amounts of the bright and interlocking striped perovskite is precipitated in the high temperature zone,and the fine perovskite and BaAl2O4 are precipitated in the low temperature zone.The thickness of liquid slag film and crystallization slag film are respectively decreased and increased among the meniscus and outlet of the mold,but the liquid slag film still exists at the mold outlet.The liquid slag film,crystallization slag film and glass slag film are always exist between the hot surface mold and initial shell,which indicates that CaO-Al2O3-TiO2 based mold flux can play the role of controlling heat transfer and lubrication in the process of casting high titanium steel.
high titanium steelcritical cooling rateincubation timemicrostructure of slag filmsvisualization
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