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The present work discusses the evolution of microstructure and non-metallic inclusions during wire drawing process in a synthetic slag-treated 5.5 mm diameter high carbon wire rod steel. It has been observed that failure of the as-received wire rod (without synthetic slag treatment) takes place at different stages of deformation during wire drawing operation. However, in case of the synthetic slag-treated wire rods (TW specimen), failure takes place consistently at ~ 95% reduction in the cross-sectional area of the wire. In a quest to understand the failure mechanisms during wire drawing process, a systematic study has been carried out by analyzing the microstructures and non-metallic inclusions in the steel wires drawn at various stages of deformation. The improved drawability of the treated wire specimens is attributed to the decrease in the amount of unfavourable non-deformable inclusions in the steel matrix, and this stems from the synthetic slag treatment of the liquid steel. Microstructural investigation also confirms the complete realignment of pearlite colonies along the wire drawing direction followed by thinning and disintegration of cementite lamellae at higher deformation, particularly in case of the synthetic slag-treated wire rod steel. [ABSTRACT FROM AUTHOR]

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 a r e a 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. [ABSTRACT FROM AUTHOR]

Steelmaking processes require high‐performance lining materials with high refractoriness and thermal shock resistance, such as MgO–C bricks. Therefore, the interactions between three industrially fabricated MgO–C bricks differing in the used MgO grade and liquid steel are investigated by immersion tests in an Al‐deoxidized 42CrMo4 steel at 1600 °C, herein. The trials are carried out in a steel casting simulator. Macro‐ and microstructure of immersed specimens are characterized using light microscopy, scanning electron microscopy, and X‐ray diffraction, while the inclusion population in the solidified steel is analyzed using an automated feature analysis to determine the frequency, geometric characteristics, and elemental composition of the inclusions. Newly formed structures consisting mainly of MgO are observed on the immersed specimens differing in their superficial appearance and the frequency of phases assigned to the system Al2O3–CaO–MgO–SiO2 in dependence on the MgO grade. Based on the inclusion species occurring in the solidified steel, a specific rulefile is developed to classify the non‐metallic inclusions by their elemental composition. Significant differences in the frequency of detected inclusions and their distribution according to the developed rulefile depending on the MgO grade are identified by keeping the processing in the steel casting simulator constant. [ABSTRACT FROM AUTHOR]

Fasteners are widely used as machine parts, structures and mechanisms. Medium-carbon alloy steels and boron-containing alloy steels are used as materials in production. Boron-containing steels have a good combination of strength and plastic properties, as well as a high level of hardenability. This article describes the research work carried out in the laboratory, and considers the reasons for obtaining low values of physical and mechanical parameters of parts manufactured at competitive enterprises. The qualitative characteristics of the metal are determined. The results of chemical, physical-mechanical and metallographic tests, as well as the results of the chemical composition of non-metallic inclusions are presented. The reasons for the discrepancy of mechanical properties in boron-containing steels are considered. The dependence of the introduction of chemical elements into steel: nitrogen, titanium, aluminum is determined. The possibility of evaluating the content of “effective boron” at OJSC “BSW” – the Management Company of the Holding “BMC” is described. The mathematical model used at OJSC “Oskol electrometallurgical combine”, which allows to carry out a theoretical calculation of the value of “effective” boron, is described. Recommendations for improving the technological process of smelting boron-containing steels are given.

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.

Research on non-metallic inclusions is of critical importance, as they have a significant influence on the final properties of steel products. In this regard, the 3D analysis of inclusions isolated from steel samples allows for the accurate measurement of their chemical composition, without the influence of the steel matrix, and detailed insights into their morphology. Inclusions can be extracted from the steel sample matrix using extraction methods followed by their measurement with scanning electron microscopy. Extraction methods can be broadly classified into chemical and electrolytic analyses. There have been numerous studies documenting the different extraction methods for the isolation of different inclusion types in a range of steels. The focus of this paper is to briefly review their developments over a century up until the present period. The most relevant methods and the corresponding steels and observed inclusions are also summarized in a table which could be a useful reference for researchers in this field. [ABSTRACT FROM AUTHOR]

