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  • 1.
    Al-Saadi, Munir
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Sandberg, Fredrik
    Karasev, Andrey
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Jonsson, Stefan
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Microstructure characterisation in alloy 8252018Conference paper (Refereed)
  • 2.
    Al-Saadi, Munir
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Karasev, Andrey
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Sandberg, Fredrik
    Comparative Study of Microstructures Evolution of Columnar and Equiaxed Grain Structurs in Alloy 825 after Hot Compression2018In: 3rd InternationalConference on Ingot Casting, Rolling and Forging, ICRF2018, in Stockholm, 16-19October, 2018, article id 114Conference paper (Refereed)
  • 3.
    Al-Saadi, Munir
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing. R&D, AB Sandvik Materials Technology, SE-811 81Sandviken, Sweden..
    Sandberg, Fredrik
    R&D, AB Sandvik Materials Technology, SE-811 81Sandviken, Sweden..
    Hulme-Smith, Christopher
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Karasev, Andrey
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    A study of the static recrystallization behaviour of cast Alloy 825 after hot-compressions2019In: Journal of Physics: Conference Series, 2019, Vol. 1270Conference paper (Refereed)
    Abstract [en]

    The static recrystallization behaviour of a columnar and equiaxed Alloy 825 material was studied on a Gleeble-3800 thermo-simulator by single-hit compression experiments. Deformation temperatures of 1000-1200 °C, a strain of up to 0.8, a strain rate of 1s-1, and relaxation times of 30, 180, and 300 s were selected as the deformation conditions to investigate the effects of the deformation parameters on the SRX behaviour. Furthermore, the influences of the initial grain structures on the SRX behaviors were studied. The microstructural evolution was studied using optical microscopy and EBSD. The EBSD measurements showed a relaxation time of 95 % for fractional recrystallization grains, 𝑡95, in both structures, was less than 30 seconds at the deformation temperatures 1100 °C and 1200 °C. However, fewer than 95% of recrystallized grains recrystallized when the deformation temperature was lowered to 1000 °C. From the grain-boundary misorientation distribution in statically recrystallized samples, the fraction of high-angle grain boundaries decreased with an increasing deformation temperature from 1000 °C to 1200 °C for a given relaxation time. This was attributed to grain coarsening

  • 4.
    De Colle, Mattia
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Karasev, Andrey
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Gauffin, Alicia
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Renman, Agnieszka
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Water and Environmental Engineering.
    Renman, Gunno
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Water and Environmental Engineering.
    The Use of High-Alloyed EAF Slag for the Neutralization of On-Site Produced Acidic Wastewater: The First Step Towards a Zero-Waste Stainless-Steel Production Process2019In: Applied Sciences, ISSN 2076-3417, Vol. 9Article in journal (Refereed)
    Abstract [en]

    Recycling of steelmaking slags has well-established applications, such as their use in cement, asphalt, or fertilizer industries. Although in some cases, such as the electric arc furnace (EAF) high-alloyed stainless-steel production, the slag’s high metal content prevents its use in such applications. This forces companies to accumulate it as waste. Using concepts such dematerialization, waste management, industrial symbiosis, and circular economy, the article drafts a conceptual framework on the best route to solving the landfilling issue, aiming at a zero-waste process re-design. An experimental part follows, with an investigation of the use of landfill slag as a substitute of limestone for the neutralization of acidic wastewater, produced by the rinsing of steel after the pickling process. Neutralization of acidic wastewater with both lime and slag samples was performed with two different methods. Two out of four slag samples tested proved their possible use, reaching desired pH values compared to lime neutralizations. Moreover, the clean waters resulting from the neutralizations with the use of both lime and slag were tested. In terms of hazardous element concentrations, neutralization with slag yielded similar results to lime. The results of these trials show that slag is a potential substitute of lime for the neutralization of acidic wastewater.

