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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.
    Bi, Yanyan
    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, Applied Process Metallurgy.
    Jönsson, Pär G.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Investigations of inclusions in ferrochromium alloys2014In: Ironmaking & steelmaking, ISSN 0301-9233, E-ISSN 1743-2812, Vol. 41, no 10, p. 756-762Article in journal (Refereed)
    Abstract [en]

    Ferrochromium alloys are commonly added during different stages of steelmaking processes according to the specific steel grade being produced. Depending upon the ferrochromium quality, the addition can also lead to a supply of deleterious inclusions to the liquid steel. Therefore, the number, size, morphology and composition of inclusions in LCFeCr and HCFeCr alloys were investigated. The alloy samples were first treated with electrolytic extraction, followed by filtration to gather the inclusions on a film filter. Thereafter, the characteristics of the inclusions and clusters were investigated in three dimensions by SEM in combination with energy dispersive spectroscopy. The results show that the main inclusion types found in LCFeCr alloys are different to those found in HCFeCr alloys. More specifically, the inclusions in LCFeCr alloys were found to consist of Si-Cr-O and Cr-O oxides as well as intermetallic Cr-Fe inclusions. Moreover, the inclusions in HCFeCr alloys were found to consist of Cr-Mn-S, Cr-C-N, Si-Al-Ca-Mg-O and Ca-O-P inclusions. Overall, the inclusions can be divided into two categories depending on the melting point. Furthermore, the possible transformation of different inclusions after their addition to the liquid steel is discussed.

  • 4.
    Bi, Yanyan
    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, Applied Process Metallurgy.
    Jönsson, Pär G.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Three Dimensional Evaluations of REM Clusters in Stainless Steel2014In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 54, no 6, p. 1266-1273Article in journal (Refereed)
    Abstract [en]

    It is known that clusters in liquid steel have a harmful effect on the casting process and the quality of the final steel product. In this study, clusters. of rare earth metals (REM) were investigated in steel samples of a S30185 stainless steel grade from a pilot trial (PT, 250 kg) and from an industrial heat (IH, 100 t). Samples were taken from the liquid steel at different holding times after the addition of mischmetal. Thereafter, REM clusters collected on film filters after electrolytic extraction and filtration were investigated in three dimensions (3D) by SEM in combination with EDS. The morphology, composition, number and size of clusters in PT and IH steel samples were analyzed and compared as a function of holding time. It was found that typical clusters with regular and irregular inclusions were the main type of clusters (69%-98%) in all PT and IH steel samples. The composition of inclusions in clusters corresponded mostly to REM-oxides. The size of clusters that were observed in different samples varied mainly from 2 to 23 mu m. In addition, the size and number of most clusters in PT are larger than those in IH samples. Furthermore, the formation mechanisms and evolution of different type of REM clusters were discussed in both PT and IH heats.

  • 5.
    Bi, Yanyan
    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, Applied Process Metallurgy.
    Jönsson, Pär G.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Three-dimensional investigations of inclusions in ferroalloys2014In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 85, no 4, p. 659-669Article in journal (Refereed)
    Abstract [en]

    As the requirements on material properties increase, there has been a demand on an additional knowledge on the effect of impurities in the ferroalloys on the properties. Thus, the number, morphology, size, and composition of inclusions in four different ferroalloys (FeTi, FeNb, FeSi, and SiMn) were investigated. This was done in three dimensions (3D) by using scanning electron microscopy in combination with energy dispersive spectroscopy after electrolytic extraction of the ferroalloy samples. The non-metallic and metallic inclusions were successfully analyzed on the surface of film filter. Thereafter, the particle size distribution was plotted for most of the non-metallic inclusions. The non-metallic inclusions were found to be REM oxides in FeTi, FeSi, and SiMn, Al2O3, Ti-Nb-S-O oxides in FeNb and silicon oxides in SiMn. Moreover, the intermetallic inclusions were found to be a Ti-Fe phase in FeTi, Ca-Si, and Fe-Si-Ti phases in FeSi and a Mn-Si phase in SiMn. In addition, the almost pure single metallic phases were found to be Ti in FeTi, Nb in FeNb, and Si in FeSi. As the requirements on material properties increase, the effect of impurities in ferroalloys on the steelmaking process is increasingly becoming more important. The characteristic of inclusions (morphology, number, size, and composition) in ferroalloys investigated in three-dimensional after electrolytic extraction is a good method for studying the evolution of inclusions during steelmaking.

  • 6.
    Bi, Yanyan
    et al.
    KTH.
    Karasev, Andrey V.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jönsson, Pär G.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Three-dimensional determinations of the non-metallic inclusions in different ferroalloys2014Conference paper (Refereed)
    Abstract [en]

    Ferroalloys are commonly used in the steel industry to alloy or deoxidize the steel during the secondary steelmaking process before casting. Depending upon the ferroalloy quality, the addition can also lead to a supply of deleterious inclusions to the liquid steel. Thus, the number, morphology, size and composition of inclusions in six different ferroalloys (FeTi, FeNb, FeSi, SiMn LCFeCr and HCFeCr) were investigated. This was done in three dimensions (3D) by using SEM in combination with EDS after electrolytic extraction of the ferroalloy samples. Moreover, statistics of extreme values (SEV) were used to determine the largest size of inclusions.

  • 7.
    Bi, Yanyan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Karasev, Andrey Vladimirovich
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jönsson, Pär G.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Evolution of Different Inclusions during Ladle Treatment and Continuous Casting of Stainless Steel2013In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 53, no 12, p. 2099-2109Article in journal (Refereed)
    Abstract [en]

    The inclusions and clusters in steel samples of two similar steel grades of high-silicon non-calcium treated (HSiNC) stainless steels were investigated and compared during ladle treatment and continuous casting. Samples of liquid steel and slag were taken at different stages of the ladle treatment and casting during two plant trials: Low Al steel (LAI) and High Al steel (HAI). After electrolytic extraction of the steel samples, characteristics of inclusions and clusters (such as morphology, composition, size and number) were investigated in three dimensions (3D) by SEM in combination with EDS. Moreover, the composition of typical inclusions and clusters was analyzed on a polished cross section of steel samples. Spherical (SP), irregular and regular (IR) inclusions and clusters (CL) were observed in the samples from both heats. It was found that the morphology and composition of inclusions and clusters in both heats were significantly changed during the ladle treatment and casting. Most of inclusions (44-98%) in a Low Al steel are MgO-CaO-SiO2-Al2O3 spherical inclusions. The compositions of IR inclusions and clusters in steel samples of a High Al steel were mostly MgO center dot Al2O3 spinet, but also the complex SP inclusions containing Al2O3-MgO-CaO-SiO2. In addition, phase stability diagram based on Darken's quadratic formalism and Redlich-Kister type polynomial was estimated for both heats at a non-infinite solution.

