Interaction between refractory for refining ladle and low-carbon low-silicon Al-killed molten steel

Abstract

To investigate the interaction between low-carbon low-silicon Al-killed molten steel and the refractory materials employed in refining ladles, the study focused on the interface reaction between molten steel with a composition of Fe-0.03C-0.01Si-0.2Mn-0.03Al (wt%) and the four types of refractory materials used in different positions of refining ladles at 1873 K. The results show that different interface layers form after 60 min of contact between the refractory materials and the molten steel. The MgO-C refractory generates a dense MgO layer, the MgO-Al₂O₃ refractory produces a (Fe, Mg)Al₂O₄ layer, the Al₂O₃-SiC refractory forms a Mg Al₂O₄ layer rich in Si, and the MgO-Al₂O₃-C refractory generates a MgAl₂O₄ spinel layer. The average content of Mg at the interface decreases in the following order: MgO-C, MgO-Al₂O₃-C, Al₂O₃-SiC and MgO-Al₂O₃ refractory, and SiC available in Al₂O₃-SiC refractory supplies more Si to the interface. The thermodynamic simulation is consistent with the actual results.

Keywords

refractory interface MgO spinel low-carbon low-silicon Al-killed steel

Introduction

Refractory materials are crucial to the steel industry's refining process. To endure the extreme conditions in the refining process, a range of refractory materials are utilised in different segments of the refining ladle. These include MgO-C brick, MgO-Al₂O₃-C brick and MgO-Al₂O₃ refractory materials.^1–4 Refractory materials within the refining ladle will be in direct contact with molten steel during the refining process. The reaction between refractory materials and molten steel can result in corrosion and structural spalling of the refractory,^5,6 ultimately impacting the composition, inclusion and performance of the molten steel.^7–10 Therefore, a thorough understanding of the interaction between refractory materials used in refining ladles and low-carbon low-silicon Al-killed molten steel is essential to optimising the refining process and improving product quality.

The dissolution of refractory materials into molten steel has been thoroughly studied by scholars. Some elements in refractory materials dissolve into molten steel, creating pollution. Liu et al.^11,12 examined the dissolution behaviour of Mg, Cr and C in Al-killed steel by studying MgO-Cr₂O₃ and MgO-C refractories, and they concluded that the amount of Mg dissolved in the molten steel from MgO-C refractory is related to the C and Al content in the refractories. Ren et al.¹³ investigated the dissolution behaviour of Mg and Ca in dolomite refractory into molten steel and discovered that MgO in dolomite refractories would reduce due to the presence of Al in molten steel, while Ca content remained mostly unchanged. Furthermore, refractory materials impact the O content of molten steel.^14,15 Wei et al.¹⁶ conducted in situ decomposition of limestone that contained CaO refractory. This research revealed that the CO₂ produced during high-temperature limestone decomposition reacted with Mn in steel, leading to oxygenation and carburisation.

Additionally, a crucial research focus is the ability of the interfacial layer to obstruct the infiltration of molten steel into the refractory, as well as the effect of the refractory's spalling behaviour on the molten steel. Chen et al.¹⁷ investigated the interaction between Al-killed steel and Al₂O₃-MgAl₂O₄ refractory when infiltrated by molten steel. The research found that at the slag-refractory interface, the combination of Al₂O₃-MgAl₂O₄ refractory and molten steel created a barrier referred to as the iron-containing spinel layer and iron reaction product layer, which impedes direct mass transfer between the two materials. Kong et al.¹⁸ discovered that [Mn] from Al-killed medium-Mn steel would interact with the MgO-Al₂O₃ refractory to form the (Mn, Mg)O·Al₂O₃ complex layer on the surface of the refractory, and effectively controlling the spalling of the (Mn, Mg)O·Al₂O₃ interface layer can thus control the amount of this type of foreign inclusion in steel. Wang et al.¹⁹ investigated the interfacial reactions among high-Mn high Al steel, MgO-C refractory and refining slag. The research discovered an interface layer composed of spinel and a transition layer composed of the CaO-Al₂O₃ phase, along with trace spinel and MgO particles. Additionally, Mg-rich inclusions have been observed. The study above demonstrates that the composition of both refractory materials and molten steel affects the composition of the reaction interface. Nevertheless, there are limited studies on the reaction behaviour between low-carbon low-silicon Al-killed molten steel and refractory materials.

