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This study provides a thorough analysis of the fatigue resistance of two low-alloy ultrahigh-strength steels (UHSSs): Steel A (fully martensitic) and Steel B (martensitic–bainitic). The investigation focused on the fatigue behaviour, damage mechanisms, and failure modes across different microstructures. Fatigue strength was determined through fully reversed tension–compression stress-controlled fatigue tests. Microstructural evolution, fracture surface characteristics, and crack-initiation mechanisms were investigated using laser scanning confocal microscopy and scanning electron microscopy. Microindentation hardness (HIT) tests were conducted to examine the cyclic hardening and softening of the steels. The experimental results revealed that Steel A exhibited superior fatigue resistance compared to Steel B, with fatigue limits of 550 and 500 MPa, respectively. Fracture surface analysis identified non-metallic inclusions (NMIs) comprising the complex MnO-SiO2 as critical sites for crack initiation during cyclic loading in both steels. The HIT results after fatigue indicated significant cyclic softening for Steel A, with HIT values decreasing from 7.7 ± 0.36 to 5.66 ± 0.26 GPa. In contrast, Steel B exhibited slight cyclic hardening, with HIT values increasing from 5.24 ± 0.23 to 5.41 ± 0.31 GPa. Furthermore, the martensitic steel demonstrated superior yield and tensile strengths of 1145 and 1870 MPa, respectively. Analysis of the fatigue behaviour revealed the superior fatigue resistance of martensitic steel. The complex morphology and shape of the NMIs, examined using the 3D microstructure characterisation technique, demonstrated their role as stress concentrators, leading to localised plastic deformation and crack initiation.

This research was focused on the effect of Ti and S content on the formation of non-metallic inclusions and their influence on the mechanical properties and machinability of low-carbon ferritic–pearlitic steels. An analysis and classification of the non-metallic inclusions were carried out. The tensile strength and impact toughness were determined from samples taken in the rolling direction. Machinability investigations were carried out on a CNC turning machine and by analyzing the surface roughness. TiO-TiN inclusions are present in steels with an increased Ti content. In these steels, the hardness, tensile strength, and cutting forces increase with a higher proportion of Ti. In the second group of steels with increased contents of S, Al, and Ca, MnS and CaO-Al2O3-MnS non-metallic inclusions are formed. As the S content increases, the tensile strength and cutting forces decrease, while the impact toughness increases. In steels with added Ti, the machining is more difficult, but a finer surface is achieved after turning, while a higher S content results in an increased fraction of softer sulfide inclusions, which reduce the cutting forces but also result in a reduced surface quality.

Since steel cleanness comes to the fore of steel producers worldwide, it is necessary to understand the formation mechanism and modification of non-metallic inclusions (NMIs) in more detail. One central point is the identification of the source of especially interfering NMIs to prevent their evolution in the future. The present study applies two approaches to determine the source of NMIs in Ti-stabilized ultra-low carbon (ULC) steels—the active and the passive tracing. Both approaches are applied to an industrial experiment. The active tracing technique is focused on investigating the clogging layer formation in submerged entry nozzles and, hence, the origin of alumina particles. This method adds rare earth elements (REEs) directly to the melt to mark pre-existing deoxidation products at a certain point of the steelmaking process. The main concern of the passive method, the so-called REE fingerprint, is the determination of the source of mesoscopic NMIs. For the REE fingerprint, the pre-existing concentration of REEs in different potential sources and the investigated NMIs are measured by using an inductively coupled plasma mass spectrometer (ICP-MS). The resulting patterns are compared after normalizing the contents to chondrites, and the NMIs’ origins are identified. Concerning the EDS analysis and the resulting patterns from the REE fingerprint, the mold slag and, respectively, the casting powder were the sources of the investigated NMIs.

Super 13Cr steels, which combine high strength and excellent corrosion resistance, are the optimal choice for developing and exploiting complex oil and gas wells, particularly in high-CO2 environments. In this study, we conducted a corrosion assessment of several high-strength steels of the 13Cr type with different alloying systems. We identified the primary parameters responsible for the corrosion resistance of these steels based on our research findings and suggested ways to optimize their chemical composition and select the most economically viable option. We demonstrate the importance of selecting the appropriate alloying system and the impact of non-metallic inclusions (NMIs) on the corrosion properties of the high strength 13Cr material.