  • 8.
    Davydenko, Arkadiy
    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, Applied Process Metallurgy.
    Lindstrand, Gunnar
    Outokompu.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Investigation of Slag Foaming by Additions of Briquettes in the EAF during Stainless Steel Production2015In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 86, no 2, p. 146-153Article in journal (Refereed)
    Abstract [en]

    Nowadays, an effective application of energy required for stainless steel production in the electric arc furnace (EAF) by a slag foaming practice and recycling of waste products play two of the most significant roles for a sustainable steel production. In this study, briquettes were used to obtain a combined slag foaming and waste product reduction in the EAF process. Briquettes with different densities produced partly from waste products were tested in an industrial scale to study slag foaming in the EAF process during stainless steel production. The slag foaming tendency was determined based on visual estimations of slag foaming, evaluations of the slag density before and after addition of different briquettes, and by calculating a foaming index. The influence of the main parameters of briquettes (composition, density) and the furnace slag (composition, basicity, and, etc.) on slag foaming was studied. It was found that both heavy and light briquettes can be used for slag foaming. The heavy briquettes, with FeCr, produce about half the amount of gas compared to the light briquettes, without FeCr. The main part of the gas, >80%, was generated during the first 2-3min, Moreover, the highest slag foaming rate was obtained for slags with a basicity in the range of 1.31-1.49.

  • 9.
    Davydenko, Arkadiy
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Mostafaee, Saman
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy. Ovako Hofors.
    Karasev, Andrey
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Characterization of Briquettes Used for Slag Foaming in the EAF during Stainless Steel Production2014In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 86, no 2, p. 137-145Article in journal (Refereed)
    Abstract [en]

    The modern sustainable stainless steel making industry is characterized by different factors such as an efficient utilization of energy in the Electric Arc Furnace (EAF) by a slag foaming practice and an utilization of waste products from its own production facilities. In this study, the foaming briquettes applied for a combined slag foaming and waste product reduction in the EAF are characterized. The recipes of the briquettes were made based on a literature review and previous experience. Afterwards, the composition and density of briquettes were estimated and compared to calculated data. Moreover, weight reduction experiments were made on a laboratory scale at temperatures up to 1500-°C in an argon atmosphere in order to characterize the products (metal, slag, and gas). Based on these results, the calculations were compared with experimental data. The following main results were found: (i) the density of briquettes can be successfully verified, (ii) briquettes have different mechanical properties depending on the materials used for production of briquettes, and (iii) the briquettes yield in different amounts of metal and gas. Moreover, it was found that light briquettes (without FeCr) produced almost double the amount of gas in comparison with heavy briquettes (containing FeCr); valuable metals can be recovered from briquettes, and recipes of briquettes can be optimized based on the amount of metal droplets in briquettes and the total utilization of carbon. This study is focused on a characterization of briquettes, which are used for slag foaming and waste product reduction in the Electric Arc Furnace (EAF) during the stainless steel production. The experimental data is compared with calculations according to the obtained results.

  • 10.
    Doostmohammadi, Hamid
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Andersson, Margareta
    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, Applied Process Metallurgy.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Use of Computational Thermodynamic Calculations in Studying the Slag/Steel Equilibrium during Vacuum Degassing2010In: STEEL RES INT, ISSN 1611-3683, Vol. 81, no 1, p. 31-39Article in journal (Refereed)
    Abstract [en]

    The effectiveness of a ladle refining process for production of tool steel with focus on the top slag is studied using computational thermodynamic calculations. The theoretical assessment was based on compositional data of steel and slag samples collected during trials in a plant equipped with a 65-t EAF, a ladle furnace and a vacuum degasser The calculation of slag-metal equilibrium during ladle treatment was performed for top slag excluding (Case A) and including (Case B) slag carryover and deoxidation products. The predictions showed that slag carryover and deoxidation products in the ladle significantly affect the composition of the top slag. Thus, these conditions must be taken into consideration when predicting the actual top slag composition. It was also found that it is possible to predict the final aluminium and sulphur content in steel based on the same calculation approach.

  • 11.
    Doostmohammadi, Hamid
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Andersson, Margareta
    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 G.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Thermodynamic and Experimental Considerations of the Inclusion Characteristics during Vacuum Degassing of Tool SteelManuscript (preprint) (Other (popular science, discussion, etc.))
  • 12.
    Doostmohammadi, Hamid
    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, Applied Process Metallurgy.
    A Comparison of a Two-Dimensional and a Three-Dimensional Method for Inclusion Determinations in Tool Steel2010In: STEEL RES INT, ISSN 1611-3683, Vol. 81, no 5, p. 398-406Article in journal (Refereed)
    Abstract [en]

    To produce clean commercial tool steel the non-metallic inclusions characteristics have to be known, since they influence the mechanical properties of steel. In this work, inclusion characteristics in steel samples from plant trials were studied. The samples were collected in the steel plant according the two following methods: (a) 2D investigations of inclusions by a cross sectional method and (b) 3D investigations of inclusions collected on a film filter after electrolytic extraction. More specifically, the chemical composition, morphology, number and size distribution of inclusions in tool steel samples taken from ladle during melt treatment were determined by both methods. In both methods SEM equipped with EDS was used for compositional analysis of inclusions. In addition, in the cross sectional method an automated detection program called 'INCAFeature' was used to collect more statistics of non-metallic inclusions. The composition of inclusions larger than 5 mu m was found to contain 49% CaO based on the results from both methods. However, for smaller inclusions it was found that the accuracy of the 2D method was less than that of the 3D method due to the influence of the metal matrix on the results. In addition, it was found that a critical inclusion size of 4 mu m could be defined for the 3D method, above which the standard deviation in composition determination was very low.

