MgO Inclusions Research Articles

STUDY OF THE EFFECT OF THE FORMATION OF TWO-PHASE CERAMICS BASED ON NEODYMIUM ZIRCONATE DUE TO DOPING WITH MGO AND Y2O5 ON THE STABILITY OF STRENGTH AND THERMOPHYSICAL PARAMETERS UNDER IRRADIATION

The work presents the study results of the determination of the resistance of neodymium zirconate doped with MgO and Y2O5 to radiation damage stemming from irradiation with heavy ions akin to nuclear fuel fission fragments. The attraction towards this type of ceramics stems from its potential to raise the operational temperatures within the core of next-generation nuclear reactors. This is owed to its superior thermal conductivity when compared to zirconium dioxide, coupled with the heightened strength parameters that signify the ceramics' resistance against external factors. The main results of this study are to determine the influence of the formation of substitution or interstitial phases when adding magnesium and yttrium oxides to the composition, on increasing the stability of the strength and thermophysical parameters of neodymium zirconate to the radiation defects accumulation in the damaged surface layer. During the studies, it was found that the formation of impurity phases in the form of MgO inclusions (when it is added to the composition) and a substitution phase of the Y2Zr2O7 type (with the addition of Y2O5) results in an elevation in the hardness and crack resistance stability of neodymium zirconate ceramics, which indicates the positive effect of doping linked to the formation of additional interphase boundaries that prevent strain embrittlement of the damaged layer under high-dose irradiation. During determination of the thermophysical parameters of the studied neodymium zirconate ceramics, it was observed that the formation of interphase boundaries during doping not only enhances thermal conductivity but also mitigates the decline in the thermal conductivity coefficient during irradiation for two-phase ceramics in comparison with undoped neodymium zirconate ceramics.

Synergetic impact of MgO on PMMA-ZrO2 hybrid composites: Evaluation of structural, morphological and improved mechanical behavior for dental applications

This work aims to demonstrate the effect of ZrO2 and MgO inclusion into the Poly(methyl methacrylate) (PMMA). To fabricate novel hybrid composites via heat cure method, various composites (PZM2, PZM4 and PZM6) were synthesized in the system [(95-x) PMMA + 5 ZrO2 + x MgO] (x = 2, 4, and 6) respectively. Density of the prepared composites were determined and varying between 1.035–1.152 g/cm3. X-ray Diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) followed by EDAX and mechanical testing were performed to evaluate the fabricated composite properties. Moreover, to explore the structure of the fabricated composites the 13 C CP-MAS SSNMR and 1 H-13 C Phase-Modulated Lee Goldberg (PMLG) HETCOR Spectrum were recorded which clarify chemical shifting and motional dynamics of the composites. Mechanical tests were performed by UTM and the obtained parameters such as compressive strength, Young’s modulus, fracture toughness, brittleness coefficient, flexural strength and flexural modulus are found to be in the range of 91–100 MPa, 0.48–0.51 GPa, 9.122–9.705 MPa.m1/2, 0.66–0.815, 51.03–42.78 MPa and 499–663 MPa respectively. Some more mechanical parameters such as proportional limit, elastic limit, failure strength, modulus of resilience and modulus of toughness were also calculated. Furthermore, tribological properties were also determined and the coefficient of friction (COF) was decreased by 17.4 % and 38 % for composite PZM6 at 20 N and 40 N as compared to the composite PZM2 and the lowest wear volume of 1.55 mm3 was observed for PZM2, whereas the maximum volume loss of 5.64 mm3 is observed for composite PZM6. To check out the biocompatibility, cytotoxicity and genotoxicity of the fabricated composites the Trypan-blue assay was also performed for PZM2 and PZM6 composites. Dissection on the gut of larvae was also performed on the both composites followed by DAPI and DCFH-DA staining. Therefore, these synthesized samples can be used for the fabrication of denture materials.