  • 5.
    Du, Hongying
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Karasev, Andrey
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Sundqvist, Olle
    Sandv Mat Technol AB, S-81181 Sandviken, Sweden..
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Modification of Non-Metallic Inclusions in Stainless Steel by Addition of CaSi2019In: METALS, ISSN 2075-4701, Vol. 9, no 1, article id 74Article in journal (Refereed)
    Abstract [en]

    The focus of this study involved comparative investigations of non-metallic inclusions in 316L stainless steel bars without and with Ca treatments. The inclusions were extracted by using electrolytic extraction (EE). After that, the characteristics of the inclusions, such as morphology, size, number, and composition, were investigated by using a scanning electron microscope (SEM) in combination with an energy dispersive X-ray spectroscopy (EDS). The following four types of inclusions were observed in 316L steels: (1) Elongated MnS (Type I), (2) MnS with hard oxide cores (Type II), (3) Undeformed irregular oxides (Type III), and (4) Elongated oxides with a hard oxide core (Type IV). In the reference sample, only a small amount of the Type III oxides (Al2O3-MgO-MnO-TiOx) existed. However, in Ca-treated 316L steel, about 46% of the observed inclusions were oxide inclusions (Types III and IV) correlated to gehlenite and to a mixture of gehlenite and anorthite, which are favorable for the machinability of steel. Furthermore, untransformed oxide cores (Al2O3-MgO-MnO) were also found in the inclusions of Type IV. The mechanism leading to different morphologies of oxide inclusions is also discussed.

  • 6. Gorkusha, D. V.
    et al.
    Grigorovich, K. V.
    Karasev, Andrey
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Komolova, O. A.
    Content modification of different types of nonmetallic inclusions during low-carbon if steel ladle treatment2019In: Izvestiya Ferrous Metallurgy, ISSN 0368-0797, Vol. 62, no 5, p. 345-352Article in journal (Refereed)
    Abstract [en]

    Development of advanced materials for the automotive industry allows us to produce a lighter body without losing strength characteristics of the structure. It became possible by the creation and subsequent introduction into the production of such steel grades as IF (Interstitial Free)-steel with no interstitial solute atoms to strain the solid iron lattice and IF-BH (Bake Hardening)-steel with hardening during hot drying. The article provides a brief overview of the history of the emergence of IF steel and the current situation in the production of it in Russia. One of the quality criteria for steels of IF grades is purity of the metal by non-metallic inclusions (NMI), which negatively affect the plastic properties of the material, lead to the formation of surface defects of flat rolled products and reduce the manufacturability due to a decrease in the casting speed of steel, as they cause overgrowing of steel casting nozzles. The article presents investigation results of the content, composition, size and morphology of non-metallic inclusions (NMI) in the metal samples taken at all stages of ladle treatment and casting of IF steel grade production using quantitative metallographic analysis, electrochemical dissolution (ED) followed by X-ray microanalysis of isolated inclusions, Auger electron spectroscopy and fractional gas analysis (FGA). As a result of the analysis of inclusions in the studied samples using a scanning electron microscope, according to morphological features, five characteristic types of inclusions were identified, which reduce the performance properties and strength characteristics of the materials produced from them. Results of the analysis of nonmetallic inclusions in metal samples obtained by the ED method are in good agreement with the results of the determination of oxide nonmetallic inclusions by the FGA method. The method of fractional gas analysis shows the dynamics of changes in the content of various types of oxide nonmetallic inclusions during the secondary (ladle) treatment of steel. It is shown that application of the FGA me­ thod allows to make analysis of causes of the harmful NMI formation in the metal and to correct operations at ladle treatment.