  • 13.
    Ericsson, Ola
    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
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    An Experimental Study of Sampling Parameters for Liquid SteelArticle in journal (Other academic)
  • 14.
    Ericsson, Ola
    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, Applied Process Metallurgy.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Effect of Slag Protection System and Sample Geometry on Homogeneity of Total Oxygen Content in Samples from Liquid Steel2011In: Steel Research International, ISSN 1611-3683, Vol. 82, no 3, p. 222-229Article in journal (Refereed)
    Abstract [en]

    Many kinds of disposable samplers are available for sampling of liquid steel during steelmaking. Depending on slag protection, they can be divided into two main groups: metal-cap-protected and argon-protected samplers. For high quality steels, a correct determination of inclusion characteristics in metal samples is important for an improved process control. This paper seeks to investigate the effect of slag protection system, and sample geometry, on deviation and total content of oxygen within samples from the ladle treatment of liquid duplex stainless steel. The homogeneity with respect to total oxygen content was determined for different zones in the body, pin and inlet part of Bjorneborg and Lollipop (6 and 12mm thickness) samples. The results showed low, and stable, contents of oxygen in the argon-protected samples. However, the total oxygen content, and deviation of oxygen, in metal-cap-protected samples was much higher, especially in the body part of the samples. Finally, it was found that the oxygen content heterogeneity in the metal-cap-protected samples increased with a decreased sample weight. Based on the obtained results, the 6mm thick Lollipop sample with argon-protection is recommended for determination of total oxygen content and oxide inclusion characteristics.

  • 15.
    Ericsson, Ola
    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, Applied Process Metallurgy.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Experimental study of parameters for liquid steel sampling2010In: Steel Grips - Journal of Steel and Related Materials, ISSN 1611-4442, E-ISSN 1866-8453, Vol. 8, p. 115-124Article in journal (Refereed)
    Abstract [en]

    Sampling of liquid steel to control the steel making process is very important in the steel industry. However, numerous types of disposable samplers are available and no united standard for sampling exists today. The goal in this study is to investigate the effect of slag protection type and sample geometry on sampling parameters such as filling velocity and solidification rate. Three sample geometries were selected: i) Björneborg, ii) 6 mm thick Lollipop, and iii)12 mm thick Lollipop. These have been tested with two types of slag protection: metal-cap protection and argon protection. The filling velocity and solidification rate of steel samples, which are very important for inclusion characteristics and sample quality, have been experimentally measured during plant trials. The study shows that argon protected samples have lower, more even, filling velocities (0.19 ± 0.09 m/s) compared to metal-cap protected samples (1.77 - 2.08 m/s). Solidification rate results for a 304L stainless steel show that the 6 mm thick Lollipop sample solidifies at a rate of about 100 °C/s while the Björneborg and the 12 mm thick Lollipop sample solidifies at a rate of about 20 °C/s.

  • 16.
    Ericsson, Ola
    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
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Homogeneity of Steel SamplesArticle in journal (Other academic)
  • 17.
    Ericsson, Ola
    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, Applied Process Metallurgy.
    Reid, M. H.
    Monaghan, J. B.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Dispersion of non-metallic inclusions in industrial samples taken from liquid stainless steel during ladle treatment2010Report (Other academic)
  • 18.
    Ericsson, Ola
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Karasev, Andrey Vladimirovich
    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.
    Effect of sampling conditions on inclusion characteristics in samples from liquid steel2011In: CETAS-2011: proceedings of the 8th International Workshop on Progress in Analytical Chemistry and Materials Characterisation in the Steel and Metal Industries, 2011, p. 303-310Conference paper (Refereed)
  • 19.
    Ericsson, Ola
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Karasev, Andrey Vladimirovich
    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.
    Homogeneity of metal samples during sampling of liquid steel2009In: IAS-JICA 2009: proceedings of the 17th Steelmaking Conference, 2009, p. 131-137Conference paper (Refereed)
  • 20.
    Ericsson, Ola
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Lionet, Marie
    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, Applied Process Metallurgy.
    Inoue, R.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Changes in inclusion characteristics during sampling of liquid steel2012In: Ironmaking & Steelmaking, ISSN 0301-9233, Vol. 39, no 1, p. 67-75Article in journal (Refereed)
    Abstract [en]

    In order to improve the process control during the steelmaking process, it is essential to obtain knowledge, as well as interpret information, on the characteristics of non-metallic inclusions in liquid steel samples. The purpose of the present study is to evaluate the effect of different sampling conditions on the inclusion characteristics. The changes in number, size and composition of primary inclusions due to the precipitation of secondary inclusions are studied. This is investigated in laboratory scale samples from an Fe-10 mass-%Ni alloy as well as industrial steel samples with varying contents of oxygen and sulphur. The results show that in most cases, the inclusion population can be separated, using a size condition, into primary (>= 0.6 mu m) and secondary (< 0.6 mu m) inclusions. Overall, the Lollipop sample with a 6 mm thickness can be recommended, because most of the secondary inclusions in low sulphur steels can be removed from the total particle size distribution. However, during sampling of liquid steel containing high levels of sulphur, a significant amount of sulphides precipitate heterogeneously onto primary inclusions, making it impossible to use size or morphology to separate the population. Finally, the numbers of secondary inclusions in the steel samples were found to increase significantly with an increased sample cooling rate. However, the number of primary inclusions was found to be almost constant and independent of the sample cooling rate.

  • 21.
    Janis, Diana
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Inoue, Ryo
    Karasev, Andrey
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jönsson, Pär G.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Application of Different Extraction Methods for Investigation of Nonmetallic Inclusions and Clusters in Steels and Alloys2014In: Advances in Materials Science and Engineering, ISSN 1687-8434, E-ISSN 1687-8442, Vol. 2014, p. 210486-Article in journal (Refereed)
    Abstract [en]

    The characterization of nonmetallic inclusions is of importance for the production of clean steel in order to improve the mechanical properties. In this respect, a three-dimensional (3D) investigation is considered to be useful for an accurate evaluation of size, number, morphology of inclusions, and elementary distribution in each inclusion particle. In this study, the application of various extraction methods (chemical extraction/etching by acid or halogen-alcohol solutions, electrolysis, sputtering with glow discharge, and so on) for 3D estimation of nonmetallic Al2O3 inclusions and clusters in high-alloyed steels was examined and discussed using an Fe-10 mass% Ni alloy and an 18/8 stainless steel deoxidized with Al. Advantages and limitations of different extraction methods for 3D investigations of inclusions and clusters were discussed in comparison to conventional two-dimensional (2D) observations on a polished cross section of metal samples.