The dissolution of Al2O3 non-metallic inclusions in slag containing FeO was investigated in this study. The slag system used in the experiments was a quaternary system of CaO-SiO2-Al2O3-FeO. The composition of the slag was studied by fixing the basicity (CaO/SiO2 ratio) to 1 and varying the FeO content to 10 and 20 wt%. In addition, the experimental temperature was varied to 1550 °C, 1575 °C, and 1600 °C to study the effect of temperature on the Al2O3 dissolution behavior. The experimental equipment used was a single hot thermocouple apparatus. The dissolution rate of Al2O3 particles increased linearly with increasing temperature and FeO content. In addition, the mass transfer activation energy of Al2O3 dissolution in FeO 10 wt% and FeO 20 wt% was calculated through an Arrhenius-type analysis. The obtained mass transfer activation energies were 159 and 189 kJ/mole, respectively.

The non-metallic inclusions in steel mainly come from the deoxidization process of molten steel. Based on the different deoxidization processes of GCr15 bearing steel produced by a domestic steel plant, the single deoxidization curves of Al, Si, and Mn and the compound deoxidization curves of Al-Si and Si-Mn under pure molten iron and GCr15 bearing steel production conditions were calculated with the FactSage 8.1 thermodynamic software. The results show that the deoxidization curves under the two conditions are quite different. At the same time, the Al-Ti deoxidation equilibrium curve under the condition of GCr15 bearing steel was calculated. It was found that when [Ti] < 0.0015% in the steel, the equilibrium deoxidation product was Al2O3, and no titanium oxide was generated. Finally, a thermodynamic calculation and analysis of the effect of rare-earth Ce content on the modification of inclusions in GCr15 bearing steel were carried out. The results showed that when T = 1873 K, the rare-earth Ce treatment of aluminum deoxidized the GCr15 bearing steel; when [Al] = 0.015%, Al2O3 inclusions increased with the increase in [Ce] content, and the evolution path was Al11O18Ce→CeAlO3→Ce2O3. When [Si] = 0.28%, [O] > 50 ppm, and CeCrO3 and [O] 0.012% appeared. CeS inclusions appeared in the steel, and the final equilibrium product was CeS + Ce2O3. When [Ce] < 0.012%, CeS was not produced in the steel, and only Ce2O3 existed.

Damage in bearings is closely associated with the presence of microstructural alterations, known as white etching areas (WEAs) and white etching cracks (WECs). One of the main reasons for the creation of these microstructural alterations is the presence of defects in the material, such as non-metallic inclusions. Manganese sulfides and aluminum oxides are widely reported in the literature as the most common types of non-metallic inclusions found in bearing steels. This study classifies 280 non-metallic inclusions in an investigated bearing steel according to several criteria: bonded/debonded with the matrix, size, shape, orientation angle, depth below the raceway surface, and chemical composition. Contrary to the findings in the literature, this investigation reports that the chemical composition of the inclusion (MnS + Al2O3) is of secondary importance when considering factors for damage initiation. The orientation of the microstructural alterations is observed to coincide with the high-stress regions, indicating a relation between the formation of butterfly wings and the white etching crack. In our investigation, butterfly wings typically exhibit a 45-degree pattern originating from the non-metallic inclusions. Conversely, the white etching crack starts from the non-metallic inclusion at a shallower angle in correspondence to the raceway. This can be attributed to the stress state, which corresponds to a region where extensive white etching cracks are formed. In conclusion, the microstructural observations demonstrate that the state of non-metallic inclusion—i.e., whether they are bonded or not to the steel matrix—plays an essential role in initiating rolling contact fatigue damage.

Few reports exist on the effect of the basicity of refining slag on inclusions in 15-5PH stainless steel and its removal efficiency. In this study, the effects of various basicities on the formation and removal efficiency of inclusions in molten steel were investigated. To investigate the effect of the chemical makeup of slag on the non-metallic inclusions in liquid steel, laboratory experiments and thermodynamic calculations were conducted on CaO-MgO-SiO2-Al2O3-CaF2 slag with various slag basicities and 15-5PH stainless steel. In the steel samples that had reacted with high-basicity slag samples, the magnesium content and aluminum yield were higher. Thermodynamic findings according to the ion and molecule coexistence theory showed that log (aSiO23/aAl2O32) decreases as slag basicity increases. This increases the Al concentration in liquid steel while decreasing the Si content. Log (aMgO3/aAl2O3) also increases, increasing the Mg content of the molten steel. With this, the transformation order of oxide inclusions is Al2O3 → MgAl2O4 → MgO. High-basicity slag increases the attachment of slag to inclusions and generates MgAl2O4 inclusions that are more easily adsorbed by inclusions in molten steel, thereby improving the cleanliness of molten steel.