Effect of steel-refractory reactions on inclusion modification in lanthanum-, cerium-, and yttrium-added steels

The reactions of rare earth elements (REEs) with refractory materials significantly affect their effective concentrations and inclusion modifications in molten steel. This study investigated the influence of steel-refractory reactions on the modification of inclusions in lanthanum-, cerium-, and yttrium-added steels utilizing three types of commonly used crucibles as smelting vessels. Steel-refractory reactions were found to strongly affect inclusions with different outcomes for smelting in MgO, Al2O3, and MgO·Al2O3 crucibles. The RE-crucible reactions affected the evolution and size of inclusions in molten steel by influencing the content of [Mg] and [Al]. The RE-MgO crucible reactions increased [Mg] content, leading to more MgO inclusions and a smaller average size. The RE-Al2O3 crucible reactions increased [Al] content, resulting in more REAlO3 inclusions and a bigger average size. The reactions of La, Ce, and Y with MgO·Al2O3 crucibles had varying effects on the evolution of inclusions. La and Ce selectively eroded the crucible, mostly reacting with the Al2O3 component and generating REAlO3 inclusions. In contrast, the slow reaction rate of Y with the crucible and the formation of the dense Y2O3 layer at the steel/crucible interface made it react almost simultaneously with both MgO and Al2O3 components, and the modification of inclusions was dominated by [Mg] rather than [Al]. The above conclusions provided more information on how the reactions between rare earth elements and refractory materials affected inclusions in rare earth steels during smelting. They also enriched the theory of inclusion control in steel and offered new controlling strategies.

Evolution of MnO–SiO2–Al2O3–MgO inclusions during heat treatment at 1100 °C

Evolution of MnO–SiO2–Al2O3–MgO inclusions during heat treatment at 1100 °C

Effects of refining slag basicity and vacuum treatment on the cleanliness of bearing steel

The effect of vacuum treatment on the cleanliness of low Ti steel treated with low basicity refining slag was studied by analyzing the change of oxygen content and inclusions characteristics in the steel after the interaction between different basicity slags and GCr15 bearing steels and after vacuum treatment. The results show that the oxide inclusions in the steel are mainly MgO·Al2O3 after slag-steel interaction. The low basicity slag refining is beneficial for decreasing the harm of TiN inclusions due to the better low Ti content control. However, the oxygen content and the number of inclusions in the steel increase with the decrease of slag basicity (CaO/SiO2 mass ratio), which means that the decrease in the basicity is disadvantageous to the cleanliness of steel. Typical inclusions in the steel transform into smaller MgO inclusions and MgS–MgO-(MnS) composite inclusions after vacuum treatment, and the oxygen content of steel is decreased to the same level. Furthermore, the size and number density of inclusions are significantly decreased after the vacuum treatment. It indicates that the combined process of low basicity slag refining and vacuum carbon deoxidation can realize the TiN inclusion control and cleanliness improvement of GCr15 bearing steel.

Sulfide Inclusions in an Al‐Killed Nonoriented Electrical Steel with Lanthanum Addition

Herein, laboratory experiments are conducted to evaluate the effect of sulfur and lanthanum content in the steel on the modification of inclusions. The amount, composition, morphology, and size of nonmetallic inclusions in the steel are observed using an automatic scanning electron microscope. Results show that as the lanthanum content in the steel increased from 0 to 72 ppm, the inclusions in the steel with 12 ppm sulfur are modified in the following order: Al2O3–CaO–MgO → LaAlO3 → LaAlO3–La2O2S → La2O2S. Similarly, when the sulfur content is 27 ppm, inclusions transformed in the order of Al2O3–CaO–MgO → LaAlO3 → LaAlO3–La2O2S → La2O2S → La2O2S–LaxS → LaxS as the lanthanum content increases from 0 to 150 ppm. Thermodynamic analysis using FactSage based on a private database is employed to reveal the mechanism for the modification of inclusions. Additionally, a kinetic model is established to study the transformation rate of inclusions in the steel after the addition of lanthanum and sulfur. Liquid Al2O3–CaO–MgO inclusions disappear after 800 s when the steel contains 12 ppm sulfur and 12 ppm lanthanum. The composition of inclusions is 53%LaAlO3–47%La2O2S at 1800 s, while it is 100%La2O2S and 80%La2O2S–18%LaxS–2%CaS when the lanthanum content is 33 and 72 ppm, respectively.

Mg/MgO interfaces as efficient hydrogen evolution cathodes causing accelerated corrosion of additive manufactured Mg alloys: A DFT analysis

The corrosion rates of additive-manufactured Mg alloys are higher than their as-cast counterparts, possibly due to increased kinetics for the hydrogen evolution reaction on secondary phases, which may include oxide inclusions. Scanning Kelvin Probe Force Microscopy demonstrated that MgO inclusions could act as cathodes for Mg corrosion, but their low conductivity likely precludes this. However, the density of state calculations through density functional theory using hybrid HSE06 functional revealed overlapping electronic states at the Mg/MgO interface, which facilitates electron transfers and participates in redox reactions. Subsequent determination of the hydrogen absorption energy at the Mg/MgO interface reveals it to be an excellent catalytic site, with HER being found to be a factor of 23x more efficient at the interface than on metallic Mg. The results not only support the plausibility of the Mg/MgO interface being an effective cathode to the adjacent anodic Mg matrix during corrosion but also contribute to the understanding of the enhanced cathodic activities observed during the anodic dissolution of magnesium.