The article presents the results of numerical simulations of liquid steel flow in the main steelmaking ladle. The paper analyses the mechanism of the outflow of non-metallic Al2O3 and MnS inclusions with diameters in the range of 4–27 µm. The simulations were performed with ANSYS Fluent software. In order to determine the shape and size of non-metallic inclusions formed in the main ladle during steel refining, the collected samples of liquid metal were analysed using a scanning microscope with SEM/EDS and LM (light microscopy). Simulation tests and calculations were carried out for the case of steel refining under the conditions of the Cognor SA HSJ Department in Stalowa Wola (Poland). The presented method of using simulation tests to optimize the technology of steel refining in the ladle is an example. The analysis of the results shows that the gas flow in the metal volume has the greatest impact on the outflow of non-metallic inclusions in the steelmaking ladle. [ABSTRACT FROM AUTHOR]

Typical non-metallic inclusions in two industrial low-carbon steels for oil pipelines were investigated as three-dimensional objects on film filters after electrolytic extraction and filtration of metal samples. A method of soft chemical extraction using a 10%AA electrolyte was used to study the initial corrosion process in the steel matrix surrounding various non-metallic inclusions. To determine and compare "corrosive" inclusions and their influence on the initial stages of corrosion of the adjacent layer of the steel matrix, quantitative parameters (such as the diameter of the corrosion crater (Dcr) and pit (Dpit), and the relative dissolution coefficient of the metal matrix (KD) around various inclusions) were determined after chemical extraction. It was found that CaO-Al2O3-MgO oxides and TiN inclusions did not cause an initial corrosion of the steel matrix surrounding these inclusions. However, tensile stresses in the steel matrix occurred around CaS inclusions (or complex inclusions containing a CaS phase), which contributed to the initiation of corrosion around these inclusions. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The steel 42CrMo4 with improved machinability was studied. The steel containing high amount of sulfur was calcium treated during metallurgical production stage. The size and area distribution of non-metallic inclusions present in the studied steel was analyzed and compared to the conventional Cr–Mn–Mo steels with low sulfur and calcium content. The dilatometric investigation was performed to reveal the features of the austenite transformations in studied Cr–Mn–Mo steels with various content of alloying elements. The mechanical properties of the high and low sulfur steels were analyzed in heat treated condition (oil quenching and tempering). The results proved that calcium treated 42CrMo4 steel with high sulfur content possessed almost the same characteristics of hardenability and mechanical behavior as the conventional low-sulfur steels. This implies that the steel with improved machinability can be successfully applied for the production of the heavy duty and high strength parts using automated lines and machines. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Non-metallic inclusions have become a matter of concern for several properties of steel. The effective evaluation of inclusions in steel would provide critical information to evaluate the steel quality. In this study, an evaluation method based on X-ray Micro-Computed Tomography (Micro-CT) experiments was proposed. First, Micro-CT experiments were carried out to characterize the inclusions. Then, the characterizations of the inclusions were collected based on the 2D slices and their 3D features. The extreme values were evaluated by statistics of extreme values method with these data. The evaluation results were compared with those obtained by international standard ASTM E2283-08. The results demonstrated that the evaluation method based on inclusion sizes collected from 3D inclusion information provided a stable result. It means that the extreme value evaluation method with the 3D data based on Micro-CT was an effective method. [ABSTRACT FROM AUTHOR]

The labor protection requirements for the smelting process of aluminum alloys and the human safety condition are provided in this work. Also it includes the metallographic analysis results of aluminum-titanium alloys. ThixometPro software was used for analysis’ performance and Thermo-Calc program used for the phase diagrams drawing of triple systems.