This study aims to examine the reaction behaviour of low-carbon low-silicon Al-killed steel when it comes into contact with various refractory materials utilised in refining ladles and to elucidate the interaction mechanism between them. The research contributed to optimising the selection and application of refractory materials in the steel refining process, resulting in improved production efficiency and steel product quality.

Experimental

Raw materials

The refractory materials used in this experiment are the bricks used in various parts of the ladle during the secondary refining process in a domestic steel mill. These bricks include MgO-C brick for the slag line, MgO-Al₂O₃ brick and Al₂O₃-SiC pasted brick for the wall coating, and MgO-Al₂O₃-C brick for the bottom coating. Figure 1 shows the masonry structure diagram of the ladle. Significantly, the three phase coexistence of refractory, molten steel and slag at the slag line. The corrosion of molten steel in the MgO-C brick region was studied in this article without considering the presence of slag. In the initial ladle design, MgO-Al₂O₃ brick served as ladle wall bricks and made direct touch with the molten steel. Subsequently, the Al₂O₃-SiC brick is pasted to the surface of the MgO-Al₂O₃ brick in order to decrease the corrosion of the MgO-Al₂O₃ brick caused by molten steel. The composition of the refractories was examined using an inductively coupled plasma atomic emission spectrometer (ICP-AES, IRIS Advantage ER/S, Thermo Elemental), and the phase analysis was performed for four different types of refractories using X-ray diffraction (XRD, X’Pert PRO, Cu target Κα radiation).

Figure 1.

Schematic diagram for steel ladle masonry structure.

Table 1 provides the composition content and physical properties of refractory materials, and their respective phase composition results are presented in Figure 2. The data in Table 1 show that the main composition of refractories accounts for more than 90% and contains only a small quantity of impurities. XRD phase analysis results also confirm this, as other phases do not significantly exist in the four different types of refractories, except for the main phases of MgO, Al₂O₃, graphite or SiC.

Figure 2.

Mineralogical phases in different refractory observed by XRD.

Table 1.

Physical properties and chemical composition of the employed refractory.

Refractories	Composition (wt%)								Bulk density (g/cm³)	Porosity(%)
Refractories	SiO₂	CaO	Al₂O₃	MgO	C	SiC	TiO₂	Others	Bulk density (g/cm³)	Porosity(%)
MgO-C	2.09	1.23	2.38	75.30	17.02	–	–	1.98	2.95	3.70
MgO-Al₂O₃	2.17	1.98	77.8991	12.27	–	–	–	5.52	2.96	16.10
Al₂O₃-SiC	1.80	0.39	88.21	0.43	2.71	3.41	2.70	0.35	3.32	5.39
MgO-Al₂O₃-C	1.80	0.16	78.37	7.27	10.40	–	0.01	1.99	3.25	7.23

Experimental process

The brick was cut into square bars measuring 10 mm × 10 mm × 100 mm. It was then subjected to drying treatment in a drying oven at (393 ± 5) K for more than 12 h to ensure dryness. This was taken to avoid any water adsorption by the refractory that could affect experimental results. The steel composition was designed as Fe-0.03C-0.01Si-0.2Mn-0.03Al (wt%). The raw materials used included electrolytic iron (99.995%), 75% ferrosilicon (99.95%), electrolytic manganese (99.99%), aluminium particles (99.95%), graphite powder (99.95%) and high-purity argon gas (99.999%) that was introduced during the experiment.

The experiment employed a Si-Mo resistance furnace, and the setup is depicted in Figure 3. Prior to initiating the experiment, roughly 300 g of pre-configured metal was loaded into an alumina crucible and placed in a graphite crucible. The crucible, along with the metal materials, was then set in the corundum tube's constant temperature zone.

Figure 3.

Schematic diagram of the furnace.