Heat-resistant P91 martensitic steel is used to produce high-temperature steam pipelines in (ultra) critical power plants. However, non-metallic inclusions are inevitably produced in the metallurgical process. The type, composition, morphology, quantities, size and distribution of these inclusions have significant influences on the properties of materials. The present work developed an original position statistical distribution analysis method to characterize non-metallic inclusions in P91 steel based on scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS). Two samples from P91 steel pipes fabricated by different processes were examined. The non-metallic inclusions in these samples could be divided into spherical oxides, strand-shaped oxides, spherical sulfides, spherical oxygen–sulfur compounds, strip sulfides and other inclusions. The amount, proportional area, particle sizes, original positions and statistical distribution results of non-metallic inclusions in different processed samples were assessed, and the causes and effects of these inclusions were analyzed. This novel method could provide diversified information on inclusions, which is helpful for the improvement of metallurgical processes and service performance evaluations.

Non-metallic inclusions (NMIs) in steels have been the focus of various experimental studies due to their detrimental character. While isolated processes, such as agglomeration or dissolution, have been well investigated, holistic in-situ views with high-temperature confocal scanning laser microscopy (HT-CSLM) have been rare. In this work a novel and suitable method is presented to simultaneously observe agglomeration, movement, detachment, and dissolution of non-metallic inclusions by combined the melting of steel and slag with a dual-crucible approach. Therefore, different steel/slag combinations were tested. It is shown that, with transparent that does not become tarnished by the ions stemming from the steel, the steel’s surface and non-metallic inclusions are observable. Furthermore, technological limitations are discussed, including restrictions regarding the melting point of steels and certain steel/slag combinations.

Identification and characterization play an essential role in the study of non-metallic inclusions (NMIs) in monitoring the steel casting process and product quality. This study uses Raman spectroscopy, a versatile, relatively fast, and non-destructive technique for characterizing oxide and sulfide-based inclusion phases in steel samples. The relative Raman peak intensities and positions were used to qualitatively estimate the inclusion phases of Al2O3, CA, C12A7, C3A, MgO·Al2O3, and CaS. For a quantitative estimation, FESEM-EDS (field emission scanning electron microscope with energy dispersive X-ray spectroscopy) was used to evaluate the inclusion phases in the samples. This study demonstrates that Raman spectroscopy can be used to rapidly estimate the content of Al2O3, magnesium aluminate spinel (MgO·Al2O3), and the calcium aluminate phases of CA, C3A, and C12A7 in steel samples to complement established characterization techniques for NMIs analysis such as FESEM-EDS.

The origin, evolution, and formation mechanism of MgO-based inclusions in Si-Mn-killed steel were studied in industrial trials with systematical samplings of the refining ladle, casting tundish, and as-cast bloom. In the present study, there were large numbers of MgO-based non-metallic inclusions, which started to form in the LF final process, and the MgO content in the lime-silicate slag increases from LF to VD process. The reason for the formation of MgO-based inclusions in refining process was analyzed using FactSage8.1 software. It was found that MgO-based inclusions were caused by the violent reaction between the slag and steel and the serious erosion of MgO-C refractory. The MgO solubility decreased in the lime-silicate slag and precipitated the periclase phase with basicity increasing. The solubility of MgO increased with an increase in the temperature. Measures were taken to optimize the refining process based on the above result. By increasing the slag basicity and increasing the content of MgO in the slag, erosion of the MgO-C refractory was reduced and the number of MgO-based non-metallic inclusions decreased from 0.2 to 0.04 per square millimeter.