The quality of carbon steels working at variable loads mainly depend of microstructure, but also of impurities. The quantity and morphology of non-metallic inclusions and spaces between impurities are correlated with the content of admixtures in the alloy, while their phase composition and structure, in particular shape, dimensions and dispersion, are determined by the course of metallurgical processes. Non-metallic inclusions as impurities found in steel can affect its performance characteristics. Their impact depends not only on their quality, but also, among others, on their size and distribution in the steel volume. The literature mainly describes the results of tests on hard steels. The article discusses the results of a study investigating the effect of the number of large non-metallic inclusions (over 10 μm in size) on the fatigue strength of structural steel during rotary bending. The study was performed on 6 heats produced in an industrial plant. Fourteen heats were produced in 140 ton electric furnaces. All heats were desulfurized and refined with argon. The experimental variants were compared in view of the tempering the research steel. The fatigue strength of steel with an impurity spaces was determined during rotary bending: the results revealed that fatigue strength is determined by the impurity spaces and tempering temperature.

The results of studies of the reasons for the blistering (blisters) formation after testing the rolled products and pipes made of 13KhFA and 05KhGB steels for resistance to hydrogen-induced cracking and sulfide stress cracking (SSC) have been presented. It has been found that swelling on the surface of samples after the corrosion tests, which can be characterized as blisters, are caused by the presence of cracks both in the axial zone of rolled products and outside it. As a rule, the occurrence of these cracks is associated with the presence of non-metallic inclusions with a complex composition and with the microstructural features of rolled products. Based on the studies of the nature of blister formation, the classification of these surface defects was carried out. [ABSTRACT FROM AUTHOR]

In steel foundries, ceramic filters are often used to capture non-metallic inclusions. It is well documented that solid inclusions are captured and retained within the filter macropores at the metal-refractory interface. However, liquid inclusions appear to be captured and retained by two mechanisms: one within the filter web micropore structure and another as a liquid film at the metal-filter macropore interface. Experiments were carried out to study the removal of various non-metallic liquid inclusions by magnesia-stabilized zirconia filters. The results documented the effective removal of liquid inclusions in all experiments. Samples were extracted from filter element to investigate the inclusion attachment mechanism during deep bed filtration. Energy-dispersive X-ray spectroscopy and associated scanning electron microscopy was employed to evaluate the inclusion attachment mechanism with the ceramic filters. Liquid inclusion retention in the filter micropores followed an exponential trend from entry to exit side of the filter, until the micropores became completely saturated. After complete saturation, the retained inclusion distribution remained constant through the thickness of the filter. Filters were found to capture the liquid inclusions, drawing them into the open micropores due to inclusion-refractory favorable wetting conditions. Once the accessible micropores were fully saturated, liquid inclusion films developed at the metal-filter macropore interface, increasing the possibility for the release of large liquid inclusions from the filter. [ABSTRACT FROM AUTHOR]

There is a large number of investigations on the impact of distribution of non-metallic inclusions in the weld metal on its structure and mechanical properties. However, the authors of these works do not describe the kinetics of forming such a distribution. The results of the development of a distribution model in the weld metal of non-metallic inclusions by sizes are presented. Formation of the calculation part of the model is based on the processing of experimental data on the sizes of nonmetallic inclusions in the metal of welds, deposited by the methods of submerged welding in the medium of shielding gas. Generalization and analysis of experimental data showed that the final distribution of inclusions in the metal of the studied welds is submitted to the law of gamma distribution (probability is > 95%). To describe the evolution of the distribution of non-metallic inclusions during weld formation, the authors proposed to apply a probabilistic model in the form of gamma-distribution with time-dependent parameters. [ABSTRACT FROM AUTHOR]

There is a large number of investigations on the impact of distribution of non-metallic inclusions in the weld metal on its structure and mechanical properties. However, the authors of these works do not describe the kinetics of forming such a distribution. The results of the development of a distribution model in the weld metal of non-metallic inclusions by sizes are presented. Formation of the calculation part of the model is based on the processing of experimental data on the sizes of non-metallic inclusions in the metal of welds, deposited by the methods of submerged arc welding and in shielding gas. Generalization and analysis of experimental data showed that the final distribution of inclusions in the metal of the studied welds is submitted to the law of gamma-distribution (probability is > 95 %). To describe the evolution of the distribution of non-metallic inclusions during weld formation, the authors proposed to apply a probabilistic model in the form of gamma-distribution with time-dependent parameters. [ABSTRACT FROM AUTHOR]