  • 7.
    Jarnerud, Tova
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Technology.
    Karasev, Andrey
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Jönsson, Pär G.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Briquetting of wastes from pulp and paper industries by using AOD converter slag as binders for application in metallurgy2019In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 12, no 18, article id 2888Article in journal (Refereed)
    Abstract [en]

    A number of carbon-rich (containing up to 47 wt% C) and lime-rich (containing up to 96 wt% of CaO-compounds) waste products from the pulp and paper industries can be used in iron and steel industry as fuels and slag formers for various metallurgical processes such as blast furnaces (BF), cupola furnaces (CF), argon oxygen decarburization (AOD) converters and electric arc furnaces (EAF). In most cases, these wastes consist of different size powders. In order to facilitate loading, transportation and charging of these powder wastes, briquetting is required. In this study, a pulverized AOD slag was tested as a binder component for briquetting of CaO-containing wastes (such as mesa, lime mud and fly ash) from pulp and paper industries. Moreover, mechanical testing of the possibilities for loading, transportation and unloading operations were done, specifically drop test trials were done for briquettes with different chemical compositions and treatments such as heating and storage. The results showed that an addition of 10-20% of AOD slag as a binder component followed by heat-treatment at 850 °C significantly improved the mechanical properties of the CaO-containing briquettes. An application of these briquettes will significantly reduce the consumption of natural resources (such as nature lime) in the metallurgical processes. Moreover, it can reduce the landfill area of wastes from pulp and paper industries, which is important from an environmental point-of-view.

  • 8.
    Kellner, Hans E. O.
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. Dalarna University, Sweden.
    Karasev, Andrey
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Sundqvist, Olle
    Memarpour, Arashk
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Estimation of Non-Metallic Inclusions in Industrial Ni Based Alloys 8252017In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 88, no 4, article id UNSP 1600024Article in journal (Refereed)
    Abstract [en]

    It is well known that inclusions affect the properties of the steel and other alloys. The importance of understanding the behavior of the inclusions during production can never be overstated. This study has examined the main types of big size (> 10 mu m) inclusions that exist in Ni-based Alloy at the end of ladle treatment and after casting during industrial production of Ni based Alloys 825. Sources, mechanisms of formation and behavior of different type large size inclusions in Alloy 825 are discussed based on 2 and 3D investigations of inclusion characteristics (such as, morphology, composition, size, and number) and thermodynamic considerations. The large size inclusions found can be divided in spherical (Type I and II) inclusions and in clusters (Type III-V). Type I-A inclusions (Al2O3-CaO-MgO) originate from the slag. Type I-B inclusions and Type II inclusions consist of CaO-Al2O3-MgO and Al2O3-TiO2-CaO, respectively. Both types originate from the FeTi70R alloy. Type III clusters (Al2O3-MgO-CaO) are formed during an Al deoxidation of the Ni-based alloy. Type IV clusters (Al2O3-TiO2-CaO) formed from small inclusions, which are precipitated in local zones which contain high Ti and Al levels. These clusters are transformed to Type III clusters over time in the ladle. Finally, Type V clusters are typical TiN clusters.

  • 9. Nabeel, M.
    et al.
    Alba, M.
    Sun, S.
    Karasev, Andrey
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Dogan, N.
    Characterization of inclusions in high-Mn steel using two-dimensional and three-dimensional methods2018In: AISTech - Iron and Steel Technology Conference Proceedings, Association for Iron and Steel Technology, AISTECH , 2018, p. 1483-1491Conference paper (Refereed)
  • 10. Nabeel, M.
    et al.
    Alba, M.
    Sun, S.
    Karasev, Andrey
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Processing.
    Dogan, N.
    Characterization of inclusions in high-Mn steel using two-dimensional and three-dimensional methods2019In: Iron & Steel Technology, ISSN 1547-0423, Vol. 16, no 7, p. 74-82Article in journal (Refereed)
    Abstract [en]

    The characteristics of inclusions in high-manganese steel samples from laboratory-scale experiments were investigated. This was done by two-dimensional and three-dimensional methods. In the two-dimensional investigations, inclusions on polished cross-sections were observed by using automatic scanning electron microscopy analysis. For the three-dimensional investigations, inclusions collected on a film filter after electrolytic extraction were observed. It was found that electrolytic extraction could be successfully applied to high-manganese steels. Further, automatic analysis, which is a common practice in steel industry, has limitations for the detection and classification of nitride inclusions, whereas it was possible to detect nitrides using the three-dimensional method.