To ensure an optimal atmosphere in the furnace, and reduce the oxygen content in the reaction tube, high-purity argon flowed into the furnace at a rate of 4 L/min for 30 min before the experiment. The flow rate of the gas was adjusted to 3 L/min, during the melting and reaction processes. Before immersion into the molten steel, the refractory rod and molybdenum wire were connected and suspended 10 cm above the steel. The furnace was then heated at a rate of 5 K/min until the temperature reached 1873 K. At 1873 K, the temperature was held for 10 min to ensure that the metal material was fully melted. Aluminium particles were added and stirred into the molten steel, followed by a standing time of 10 min to simulate the deoxidation process of the Al-killed steel. The refractory rod was then immersed beneath the molten steel level to indicate the start of the reaction. After approximately 60 min of the reaction, the tube furnace lifting mechanism was used to lift the refractory rod for air cooling. Meanwhile, the molten steel was extracted using a quartz glass tube and water quenched to room temperature.

Experimental analysis

The steel samples and refractory materials were cut along the longitudinal axis (steel: φ 5 mm × 5 mm; refractory:10 mm × 10 mm × 10 mm). After sandpaper grinding and polishing, the samples were placed in alcohol and cleaned by an ultrasonic cleaning instrument. The scanning electron microscope (SEM) equipped with an energy dispersive spectrometer (EDS) (SEM-EDS, Nova NanoSEM400, FEI USA) was used to analyze the phase change of the refractory reaction interface layer.

Results and discussion

Initial microstructure of different refractories

Figure 4 shows the pre-reaction microstructure and composition of refractories used in ladles. It can be seen from Figure 4(a) that MgO-C refractory is mainly composed of MgO particles with different particle sizes, graphite and a small amount of impurities composed of MgO, CaO and SiO₂. The graphite phase fills the gaps between the MgO particles of different sizes, and some large particles of MgO contain a minor quantity of impurities. Figure 4(b) shows that Al-Mg refractory is mainly composed of MgO and Al₂O₃ particles with different particle sizes. The dark area is MgO particles, and the bright area is the Al₂O₃ particle aggregation area. In addition, some spinel phases were found in the MgO-Al₂O₃ castable.

Figure 4.

Initial microstructure and composition of different refractories used in refining ladle. (a) MgO-C; (b) MgO-Al₂O₃; (c) Al₂O₃-SiC; (d) MgO-Al₂O₃-C.

Figure 4(c) shows that Al₂O₃-SiC refractory is mainly composed of Al₂O₃ particles with different particle sizes and a small amount of SiC particles. There are many impurity phases in bricks, including a light gray impurity phase containing Mg-Ca-Si-Ti in large particles of Al₂O₃, bright white Fe particles, CaTiO₂, metallic aluminium and a small amount of MgO particles. Figure 4(d) shows that the structure of MgO-Al₂O₃-C brick is similar to that of MgO-C brick. The structure is mainly composed of Al₂O₃ particles, MgO, graphite and a small amount of impurities with different particle sizes. The graphite phase fills the gaps between oxide particles of different sizes.

Interface structure

MgO-C refractory

Figure 5 presents the microstructure of MgO-C refractory after 60 min of reaction with the molten steel. The surface scanning indicates the formation of a dense MgO layer at the interface. The eroded layer averages 69 μm in thickness. A low melting point compound (Ca_3.6MgSi₂O_7.5) is generated in the CaO-SiO₂ impurity phase of large particle MgO at 1873 K, which shrinks inward and causes channels to form on the surface of the refractory. This phenomenon is shown in the yellow line segment within Figure 5. Nonetheless, the MgO layer formed at the interface separates the refractory material from molten steel, effectively blocking the invasion of molten steel through the gaps between MgO particles. The white arrows shown on the micro-structure diagram indicate the position and direction of linear scanning. Figure 6 displays the linear scanning results of the MgO-C refractory interface layer. It confirms that the main elements present at the MgO-C refractory interface are Mg and O, and the generated interface is MgO. The discrepancy in the outcomes of spinel interface generation observed in previous research can be attributed to the lower [Al] concentration in the steel used in this investigation compared to the studies mentioned.^19,20

Figure 5.