The parameters of high-grade steel are influenced by a combination of factors, including chemical composition and production technology. The impurity content is also a key determinant of the quality of high-grade steel. Inclusions may also play an important role, subject to their type and shape. Inclusions may increase the strength of steel by inhibiting the development of micro-cracks. The analyzed material was one grade of medium-carbon structural steel. The study was performed on 6 heats produced in an industrial plant in 140 ton electric furnaces. The experimental variants were compared in view of the five heat treatment options. The results were presented to account for the correlations between the fatigue strength coefficient during rotary bending, the diameter of and spacing between impurities. The relationship between the fatigue strength and hardness of high-grade steel vs. the quotient of the diameter of impurities and the spacing between impurities was determined. The proposed equations contribute to the existing knowledge base of practices impact of impurities with various diameters and spacing between non-metallic inclusion on fatigue strength.

The article contains the results of research performed on the determination of the quantity and morphology of nonmetallic inclusions identified at the secondary metallurgy process during the cold-swelling steel production. Continuous improvement of steel quality standards, which today is primarily associated with the amount of inclusions contained in the steel product, enforces actions taken to remove the largest possible number of inclusions from steel and/or by their modification at the final stage of secondary metallurgy processing. Therefore, research was undertaken at the ladle furnace industrial stand, and the steel samples were subjected to metallographic testing. It was shown that the number and/or the size of inclusions identified in the samples taken at the beginning and end of the process decreased, and in addition they were modified.

Non-metallic inclusions are unavoidable defects in steel, and their type, quantity, size, and distribution have a great impact on the quality of steel. At present, non-metallic inclusions are mainly detected manually, which features high work intensity, low efficiency, proneness to misjudgment, and low consistency of results. In this paper, based on deep neural network algorithm, a small number of manually labeled, low-resolution metallographic images collected by optical microscopes are used as the dataset for intelligent boundary extraction, classification, and rating of non-metallic inclusions. The training datasets are cropped into those containing only a single non-metallic inclusion to reduce the interference of background information and improve the accuracy. To deal with the unbalanced distribution of each category of inclusions, the reweighting cross entropy loss and focal loss are respectively used as the category prediction loss and boundary prediction loss of the DeepLabv3+ semantic segmentation model. Finally, the length and width of the minimum enclosing rectangle of the segmented inclusions are measured to calculate the grade of inclusions. The resulting accuracy is 90.34% in segmentation and 90.35% in classification. As is verified, the model-based rating results are consistent with those of manual labeling. For a single sample, the detection time is reduced from 30 min to 15 s, significantly improving the detection efficiency.

The metallographic and fractographic analysis methods were used to study the influence of the cast metal quality on the causes of the destruction of a railway carriage under high dynamic and cyclic loads. As a result of study structure fracture surface of the side frame freight car truck, the detected elements indicate simultaneous presence of fatigue and static fracture. The focus of nucleation fatigue crack was a surface defect of casting origin such as a blockage. Volumes with a concentrated arrangement of gas bubbles and non-metallic inclusions of various nature was found in the individual elements of the side frame. As a result of acceleration of moving fatigue crack, there are achievements of continuous decrease of construction of strength side frame. The meeting of the fatigue crack with volumes metal with an increased concentration of gas bubbles and non-metallic inclusions accelerated the transition to the phase of static fracture. Improving the operational safety of the side frame is possible by improving the foundry technology of its manufacture and changing the regulatory documentation to limit non-metallic inclusions and pores in the metal.

Improvement of nondestructive inspection techniques has allowed more frequent detection of closely spaced zones of non-metallic inclusions in pressure vessels made of low carbon steel. In the present study, closely spaced inclusions in an in-service cylindrical horizontal pressure vessel were detected by Scan-C ultrasonic inspection and considered as laminations to be assessed by Part 13 of the API 579-1/ASME FFS-1 2016 standard. The outcoming results were considered as a rejection for Level 1 assessment, and a repair or replacement of the component was required, even though it retained a significant remaining strength. Thus, an alternative procedure to assess the mechanical integrity of pressure vessels containing zones of non-metallic inclusions is proposed by adopting some criteria of the API 579-1/ASME FFS-1 Part 13 standard procedure and taking into consideration the dimensions and grouping characteristics of the inclusion zones.