Effect of sulfur content on precipitation behaviour of MnS-containing inclusions in X70 pipeline steel

The presence of oxide-MnS complex inclusions is beneficial for the improvement of hydrogen resistance in pipeline steel. The effect of S and Mg contents on the generation mechanism of MnS, MgAl2O4, and MgO inclusions, and the heterogeneous nucleation principle of MnS on the surfaces of MgAl2O4 and MgO were revealed using laboratory experiments, thermodynamic calculations, and density functional theory (DFT) computations. The inclusion characteristics in steel were evaluated by using a Scanning Electron Microscope in combination with an Energy Dispersive Spectrometer (SEM + EDS). It has been found that as the Mg content increased, MgAl2O4 transformed into MgO, which can be well predicted by thermodynamic calculations. It was found that MnS exhibited the ability to nucleate heterogeneously on the surfaces of MgO and MgAl2O4 inclusions. Furthermore, proper S content (approximately 30 ppm) can facilitate the formation of oxide-MnS complex inclusions, excess S content was not desired. The smaller the oxide inclusion, the easier to form wrapped MnS on the oxides. The nucleation ability of MnS and MgAl2O4 was identified by DFT calculations and found that they followed the order of (111)MnS//(111)MgAl2O4>(100)MnS//(100)MgAl2O4>(110)MnS//(110)MgAl2O4. Furthermore, the heterogeneous nucleation ability of MnS and MgO followed in the order of (111)MnS//(111)MgO > (100)MnS//(111)MgO > (100)MnS//(100)MgO. This study provides theoretical evidence supporting the heterogeneous nucleation ability of MnS on the surfaces of MgO and MgAl2O4. Moreover, it helps bridge the disparity between the calculation of MnS and MgO nucleation using the two-dimensional mismatch degree and the experimental findings.

Formation and aggregation behavior of inclusions in Ni-based alloys with different Mg contents

Large non-metallic inclusions affect the mechanical properties and service life of nickel-based superalloys. This study investigates the effects of magnesium elements on non-metallic inclusions in K4169 nickel-based superalloys, exploring the formation mechanisms and aggregation relationships of the inclusions. Four gradients of the magnesium content were used to simulate the erosion of MgO refractories on inclusions in the vacuum induction melting of nickel-based superalloys. The observed inclusions mainly comprised MgO, TiN, MgAl2O4, and MgAl2O4–TiN composites. To study the formation mechanism of inclusions in Ni-based alloys with different Mg contents, the predominance diagram of Mg–Al–Ti–O inclusions in nickel-based superalloy systems was calculated using Factsage thermodynamics software and classical thermodynamics separately. The aggregation behavior of MgAl2O4 and MgO inclusions on the surface of molten nickel-based superalloys was observed in situ under a high-temperature confocal laser scan microscope. The capillary force acting on inclusions in nickel-based superalloys was calculated using the Kralchevsky–Paunov model (K–P model), the calculation was verified with experimental results, and the influencing factors were analyzed. The capillary force acting on inclusions on the surface of molten nickel-based superalloys weakened in the order of MgAl2O4 > MgO > Al2O3, which is the opposite of the order for the force acting on inclusions in molten steel. Minimizing the magnesium content in the alloy is crucial to preventing the formation of large inclusions in nickel-based superalloys, and the use of magnesium-containing materials in the smelting process should thus be avoided.