MgO-C refractory interface after reaction with molten steel for 60 min.

Figure 6.

Linear scanning results of the interface between MgO-C refractory and molten steel.

The MgO-C refractory matrix is graphite phase and fine MgO powder, and the aggregate is large-diameter MgO particles, which are surrounded by the graphite phase. At the temperature of steelmaking, the graphite and MgO particles within MgO-C refractory are not stable and can be decomposed to generate Mg(g) and CO,^20–22 as shown in Equation (1). As carbon present at the interface dissolves into the molten steel, the surface consistently becomes invaded by molten steel. Consequently, Mg(g) enclosed inside the refractory cannot be sufficiently released via the pores. When [O] present in the molten steel reacts with Mg(g), it converts into MgO particles as depicted in Equation (2).²³ As the magnesium oxide particles form, they increase in size and eventually merge together, resulting in the formation of a compact MgO layer.

MgO (s) + C (s) = Mg (g) + CO (g)

(1)

[Mg] + [O] = MgO (s)

(2)

Figure 7 shows the SEM image of the reaction between the low-carbon low-silicon Al-killed molten steel and MgO aggregate. The EDS apparatus attached to the SEM detected a chemical composition corresponding to the Fe₁₃MgO₁₀ phase as the reaction product. The reaction between the molten steel and MgO aggregate is minor. Therefore, the newly formed dense MgO layer separates the refractory from molten steel, preventing further penetration of molten steel along the gaps inside the refractory.

Figure 7.

SEM image of the reaction between the molten steel and MgO aggregate.

MgO-Al₂O₃ refractory

The microstructure and the element mapping of MgO-Al₂O₃ refractory material after reacting with molten steel for 60 min are presented in Figure 8. Figure 8 reveals multiple silver-white areas within and at the interface of refractory material. These areas are the result of steady penetration and corrosion of the molten steel along the aggregate edge's loose area to the inside of the refractory material. A composite spinel layer of (Mg, Fe)Al₂O₄, around 20 μm in thickness, is formed at the material's interface. The linear scanning outcomes for the MgO-Al₂O₃ refractory interface layer are visible in Figure 9. It can be seen from Figure 9 that the interface has a higher concentration of Mg and Fe elements. The Fe gradient is apparent along the interface and gets weaker as the scan distance increases. The strength of Fe elements decreases the closer they are to the interior of the refractory. This aligns with the findings of Cheng et al.¹⁷ The absence of the CA6 layer in this work can be attributed to the no slag added to the crucible.

Figure 8.

MgO-Al₂O₃ refractory interface after reaction with molten steel for 60 min.

Figure 9.

Linear scanning results of the interface between MgO-Al₂O₃ refractory and molten steel.

Figure 8 demonstrates that the reaction of Equation (3) occurred between MgO and Al₂O₃ in MgO-Al₂O₃ refractory at 1873 K, leading to the production of in situ spinel and its solid solution. This reaction results in a specific volume expansion,²⁴ which creates a loose area around the aggregate. During the reaction, molten steel continuously permeates inward along the loose area of the aggregate's edge, and FeAl₂O₄ spinel is formed through Equation (4). The resulting product reacts further with spinel in refractory to form (Fe, Mg)Al₂O₄, as shown in Figure 10.^17,25

MgO (s) + {Al}_{2} O_{3} (s) = {MgAl}_{2} O_{4} (s)

(3)

Fe (l) + {Al}_{2} O_{3} (s) + [O] = {FeAl}_{2} O_{4} (s)

(4)

Figure 10.

(Fe, Mg)Al₂O₄ formed at the MgO-Al₂O₃ refractory interface.

Al₂O₃-SiC refractory

Figure 11 displays the microstructure and element mapping of Al₂O₃-SiC refractory after reacting with molten steel for 60 min. From the interface scan results in Figure 12, it can be observed that the Al, Si and Mg elements exist at the interface with an average thickness of approximately 65 μm. This suggests that the Al₂O₃-MgO solid solution phase is generated at the interface after the Al₂O₃-SiC refractory reacts with molten steel for 60 min. From the linear scanning results at the interface of Al₂O₃-SiC refractory in Figure 12, it is evident that the interface layer is enriched with Al, Mg and Si elements, while a small quantity of Fe is found in the outer area.

