LAUSR

Abstract Crystallization behavior and melt structure of two typical mold fluxes A (CaO–SiO2-based) and B (CaO–Al2O3-based) for casting high-aluminum steel were investigated using double hot thermocouple technology (DHTT), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The results suggest that the crystallization temperature of Flux B is higher, and its crystallization incubation time is shorter compared with Flux A. The precipitated phase in Flux A is CaSiO3, whereas BaAl2O4 and Ca2Al2SiO7 form in Flux B. The structure analyses suggest that the degree of polymerization of Flux A is larger than that of Flux B. In addition, the major structural units of Flux A are Si–O–Si, Q0Si, Q1Si, Q2Si and Q3Si, but those of Flux B are mainly aluminate (Al–O–Al, Al–O-), aluminosilicate (Al–O–Si) and silicate units (Q0Si, Q1Si, Q2Si and Q3Si). These different melt structures are the main reasons why the precipitated phases in these two mold fluxes are different, and the crystallization ability of Flux A is weaker than Flux B.