  • 11.
    Nabeel, Muhammad
    et al.
    McMaster Univ, 1280 Main St West, Hamilton, ON L8S 4L7, Canada..
    Alba, Michelia
    McMaster Univ, 1280 Main St West, Hamilton, ON L8S 4L7, Canada..
    Karasev, Andrey
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Jönsson, Pär G.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Dogan, Neslihan
    McMaster Univ, 1280 Main St West, Hamilton, ON L8S 4L7, Canada..
    Characterization of Inclusions in 3rd Generation Advanced High-Strength Steels2019In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 50, no 4, p. 1674-1685Article in journal (Refereed)
    Abstract [en]

    Samples taken from laboratory-produced 3rd generation advanced high-strength steels, solidified at a low cooling rate, have been investigated to study the characteristics of non-metallic inclusions. Two steels, containing 2 and 5 pct Mn content, were produced for this purpose. A higher number of total inclusions were observed in 5 pct Mn steel. The four main types of inclusions observed were Al2O3, AlN, MnS, and AlSiMn-oxide. These classes were divided into subclasses according to variations in their chemistry. The major subclasses of AlN inclusions are either plate-like or regular in shape and have different size distributions. Thermodynamic calculations suggest that plate-like AlN inclusions are formed at the initial stage of solidification, while faceted/regular-shaped inclusions are precipitated toward the end of solidification. Moreover, it was found that the size of nitride inclusions is related to their N content. This phenomenon is discussed from the viewpoint of nucleation theory.

  • 12.
    Nabeel, Muhammad
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy. KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Physical Metallurgy.
    Karasev, Andrey
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Extreme Value Distribution of clusters in REM-alloyed stainless steelsManuscript (preprint) (Other academic)
    Abstract [en]

    An extreme value distribution (EVD) analysis has been applied for three dimensional (3D) investigations of clusters observed in REM alloyed stainless steel samples. The presence of observed unit areas without any clusters has been discussed. It has been shown that an increase of the observed unit area (AO) significantly improves the correlation of EVD regression lines. Moreover, three different size parameters were considered for EVD analysis. The results show that using the maximum length of clusters (LC) results in a better correlation of EVD regression lines by improving R2 value up to 0.9876 as compared to 0.9656 – 0.9774 for other size parameters. Moreover, a comparison of predicted and observed maximum lengths of clusters showed that there is need of further work on validation of EVD analysis. 

  • 13.
    Nabeel, Muhammad
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Karasev, Andrey
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Friction forces and mechanical dust generation in an iron ore pellet bed subjected to varied applied loadsManuscript (preprint) (Other academic)
    Abstract [en]

    Iron ore pellets degrade and generate dust during transportation and handling as well as during the iron making process. This leads to material losses and effects the process efficiency in a negative manner. In order, to reduce the generation of dust it is important to understand the influence of process parameters on the dust formation. An experimental setup was used to measure the dust generation and friction forces caused by abrasion of iron ore pellets in a closed pack bed. A varied load of 1 to 3 kg was applied on the pellet bed but at a constant air flow rate to capture the airborne dust particles. It was observed that an increase of ~67% is observed in the friction and the dust generation in the bed as the applied load increased from 1 to 3 kg. Moreover, the evaluation of the particle size distribution of the generated dust showed that a higher friction in the pellet bed can lead to an increased amount of airborne particles. Moreover, it has been shown that in an air flow the morphology and the orientation of dust particles can influence the air velocity required to transport the particles upwards.   