Figure 11.

Al₂O₃-SiC refractory interface after reaction with molten steel for 60 min.

Figure 12.

Linear scanning results of the interface between Al₂O₃-SiC refractory and molten steel.

The oxidation mechanism of Al₄C₃ to Al₂O₃ whisker was proposed by Hashimoto et al.,²⁶ who suggested that Al₄C₃ oxidises to AlC_1−xO _x , resulting in the AlC_1−xO _x region. The authors then demonstrated that AlC_1−xO _x undergoes further reaction with oxygen to convert into Al₂O₃.^27,28 Moreover, Wei et al.²⁹ concluded from simulations using ThermoCalc software that the formation of Al₄O₄C and Al₄C₃ is possible for the Al₂O₃-C system when P_O2 is less than 1 × 10⁻²⁰ bar. Within the carbon-containing system, carbon significantly decreases the partial pressure of oxygen within the refractory material, enhance the formation of Al-containing gas, solid phase Al₄C₃ and Al₄O₄C. During the cooling process, these species react with oxygen to form Al₂O₃ and C. Unlike Wei's research, the presence of MgO was discovered at the interface.²⁹

The interface containing MgO is likely the result of the combined action of SiC and MgO impurities in refractory. As reported by Li et al.,³⁰ by consuming CO, SiC produces SiO(g), which shifts the equilibrium of the reaction in Equation (1) to the right and encourages the reduction of MgO, as shown in Equation (5). The Mg enrichment at the interface is due to the reaction of impurities in refractory containing MgO with C to form Mg(g), which diffuses and escapes to the interface of refractory material and molten steel. Furthermore, SiO(g) generated by Equation (5) diffuses to the interface and oxidises, as shown in Equation (6). This is the main reason for Si enrichment at the interface.

SiC + CO = SiO (g) + 2 C (s)

(5)

SiO (g) + CO (g) = {SiO}_{2} + C (s)

(6)

MgO-Al₂O₃-C refractory

Figure 13 depicts the microstructure and element mapping of MgO-Al₂O₃-C refractory after reacting with low Si low C Al-killed molten steel. As displayed in Figure 13, the slightly lighter layer at the interface is the Mg-Al spinel layer with an average thickness of 41 μm. Moreover, the refractory particles at the interface evidence apparent spalling and corrosion, and a certain number of refractory oxide particles will inevitably permeate into the molten steel and transform into large particle inclusions, adversely influencing the quality of molten steel. The refractory linear scanning results obtained by the reaction between Al₂O₃-MgO-C refractory and molten steel for 60 min show that the main elements accumulated at the interface are Mg, Al and O, as shown in Figure 14.

Figure 13.

MgO-Al₂O₃-C refractory interface after reaction with molten steel for 60 min.

Figure 14.

Linear scanning results of the interface between MgO-Al₂O₃-C refractory and molten steel.

MgO-Al₂O₃-C refractory is composed of graphite phase and fine powders of Al₂O₃ and MgO. The aggregates are large-diameter Al₂O₃ particles, and the graphite phase is packed in the spaces between them. When molten steel is in contact with refractory materials, the graphite phase at the interface is directly exposed to the molten steel. This causes dissolution and decarbonisation of the graphite phase, resulting in damage and continuous penetration of molten steel. The corrosion mechanism of MgO-Al₂O₃-C refractory with low-carbon and low-silicon molten steel is similar to that of MgO-C bricks. In contrast to the study conducted by Zhong et al.,⁴ only a single layer of spinel was discovered in this study, and there was no significant gradient change of Mg at the interface. This is because the formation region of spinel is close to the interface of molten steel and does not contact MgO. The diffusion rate of Mg²⁺ in the reaction process is limited by solid phase diffusion, which makes it difficult for MgO inside the refractory to generate a large amount of MgO·Al₂O₃ spinel at the interface only through Mg²⁺ diffusion. Thus, the formation of MgO·Al₂O₃ spinel layers at the interface is due to the outward diffusion of Mg(g) produced by carbon reduction along the internal channels of refractory, which then reacts with Al₂O₃ aggregates.