Inclusion-initiated fracture in high-strength spring steel is studied for axial and torsion very high cycle fatigue (VHCF) loading at load ratios of R = −1, 0.1 and 0.35. Ultrasonic S-N tests are performed with SWOSC-V steel featuring intentionally increased numbers and sizes of non-metallic inclusions. The fatigue limit for axial and torsion loading is considered the threshold for mode I cracks starting at internal inclusions. The influence of inclusion size and Vickers hardness on cyclic strength is well predicted with Murakami and Endo’s area parameter model. In the presence of similarly sized inclusions, stress biaxiality is considered by a ratio of torsion to axial fatigue strength of 0.86. Load ratio sensitivity is accounted for by the factor ((1 − R)/2)α, with α being 0.41 for axial and 0.55 for torsion loading. VHCF properties under torsion loading cannot appropriately be deduced from axial data. In contrast to axial loading, the defect sensitivity for torsion loading increases significantly with superimposed static mean load, and no inclusion-initiated fracture is found at R = −1. Size effects and the stress gradient effective under torsion loading are considered to explain smaller crack initiating inclusions found in torsion ultrasonic fatigue tests.

In situ study of the inclusion dissolution behavior in a slag utilizing high-temperature confocal scanning laser microscopy helps to understand the phenomenon of the removal of non-metallic inclusions from liquid steel before the casting process. The current work introduces an image processing procedure to automate and measure the inclusion diameter during its dissolution. Silica and alumina particle dissolution were considered as they appear differently when suspended in the slag (bubble-like transparent and solid-like opaque, respectively). The procedure consists of two parts: (1) morphological isolation and construction of the inclusion, and (2) inclusion diameter calculation. The inclusion diameters could be successfully measured over a series of images and showed good agreement with the manually measured diameters. The image processing procedure has the advantages of significant time saving and standardization compared to manual measurements.

The occurrence of non-deformable, non-metallic inclusions is the dominant reason for failure of wire during drawing and degrades service life for some steel grades, e.g., tire cord steel. To investigate the deformability of glassy inclusions in CaO-Al2O3-SiO2 and MnO-Al2O3-SiO2 systems, experimental and numerical methods were used. Young’s modulus values of some glasses based on the CaO-Al2O3-SiO2 and MnO-Al2O3-SiO2 systems, which correspond to typical inclusions in tire cord steel, were measured with resonant ultrasound spectroscopy. The effect of basicity, defined as the ratio of mass percentage of CaO to SiO2, on Young’s modulus and Poisson’s ratio were investigated. The Young’s moduli of glasses are enhanced with increasing basicity, which could be attributed to the high field strength of calcium ions. The Poisson’s ratios of glasses also show an increase tendency with increasing basicity, which could be due to the loss of rigidity of network with introduction of calcium ions. The equations in the literature for Young’s modulus calculation were evaluated based on the present and literature data. Appen’s equation is modified by re-fitting the present and literature data to give accurate estimation of Young’s modulus with the mean deviation of 2%. The iso-Young’s modulus diagrams for CaO-Al2O3-SiO2 systems were constructed. It is proposed that the iso-Young’s modulus diagram could be combined with liquid area in CaO-Al2O3-SiO2 ternary phase diagram to optimize the inclusion composition during both hot rolling and cold drawing.

In this paper an exhaustive scientific work is performed, by means of metallographic and scanning electron microscope (SEM) techniques, of the microstructural defects exhibited by pearlitic steels and their evolution with the manufacturing process by cold drawing, analyzing the consequences of such defects on the isotropic/anisotropic fracture behavior of the different steels. Thus, the objective is the establishment of a relation between the microstructural damage and the fracture behavior of the different steels. To this end, samples were taken from all the intermediate stages of the real cold drawing process, from the initial hot rolled bar (not cold drawn at all) to the heavily drawn final commercial product (prestressing steel wire). Results show the very relevant role of non-metallic inclusions in the fracture behavior of cold drawn pearlitic steels.

The production of clean steel is associated with high-quality steel grades for demanding applications. The formation of oxide inclusions mainly depends on the deoxidation practice; it is usually carried out through Al additions, but alumina inclusions can have detrimental effects. An alternative zirconium inclusion modification was used in a creep-resistant steel to improve the cleanliness of laboratory-made steel. The thermodynamics behind the inclusion modification are presented, the reaction products are identified and the steel cleanliness improvement is quantified. The resulting influence of zirconium addition on non-metallic inclusions and mechanical properties is discussed. While the Zr additions drastically reduce the non-metallic inclusion size and area, additions above a certain amount result in the formation of zirconium nitrides that ultimately soften the martensitic steel due to the depletion of nitrogen in solid solution.