  • 14.
    Nabeel, Muhammad
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Physical Metallurgy.
    Karasev, Andrey
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Friction Forces and Mechanical Dust Generation in an Iron Ore Pellet Bed Subjected to Varied Applied Loads2017In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 57, no 4, p. 656-664Article in journal (Refereed)
    Abstract [en]

    Iron ore pellets degrade and generate dust during transportation and handling as well as during the iron making process. This leads to material losses and effects the process efficiency in a negative manner. In order, to reduce the generation of dust it is important to understand the influence of process parameters on the dust formation. An experimental setup was used to measure the dust generation and friction forces caused by abrasion of iron ore pellets in a closed pack bed. A varied load of 1 to 3 kg was applied on the pellet bed but at a constant air flow rate to capture the airborne dust particles. It was observed that an increase of similar to 67% is observed in the friction and the dust generation in the bed as the applied load increased from 1 to 3 kg. Moreover, the evaluation of the particle size distribution of the generated dust showed that a higher friction in the pellet bed can lead to an increased amount of airborne particles. Moreover, it has been shown that in an air flow the morphology and the orientation of dust particles can influence the air velocity required to transport the particles upwards.

  • 15.
    Nabeel, Muhammad
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy. KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Physical Metallurgy.
    Karasev, Andrey
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Glaser, Bjoern
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Micro-Modelling.
    Characterization of dust generated during mechanical wear of partially reduced iron ore pelletsManuscript (preprint) (Other academic)
    Abstract [en]

    During reduction in a blast furnace (BF), the iron ore pellets undergo structural changes which facilitate dust generation due to the mechanical wear / disintegration of the pellets. The generated dust decreases the permeability and productivity of the BF process. Thus, this study investigates the mechanical wear of iron ore pellets reduced at 500 °C (P500) and 850 °C (P850) and compares the results to the wear of unreduced pellets (P25). Moreover, the dust generated during the wear experiments is also characterized. It was found that pellets reduced at 500 °C exhibit a ~ 16 to 35% higher wear rate than reference unreduced pellets. For the pellets reduced at 850 °C, the mechanical wear is inhibited by a formation of a metallic layer at the outer surface of the pellets. Further, the dust generated due to mechanical wear of reduced pellets contained 3 to 6 times higher amount of coarse particles (>20µm) as compared to the dust from unreduced pellets. The obtained results are explained on the basis of the structural changes which take place during the reduction of pellets. 

  • 16.
    Sidorova, Elena
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. Natl Univ Sci & Technol MISIS, Dept Funct Nanosyst & Hightemp Mat, Leninsky Prospect 4, Moscow 119049, Russia..
    Karasev, Andrey
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Kuznetsov, Denis
    Natl Univ Sci & Technol MISIS, Dept Funct Nanosyst & Hightemp Mat, Leninsky Prospect 4, Moscow 119049, Russia..
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Modification of Non-Metallic Inclusions in Oil-Pipeline Steels by Ca-Treatment2019In: METALS, ISSN 2075-4701, Vol. 9, no 4, article id 391Article in journal (Refereed)
    Abstract [en]

    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.

  • 17.
    Svensson, Jennie
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy. Högskolan Dalarna.
    Roos, Erik
    SSAB, Oxlösund.
    Lagerstedt, Anders
    SSAB, Oxelösund.
    Karasev, Andrey
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Brabie, Voicu
    Högskolan Dalarna, Borlänge.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Experimental Study of non-metallic inclusions behaviour in the Tundish during Continuous Casting of SteelManuscript (preprint) (Other academic)
    Abstract [en]

    The tundish has been experimentally mapped to study reactions between the molten steel and the cover powder as well as between the steel and the tundish lining. Steel samples were collected before casting, in the tundish during the casting process, and after casting. During sampling in the tundish the MISS sampler was used in order to make an in-depth study of two parallel positions of the steel/slag and steel/refractory interfaces. Thereafter, the samples were analysed with SEM in combination with EDS to determine the size and compositions of inclusions. The inclusion data were mapped in ternary phase diagrams to determine the origin of the inclusions. The results showed that two main inclusions groups, slag and deoxidation products, could be found in the samples. In addition, the samples contained inclusions that had been formed due to interactions with the refractory lining material. 