Figure 15 depicts the average proportion of elements in the reaction interface. As illustrated by Figure 15, the average content of Mg at the interface decreases in the following order: MgO-C, MgO-Al₂O₃-C, Al₂O₃-SiC and MgO-Al₂O₃ refractory. Mg content in the MgO-C refractory interface was significantly higher than in the other refractory materials. Meanwhile, MgO-Al₂O₃ refractory did not yield detectable Mg element at the interface. The peculiar outcome can be attributed to the lack of exposed MgO particles at the interface between MgO-Al₂O₃ refractory and MgO-Al₂O₃-C refractory, as well as the presence or absence of carbon. Due to the reaction between carbon and MgO, the Al₂O₃ on the interface of MgO-Al₂O₃-C refractory dissolved a little MgO. However, MgO-Al₂O₃ refractory did not release Mg into the interface. After quantifying the elements at the interface of MgO-Al₂O₃ refractory, it became evident that FeAl_2.5O₄ is the chief product at the interface, which affirms the main reaction between MgO-Al₂O₃ refractory and molten steel expressed in Equation (4). Additionally, the Si content in Al₂O₃-SiC refractory is 2∼3 times higher than that observed in MgO-C and MgO-Al₂O₃-C refractories. Since the SiO₂ proportions in all four refractories were comparable, the SiC available in Al₂O₃-SiC refractory supplies more Si to the interface.

Figure 15.

Average content of elements at the interface of four kinds of refractories (wt%).

Thermodynamic simulation

In order to better explain the corrosion process of refractory and molten steel, thermodynamic calculations of corrosion behaviour were performed using FactSage 8.1 software and databases including FactPS, FToxide, and FSstel. The coefficient of refractory material and the ratio between molten steel are defined by the parameter alpha (α = A/(A + B)), where A and B represent the fractions of molten steel and refractory, respectively, and A + B = 1. The thermodynamic calculations were conducted by combining refractory components such as MgO-C, MgO-Al₂O₃, Al₂O₃-SiC and MgO-Al₂O₃-C with Fe-0.03C-0.01Si-0.2Mn-0.03Al-0.003O (wt%) to analyze the phases and quantities of materials.

Figure 16 depicts the results of thermodynamic calculations of corrosion between low-carbon low-silicon Al-killed molten steel and four refractory materials at 1873 K. The outcome indicates that carbon-containing refractories create CO(g) during the corrosion calculation of molten steel. However, MgO-Al₂O₃ refractories do not generate CO(g), instead produce a certain amount of FeAl₂O₄. This is consistent with the results of SEM-EDS, as shown in Figure 10. Moreover, the SiC content in Al₂O₃-SiC refractory reduces rapidly with increasing proportion factor α. Once the SiC disappears, the refractory no longer performs the reaction of Equation (5), and the amount of CO(g) produced begins to increase.

Figure 16.

Thermodynamic calculations for the corrosion of different refractories by molten steel at 1873K.

Figure 17 shows the production of Mg(g) in refractories and their impact on the [Mg] content in molten steel. It can be seen from Figure 17 that the production of Mg(g) and its effect on the average [Mg] content in molten steel are much higher when using other refractory materials. MgO-Al₂O₃ refractory did not produce Mg(g), which is consistent with the results of Deng.^9,31 Deng et al.^9,31 investigated the effect of spinel refractory on non-metallic inclusions in Al-killed steel. Since the activity of MgO in spinel refractors is minimal, producing dissolved Mg in molten steel becomes challenging. Hence, spinel refractories have little influence on non-metallic inclusions in Al-killed steel.

Figure 17.

Production of Mg(g) in various refractories and their impact on the [Mg] content in molten steel.

Despite the much lower MgO content in Al₂O₃-SiC compared to MgO-Al₂O₃-C refractory, Mg(g) production is higher in Al₂O₃-SiC refractory due to the presence of SiC, when α＜0.34. The amount of produced Mg(g) is less than 0.002 g in both of them, and their effect on the [Mg] content in molten steel is less than 0.00005 wt% after α value greater than 0.13.

