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Publications (10 of 39) Show all publications
Siafakas, D., Matsushita, T., Lauenstein, Å., Ekerot, S. & Jarfors, A. (2018). A particle population analysis in Ti- and Al-deoxidized Hadfield steels. International Journal of Cast Metals Research, 31(3), 125-134
Open this publication in new window or tab >>A particle population analysis in Ti- and Al-deoxidized Hadfield steels
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2018 (English)In: International Journal of Cast Metals Research, ISSN 1364-0461, E-ISSN 1743-1336, Vol. 31, no 3, p. 125-134Article in journal (Refereed) Published
Abstract [en]

A quantitative analysis of the amount, size and number of particles that precipitate in situ in titanium- and aluminium-treated Hadfield steel cast during pilot-scale experiments has been performed. SEM with EDS and automated particle analysis abilities was utilized for the analysis. Additionally, Thermo-Calc was used for thermodynamic calculations and Magma 5 for solidification and cooling simulations. Predicted particles sizes calculated with a model based on the Ostwald ripening mechanism were compared with the experimental data. The effect of solute availability, cooling rate and deoxidation practice on the particle population characteristics was determined. It was concluded that the amount, size and number of precipitating particles in Hadfield steel castings is possible to be controlled according to certain requirements by a careful selection of proper additives in proper amounts and also by the optimization of the casting process in aspects of deoxidation timing and control of the cooling rate of the castings.

Place, publisher, year, edition, pages
Taylor & Francis, 2018
Keywords
Hadfield steel, particles population, deoxidation, casting, titanium, aluminum, inclusion control, particle growth
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-37418 (URN)10.1080/13640461.2017.1379262 (DOI)000437344000001 ()2-s2.0-85019740665 (Scopus ID)
Available from: 2017-09-27 Created: 2017-09-27 Last updated: 2018-08-22Bibliographically approved
Siafakas, D., Matsushita, T., Hakamada, S., Onodera, K., Kargl, F., Jarfors, A. E. .. & Watanabe, M. (2018). Measurement of Viscosity of SiO2-CaO-Al2O3 Slag in Wide Temperature Range by Aerodynamic Levitation and Rotating Bob Methods and Sources of Systematic Error. International journal of microgravity science and application, 35(2), Article ID 350204.
Open this publication in new window or tab >>Measurement of Viscosity of SiO2-CaO-Al2O3 Slag in Wide Temperature Range by Aerodynamic Levitation and Rotating Bob Methods and Sources of Systematic Error
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2018 (English)In: International journal of microgravity science and application, ISSN 0915-3616, Vol. 35, no 2, article id 350204Article in journal (Refereed) Published
Abstract [en]

Viscosity measurements for SiO2-CaO-Al2O3 based ternary slags with low SiO2 content were performed for a wide temperature range utilizing the aerodynamic levitation and rotating bob methods. Aerodynamic levitation was used for temperatures >= 2229 K and the viscosity was calculated by the sample oscillation decay time. The rotating bob method was used for temperatures <= 1898 K and the viscosity was determined by the variation of the torque at different rotation speeds. Fitting curves were created using Mauro’s viscosity equation. The main sources of systematic error were identified to be the sample weight measurement, the resolution of the high-speed camera, the fitting of the linear trend line in the torque against rpm diagrams and the vertical position of the bob. The combined standard uncertainty from all error sources was calculated for both measurement methods.