  • 22.
    Janis, Diana
    et al.
    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, Applied Process Metallurgy.
    Karasev, Andrey
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Janis, Jesper
    Application of the PDA/OES method during Production of Duplex Stainless SteelManuscript (preprint) (Other academic)
  • 23.
    Janis, Diana
    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, Applied Process Metallurgy.
    Jönsson, Pär G.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    A Study of Cluster Characteristics in Liquid Stainless Steel and in a Clogged Nozzle2015In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 86, no 11, p. 1271-1278Article in journal (Refereed)
    Abstract [en]

    Clusters of Al2O3 inclusions in a liquid stainless steel (18/8) and in a clogged ZrO2 nozzle after casting were studied during a pilot plant trial. Samples were taken from the melt at different holding times after an addition of 0.1 mass% Al. The characteristics (composition, size, number, and morphology) of clusters and clustered inclusions in the steel samples and in the clogged nozzle were investigated after electrolytic extraction and etching by using SEM. It was found that the Al2O3 inclusions in the clusters are transformed from a spherical into irregular and regular (with sharp edges) shape during the holding time. Most of the inclusions in the clusters (>80%) after a 6 min holding time are regular inclusions, which have sharp edges and flat faces. The size of the inclusions in clusters in the melt increased on average from 1.0 μm at a 1 min to 5.2 μm at a 12 min holding time. While the sizes of different types of inclusions in the clogged nozzle correspond to those present in the liquid steel at respective time, the frequency of spherical inclusions in the clogged nozzle is about 2–4 times larger (particularly near the nozzle wall) compared to that in the melt. Growth and transformation of Al2O3 clusters in the liquid steel at different holding times after an addition of Al and during casting were considered based on the obtained results.

  • 24.
    Janis, Diana
    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, Applied Process Metallurgy.
    Jönsson, Pär G.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Evaluation of Inclusion Characteristics in Low-Alloyed Steels by Mainly Using the PDA/OES Method2015In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 55, no 10, p. 2173-2181Article in journal (Refereed)
    Abstract [en]

    The characteristics of non-metallic inclusions (such as number, size and volume fraction) in liquid steel samples taken during ladle treatment and casting of industrial heats of two low-alloyed Ca-treated steel grades were evaluated by using the Pulse Distribution Analysis with Optical Emission Spectroscopy (PDA/OES) method. These results were compared to data obtained by Scanning Electron Microscope observations of inclusions after electrolytic extraction from steel samples (the EE method). It was found that the PDA/OES method can be used for a relative estimation of the homogeneity of the distribution of non-metallic inclusions in steel samples. Bottom and middle parts of the steel samples showed more homogeneous results with respect to the characteristics of the investigated Al2O3, CaO-Al2O3 and CaO-Al2O3-CaS inclusions. The numbers of inclusions in the size ranges 2.0-5.7 mu m and 1.4-5.7 mu m in samples taken before and after a Ca addition, respectively, showed a relatively good agreement between both methods. Furthermore, the calculated volume fractions for inclusions in the size range 2-13 mu m obtained by the PDA/OES method agreed satisfactorily well with those obtained from the EE method. Finally, the minimum sizes of inclusions in steel samples, which can reliably be detected by the PDA/OES method, were estimated for steels with different concentrations of Al in steel and Al2O3 in inclusions.

  • 25.
    Janis, Jesper
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Inoue, Ryo
    Tohoku Univ..
    Karasev, Andrey
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Nakajima, Keiji
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Characteristics of Ti-Ce Complex Deoxidation Products in a Fe-20mass%Cr Alloy2009In: STEEL RES INT, ISSN 1611-3683, Vol. 80, no 6, p. 450-456Article in journal (Refereed)
    Abstract [en]

    The particle characteristics such as size distribution, composition and morphology have been studiedin an Fe-20mass%Cr alloy as a function of holding time at 1600°C. The alloy was deoxidised with Tiand Ce, followed by holding at 1600°C and cooling to 1400°C and quenching. The inclusion particleswere investigated on a surface of film filter with an open pore size of 0.05 or 5 μm after electrolyticextraction of the metal samples. Different electric charge and electrolytes (2%TEA and 10%AA) werecompared for extraction of the Fe-20mass%Cr alloy. 300 Coulombs with 10%AA was found mostsuitable for the electrolytic extraction of particles to determine the particle composition and sizedistribution. Most of the particles were found to be complex oxides containing Ti, Ce and Cr.Furthermore, the composition of the particles was found to change from a high Ce-content to a highCr-content with longer holding time at 1600°C.

  • 26.
    Janis, Jesper
    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, Applied Process Metallurgy.
    Nakajima, Keiji
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jonsson, Stefan
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jönsson, Pär G.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Dissolution of Nitrides and Precipitation of an AusteniticPhase on the Surface of Fe-20%Cr alloys2010Report (Other academic)
    Abstract [en]

    New phases have been observed on surfaces of metal specimens duringcooling after heat treatment at 1200, 1300 and 1400 °C of an Fe-20mass% Cr alloywith different nitrogen contents (65, 248 and 490 ppm) and deoxidised by Ti andZr. These phases were assumed to be related to a phase transformation. Theanalysis of nitrogen content in matrix metal and new phase crystals was carried outbased on point analysis of nitrogen using SEM. According to obtained results itwas concluded that the nitrogen had been dissolved from the nitrides during 60minutes of heat treatment at high temperature and diffused in to the matrix. Theseareas of enriched nitrogen content were then transformed to a new phase duringcooling. This new phase was assumed to be austenite because the nitrogen is a wellknown element for promotion of austenite formation. The possibility of austeniteformation in Fe-20mass% Cr alloys with different nitrogen content was consideredand confirmed thermodynamically by using the Thermo-Calc software.