In addition, the yield of Mg(g) from MgO-C refractory shows an increasing trend, followed by a decrease with an increase in the value of α. This is similar to the trend of CO(g) observed in MgO-C refractory in Figure 16. However, the low initial α value signifies a lower amount of molten steel. As a result, the production of Mg(g) in molten steel increases the [Mg] content, which subsequently decreases with an increase in α. Figure 15 provides support for the claims made in the text and enhances the reliability of the conclusions.

Conclusions

In this study, the reaction behaviour of low-carbon low-silicon Al-killed steel in contact with various refractory materials utilised in refining ladles was examined, leading to the following conclusions:

The contact between refractory materials and molten steel can produce an obvious interface layer. MgO-C refractory produces a dense MgO layer, MgO-Al₂O₃ refractory forms a (Fe, Mg)Al₂O₄ layer, Al₂O₃-SiC refractory generates Si-enriched MgAl₂O₄ layers and MgO-Al₂O₃-C refractory generates a MgAl₂O₄ spinel layer.

The average content of Mg at the interface decreases in the following order: MgO-C, MgO-Al₂O₃-C, Al₂O₃-SiC and MgO-Al₂O₃ refractory, and SiC available in Al₂O₃-SiC refractory supplies more Si to the interface.

Thermodynamic calculations reveal that MgO-C refractory has the greatest effect on the [Mg] content of molten steel in this study.

Footnotes

Declaration of conflicting interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was supported by the National Natural Science Foundation of China (grant number 52104339).

ORCID iD

Xiang Zhang

References

Volkova

Scheller

Lychatz

. Kinetics and thermodynamics of carbon isothermal and non-isothermal oxidation in MgO-C refractory with different air flow. Metall Mater Trans B 2014; 45: 1782–1792.

Wei

Miao

, et al. Chemical attack of Al₂O₃-MgAl₂O₄ refractory castables in the non-slag-tapping side of refining ladle. Ceram Int 2022; 48: 16832–16838.

Tabatabaie-Hedeshi

Bavand-vandchali

Naghizadeh

. Characterization and post-mortem analysis of Al₂O₃-MgO-C refractories used in steelmaking ladle furnaces. Eng Fail Anal 2020; 116: 104697.

Zhong

Han

Wei

, et al. Post-mortem analysis of MgO-Al₂O₃-C bricks containing bauxite used in steel ladle walls. Ceram Int 2023; 49: 2026–2033.

Dai

Yan

, et al. Corrosion mechanism and protection of BOF refractory for high silicon hot metal steelmaking process. J Mater Res Technol 2020; 9: 4292–4308.

Melo

PHRVD

Peixoto

JJM

Galante

, et al. The influence of flow asymmetry on refractory erosion in the vacuum chamber of a RH degasser. J Mater Res Technol 2019; 8: 3764–3771.

Chen

Wei

, et al. Corrosion and penetration behaviors of slag/steel on the corroded interfaces of Al₂O₃-C refractories: role of Ti₃AlC₂. Corros Sci 2018; 143: 166–176.

Lee

Jung

S-M

Min

D-J

. Interfacial reaction between Al₂O₃-SiO₂-C refractory and Al/Ti-Killed steels. ISIJ Int 2014; 54: 827–835.

Deng

Zhu

. Effect of refractory on nonmetallic inclusions in Al-Killed steel. Metall Mater Trans B 2016; 47: 3158–3167.

10.

Poirier

. A review: influence of refractories on steel quality. Metall Res Technol 2015; 112: 410.

11.

Liu

Yagi

Gao

, et al. Dissolution behavior of Mg from magnesia-chromite refractory into Al-killed molten steel. Metall Mater Trans B 2018; 49: 2298–2307.

12.

Liu

Gao

Kim

, et al. Dissolution behavior of Mg from MgO-C refractory in Al-killed molten steel. ISIJ Int 2018; 58: 488–495.

13.

Ren

Liu

Gao

, et al. Dissolution behavior of Mg and Ca from dolomite refractory into Al-killed molten steel. ISIJ Int 2021; 61: 2391–2399.

