Study of a New Mold Flux for Heat‐Resistant Steel Containing Cerium Continuous Casting

Abstract

New mold fluxes with CaO–Al2O3–Li2O–CeO2 system are proposed for heat‐resistant steel continuous casting. The fundamental properties are investigated systematically. It is found that the appropriate content of CeO2 is determined to be ≈10 wt%, the melting temperature did not change much with increasing CeO2 content, which indicates that the mold fluxes could show steady smelting properties after continuously absorbing inclusions containing cerium in the continuous casting process. After adding CeO2, the precipitation of CaO in the crystallization process is restrained, and the crystalline phases are shifted from CaO/LiAlO2 to CaCeAlO4/LiAlO2. It is further evidenced that the precipitation of CaCeAlO4 and LiAlO2 can be restrained by CeO2. CeO2 shows significantly positive influence in decreasing the viscosity. Above the breaking temperature, the decrease of viscosity is attributed by the cutting off the chain structure of the molten slag from CeO2. Below the breaking temperature, it is caused by the effect of CeO2 on restraining the crystallization process. The optimal content of Li2O is 14 wt%, with a content of less than 14 wt%, Li2O can reduce the melting temperature and viscosities obviously, but the fluxing action of Li2O becomes ineffective when the content of Li2O exceeds 14 wt%. The results have great theoretical significance for developing mold fluxes for heat‐resistant steel.

Effects of CeO₂ on Melting Temperature, Viscosity, and Structure of CaF₂-bearing and B₂O₃-containing Mold Fluxes for Casting Rare Earth Alloy Heavy Rail Steels

“…There are some studies on the CaO-Al 2 O 3 -based mold fluxes and CaO-SiO 2 -based mold fluxes with different RE x O y contents. Some researchers 14,17) suggested that the CaO-Al 2 O 3 -based mold fluxes with low reactivity can be used in the casting process of the rare earth alloy heating resisting steels. CeO 2 showed good properties of decreasing the viscosity.…”

“…Then it increased to 16.58% after the second furnace. 11) It was also reported that the rare earth oxides have a great effect on the melting temperature, viscosity, [12][13][14] structure [15][16][17][18][19] and crystallization 18,20) of mold fluxes. Specifically, the melting temperature and the viscosity property have direct influence on the lubrication between the solidified shell and the casting mold, [21][22][23] even the quality of the casting block.…”

Viscosity-structure-crystallization of the Ce₂O₃-bearing Calcium-aluminate-based Melts with Different Contents of B₂O₃

“…The results are shown in the following discussions. [24][25][26] show that Li ion, which has the minimum ionic radius, has just one positive charge, implying Li + could freely move in the space of [AlO 4 ]-tetrahedrons and Li + ions have the priority to compensate the highly-polymerized [AlO 4 ]-tetrahedrons. Moreover, ionic bonds between cations and anions also exist in the molten slag, such as Ca-O ionic bond and Ce-O ionic bond.…”

Effect of Mold Flux Containing Ce2O3 on the Contents of Aluminum, Silicon, and Titanium in Incoloy825 Super Alloy

“…In order to solve the abovementioned problems, researchers have proposed the use of low-reactive CaO-Al 2 O 3based mold uxes with SiO 2 ≤ 10 wt% (as shown in region B in Figure 1) for steel grades with serious slag-steel reaction [13][14][15][16]. However, the high activity of CaO in the mold uxes tends to generate high melting point CaTiO 3 with TiO 2 , as shown in Eq.…”