  • 27.
    Janis, Jesper
    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, Applied Process Metallurgy.
    Nakajima, Keiji
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Jönsson, Pär Göran
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Effect of Secondary Nitride Particles on Grain Growth in a Fe-20 mass% Cr Alloy Deoxidised with Ti and Zr2013In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 53, no 3, p. 476-483Article in journal (Refereed)
    Abstract [en]

    The pinning effects of different particles on grain growth were investigated in Fe-20 mass% Cr alloys deoxidised with Ti and Zr. More specifically, in-situ observations of the specimen surface were made during heat treatment at 1 200 and 1 400 degrees C in a High Temperature - Confocal Scanning Laser Microscope (HT-CSLM). Initially, primary and secondary particles were investigated using thermodynamic equilibrium calculations and the SEM/EDX observations. Thereafter, the pinning effect of secondary nitride particles on grain boundary migration and the kinetics of the grain growth process were investigated. It was found that secondary nitride particles generally have a considerable effect on the pinning of grain boundary migration during heating treatment. This is especially true for heat treatment at 1 400 degrees C. Despite that the pinning effect of TIN particles decreases due to dissolution of these particles, the implicit pinning effects of ZrO2, ZrO2-ZrN and ZrO2-ZrN-TiN particles appear. Thus, despite that TIN individually is ineffective in causing grain-boundary pinning at high-temperature, TiN is effective as a compound with ZrO2 and ZrN in pinning grain-boundaries at high temperatures. The changing of the uniformity of grain size distributions during grain growth at different N contents and temperatures was discussed based on the consideration of the geometric standard deviation of the grain size distribution (sigma(g)).

  • 28.
    Janis,, Jesper
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Karasev, Andrey V.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Nakajima, Keiji
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Jönsson, Pär G.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Effect of Primary and Secondary Particles on Grain Sizein a Fe-20mass% Cr Alloy Deoxidised with Ti and Zr2010Report (Other academic)
    Abstract [en]

    Because of the high and volatile Ni price in recent times, it becomesmore important to develop ferritic stainless steels with low level of Ni. Here,it is known that these steel grades usually contain oversized grains, which asa consequence leads to poor mechanical properties. One way to deal withthis problem is to control the microstructure and the size of grains in ferriticstainless steels. This would also make ferritic stainless steels morecompetitive in comparison to the more commonly used austenitic stainlesssteels. This study focuses on the grain refining effect of particles present in aferritic stainless steel. The particles were created by additions of Ti and Zr into a liquid Fe-20mass% Cr alloy, before the start of solidification. Aconstant O content (150 ppm) together with varying N contents (65, 248 and490 ppm) in the metal samples were used to vary the number, compositionand location of the precipitated particles. The grain sizes and particles werestudied in as-cast samples as well as for specimens heat treated for 60minutes at 1200 and 1400°C. It was found that the formation of particles isenhanced by an increased N content in the alloy. Based on SEMdeterminations, the precipitated particles were divided as primary (mainlyZr-oxides and Zr-nitrides) and secondary (mainly Ti-nitrides) particles andthe effect was studied for each of the types. An increased content of primaryparticles as “nucleators” for precipitation of α-ferrite during solidification ofthe melt lead to an increased formation of equiaxed small-size grains. Inaddition, an increased N content in the metal samples resulted in anincreased number of secondary particles, which are located near the grainboundaries. Therefore, the pinning effect of these particles on grain growthincreased at a holding temperature of 1200oC. However, most of the nitrideswere found to dissolve during heating and holding at a 1400 °C temperature.Thus, as a consequence, the pinning effect of these particles on grain growthdecreased rapidly with the holding time.

  • 29.
    Janis, Jesper
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Nakajima, Keiji
    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.
    Inoue, Ryo
    Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Japan.
    Karasev, Andrey Vladimirovich
    Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Japan.
    Characteristics of Ti-Ce complex deoxidation products in Fe-20mass% Cr alloy2008In: Scanmet III: Proceedings of the 3rd International Conference on Process Development in Iron and Steelmaking, 2008, p. 163-172Conference paper (Refereed)
  • 30.
    Janis, Jesper
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Nakajima, Keiji
    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, Applied Process Metallurgy.
    Jonsson, Stefan
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Inoue, Ryo
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Effects of Nitride-Oxide Particles on Solidified Structure inFe-20mass%Cr Alloy Deoxidised with Ti/M (M = Zr or Ce)2010Report (Other academic)
    Abstract [en]

    The ratio of equiaxed grains on a cross section and average grain sizein Fe-20mass% Cr alloy deoxidised with Ti/M (M = Zr or Ce) were studiedas function of nitrogen content and particle characteristics such as sizedistribution, morphology and composition. Fe-20mass%Cr alloys weremelted at 1600ºC, deoxidised, cooled to 1400ºC followed by waterquenching. The particles were investigated on a surface of film filter afterelectrolytic extraction of metal samples with 10%AA electrolyte. It wasfound that the number of particles increases with increasing the N content.The as-cast solidification structure and grain size were clearly affected bythe number of oxide and oxide-nitride particles in Ti/Zr experiments. Theeffect in the Ti-Ce case was almost undetectable.

  • 31.
    Janis, Jesper
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Nakajima, Keiji
    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, Applied Process Metallurgy.
    Jonsson, Stefan
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Mechanical Metallurgy.
    Inoue, Ryo
    Jönsson, Pär Göran
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Effects of Primary Oxide and Oxide-Nitride Particles on the Solidification Structure in a Fe-20 mass%Cr Alloy Deoxidised with Ti and M (M = Zr or Ce)2013In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 53, no 2, p. 221-229Article in journal (Refereed)
    Abstract [en]

    The ratio of equiaxed grains on a cross section and the size of equiaxed grains in a Fe-20 mass% Cr alloy deoxidised with Ti/M (M = Zr or Ce) were studied as function of nitrogen content and particle characteristics such as size distribution, morphology and composition. Fe-20 mass% Cr alloys were melted at 1 600 degrees C, deoxidised, and cooled to 1 400 degrees C followed by water quenching. Thereafter, the particles were separated from the matrix using electrolytic extraction using a 10%AA electrolyte and collected on a film-filter surface. The inclusion characteristics were determined using SEM. It was found that the number of particles increases with an increased N content. Furthermore, that the solidification structure was clearly affected by the number of primary oxide and oxide-nitride particles in the Ti/Zr deoxidation experiments. However, a similar effect could not be detected in the Ti/Ce deoxidation experiments.