Place, publisher, year, edition, pages
Japan Society of Microgravity Application, 2018
Keywords
Aerodynamic levitation; Slag; Viscosity; Rotating bob; Gravity
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-41082 (URN)10.15011//jasma.35.350204 (DOI)000431604700004 ()JTHMaterialIS (Local ID)JTHMaterialIS (Archive number)JTHMaterialIS (OAI)
Available from: 2018-08-02 Created: 2018-08-02 Last updated: 2018-08-02Bibliographically approved
Matsushita, T., Saro, A. G., Elmquist, L. & Jarfors, A. E. .. (2018). On the thermal conductivity of CGI and SGI cast irons. International Journal of Cast Metals Research, 31(3), 135-143
Open this publication in new window or tab >>On the thermal conductivity of CGI and SGI cast irons
2018 (English)In: International Journal of Cast Metals Research, ISSN 1364-0461, E-ISSN 1743-1336, Vol. 31, no 3, p. 135-143Article in journal (Refereed) Published
Abstract [en]

The thermal conductivity of Compacted Graphite Iron (CGI) and spheroidal graphite iron (SGI) was established in the temperature range from room temperature up to 500 °C using the experimental thermal diffusivity, density and specific heat values. The influence of nodularity, graphite amount, silicon content and temperature on the thermal conductivity of fully ferritic high-silicon cast irons was investigated. It was found that the CGI materials showed higher thermal conductivity than the SGI materials. The thermal conductivity tended to increase with increasing temperature until it reached a maximum followed by a subsequent decrease as temperature was increased up to 500 °C. Conventional models were applied to estimate thermal conductivity and the predictive accuracy of each model was evaluated. The thermal conductivity could be estimated by the Helsing model. The Maxwell model, Bruggeman model and Hashin–Shtrikman model were also in fair agreement using the thermal conductivity value of graphite parallel to the basal planes in graphite. 

Place, publisher, year, edition, pages
Maney Publishing, 2018
Keywords
cast iron, high-silicon, modelling, Thermal conductivity, Ferritic steel, Graphite, Iron, Models, Silicon, Specific heat, Compacted graphite iron, Conventional models, Increasing temperatures, Predictive accuracy, Silicon cast iron, Silicon contents, Spheroidal graphite, Temperature range
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-38338 (URN)10.1080/13640461.2017.1379263 (DOI)000437344000002 ()2-s2.0-85029576971 (Scopus ID)
Available from: 2018-01-04 Created: 2018-01-04 Last updated: 2018-08-22Bibliographically approved
Matsushita, T., Saro, A. G., Elmquist, L. & Jarfors, A. E. W. (2017). On the specific heat and thermal diffusivity of CGI and SGI cast irons. International Journal of Cast Metals Research, 30(5), 276-282
Open this publication in new window or tab >>On the specific heat and thermal diffusivity of CGI and SGI cast irons
2017 (English)In: International Journal of Cast Metals Research, ISSN 1364-0461, E-ISSN 1743-1336, Vol. 30, no 5, p. 276-282Article in journal (Refereed) Published
Abstract [en]

The specific heat and thermal diffusivity of Compacted Graphite Iron (CGI) and Spheroidal Graphite Iron (SGI) were measured at temperatures ranging between 373 and 773 K (100 and 500 °C) using differential scanning calorimetry (DSC) and between 298 and 773 K (25 and 500 °C) using the laser flash method, respectively. Specific heat increased with increasing amounts of graphite and pearlite, as well as with Si content. As a recommended value of the specific heat for fully ferritic high-silicon SGI, the following relation was suggested:(Formula presented.) where T is the temperature in Celsius, (Formula presented.) is the mass% of Si, and fg is the area fraction of graphite (%). The thermal diffusivity of cast irons tends to increase with increasing amounts of graphite, and decrease with greater nodularity. It was found that nodularity had a strong influence on thermal diffusivity in the nodularity range of 15–30%. 

