Modelling inclusion evolution in Al–Ti-killed steels during ladle mixing process

Abstract

A reaction model was developed to better understand the evolution of inclusions in Al-Ti-killed steels during the ladle mixing process. The fluctuation of steel chemistry gave rise to the transient evolution of inclusions during the mixing process. The formed Al 2 O 3 in the steel can be hardly influenced by the addition of FeTi, while adding Al can effectively modify the TiO xcontaining oxides to solid Al 2 O 3 . The formation of Al 2 O 3 -TiO x inclusions can be suppressed by increasing Al and lowering Ti in the steel. The alloying sequence of adding Ti after the Al addition is beneficial to improve the recovery of Ti. The one-point strong air absorption may cause the formation of the unwanted Al 2 O 3 -TiO x inclusions in Al-Ti-killed steels. The critical oxygen contents in the molten steel with varying Al and Ti concentrations were predicted to avoid the formation of Al 2 O 3 -TiO x inclusions and Ti loss.

Transient Evolution of Inclusions during Al and Ti Additions in Fe-20 Mass pct Cr Alloy

“…These newly produced Ti-bearing particles may increase the Ti loss because of the adsorption of refining slag in practical production. Hence, along with the steel chemistry (Al, Ti, and O contents) [39], the morphology of existing Al 2 O 3 -based inclusions is a contributing factor affecting the Ti yield. This means the large Al 2 O 3 -based particles including larger aggregates, clusters, and some flower-shaped inclusions, should be eliminated by stirring to the extent possible before Ti addition.…”

“…Second, although various factors including the sequence of alloy addition [18,20,32,33], titanium source [34], titanium/aluminum ratio [35], and element contents [19,[36][37][38][39] have been examined their impacts on the inclusion behaviors during Al and Ti additions, several fundamental questions remain about the evolution mechanism of the inclusion behaviors. In a laboratory study of deoxidation by Al and Ti at 1873 K, Nagata et al [40] found that alumina particles were formed with an acicular shape at first and gradually changed to clusters of granular Al 2 O 3 spheres, but the inclusion characteristics were, nevertheless, not significantly affected by the subsequent Ti feeding.…”

Evolution of Mg–Al-based Inclusions with Changes in Mg Content during Ladle Treatment Based on a Coupled Reaction Model

“…In this model, the ladle furnace is divided into several tanks that are circulated using the stirring energy generated by an Ar flow. This model can predict compositional changes in molten steel, slag, and inclusions, such [16][17][18][19] developed a kinetic model based on FactSage macro processing to predict the formation of inclusions using Alkilled steel and Al-Ti-killed steel. The reactions between steel and inclusions were assumed to be equilibrated, and the reactions between bulk area and interface area in steel and slag were simulated by mass transfer.…”

“…In previous models, the generation of spinel was simulated when the mole fraction of MgO and Al 2 O 3 in the spinel was halved and the activity in the spinel was fixed. [12][13][14][15][16][17][18][19][20][21][22] However, in the proposed enhanced model, the activities of Al 2 O 3 , MgO, and spinel change with increasing MgO content in Mg-Al-based inclusions.…”

Modeling of Ladle Refining Process Considering Mixing and Chemical Reaction

“…The predicted inclusion development and compositions of steel and slag agreed well with the industrial practice from 210 and 30 ton ladle treatment. Additionally, similar models were also developed by the researchers with the specified targets due to the high efficiency, [9][10][11][12][13][14][15][16][17] as shown in Table 1. 1) Most researchers used commercial software (FactSage, Metsim, ChemApp, and SimuSage) for thermodynamic calculations, whereas the empirical models offer a faster calculation speed.…”