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.

Impact toughness is affected by chemical composition, defects, microstructure and ambient temperature. Higher impact toughness can prevent premature failure of the bearings. In present work, the microstructure evolution and impact toughness of high-carbon chromium bearing steels with and without rare earth (RE) addition have been investigated after cold rolling, quenching and tempering (QT) treatment. The results show that the addition of RE elements converts irregular MnS, TiN and Al2O3 inclusions with an average size of 9.02 μm into RE inclusions with an average size of 3.76 μm. As a consequence, the impact toughness of specimens with RE is 2.2 times that of without RE. When the cold rolling is applied, since the prior cold rolling can refine the prior austenite grain and increase the residual austenite after QT treatment, the impact toughness also exhibits a significant enhancement from 6.4 to 15.9 J. In addition, for the RE-GCr15 subjected to cold rolling process, the impact toughness can be further increased. This should be attributed to that the refined RE inclusions with good roundness reduce the crack initiation caused by cold rolling, so as to maximize the advantages of cold rolling. The results obtained in this work suggest a good prospect to combine cold rolling process with bearing steel with RE addition. [ABSTRACT FROM AUTHOR]

Analysis of the existing trends in development of technologies for production of welding and surfacing fluxes showed that one of the actively developing areas is the production of fluxes using man-made waste (including metallurgical one) as components of the initial charge. This is due to the fact that the slag waste of metallurgical production contains a large amount of manganese and silicon, which in turn are the basis in welding fluxes. Within the framework of this direction development, the article describes principal possibility and efficiency of using materials based on ladle electric steelmaking slag from JSC "EVRAZ United West Siberian Metallurgical Combine" and slag produced by silicomanganese from LLC "West Siberian Electrometallurgical Plant" in the charge for production of fluxes used in the surfacing of rolling rolls. All the laboratory tests were made using the equipment of the scientific and production center "Welding Processes and Technologies". For surfacing steel samples, the authors used a flux additive obtained by mixing ladle electric steelmaking slag of a fraction less than 0.2 mm with liquid sodium glass in a ratio of 62 and 38%. The resulting flux additive was mixed with slag from the production of silicomanganese of a fraction of 0.45–2.50 mm in various ratios. Chemical composition studies (by the spectral method) and metallographic studies of the deposited layer revealed a tendency to an increase in sulfur content and in contamination with non-metallic inclusions in it with an increase in content of the flux additive in the charge of more than 20%. According to the results of visual quality control of the deposited layer macrostructure, the absence of defects was established with a flux additive content of up to 30%. [ABSTRACT FROM AUTHOR]

The effects of the Al2O3 content and basicity of CaO–SiO2–Al2O3–10 wt.% MgO refining slag on inclusions removal in 55SiCr spring steel were investigated. The viscosity of slag was studied using a viscometer, while the microstructure investigation involved using a water-quenching furnace and a Fourier-transform infrared spectrometer. The influence mechanism of the slag adjustment on inclusions was explored through thermodynamic calculations and kinetic analysis. The results indicated that the viscosity of the molten slag increased gradually with the content of Al2O3 increasing due to it increasing the degree of polymerization of the slag network structure, especially the [AlO4]5− and [Si-O-Si] structures. In contrast, the viscosity of molten slag experienced the opposite pattern, with the basicity of molten slag increasing. This was due to the fact that Ca2+ can significantly reduce the degree of polymerization of a slag network structure, especially the percentages of the [SiO4]4−, [AlO4]5− and [Si-O-Si] network structures. Finally, the changes in physical properties and structure of slag significantly affected the removal effect of the inclusions in molten steel. As a result, the number, size distribution, composition distribution and morphology of the inclusions displayed significant changes when the content of Al2O3 increased from 3 wt.% to 12 wt.% and the basicity of the slag gradually increased from 0.5 to 1.2.