Place, publisher, year, edition, pages
Maney Publishing, 2017
Keywords
differential scanning calorimetry, high-silicon cast iron, laser flash method, Specific heat capacity, thermal diffusivity, Calorimeters, Calorimetry, Cast iron, Diffusion, Graphite, Iron, Superconducting materials, Area fraction, Compacted graphite iron, Laser flash methods, Nodularity, Recommended values, Si content, Silicon cast iron, Spheroidal graphite, Specific heat
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-35158 (URN)10.1080/13640461.2017.1292987 (DOI)000413699700002 ()2-s2.0-85013031429 (Scopus ID)
Available from: 2017-03-06 Created: 2017-03-06 Last updated: 2017-12-21Bibliographically approved
Siafakas, D., Matsushita, T., Lauenstein, Å., Jarfors, A. E. .. & Ekengård, J. (2017). The Influence of Deoxidation Practice on the As-Cast Grain Size of Austenitic Manganese Steels. Metals, 7(6), Article ID 186.
Open this publication in new window or tab >>The Influence of Deoxidation Practice on the As-Cast Grain Size of Austenitic Manganese Steels
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2017 (English)In: Metals, ISSN 2075-4701, Vol. 7, no 6, article id 186Article in journal (Refereed) Published
Abstract [en]

The effect of in-situ precipitating particles on the grain size of Al-Ti-treated and untreated Hadfield steel cast in a pilot scale environment was studied. Hadfield steel was melted in an induction furnace and cast in Y-Block samples. Light Optical Microscopy (LOM) and the intercept method were utilized for the grain size measurements. Additionally, Thermo-Calc Software TCFE7 Steels/Fe-alloys database version 7 was used for thermodynamic equilibrium calculations of the mole fraction of particles. The planar disregistry values between the austenite and the precipitating particles were calculated. It was observed that increasing oxide content in samples with low Ti(CN) content resulted in a finer microstructure, while increasing the Ti(CN) content under similar oxide content levels led to a coarser microstructure. The potency of each type of particle to nucleate austenitic grains was determined. Spinel (MnAl2O4, MgAl2O4) particles were characterized as the most potent, followed by olivine (Mn2SiO4), corundum (Al2O3, TiO2), and finally Ti(CN), the least potent particle.

Place, publisher, year, edition, pages
MDPI, 2017
Keywords
Hadfield steel, grain size, austenite, deoxidation, particles, aluminum, titanium, oxides, titanium nitrides
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-35598 (URN)10.3390/met7060186 (DOI)000404056600003 ()2-s2.0-85019680224 (Scopus ID)
Available from: 2017-05-24 Created: 2017-05-24 Last updated: 2018-09-19Bibliographically approved
Jarfors, A., Matsushita, T., Bogdanoff, T., Börrisson, M. & Beste, U. (2016). Effect of Use in High Pressure Die Casting on Vibenite®60 Tool Inserts Madeby Additive Manufacturing. In: B. Müller (Ed.), DDMC2016 Frauenhofer Direct Digital Manufacturing Conference: Conference Proceedings, March 2016, Berlin, Germany. Paper presented at DDMC2016 Frauenhofer Direct Digital Manufacturing Conference. Fraunhofer IRB Verlag
Open this publication in new window or tab >>Effect of Use in High Pressure Die Casting on Vibenite®60 Tool Inserts Madeby Additive Manufacturing
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2016 (English)In: DDMC2016 Frauenhofer Direct Digital Manufacturing Conference: Conference Proceedings, March 2016, Berlin, Germany / [ed] B. Müller, Fraunhofer IRB Verlag, 2016Conference paper, Published paper (Refereed)
Abstract [en]

The thermo-physical and mechanical properties of Vibenite®60 was investigated in the as-manufactured, soft annealed and hardened state as well as after use in full scale high pressure die casting. Thermal conductivity in the as manufactured state was 23.3 to 27.5 W/mK in the temperature range from 25°C to 500°C. Annealing increased thermal conductivity to 25.0 up to 29.2 W/mK. Hardening reduced thermal conductivity of 19.8 to 26.1 W/mK. The tool wastested in production in the as fabricated state displayed a slight increase in thermal conductivity, which was interpreted as a slight tempering during use. Hardness measurements were made at room temperature and followed the same pattern as the thermo-physical properties. Rockwell and Vickers Hardness was lowest in the as lowest in the annealed state and hardest in the hardened state. Rockwell hardness was not affected by use in production while Vickers hardness decreased slightly.