Mechanical Characteristics of Structural Thick Plates Depending on Vacuum Time of RH Process

The structural thick plates were manufactured by varying the vacuum time at a constant argon gas flow rate and degree of vacuum during the Ruhrstahl Heraeus (RH) refining process. The inclusion and mechanical properties of the structural thick-plate specimens were evaluated according to vacuum time. The nitrogen in the converter had an effect after the RH process, and as the vacuum time of the RH process increased, the nitrogen content also increased. The nitrogen in the continuous casting (CC) decreased more than that in the converter, and as the vacuum time increased, the hydrogen decreased. Al2O3·CaO, MnS and Al2O3·MgO inclusions were observed in the structural thick plate. The average size of the oxides was (6.1 to 33.46) μm, while the average size of the Al-O-based inclusions was (4.26 - 6.3) μm. The mechanical properties, such as tensile strength, yield strength, and elongation, were affected by the vacuum time of the RH process with 10 min being the best. The micro-Vickers hardness showed dispersion regardless of the vacuum time of the RH process, which can be explained by the Weibull probability distribution. From the shape and scale parameters, although the specimen with the vacuum time of the RH process of 10 min showed a large dispersion in the micro-Vickers hardness, the characteristic value of 63.2 % was the best.

Transient evolution of non-metallic inclusions in molten high aluminum and high manganese steel contacting with slag and crucible: experimental investigation and FactSage macros modeling

In this work, high temperature experiments of high Al molten steel contacting with crucible and slag were performed to investigate the effect of crucible–slag–steel reaction on transient evolution of inclusions in the high Al molten steel. Processing samples were taken for the chemical compositions of steel and also the inclusions have been characterized by using SEM and EDS AZtec. FactSage macros have been applied to simulate the evolution of molten steel composition and inclusions in molten steel during steel-slag reaction and comparing to the experimental results. Due to the steel–crucible–slag reactions especially under the condition of the high Al molten steel, the Ca and Mg transferred from slag and crucible to the molten steel and then subsequently led to the evolution of Mg and Ca-containing inclusions. The Mg inclusions transferred from MgAl2O4 to MgO inclusions while Ca transferred to steel and modified MgAl2O4 at crucible interface to form CaMgAl2O5 phase. The FactSage macros modeling did agree reasonably well with the experimental results.

Formation and Evolution Mechanism of the Inclusions of Al2O3·SiO2·CaO and Al2O3·SiO2·CaO·MgO in Seamless Steel Tube Steel

Herein, the formation and evolution mechanism of inclusions of Al2O3·SiO2·CaO and Al2O3·SiO2·CaO·MgO in seamless steel tube steel are investigated. In the long strip defects on the longitudinal cross section of the steel tube after the rolling bar piercing, the defect is mainly formed by Al2O3·SiO2·CaO·MgO inclusions and Al2O3·SiO2·CaO·inclusions dotted with·CaS inclusions after the rolling. The typical inclusions in the different steelmaking stages are mainly composed of CaS, Al2O3·(SiO2), CaO·(SiO2), MnS·(TiN), Al2O3·SiO2·CaO·(CaS)·(MnS), Al2O3·SiO2·CaO·MgO·(MnO), Al2O3·SiO2·CaO·MgO·(CaS)·(MnS), etc. In the billet, the average sizes of Al2O3·SiO2·CaO‐based and Al2O3·SiO2·CaO·MgO‐based inclusions are much larger than those of the other types of inclusions. Part of SiO2 in the deoxidized products SiO2 can be reduced by [Al], resulting in the formation of the Al2O3·SiO2 composite inclusions. The SiO2 in Al2O3·SiO2 inclusions can continuously be reduced by the dissolved [Ca] to form the Al2O3·SiO2·CaO composite inclusions. The SiO2 in the Al2O3·SiO2·CaO inclusions can be reduced by the dissolved [Mg] to form the Al2O3·SiO2·CaO·MgO composite inclusions. Another formation process of Al2O3·SiO2·CaO·MgO inclusions is the entrapment of ladle slag in the vacuum degassing (VD) stage, due to the strong agitation of the rising Ar bubbles in the vacuum condition of the VD stage.

Influence of Mg on Inclusions in 21-4N Valve Steel

In order to explore the influence of different magnesium contents on the morphology, size, distribution and composition of inclusions in 21-4N austenitic valve steel, the inclusions in 21-4N austenitic valve steel with different magnesium contents smelted by high temperature resistance furnace were analyzed by Zeiss metallographic microscope and scanning electron microscope. The results show that the average yield of magnesium in steel is only 4.50% due to the high vapor pressure of magnesium in the laboratory smelting process. When the mass fraction of magnesium is 0-60ppm, with the increase of magnesium content, the main inclusions in steel mostly change from the initial Al2O3 and Al-Mn-O inclusions to Al-Mg-O spinel inclusions and Al-Mg-O composite inclusions. With the further addition of Mg, a large number of large-size MgO inclusions began to appear in steel. The average size of inclusions in 21-4N steel decreased from 4.576μm to 2.89μm, and the density of inclusions increased from 54 to 132 /mm2. The distribution uniformity of inclusions is obviously improved.

