Effects of B2O3 and BaO on the Crystallization Behavior of CaO-Al2O3-Based Mold Flux for Casting High-Al Steels

The non-reactive lime-alumina-based mold flux has been proposed to overcome the aluminum introduced slag/steel interaction problems during the casting of high aluminum bearing steels. In this article, a new mold flux with CaO/Al2O3 (C/A) ratio of 2 was designed, and the effects of BaO substituting for CaO to replace B2O3 on the mold flux crystallization behaviors have been investigated through the using of single hot thermocouple technology and double hot thermocouple technology (DHTT). The results suggested that BaO shows the stronger tendency to inhibit crystallization of mold flux comparing with B2O3; however, the synergic effect of the combination of BaO and B2O3 tends to improve the mold flux crystallization in this non-reactive mold flux system. The analysis of the crystallized phases for different samples and the crystallization behaviors under simulated thermal gradient through DHTT were also conducted to support the reliability of above conclusions. (C) The Minerals, Metals & Materials Society and ASM International 2015