Place, publisher, year, edition, pages
Fraunhofer IRB Verlag, 2016
Keywords
Tooling, 3D printing, additive manufacturing
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-29660 (URN)978-3-8396-1001-5 (ISBN)
Conference
DDMC2016 Frauenhofer Direct Digital Manufacturing Conference
Projects
ADDING
Funder
VINNOVA
Available from: 2016-03-28 Created: 2016-03-28 Last updated: 2018-09-12Bibliographically approved
Siafakas, D., Matsushita, T., Jarfors, A., Lauenstein, Å. & Ekerot, S. (2016). Particles precipitation in Ti and Al deoxidized Hadfield steels. Steel Research International, 87(10), 1344-1355
Open this publication in new window or tab >>Particles precipitation in Ti and Al deoxidized Hadfield steels
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2016 (English)In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 87, no 10, p. 1344-1355Article in journal (Refereed) Published
Abstract [en]

The characteristics and precipitation mechanism of particles in titanium and aluminum treated Hadfield steel casted during pilot scale experiments have been studied. Light Optical Microscopy (LOM), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS) were utilized for the particle analysis and characterization. Additionally, thermodynamic equilibrium calculations were performed using Thermo-Calc software. Aluminum oxides, titanium carbon nitrides, titanium carbides and manganese sulfides were the main types of particles found. The order of precipitation during solidification and chemical composition range of each type of particle was determined. Aluminum Oxides were found to act as nucleation sites fortitanium carbon nitrides. Thermodynamic equilibrium calculation for particles characteristics were in good agreement with the experimental findings. Titanium carbides were found to form during initial stages of the Ferro-titanium additions dissolution.

Place, publisher, year, edition, pages
John Wiley & Sons, 2016
Keywords
Hadfield steel; particles; Titanium; Aluminum; Deoxidation
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-29401 (URN)10.1002/srin.201500400 (DOI)000387017200011 ()2-s2.0-84959496093 (Scopus ID)
Projects
InDeGrainS
Funder
Knowledge Foundation, 20130149
Available from: 2016-02-15 Created: 2016-02-15 Last updated: 2017-11-30Bibliographically approved
Matsushita, T., Ghassemali, E., Saro, A. G., Elmquist, L. & Jarfors, A. E. .. (2015). On Thermal Expansion and Density of CGI and SGI Cast Irons. Metals, 5(2), 1000-1019, Article ID met5021000.
Open this publication in new window or tab >>On Thermal Expansion and Density of CGI and SGI Cast Irons
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2015 (English)In: Metals, ISSN 2075-4701, Vol. 5, no 2, p. 1000-1019, article id met5021000Article in journal (Refereed) Published
Abstract [en]

The thermal expansion and density of Compacted Graphite Iron (CGI) and Spheroidal Graphite Iron (SGI) were measured in the temperature range of 25–500 °C using push-rod type dilatometer. The coefficient of the thermal expansion (CTE) of cast iron can be expressed by the following equation: CTE = 1.38 × 10−5 + 5.38 × 10−8 N − 5.85 × 10−7 G + 1.85 × 10−8 T − 2.41 × 10−6 RP/F − 1.28 × 10−8 NG − 2.97 × 10−7 GRP/F + 4.65 × 10−9 TRP/F + 1.08 × 10−7 G2 − 4.80 × 10−11 T2 (N: Nodularity, G: Area fraction of graphite (%), T: Temperature (°C), RP/F: Pearlite/Ferrite ratio in the matrix).