  • 18.
    Wang, Yong
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Karasev, Andrey
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Jönsson, Pär G.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    An Investigation of Non-Metallic Inclusions in Different Ferroalloys using Electrolytic Extraction2019In: Metals, ISSN 2075-4701, Vol. 9, no 6Article in journal (Refereed)
    Abstract [en]

    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.

  • 19.
    Yoshioka, Takanori
    et al.
    KTH.
    Ideguchi, Takahiro
    Karasev, Andrey
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Ohba, Yasuhide
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Study of formation behavior of CaO-Al2O3 inclusions in steel melts during an LF processManuscript (preprint) (Other academic)
    Abstract [en]

    Experiments were carried out during an LF process to investigate the formation behavior of CaO-Al2O3 inclusions in a steel melt. Samples were taken during the production of two different steel grades: a low-Al steel (Al=0.023%) and a high-Al steel (Al=1.1%). Liquid CaO-Al2O3 inclusions were detected in the low-Al steel samples. On the other hand, liquid CaO-Al2O3 inclusions were not detected in the high-Al steel samples. Instead, the inclusions consisted of MgO∙Al2O3 and Al2O3. The conditions of the LF operations, such as slag viscosities, temperatures, and gas flow rates, were almost the same in the two steel grades. This fact indicates that the detected liquid CaO-Al2O3 inclusions in the low-Al steel melt were not generated by slag entrapment, but by inclusion evolutions. In the low-Al steel, the thermodynamically stable phase of inclusion composition was calculated to be a liquid CaO-Al2O3 phase. On the other hand, the stable phase was found to be a CaO∙2Al2O3 phase in the high-Al steel. These differences in thermodynamic stable phases can influence the degree of inclusion evolution in the steel melts. However, in the high-Al steel, most inclusions have much lower CaO contents than that of the calculated phase (CaO∙2Al2O3). This large inconsistency between the detected and calculated inclusion compositions in the high-Al steel melt can be explained by two reasons: one is the low thermodynamic driving force of an Al2O3 modification and the other is the high removability of the inclusion types in the steel melt.

  • 20.
    Yoshioka, Takanori
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Ideguchi, Takahiro
    Karasev, Andrey
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Ohba, Yasuhide
    Jönsson, Pär Göran
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    The Effect of a High Al Content on the Variation of the Total Oxygen Content in the Steel Melt during a Secondary Refining Process2018In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 89, no 2, article id 1700287Article in journal (Refereed)
    Abstract [en]

    The aim of this study is to clarify the mechanism of low total oxygen (T.O) contents in high-Al containing steel grades. Steel samples are taken from a ladle during an LF-RH process, and the compositions of both the steels and inclusions are determined. According to thermodynamic considerations, the low T.O contents of high Al steel grades are due to the low insoluble oxygen contents. Due to the high Al contents in a steel melt, thermodynamic driving forces of the Al2O3 modification are lower than those in ordinary Al-killed steels. Both the low thermodynamic driving force of the Al2O3 modification and the inclusion removal from the melts contribute to the low CaO contents in inclusions in high-Al steel melts. The contact angles of inclusions in high Al steel melts are higher than 90 degrees due to the low CaO content in inclusions. Therefore, the removal tendency of inclusions in high Al steel melts is kept high throughout an LF-RH process. Due to this high removal tendency, the T.O contents in high Al steel melts decreases remarkably during an LF refining process. Thereafter, they decrease further during the following RH treatment.

  • 21.
    Yoshioka, Takanori
    et al.
    KTH.
    Shimamura, Yuta
    Karasev, Andrey
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Ohba, Yasuhide
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Mechanism of a CaS Formation in an Al-Killed High-S Containing Steel during a Secondary Refining Process without a Ca-Treatment2017In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 88, no 10, article id UNSP 1700147Article in journal (Refereed)
1 - 21 of 21
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