  • 32.
    Janis, Jesper
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Nakajima, Keiji
    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, Applied Process Metallurgy.
    Shibata, Hiroyuki
    Jönsson, Pär G.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    An experimental study on the influence of particles on grain boundary migration2010In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 45, no 8, p. 2233-2238Article in journal (Refereed)
    Abstract [en]

    The pinning effect of particles on grain boundary migration was studied in a Fe-20 mass % Cr alloy deoxidised with Ti and Zr. The different nitrogen contents (65, 248 and 490 ppm) were used to vary the number of precipitated inclusions. The specimens from equiaxed zones of metal samples with different particle densities were examined by in situ observations during a 60-min holding time at 1200 and 1400 degrees C in a Confocal Scanning Laser Microscope. The change of particles pinning effect on the grain growth was described by an average grain size, (D) over bar (A), and the ratio between the perimeter and area of grains, P-GB/A(G). It was found that the pinning effect of particles (mostly complex Ti-Zr oxynitrides) on grain growth decreased with a decreased nitrogen content in the metal. Furthermore, the effect of particles decreased with an increased temperature of treatment, due to the reduction of the number of particles on the grain boundaries.

  • 33.
    Kanbe, Yoichi
    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, Applied Process Metallurgy.
    Todoroki, Hidekazu
    Jönsson, Pär G.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Application of Extreme Value Analysis for Two- and Three-Dimensional Determinations of the Largest Inclusion in Metal Samples2011In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 51, no 4, p. 593-602Article in journal (Refereed)
    Abstract [en]

    The maximum size of single inclusion particles and clusters in an Fe-10 mass% Ni alloy deoxidized with Al or Ti/Al were examined using extreme value analysis. The results obtained from conventional two-dimensional observations of inclusions on a polished cross section of metal sample (the CS-method) were compared to those from three-dimensional investigations of inclusions on a film filter after electrolytic extraction (the EE-method). It was found that the EE-method can successfully be used as a reference method for estimation of the probable maximum size of single inclusion particles and clusters by using an extreme value distribution (EVD). The EVD results for single inclusion particles obtained from the EE-method agreed satisfactorily well with those from a conventional CS-method. However, this required identification as well as neglect of pores on an investigated cross section of a metal sample. The predicted maximum size of single inclusion particles in a 1 mm(3) volume was confirmed by results from the EE-method.

  • 34.
    Kanbe, Yuichi
    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.
    Todoroki, Hidekazu
    Jönsson, Pär G.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Analysis of Largest Sulfide Inclusions in Low Carbon Steel by Using Statistics of Extreme Values2011In: Steel Research International, ISSN 1611-3683, Vol. 82, no 4, p. 313-322Article in journal (Refereed)
    Abstract [en]

    The statistics of extreme values was applied for the determination of the largest sulfide inclusions with different morphology in low carbon steel samples by using both two-dimensional (2D) observations on the polished cross section and three-dimensional (3D) observations on a surface of a film filter after electrolytic extraction of the samples. It was found that the globular, rod-like and dendritic sulfides in the molten steel sample as well as the elongated sulfides in the rolled steel sample can be successfully extracted from the both samples, and analyzed precisely by using extreme value analysis in 3D. Based on the geometrical considerations of the probability for measurement of the true length of rod-like and elongated inclusions on a cross section, it was found that this probability for inclusions decreases dramatically with an increasing real aspect ratio value of them. Particularly for the determination of the true length for elongated inclusions in the rolled steel sample by 2D investigations on a metal cross section, it is required to be cut investigating section of steel sample within +/- 1 degree against rolling direction. Therefore, a 3D observation is considered to be more preferable and accurate than the conventional cross sectional observation in 2D, due to the possibility for the measurements of the real size of them.

  • 35.
    Kanbe, Yuichi
    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, Applied Process Metallurgy.
    Todoroki, Hidekazu
    Jönsson, Pär G.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Application of Statistics of Extreme Values for the inclusions in Type 304 Stainless Steel throughout the Steel Making Process2010Report (Other academic)
    Abstract [en]

    Application of statistics of extreme values was applied to determine the inclusion sizes in Type 304 stainless steel. The samples taken from a tundish, slab and hot rolled steel in one heat were examined by using a cross sectional observation. In the molten steel sample, the extreme value distribution (EVD) containing two different types of inclusions, which are deoxidation products (SiO2-CaO-MgO-Al2O3) and reoxidation products (SiO2-MnO-Cr2O3), resulted in two different slopes in one EVD. Meanwhile, the inclusions in the slab sample provided a good linearity with respect to the EVD. The correlation coefficients of the regression lines for both the slab and rolled steel samples were found to increase with an increased number of measurements between 40 and 80. Based on the EVD data obtained from the slab and rolled steel samples, it was found that the EVD data for the area of fractured inclusions on a parallel cross section of rolled steel agrees well with that for the initial undeformed inclusions area in a slab sample. According to the geometrical considerations of morphological change of inclusion during the hot rolling, the EVD for the length of fractured inclusions after the rolling is possible to estimate from their initial sizes in the case of the fracture into the equivalent particle size.

  • 36. Kanbe, Yuichi
    et al.
    Karasev, Andrey
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Todoroki, Hidekazu
    Jönsson, Pär Göran
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Determination of Size Distribution and Probable Maximum Size of Inclusions in AISI304 Stainless Steel2013In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 53, no 11, p. 1968-1973Article in journal (Refereed)
    Abstract [en]

    The probable maximum sizes (PMS) of inclusions in AISI304 stainless steels were predicted by two methods of the statistics of extreme values (SEV) and the particle size distributions (PSD). Firstly, the PMS of inclusions in the molten steel taken from a tundish agreed well with those in the slab sample. The particle size distributions (PSD) of inclusions almost obeyed exponential functions. The results of comparison between the two methods showed that the PMS by the SEV analysis agreed with that by the PSD approximation in the case of the steel with the higher oxygen content. However, in the case of the steel with the lower oxygen content, the PMS by the PSD approximation overestimated the predicted size with the reference to the SEV analysis. In this case, the approximations with elimination of some largest inclusions which were deviated from an exponential distribution were found to be effective to predict the probable largest size in a reference area. This above result suggests that it is necessary to decide if some largest inclusions are employed for adequate predictions. It is considered that necessity of this operation increases with decreasing oxygen content.