Removing inclusions from the melt is an important task in metallurgy with critical impact on the quality of the final alloy. Processes employed with this purpose, such as flotation, crucially depend on the particle size. For small inclusions, the aggregation kinetics constitute the bottleneck and, hence, determine the efficiency of the entire process. If particles smaller than all flow scales are considered, the flow can locally be replaced by a plane shear flow. In this contribution, particle interactions in plane shear flow are investigated, computing the fully resolved hydrodynamics at finite Reynolds numbers, using a lattice Boltzmann method with an immersed boundary method. Investigations with various initial conditions, several shear values and several inclusion sizes are conducted to determine collision efficiencies. It is observed that although finite Reynolds hydrodynamics play a significant role in particle collision, statistical collision efficiency barely depends on the Reynolds number. Indeed, the particle size ratio is found to be the prevalent parameter. In a second step, modeled collision dynamics are applied to particles tracked in a fully resolved bubbly flow, and collision frequencies at larger flow scale are derived.

In order to study the influence of MgO refractory on inclusions during the steelmaking process, laboratory quasi-equilibrium experiments were performed in MgO crucibles at 1873 K. It was found that there were no MgO-containing inclusions formed when ultra-low Al ultra-low C steel was used. When the contents of dissolved Al and C in steel changed, different composition ranges led to different types of inclusions. It was shown as well that for both low Al high C steel and high Al low C steel, the order of average MgO content in inclusions from large to small was: MgO-10% slag addition > MgO-free slag addition > no slag addition. Based on the results, a simple formation mechanism of MgO-containing inclusions in the steel with different compositions in MgO crucibles was proposed. The results could provide guidance for the reduction of MgO-containing inclusions in the industrial production of steels.

To provide fundamental information on the control of rare earth inclusions in solid steel, two 18 mass% Cr-8 mass% Ni stainless steels with different yttrium additions were prepared using an electric resistance furnace and the evolution of yttrium-based oxide inclusions during heat treatment of the steels at 1473 K was investigated. In both as-cast steels, homogeneous spherical Al-Y-Si(-Mn-Cr) oxide inclusions were observed; however, the steel with larger yttrium additions also had some heterogeneous oxide inclusions with double phases. After heating, a new oxide phase with higher yttrium content precipitated from the original inclusions and resulted in partitioning to Y-rich and Al-rich parts in both steels. The average size and number density of inclusions slightly increased, and the morphology of inclusions changed from spherical to irregular. The transformation mechanism during isothermal heating was proposed to be the mutual effects of (i) internal transformation of the yttrium-based inclusions owing to crystallization of glassy oxide and (ii) interfacial reaction between inclusions and the steel matrix.

The combination of high strength and formability of transformation induced plasticity (TRIP) steels is interesting for the automotive industry. However, the poor weldability limits its industrial application. This paper shows the results of six low-alloy TRIP steels with different chemical composition which were studied in order to correlate retained austenite (RA) and non-metallic inclusions (NMI) with their resistance spot welded zones to their joints’ final mechanical properties. RA volume fractions were quantified by X-ray microdiffraction (µSXRD) while the magnetic saturation technique was used to quantify NMI contents. Microstructural characterization and NMI of the base metals and spot welds were assessed using scanning electron microscopy (SEM). Weld nuggets macrostructures were identified using optical microscopy (OM). The lap-shear tensile test was used to determine the final mechanical properties of the welded joints. It was found that NMI content in the fusion zone (FZ) was higher than those in the base metal and heat affected zone (HAZ). Whereas, traces of RA were found in the HAZ of highly alloyed TRIP steels. Lap-shear tensile test results showed that mechanical properties of spot welds were affected by NMI contents, but in a major way by the decomposition of RA in the FZ and HAZ.

Ferroalloys are integral constituents of the steelmaking process, since non-metallic inclusions (NMIs) from ferroalloys significantly influence the transformation of inclusions present in liquid steel or they are directly involved in casted steel. In this study, the characteristics of inclusions (such as the number, morphology, size, and composition) in different industrial ferroalloys (FeV, FeMo, FeB, and FeCr) were investigated using the electrolytic extraction (EE) technique. After extraction from the ferroalloy samples and filtration of the solution, the inclusions were investigated on a film filter. The three-dimensional (3D) investigations were conducted using a scanning electron microscopy in combination with energy dispersive spectroscopy (SEM-EDS). The characteristics of inclusions observed in the ferroalloys were compared with previous results and discussed with respect to their possible behaviors in the melt and their effects on the quality of the cast steels. The particle size distributions and floatation distances were plotted for the main inclusion types. The results showed that the most harmful inclusions in the ferroalloys investigated are the following: pure Al2O3 and high Al2O3-containing inclusions in FeV alloys; pure SiO2 and high SiO2-containing inclusions in FeMo alloys; Al2O3 and SiO2-containing inclusions in FeB alloys; and MnO-Cr2O3, Al2O3, and Cr2O3-based inclusions in FeCr alloys.