Non-metallic inclusions are one of the many factors influencing the strength of materials operating under variable loads. Their influence on the strength of the material depends not only on the morphology of the impurities themselves, but it is also closely related to the microstructure of the material. This microstructure is the matrix for non-metallic inclusions. This article discusses the results of a study investigating the effect of non-metallic inclusions on the fatigue strength of structural steel during rotary bending. The study was performed at 12 heats produced in an industrial plant’s 140-ton electric furnaces. Six heats were desulphurised, and six were refined with argon. This paper presents the bending fatigue strength of steel hardened and tempered at different temperatures, subject to the relative volume of inclusions. This paper also presents the dimensional structure of non-metallic inclusions divided by different two technologies. The research shows that the main fraction of non-metallic inclusions is Al2O3; the most numerous were impurities with a diameter of less than 2 µm; argon refining does not affect the proportion of non-metallic inclusions of large dimensions (with a diameter of over 15 µm); the influence of non-metallic inclusions on the strength of the steel is also related to the microstructure of the steel constituting the matrix of inclusions.

Non-metallic inclusions are unavoidably produced during steel casting resulting in lower mechanical strength and other detrimental effects. This study was aimed at developing a machine learning algorithm to classify castings of steel for tire reinforcement depending on the number and properties of inclusions, experimentally determined. 855 observations were available for training, validation and testing the algorithms, obtained from the quality control of the steel. 140 parameters are monitored during fabrication, which are the features of the analysis; the output is 1 or 0 depending on whether the casting is rejected or not. The following algorithms have been employed: Logistic Regression, K-Nearest Neighbors, Support Vector Classifier (linear and RBF kernels), Random Forests, AdaBoost, Gradient Boosting and Artificial Neural Networks. The reduced value of the rejection rate implies that classification must be carried out on an imbalanced dataset. Resampling methods and specific scores for imbalanced datasets (recall, precision and AUC rather than accuracy) were used. Random Forest was the most successful algorithm providing an AUC in the test set of 0.85. No significant improvements were detected after resampling. The optimized Random Forest allows the samples with a higher probability of being rejected to be selected, thus improving the effectiveness of the quality control. In addition, the optimized Random Forest has enabled to identify the most important features, which have been satisfactorily interpreted on a metallurgical basis. [ABSTRACT FROM AUTHOR]

The labor protection requirements for the smelting process of aluminum alloys and the human safety condition are provided in this work. Also it includes the metallographic analysis results of aluminum-titanium alloys. ThixometPro software was used for analysis’ performance and Thermo-Calc program used for the phase diagrams drawing of triple systems. [ABSTRACT FROM AUTHOR]

The influence of Ca-containing additional alloy on the composition and contamination of steel 26KhMFBA with non-metallic inclusions during secondary refining and continuous casting is investigated. It is shown that the use of the SK30wire silicocalcium alloy after degassing leads to the inoculation of refractory aluminate inclusions and, as a consequence, to a decrease in the total inclusions rating. The presence of low-melting inclusions is more preferable, since this type of inclusions is not deposited on the pouring nozzle walls and does not adversely affect the contamination of the continuously cast billet and products obtained from it. [ABSTRACT FROM AUTHOR]

In this work, the authors proposed a modification of the working space one-strand tundish adapted for slab casting process. Numerical simulations of liquid steel flow in the considered flow reactor were performed. The tundish is equipped with a dam with a multi-hole filter. Two variants of the filter hole arrangement were tested and their effect on the liquid steel flow hydrodynamic structure in the tundish was examined. The computer calculations results were verified by performing experiments on the water model. The result of numerical and physical simulations an RTD (Residence Time Distribution) type F curve was generated, which define the transition zone between the cast steel grades during the sequential casting process. The results of the researches showed that the modification of a dam with a multi-hole filter affects on the formation of the liquid steel flow hydrodynamic structure and the transition zone. Furthermore, examinations of the liquid steel refining ability in the considered tundish were carried out. The influence of the filter holes arrangement on the non-metallic inclusions flotation process to the slag phase and liquid steel filtration processes was checked. Numerical simulations were performed in the Ansys-Fluent computer program.