  • 37.
    Kanbe, Yuichi
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Karasev, Andrey Vladimirovich
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Todoroki, Hidekazu
    Nippon Yakin Kogyo Co., Ltd., Technical Research Center, Japan.
    Jönsson, Pär G.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Application of Statistics of Extreme Values for Inclusions in Stainless Steel on Different Stages of Steel Making Process2011In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 51, no 12, p. 2056-2063Article in journal (Refereed)
    Abstract [en]

    A statistics of extreme values was applied to determine the largest inclusion sizes in the Type 304 stainless steel. The samples taken from a tundish, slab and hot rolled steel in one heat were examined by using a two dimensional observation of inclusions on a metal cross section. It was found that the molten steel sample contained two different types of inclusions, which were deoxidation products (SiO(2)-CaO-MgO-Al(2)O(3)) and reoxidation products (SiO(2)-MnO-Cr(2)O(3)). As a result, the extreme value distribution (EVD) for different types of inclusions in the melt has two different slopes. Meanwhile, the inclusions in the slab sample provided a good linearity in one EVD. Moreover, the correlation coefficients of the regression lines for both the slab and rolled steel samples increased significantly with an increased number of measurements from 40 to 80 unit areas. It was found also that the EVD data for fractured inclusions on a parallel cross section of rolled steel agreed satisfactorily well with that for the initial spherical inclusions in the slab sample. Based on the geometrical considerations of inclusion deformation and fracture during hot-rolling, the maximum length of fractured inclusions in rolled steel can be estimated reasonably well from the EVD for initial undeformed inclusions in the slab sample.

  • 38.
    Karasev, Andrey
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Bi, Yanyan
    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, Applied Process Metallurgy.
    Statistical Analysis of the Maximum size of Inclusions in Metal SamplesManuscript (preprint) (Other academic)
  • 39.
    Karasev, Andrey
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Bi, Yanyan
    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, Applied Process Metallurgy.
    Three-dimensional investigation of large-size inclusions and clusters in steels by using the electrolytic extraction technique2013In: AISTech 2013: proceedings of the Iron & steel technology conference : 6-9 May 2013, Pittsburgh, Pa., USA, 2013, p. 1139-1145Conference paper (Refereed)
    Abstract [en]

    It is well known that the non-metallic inclusions and clusters (especially, the large size inclusions and clusters) in steels have significant harmful effects on the mechanical properties of final products. Therefore, it is important to carry out a precise quantitative analysis of inclusion and cluster characteristics in metal samples at different stages of steel production. According to the obtained experimental results during the last years, it was found that the three-dimensional (3-D) investigation of inclusions and clusters on a film filter after electrolytic extraction of steel samples (EE) has a major advantageous in comparison to commonly used two-dimensional (2-D) observations on a polished cross section of metal samples. Experimental results focusing mainly on investigations of large size inclusions and clusters in different steels are discussed in this study.

  • 40.
    Karasev, Andrey V.
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Inoue, Ryo
    Simultaneous Determination of the Composition and Size of Oxide Particles in Solid Materials by Laser Ablation-Inductively Coupled Plasma Mass Spectrometry2009In: Materials transactions, ISSN 1345-9678, E-ISSN 1347-5320, Vol. 50, no 2, p. 341-348Article in journal (Refereed)
    Abstract [en]

    Laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS) has been used for the determination of the composition and size of oxide particles consisting of SiO2, MnO, Al2O3, MgO and CaO on the surface of a glass or metal sample. The composition and size of multicomponent oxide particles such as MnO-SiO2, CaO-Al2O3 and CaO-Al2O3-MgO evaluated by LA-ICP-MS are compared with those obtained by chemical analysis and by SEM observation. It is confirmed that LA-ICP-MS method has prospects to be applied for quick and simultaneous measurement of the composition and size of particles on the surface of metals in steelmaking industry. The difference between the particle size determined by LA-ICP-MS and that by SEM ranges from 6 to 13% on an average in the range of d(V) = 7 similar to 40 mu m.

  • 41. Karasev, Andrey V.
    et al.
    Suito, Hideaki
    Nitride Precipitation on Particles in Fe-10 mass % Ni Alloy Deoxidized with Ti, M (M=Mg, Zr and Ce) and Ti/M2009In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 49, no 2, p. 229-238Article in journal (Refereed)
    Abstract [en]

    The precipitation of nitrides on deoxidation particles in an Fe-10mass%Ni alloy containing 30 similar to 130 ppm O and 14 similar to 22 ppm N has been studied in the experiments where an alloy was deoxidized with Ti, M (M=Mg, Zr and Ce) and Ti/M at 1600 degrees C and then cooled to 1200 degrees C, followed by holding for 0 and 60 min before quenching. The total number of particles above 0.1 mu m remains almost constant except in Ti deoxidation, but the proportion of cubic particles which correspond to nitrides and oxide-nitrides increases during holding at 1200 degrees C in Ti, Zr, Ti/Mg and Ti/Zr deoxidations. In 0.05% (initial amount) Ti deoxidation, the number of TiN and TiN+TiOx particles increases during holding. In 0.03%Ti/0.1%Mg deoxidation, the number of TiOx-TiN particles decreases and the number of MgO-TiN and MgO-Ti(O, N) particles increases during holding due to the reduction of TiOx with soluble Mg. In 0.03%Ti/0.04%Zr deoxidation, the number of ZrO2 particles significantly decreases during holding due to the precipitation of TiN and ZrN on Zr oxides and formation of Zr(O, N)-Ti(O, N) particles. In the cases of Ti/0.08%Zr and Ti/0.12%Ce deoxidations, most of particles at 0 and 60 min of holding are ZrO2 and Zr(O, N) and Ce2O3 oxides, respectively, because the FeO-TiOx oxide in particles is reduced completely by dissolved Zr and Ce.

  • 42.
    Karasev, Andrey Vladimirovich
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Inoue, Ryo
    Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Japan.
    Jönsson, Pär G.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Application of Laser Ablation ICP Mass Spectrometry for Rapid Aalysis of Oxide Particles in Metal Samples2011In: CETAS-2011: proceedings of the 8th International Workshop on Progress in Analytical Chemistry and Materials Characterisation in the Steel and Metal Industries, 2011, p. 487-494Conference paper (Refereed)
  • 43.
    Karasev, Andrey Vladimirovich
    et al.
    Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Japan.
    Inoue, Ryo
    Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Japan.
    Suito, Hideaki
    Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Japan.
    Inhibition of Austenite Grain Growth by Particles and Solute Elements in Fe-0.05% C and Fe-10% Ni Alloys Deoxidized by Mn-Si, Ti, Mg, Zr and Ce2007In: PRICM-6: Proceedings of the 6th Pacific Rim International Conference on Advaced Materials and Processing (Materials Science Forum), PTS 1-3, 2007, p. 1055-1058Conference paper (Refereed)
    Abstract [en]

    The inhibition effect of inclusion particles and soluble elements on the austenite grain growth has been studied in Fe-0.05% C and Fe-10% Ni alloys deoxidized by Mn (1.0%) - Si (0.2%), Ti (0.05%), Mg (0.10%), Zr (0.08%) or Ce (0.12%). It is found experimentally that total surface area of grains per unit volume, which is in inverse proportion to the grain size, increases linearly with increasing the! surface area of particles per unit volume. However, the size of grains in metal with high content of soluble Zr and Ce is significantly smaller than the predicted value from the effect of particle pinning. The additional effect of soluble Zr and Cc on austenite grain growth becomes more significant with an increase of these contents in alloys. An effect of nonrandorn dispersion of particles on grain growth is also estimated and discussed.