Keywords
thermal expansion; high-silicon cast iron; dilatometer; density; cycle test
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-26950 (URN)10.3390/met5021000 (DOI)000357508400034 ()2-s2.0-84937539498 (Scopus ID)
Projects
CompCast
Funder
Knowledge Foundation
Available from: 2015-06-04 Created: 2015-06-04 Last updated: 2016-03-22Bibliographically approved
Matsushita, T., Mukai, K. & Zeze, M. (2013). Correspondence between Surface Tension Estimated by a Surface Thermodynamic Model and Number of Bubbles in the Vicinity of the Surface of Steel Products in Continuous Casting Process. ISIJ International, 53(1), 18-26
Open this publication in new window or tab >>Correspondence between Surface Tension Estimated by a Surface Thermodynamic Model and Number of Bubbles in the Vicinity of the Surface of Steel Products in Continuous Casting Process
2013 (English)In: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 53, no 1, p. 18-26Article in journal (Refereed) Published
Abstract [en]

Surface tensions of low carbon slabs and 16 mass%Cr stainless steel were estimated using a surface thermodynamic model proposed by Mukai et al. As an application of the model, an index to evaluate the driving force for the fine bubble entrapment by the solidifying shell, the Mukai-value, M, was calculated from the surface tension values. The relationship between Mukai-value and number of entrapped bubbles was discussed. A linear relationship was found between the number of captured bubbles and Mukai-value. In the previous work, the Mukai-value was used as a relative scale to evaluate the driving force for the movement of bubbles. However, by calculating the M from the surface tension values by the surface thermodynamic model, physically reasonable Mukai-values could be obtained.

Place, publisher, year, edition, pages
Nippon Tekko Kyokai, 2013
National Category
Engineering and Technology
Identifiers
urn:nbn:se:hj:diva-20255 (URN)10.2355/isijinternational.53.18 (DOI)000315834700003 ()2-s2.0-84873871910 (Scopus ID)JTHMaterialIS (Local ID)JTHMaterialIS (Archive number)JTHMaterialIS (OAI)
Available from: 2013-01-17 Created: 2013-01-17 Last updated: 2018-10-15Bibliographically approved
Mostaghel, S., Matsushita, T., Samuelsson, C., Björkman, B. & Seetharaman, S. (2013). Influence of alumina on physical properties of an industrial zinc-copper smelting slag Part 1 – viscosity. Transactions of the Institution of Mining and Metallurgy Section C - Mineral Processing and Extractive Metallurgy, 122(1), 42-48
Open this publication in new window or tab >>Influence of alumina on physical properties of an industrial zinc-copper smelting slag Part 1 – viscosity
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2013 (English)In: Transactions of the Institution of Mining and Metallurgy Section C - Mineral Processing and Extractive Metallurgy, ISSN 0371-9553, E-ISSN 1743-2855, Vol. 122, no 1, p. 42-48Article in journal (Refereed) Published
Abstract [en]

The rotating cylinder method was applied to measure the viscosities of an industrial iron silicate slag and mixtures of this slag with 5, 10 and 15 wt-% alumina addition, in temperature range 1100–1300°C. The measured viscosities were compared with the predicted values using two of the commercially available software products for viscosity calculations, namely Thermoslag®1.5 and FactSageTM6.2. As the models can only predict viscosities for a solid free melt, obtained values by FactSageTM6.2 were modified using the Einstein–Roscoe equation. Results show that aluminium behaves as a network former cation in this type of slag, and by increasing the alumina concentration, the melt becomes progressively polymerised. Consequently, the viscosity of the slag increases at a given temperature, which is supported by thermodynamic predictions. According to the modified FactSageTM6.2 calculations, the viscosity of the solid containing slag increases from 2.1 to 5.5 poise at the industrial operating temperature (∼1250°C).

National Category
Engineering and Technology
Identifiers
urn:nbn:se:hj:diva-20045 (URN)10.1179/1743285512Y.0000000029 (DOI)2-s2.0-84877140734 (Scopus ID)
Available from: 2012-12-05 Created: 2012-12-05 Last updated: 2018-10-15Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-2929-7891

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