14.

Zou

Huang

, et al. Corrosion mechanism of lightweight microporous alumina-based refractory by molten steel. J Am Ceram Soc 2019; 102: 3705–3714.

15.

Zhang

Zheng

Yan

, et al. Formation mechanism of interface reaction layer between microporous magnesia refractories and molten steel and its effect on steel cleanliness. J Iron Steel Res Int 2023; 30: 1743–1754.

16.

Wei

Wang

. Interactions between CO₂ from limestone containing refractories and manganese steel and its influence on Mn, C and total oxygen content of steel. Ironmak Steelmak 2014; 41: 229–232.

17.

Chen

Cheng

, et al. Formation of ferrospinel layer at the corroded interface between Al₂O₃-spinel refractory and molten steel in RH refining ladle. J Am Ceram Soc 2021; 104: 6044–6053.

18.

Kong

Deng

Zhu

. Reaction behaviors of Al-killed medium-manganese steel with different refractories. Metall Mater Trans B 2018; 49: 1444–1452.

19.

Wang

Zhu

Zhao

, et al. Steel/refractory/slag interfacial reaction and its effect on inclusions in high-Mn high-Al steel. Ceram Int 2022; 48: 1090–1097.

20.

Jansson

Brabie

Jönsson

. Magnesia-carbon refractory dissolution in Al killed low carbon steel. Ironmak Steelmak 2006; 33: 389–397.

21.

Sadrnezhaad

Mahshid

Hashemi

, et al. Oxidation mechanism of C in MgO-C refractory bricks. J Am Ceram Soc 2006; 89: 1308–1316.

22.

Jansson

Brabie

Jönsson

. Corrosion mechanism of commercial MgO-C refractories in contact with different gas atmospheres. ISIJ Int 2008; 48: 760–767.

23.

Itoh

Hino

Ban-Ya

. Deoxidation equilibrium of magnesium in liquid iron. Tetsu-to-Hagané 1997; 83: 623–628.

24.

Mohan

Sarkar

. A comparative study on the effect of different additives on the formation and densification of magnesium aluminate spinel. Ceram Int 2016; 42: 13932–13943.

25.

Huang

Wang

Zou

, et al. Dynamic interaction of refractory and molten steel: corrosion mechanism of alumina-magnesia castables. Ceram Int 2018; 44: 14617–14624.

26.

Hashimoto

Yamaguchi

. Synthesis of MgAl₂O₄ whiskers by an oxidation-reduction reaction. J Am Ceram Soc 1996; 79: 491–494.

27.

Shimada

. Oxidation and mechanism of single crystal carbides with formation of carbon. J Ceram Soc Jpn 2001; 109: S33–S42.

28.

Matthews

Brown

. High temperature oxidation of Al₄C₃. Corros Sci 2020; 173: 108793.

29.

Wei

Yehorov

Storti

, et al. Phenomenon of whiskers formation in Al₂O₃-C refractories. Adv Eng Mater 2022; 24: 2100718.

30.

Chen

Xiao

, et al. Formation of liquid-phase isolation layer on the corroded interface of MgO/Al₂O₃-SiC-C refractory and molten steel: role of SiC. J Am Ceram Soc 2021; 104: 2366–2377.

31.

Deng

Cheng

Chen

, et al. Effect of refractory on nonmetallic inclusions in Si-Mn-killed steel. Steel Res Int 2019; 90: 1900268.

Interaction between refractory for refining ladle and low-carbon low-silicon Al-killed molten steel

Abstract

Keywords

Introduction

Experimental

Raw materials

Experimental process

Experimental analysis

Results and discussion

Initial microstructure of different refractories

Interface structure

MgO-C refractory

MgO-Al2O3 refractory

Al2O3-SiC refractory

MgO-Al2O3-C refractory

Thermodynamic simulation

Conclusions

Footnotes

Declaration of conflicting interests

Funding

ORCID iD

References

MgO-Al₂O₃ refractory

Al₂O₃-SiC refractory

MgO-Al₂O₃-C refractory