  • 44.
    Karasev, Andrey Vladimirovich
    et al.
    Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Japan.
    Suito, Hideaki
    Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Japan.
    Analysis of Composition and Size Distribution of Inclusions in Fe-10 Mass% Ni Alloy Deoxidized by Al and Mg Using Laser Ablation ICP Mass Spectrometry2004In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 44, no 2, p. 364-371Article in journal (Refereed)
  • 45.
    Karasev, Andrey Vladimirovich
    et al.
    Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Japan.
    Suito, Hideaki
    Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Japan.
    Characteristics of Fine Oxide Particles Produced by Ti/M (M = Mg and Zr) Complex Deoxidation in Fe-10 mass% Ni Alloy2008In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 48, no 11, p. 1507-1516Article in journal (Refereed)
  • 46.
    Karasev, Andrey Vladimirovich
    et al.
    Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Japan.
    Suito, Hideaki
    Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Japan.
    Effect of Oxide Particles and Solute Elements on Austenite Grain Growth in Fe-0.05 mass% C and Fe-10 mass% Ni Alloys2008In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 48, no 5, p. 658-666Article in journal (Refereed)
  • 47.
    Karasev, Andrey Vladimirovich
    et al.
    Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Japan.
    Suito, Hideaki
    Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Japan.
    Effect of Particle Size Distribution on Austenite Grain Growth in Fe-0.05 mass% C Alloy Deoxidized with Mn-Si, Ti, Mg, Zr and Ce2006In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 46, no 5, p. 718-727Article in journal (Refereed)
  • 48.
    Karasev, Andrey Vladimirovich
    et al.
    Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Japan.
    Suito, Hideaki
    Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Japan.
    Measurement of Inclusion Size by Laser Ablation ICP Mass Spectrometry2004In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 44, no 2, p. 356-363Article in journal (Refereed)
    Abstract [en]

    By using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), the measurement of particle size has been made for one component oxide (Al2O3 and MgO) and multicomponent oxide (12CaO.7Al(2)O(3) and CaO-Al2O3-Mgo) located on surface of iron or glass sample, The method of particle size estimation by LA-ICP-MS has been developed coupled with a new method of making samples with particles. The size calibration lines for Al2O3, MgO and CaO particles have been obtained. The results of particle size measurement by LA-ICP-MS are compared with those by SEM and single-particle optical sensing (SPOS) methods. It was confirmed that LA-ICP-MS has the perspective to be used for the quick measurement of inclusion composition and size in metal and other materials. The size frequency distributions of Al2O3 particles measured by LA-ICP-MS in iron samples with particles agree reasonably well with those by SEM and SPOS in the range of particle diameter from 2 to 20 mum. The size of Al2O3, MgO and complex oxide (12CaO.7Al(2)O(3) and CaO-Al2O3-Mgo) particles measured by LA-ICP-MS is in good agreement with that by SEM in the range of particle diameter from 10 to 40 mum.

  • 49.
    Karasev, Andrey Vladimirovich
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Suito, Hideaki
    Professor Emeritus, Tohoku University, Sendai, Japan.
    Inoue, Ryo
    Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Japan.
    Application of Laser Ablation ICP Mass Spectrometry for Analysis of Oxide Particles on Cross Section of Alloys and Steels2011In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 51, no 12, p. 2042-2049Article in journal (Refereed)
    Abstract [en]

    Some aspects for the application of Laser Ablation-Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) are considered and discussed from the viewpoint of the rapid analysis of oxide inclusions in metal samples. The inclusion characteristics in Fe-10% Ni alloy samples such as number, size and particle size distribution obtained by LA-ICP-MS method are compared with those from three-dimensional observation of particles on a film filter after electrolytic extraction. Though some limits had to be considered regarding to the content of soluble elements, the number and dispersion of analyzed inclusions in metal matrix, it was found that the LA-ICP-MS technique can be successfully applied for the rapid analysis of oxide inclusions containing Al2O3, MgO and others.

  • 50.
    Karasev, Andrey Vladimirovich
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Suito, Hideaki
    Jönsson, Pär Göran
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Effects of Soluble Ti and Zr Content and Austenite Grain Size on Microstructure of the Simulated Heat Affected Zone in Fe-C-Mn-Si Alloy2011In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 51, no 9, p. 1524-1533Article in journal (Refereed)
    Abstract [en]

    The effect of soluble Ti and Zr contents on the microstructure in a simulated heat affected zone of a Fe-0.05mass%C-1.5mass%Mn-0.20mass%Si alloy was studied. This was done as a function of the austenite grain size as well as the number and size of TiN, Ti(2)O(3), MgO(+Ti(2)O(3)), TiN(+MgO) and ZrO(2)(+Ti(2)O(3)) particles under different peak temperature (1 300 and 1 400 degrees C), peak holding time (0, 60 and 600 s) and a constant time of cooling (70 s) from 800 to 500 degrees C. The effectiveness of inclusion phases for intragranular ferrite (IGF) formation was studied from the area fraction of IGF for a given austenite grain size and soluble Ti content. For a given austenite grain size, the primary ferrite decreases and the IGF increases with an increased soluble Ti content up to about 100 ppm. After going through a maximum the replacement of IGF by lath bainitic ferrite occurs with an increased soluble Ti content. It is found that the effect of soluble Zr content on the microstructure is much stronger than that of a soluble Ti content. The area fraction of IGF decreases gradually with an increase in the austenite grain size (50-1 000 mu m) for a given soluble Ti content (50-400 ppm). By using the hardenability parameter based on the non-equilibrium grain-boundary segregation model, it is observed that the IGF formation is encouraged in the following order: TiN>{Ti(2)O(3), MgO(+Ti(2)O(3))}>ZrO(2)(+Ti(2)O(3)).

123 1 - 50 of 101
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