The article describes the prerequisites of filtration refining of metal melts. When filtering the liquid metals the refining effect is caused by the deposition on the filter surface of suspended non-metallic particles in the melt, and by the release of the non-metallic phase directly from the melt. Along with this the mechanism of melt refining from a superequilibrium dissolved impurity is realized when filtering as a result of the reaction course of chemical binding of the impurity element.

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.

The article discusses the results of a study investigating the effect of the number of fine non-metallic inclusions (up to 2 μm in size) on the fatigue strength of structural steel during rotary bending. The study was performed on 7 heats produced in an industrial plant. Fourteen heats were produced in a 100 ton oxygen converter. All heats were subjected to vacuum circulation degassing.

The goal of this research is to study the reasons for the formation of rigid non-metallic inclusions in rail steel and ways to reduce the rejection of finished rails for defects in ultrasonic testing. The research was carried out at the arc-furnace plant of JSC Ural Steel. The central plant laboratory carried out a chemical analysis of non-metallic inclusions in the specimens of finished rails, rejected by ultrasonic inspection during the rail production by Aktobe Rail and Structural Steel Plant, LLC from a billet produced by Ural Steel. In terms of composition, non-metallic inclusions are represented by aluminum oxides. The most probable reasons for the presence of non-metallic inclusions are determined as a result of ferroalloys containing aluminum in their composition, or the interaction of melt components with refractories and a mold powder. The analysis of ferroalloys used in the production of rail steel is carried out. Industrial testing of the continuous rail steel casting technology is carried out with the replacement of FS65 ferrosilicon, which contains aluminum with silicon carbide. An increase in the degree of silicon and carbon recovery is noted in experimental smeltings. The assessment of contamination with non-metallic inclusions and mechanical properties of the rail steel obtained by the experimental technology shows that the service characteristics of the rail steel metal comply with the requirements of GOST R 51685–2013. The full-scale experiment has confirmed that the technology of alloying E76F rail steel with silicon carbide under conditions of Ural Steel is technically feasible. A 17% increase in the yield of useful 100-meter rails was obtained for a pilot batch of metal, produced from Ural Steel's contcast steel billets. [ABSTRACT FROM AUTHOR]

Defects of low-carbon engineering steels 18Kh2N4MA, 25Kh2N4MA, 25G2S2N2MA reducing the operating life of components are studied. The most common metallurgical processing defects are: non-metallic inclusions, structural banding, internal cracks and pores. It is established that inclusion of titanium carbonitride significantly reduces the operating life of heavily loaded components. Defects formed during component heat and chemical heat treatment are also considered. [ABSTRACT FROM AUTHOR]

Based on the study results, it is shown that the selected ingot geometry makes it possible to obtain a solidified metal structure with a favorable distribution of physical and chemical heterogeneities of the cast metal. The temperature profile calculations have shown that 1 h 45 min after the onset of solidification of a big-end-down ingot, the advancing crystallization front closes, and an extended "closed" zone of liquid metal is formed, the height of which reaches 37% of the height of the ingot body. The provided data correlated well with the actual shrinkage defects, the length of which constituted 36% of the height of the ingot body. The comparison of the temperature distribution profiles with the assessment of steel contamination with non-metallic inclusions and specifics of segregating impurity distribution has revealed a more uniform distribution of impurities and nonmetallic inclusions due to intensive advancement of the solid phase under the hot-top part of the ingot. In this case, the optimized thermal performance of the hot top helps move segregating impurities and tertiary inclusions to the ingot head. The assessment of applicability of the big-end-up and big-end-down ingots has demonstrated the feasibility of using the former to produce round rolled products with a diameter in excess of 250 mm. The big-end-down ingot weighing 5.9 ton is feasible to use for the production of rolled products having a diameter not exceeding 200 mm due to the formation of a closed secondary pipe cavity. The use of a low hot-top height big-end-down ingot allows increasing the yield of the usable metal, while improving the quality of the rolled products. [ABSTRACT FROM AUTHOR]

