Performance and properties of mould fluxes

Abstract

The role of mould fluxes in continuous casting is reviewed. The main functions of the flux are described and the importance of the flux in providing lubrication and the right level of heat transfer between the shell and the mould is described. The major problems of longitudinal, transverse and star cracking, gas and slag entrapment and deep oscillation marks in the steel product and 'sticker breakouts' are analysed. The important physical properties of the flux in combating these various problems are identified. Physical property data for the fluxes are given.

Evolution of Compositions and Properties of CaO–SiO₂ Based Mold Flux for Continuous Casting High Mn Steel

“…It can be seen that the crystallization temperature increases with basicity of mold fluxes, while MnO tends to reduce the crystallization temperature of mold fluxes, which is consistent with previous findings. [28][29][30] For the mold flux basicity of 0.927, the increasing extent in crystallization temperature drops from 40 K without MnO to 21 K with 13.71% MnO. Meanwhile, there are at least 70 K declines in crystallization temperature when the MnO content increases from 0% to 13.71%.…”

Effect of SiO2 on the Crystallization Behaviors and In-Mold Performance of CaF2-CaO-Al2O3 Slags for Drawing-Ingot-Type Electroslag Remelting

“…As a measure of depolymerization of slag melt, non-bridging oxygen per tetrahedrally-coordinated atom NBO/T can be calculated using the following equation [4] where x is the mole fraction of the component in slag.…”

“…Horizontal heat transfer and lubrication performance of slag are strongly dependent on the crystallization characteristics of the slag. [1][2][3][4][5][6] Therefore, it is required that ESR type slags possess proper crystallization properties to meet the requirements for heat transfer control and lubrication performance in drawing-ingot-type ESR process.…”

“…[8][9][10][11][12][13][14][15] The conventional such mold fluxes contain 70 mass pct (CaO+SiO 2 ), 2 to 6 mass pct Al 2 O 3 , 2 to 10 mass pct Na 2 O(+K 2 O), 0 to 10 mass pct F with varying addition of MgO, TiO 2 , B 2 O 3 , Li 2 O, etc., and basicity (mass pct CaO/mass pct SiO 2 ) of the fluxes ranges from 0.7 to 1.3. [4] In view of the significant difference in the slag chemistry, the crystallization behaviors of ESR type CaF 2 -CaO-Al 2 O 3 -(SiO 2 ) slags should be different from those of the mold fluxes. However, limited studies have been conducted to reveal the crystallization behaviors of CaF 2 -containing slags with high Al 2 O 3 /SiO 2 ratios.…”

Influence of Raw Material Type on Heat Transfer and Structure of Mould Slag

“…[2][3][4] A great number of researches on the heat transfer of mould slag have been performed. [5][6][7][8] Mills 7) and Vermeulen 8) pointed out that there are two key factors that could affect the heat transfer of mould slag.…”