Study on the effect of Al2O3 on the crystallization behaviour of MnO–SiO2–MgO inclusions in tire cord steel

ABSTRACT Aiming at avoiding the formation of high melting point inclusions containing Al2O3 and reducing the wire breakage rate of the tire cord steel. MnO–SiO2–10wt.%MgO–(5wt.%, 10wt.%, 15wt.%, 20wt.%) Al2O3 system were designed to investigate the crystallization behaviour by XRD, SEM-EDS, FactSage 8.0. The results indicate that the Mn/Mg element ratio of the Mg-Mn olivine phase precipitated from the system varies. Mg–Mn olivine phase is formed by the interaction of the components in the melt or by the occurrence of homogeneity and the liquidus temperature of the system decreases with the increase of Al2O3 content. Al2O3 lowers the melting point of the whole system by forming the low melting point phase Mn3Al2Si3O12. To obtain low melting point plasticized inclusions, the Al2O3 content of the system needs to be controlled in the range of 15–20 wt.%.

Effect of ladle lining system refractories on the cleanliness of heavy-rail steel U75V

To understand the effect of refractories in the ladle lining system on the evolution of inclusions in the secondary refining process, refractory samples were taken from different locations in the ladle system (Slag lining bricks, Sidewall bricks, Refractory mortar, and Bottom bricks). Laboratory experiments were carried out using heavy-rail steel slab samples (Si-Mn-killed steel) and different refractory bricks. The four kinds of refractory bricks can be roughly divided into 3 categories: (1) MgO-Al2O3-C system (MAC, high MgO>55%); (2) Al2O3-MgO-C system (AMC, low MgO<13%); (3) Al2O3-SiO2 system (AS). The results show that after the reaction between molten steel and refractory materials, both AMC (slag lining bricks and sidewall bricks) and MAC (bottom bricks) will dissolve their component Al2O3, increasing [%Al] content in molten steel, forming MgO-Al2O3 type inclusions, and the dissolution of its component MgO depends on the content of MgO. When MgO>55%, MgO will dissolve. When MgO<13%, due to the low activity of MgO, MgO will not dissolve. MgO inclusions were found in the steel when the MgO content in the refractory was higher than 55%. MgO inclusions may originate from the refractory itself. The reduction of TiO2 in the AS (refractory mortar) by [%Al] and [%Si] in the steel increases the [%Ti] content of the steel, forming Ti-containing inclusions.

Insights into the influence of oxide inclusions on corrosion performance of additive manufactured magnesium alloys

The corrosion performance of binder jet additive samples is compared with cast samples through potentiodynamic polarization in Na2SO4 solution. Higher zinc levels in the magnesium matrix and the presence of MgO within the microstructure of the binder jet printed alloy contribute to increases in the anodic and cathodic kinetics, respectively. It is proposed that electron inhomogeneity at the Mg/MgO interface in the binder jet printed alloy is the source of the catalytic activity of the hydrogen evolution reaction. The removal of MgO inclusions suppressed the cathodic reaction relative to the large increase in kinetics seen in similarly treated cast samples.

A Kinetic Model for Precipitation of TiN Inclusions From Both Homogeneous and Heterogeneous Nucleation During Solidification of Steel

Complex TiN + oxide inclusions which nucleate and grow on the surface of the primary oxide inclusions, e.g. MgO, have been frequently observed in various steel grades after solidification. To describe the precipitation kinetics of TiN and TiN + MgO inclusions, a model accounting for both heterogeneous and homogeneous nucleation was proposed in this work. The model was validated by employing the literature data, and good agreement has been achieved between experimental data and calculation data. The influence of nitrogen and titanium concentrations, the interfacial tension between TiN and steel, cooling rate, and size distribution of primary oxides on the size distribution of TiN and TiN + MgO inclusions were investigated by the model calculations. It was found that nitrogen and titanium concentrations, the interfacial tension between TiN and steel, and the number density of primary MgO inclusions have an impact on the final size distributions of TiN and TiN + MgO inclusions. In contrast, the effects of cooling rate and size of MgO inclusions on the final inclusion size distribution are negligible. The large interfacial tension between TiN and steel would suppress the homogeneous nucleation and is favorable to heterogeneous nucleation. The increase of the number density of primary MgO can significantly suppress the homogeneous nucleation and reduce the size of TiN + MgO inclusions. The present model can be extended to describe the heterogeneous precipitation of other complex inclusions providing that the secondary inclusion has a low lattice mismatch with the primary inclusion. Combining the present model with our previous model for the size distribution of primary inclusions, the size distribution of inclusions in solidified steel can be well described and controlled.