Using correlation-regression analysis, the effects of structure and chemical composition on KCV impact strength anisotropy and difference in critical brittleness temperatures for longitudinal and transverse specimens of ferrite-pearlite and high-strength (ferrite + bainite) steels after thermomechanical rolling are studied. The significant effect of pearlite content and sulfide inclusions on impact strength anisotropy and difference in critical brittleness temperatures for longitudinal and transverse specimens of ferrite-pearlite steels is demonstrated. For high strength ferrite-bainite steels prepared using thermomechanical rolling technology the effect of carbon and sulfur on degree of embrittlement for transverse specimens is considered that also depends on the content of titanium carbonitride and Al2O3-based aluminum oxides. [ABSTRACT FROM AUTHOR]

The object of the research is KP-2 wheel steel modified by the Al-Mg-Si-Fe-C-Ca-Ti-Ce system. One of the most problematic places in the smelting of modern steel is the stability of the chemical composition due to the use of uncontrolled content of scrap, charge and standard modifiers, which are made by the fused method. To eliminate this problem, multifunctional modifiers were used during the study. This is due to the fact that the KP-2 steel modification method proposed in this article, has a number of features. In this case, the influence modifiers of multifunctional action on the installation of vacuum processing of steel on desulfurization of wheel steel KP-2, obtained under the conditions of the open joint-stock company Interpipe NTRP (Dnipro, Ukraine), was established. In particular, when treating a steel melt with multifunctional modifiers, not only a refining effect occurs, but also an increase in the stability of the chemical composition and level of mechanical characteristics of the KP-2 wheel steel. This is confirmed by the coefficients of variation and interfusion difference presented in the article (span), obtained by statistical processing of a large data set – 442 serial smeltings and 1 modified (6 wheels). Thanks to the multifunctional modification, the level of mechanical characteristics and the quality of the finished wheels really increases. Compared with similar mass-produced materials, such as FeSi, FeCa, FeMn, SiCa, the use of new multifunctional modifiers in KP-2 wheel steel provides a significant reduction in the mass fraction of sulfur than in the same metal that is processed in the traditional way. It has been established that the use of multifunctional modifiers changes the shape of non-metallic inclusions to globular and reduces their number, which also increases the level of mechanical properties of KP-2 wheel steel. The obtained coefficients of variation prove that the mechanical characteristics of KP-2 modified steel are more stable than in serial melts of the same steel. This will increase the demand and quality of these railway wheels. [ABSTRACT FROM AUTHOR]

Research on non-metallic inclusions is of critical importance, as they have a significant influence on the final properties of steel products. In this regard, the 3D analysis of inclusions isolated from steel samples allows for the accurate measurement of their chemical composition, without the influence of the steel matrix, and detailed insights into their morphology. Inclusions can be extracted from the steel sample matrix using extraction methods followed by their measurement with scanning electron microscopy. Extraction methods can be broadly classified into chemical and electrolytic analyses. There have been numerous studies documenting the different extraction methods for the isolation of different inclusion types in a range of steels. The focus of this paper is to briefly review their developments over a century up until the present period. The most relevant methods and the corresponding steels and observed inclusions are also summarized in a table which could be a useful reference for researchers in this field.

The article presents the results of numerical simulations of liquid steel flow in the main steelmaking ladle. The paper analyses the mechanism of the outflow of non-metallic Al2O3 and MnS inclusions with diameters in the range of 4–27 µm. The simulations were performed with ANSYS Fluent software. In order to determine the shape and size of non-metallic inclusions formed in the main ladle during steel refining, the collected samples of liquid metal were analysed using a scanning microscope with SEM/EDS and LM (light microscopy). Simulation tests and calculations were carried out for the case of steel refining under the conditions of the Cognor SA HSJ Department in Stalowa Wola (Poland). The presented method of using simulation tests to optimize the technology of steel refining in the ladle is an example. The analysis of the results shows that the gas flow in the metal volume has the greatest impact on the outflow of non-metallic inclusions in the steelmaking ladle.

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.