Corrosion rate in different steel grades (including oilfield pipeline steels) is determined by the presence of non-metallic inclusions (NMI) in steels. Specifically, the effect of different inclusions on the quality of steels depends on their characteristics such as size, number, morphology, composition, and physical properties, as well as their location in the steel matrix. Therefore, the optimization and control of NMI in steels are very important today to obtain an improvement of the material properties of the final steel products. It is well known that a Ca-treatment of liquid steels in ladle before casting is an effective method for modification of non-metallic inclusions for improvement of the steel properties. Therefore, the NMI characteristics were evaluated in industrial steel samples of low carbon Ca-treated steel used for production of oil-pipelines. An electrolytic extraction technique was used for extraction of NMI from the steel samples followed by three-dimensional investigations of different inclusions and clusters by using SEM in combination with EDS. Moreover, the number and compositions of corrosion active non-metallic inclusions were estimated in hot rolled steel samples from two different heats. Finally, the corrosion resistance of these steels can be discussed depending on the characteristics of non-metallic inclusions present in the steel.

The formation and characteristics of non-metallic inclusions in 304L stainless steel during the vacuum oxygen decarburization (VOD) refining process were investigated using industrial experiments and thermodynamic calculations. The compositional characteristics indicated that two types of inclusions with different sizes (from 1 μm to 30 μm) existed in 304L stainless steel during the VOD refining process, i.e., CaO-SiO2-Al2O3-MgO external inclusions, and CaO-SiO2-Al2O3-MgO-MnO endogenous inclusions. The calculation results obtained using the FactSage 7.1 software confirmed that the inclusions that were larger than 5 μm were mostly CaO-SiO2-Al2O3-MgO; the similarity in composition to the slag indicated that these inclusions originated from the slag entrapment. The CaO-SiO2-Al2O3-MgO-MnO inclusions that were smaller than 5 μm originated mainly from the oxidation reaction with Ca, Al, Mg, Si, and Mn. The changes in the inclusion composition resulting from changes in the Ca, Al, and O contents, and the temperature during the VOD refining process was larger for the smaller inclusions. Generating mechanisms for the CaO-SiO2-Al2O3-MgO-MnO inclusions in the 304L stainless steel were proposed.

The tundish with heating instrumentation is attracting more and more attention in continuous casting processes for maintaining a pre-determined constant pouring temperature under a given casting speed, which is beneficial for an improved and consistent steel product quality. However, the fluid flow, temperature distribution and the removal behaviors of non-metallic inclusions in it will be much different from that in a conventional tundish, due to the implementation of the heating practice. In the present work, to reduce the non-metallic inclusion amounts in billets of the second and sixth strands in a seven-strand tundish with channel type induction heating, the flow field profiles and temperature profiles of molten steel in this tundish have been investigated using hydrodynamic modeling coupled with mathematical simulation under isothermal and non-isothermal situations, respectively. The results of the isothermal experiment indicate that the prototype tundish has severe “short-circuiting flow” in the second and sixth strands, which might have caused the increased inclusion amounts in the billets of the two strands. The flow field of the tundish can be greatly improved by changing the channel design and adding two high dams at each side of the tundish. Compared with the prototype structure A0, the average residence time of the optimized case C5 is prolonged by 55.49% (from 501 to 779 s); the dead zone volume fraction is reduced by 66.18% (from 45.57% to 15.41%); and the flow of each strand becomes more consistent with lower standard deviation. The non-isothermal experiments show that the fluid presents an obvious rising tendency when it flows out from the heating induction channel. The larger the temperature difference inside and outside the channel is, the more consistent the fluid flow between different strands and the more homogeneous the flow field in the whole tundish. For the prototype tundish structure, when the temperature difference is 5 °C, the dead zone is basically eliminated, and the minimum residence time is prolonged by 789% (from 38 to 338 s), compared with the 0 °C of temperature difference. A mathematic model has been proposed accordingly, which can explain well the hydraulic phenomena. The inclusion removal rates of different cases were compared by mathematical simulation, and their removal mechanism was studied, as well.