Synthesis of Dense MgB2 Superconductor via In Situ and Ex Situ Spark Plasma Sintering Method.

In this study, high-density magnesium diboride (MgB2) bulk superconductors were synthesized by spark plasma sintering (SPS) under pressure to improve the field dependence of the critical current density (Jc-B) in MgB2 bulk superconductors. We investigated the relationship between sintering conditions (temperature and time) and Jc-B using two methods, ex situ (sintering MgB2 synthesized powder) and in situ (reaction sintering of Mg and B powder), respectively. As a result, we found that higher density with suppressed particle growth and suppression of the formation of coarse particles of MgB4 and MgO were found to be effective in improving the Jc-B characteristics. In the ex situ method, the degradation of MgB2 due to pyrolysis was more severe at temperatures higher than 850 °C. The sample that underwent SPS treatment for a short time at 850 °C showed higher density and less impurity phase in the bulk, which improved the Jc-B properties. In addition, the in situ method showed very minimal impurity with a corresponding improvement in density and Jc-B characteristics for the sample optimized at 750 °C. Microstructural characterization and flux pinning (fP) analysis revealed the possibility of refined MgO inclusions and MgB4 phase as new pinning centers, which greatly contributed to the Jc-B properties. The contributions of the sintering conditions on fP for both synthesis methods were analyzed.

Interpretation of nature of non-metallic inclusions in assessing the quality of metal products in the industrial conditions

Using an example of the quality assessment of welded pipe joints made of steel 09G2S, the method of processing the results of factory expert opinions has been developed to interprete the origin of non-metallic inclusions detected in the defects of a welded joints. Thermodynamic calculations have been made to assess the possible indigenous origin of these inclusions, the results of which are summarized in the form of radar diagrams of five clusters, which combine similar deoxidation products. According to the same method, more than 136 actual inclusions found on dozens of welded joints specimens are combined in 7 clusters. After a comparative analysis of these two types of radar diagrams, the origin of all real inclusion clusters was determined, three of which are predominantly indigenous and the other ones are predominantly exogenous. None of the clusters contains only indigenous inclusions. Several of the inclusions of one of the clusters contain pure exogenous MgO inclusions. The sources of inclusions in weld discontinuities are conglomerates consisting of exo-indigenous or indi-exogenous inclusions, which were torn off from the refractory surface. The method is implemented as a Thixomet PRO plug-in and allows to automate the process of metallographic conclusions generation under conditions of factory practice, as well as to accumulate all information in the database for subsequent processing and analysis.

Kinetics Study on the Modification Process of Al2O3 Inclusions in High-Carbon Hard Wire Steel by Magnesium Treatment

The aim of the experiment in this work is to modify the Al2O3 inclusions in high-carbon hard wire steel by magnesium treatment. The general evolution process of inclusions in steel is: Al2O3 → MgO·Al2O3(MA) → MgO. The unreacted core model was used to study the modification process of inclusions. The results show that the complete modification time (tf) of inclusions is significantly shortened by the increase of magnesium content in molten steel. For Al2O3 inclusions with radius of 1 μm and Mg content in the range of 0.0005–0.0055%, the modification time of Al2O3 inclusions to MA decreased from 755 s to 25 s, which was reduced by 730 s. For Al2O3 inclusions with a radius of 1.5 μm and Mg content in the range of 0.001–0.0035%, the Al2O3 inclusions were completely modified to MgO inclusions from 592 s to 55 s. The Mg content in the molten steel increased 3.4-fold, and the time for complete modification of inclusions was shortened by about 10-fold. With the increase of Al and O content in molten steel, the complete modification time increased slightly, but the change was small. At the same time, the larger the radius of the unmodified inclusion is, the longer the complete modification time is. The tf of Al2O3 inclusions with a radius of 1 μm when modified to MA is 191 s, and the tf of Al2O3 inclusions with a radius of 2 μm when modified to MA is 765 s. According to the boundary conditions and the parameters of the unreacted core model, the MgO content in inclusions with different radius is calculated. The experimental results are essentially consistent with the kinetic calculation results.