The solidified crust was harmful to Al-killed steel casting using a basic tundish flux. After sampling from an actual tundish, XRD, SEM and EDX examinations were carried out to analyze the microstructure of solidified...The solidified crust was harmful to Al-killed steel casting using a basic tundish flux. After sampling from an actual tundish, XRD, SEM and EDX examinations were carried out to analyze the microstructure of solidified crusts. The conclusions were obtained as follows： main crystallization phases existing in tundish crust were Ca12 A14 O23, Ca2SiO4 and a little spinel; spinel and Ca2SiO4 distributed between the grain boundaries of Ca12 A14 Oa3, which increased the connection strength of crystallization phases by pinning grain boundary, density or hardness of solidified crust maybe also significantly increases; when initial composition of tundish flux was located in spinel region of CaO-SiO2-Al2 O3-10 % MgO phase diagram, it was easier to precipitate spinel from molten slag; three approaches of spinel formation in flux were summarized. When flux was saturated with magnesia on the metal/flux interface, MgO in flux was reduced by dissolved aluminum and then formed spinel. On the interface of steel/refractory, with feasible aluminum content, it was also easy to form spinel, and spinel inclusions will be floated and captured by tundish flux.展开更多
基金Item Sponsored by National Natural Science Foundation of China(50904017)
文摘The solidified crust was harmful to Al-killed steel casting using a basic tundish flux. After sampling from an actual tundish, XRD, SEM and EDX examinations were carried out to analyze the microstructure of solidified crusts. The conclusions were obtained as follows： main crystallization phases existing in tundish crust were Ca12 A14 O23, Ca2SiO4 and a little spinel; spinel and Ca2SiO4 distributed between the grain boundaries of Ca12 A14 Oa3, which increased the connection strength of crystallization phases by pinning grain boundary, density or hardness of solidified crust maybe also significantly increases; when initial composition of tundish flux was located in spinel region of CaO-SiO2-Al2 O3-10 % MgO phase diagram, it was easier to precipitate spinel from molten slag; three approaches of spinel formation in flux were summarized. When flux was saturated with magnesia on the metal/flux interface, MgO in flux was reduced by dissolved aluminum and then formed spinel. On the interface of steel/refractory, with feasible aluminum content, it was also easy to form spinel, and spinel inclusions will be floated and captured by tundish flux.
