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Andersson, Nils A. I.ORCID iD iconorcid.org/0000-0002-2109-3731
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Publications (7 of 7) Show all publications
Pirouznia, P., Andersson, N. A. I., Tilliander, A. & Jönsson, P. G. (2019). An investigation of the Temperature Distribution of a Thin Steel Strip during the Quenching Step of a Hardening Process. Metals, 9(6)
Open this publication in new window or tab >>An investigation of the Temperature Distribution of a Thin Steel Strip during the Quenching Step of a Hardening Process
2019 (English)In: Metals, ISSN 2075-4701, Vol. 9, no 6Article in journal (Refereed) Published
Abstract [en]

The dimension quality of the strip within the hardening process is an essential parameter, which great attention needs to be paid. The flatness of the final product is influenced by the temperature distribution of the strip, specifically across the width direction. Therefore, based on physical theories, a numerical model was established. The temperature of the strip for the section before the martensitic transformation was objected in the predicted model by using a steady state approach. In addition an infrared thermal imaging camera was applied in the real process in order to validate the results and to improve the boundary conditions of the numerical model. The results revealed that the temperature of strip decreased up to 250 degrees C within the area between the furnace and the quenching bath. This, in turn, resulted in significant temperature difference across the width of the strip. This difference can be up to 69 degrees C and 41 degrees C according to the numerical results and thermal imaging data, respectively. Overall, this study gave a better insight into the cooling step in the hardening process. In addition, this investigation can be used to improve the hardening process as well as an input for future thermal stress investigations.

Place, publisher, year, edition, pages
MDPI, 2019
Keywords
continuous hardening process, martempering, heat transfer, numerical modelling, CFD
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-255579 (URN)10.3390/met9060675 (DOI)000475356500059 ()2-s2.0-85070722589 (Scopus ID)
Note

QC 20190805

Available from: 2019-08-05 Created: 2019-08-05 Last updated: 2019-10-04Bibliographically approved
Frisk, R., Andersson, N. A. I. & Rogberg, B. (2019). Cast Structure in Alloy A286, an Iron-Nickel Based Superalloy. Metals, 9(6)
Open this publication in new window or tab >>Cast Structure in Alloy A286, an Iron-Nickel Based Superalloy
2019 (English)In: Metals, ISSN 2075-4701, Vol. 9, no 6Article in journal (Refereed) Published
Abstract [en]

The structure and segregation of a continuously cast iron-nickel based superalloy were investigated. Cross-sectional samples were prepared from the central section of a 150 x 150 mm square billet. The microporosity was measured from the surface to the center and theoretical conditions for pore formation were investigated. A central porosity, up to 10 mm in width, was present in the center of the billet. The measured secondary arm spacing was correlated with a calculated cooling rate and a mathematical model was obtained. Spinel particles were found in the structure, which acted as inoculation points for primary austenite and promoted the formation of the central equiaxed zone. Titanium segregated severely in the interdendritic areas and an increase of Ti most likely lead to a significant decrease in the hot ductility. Precipitates were detected in an area fraction of approximately 0.55% across the billet, which were identified as Ti(CN), TiN, eta -Ni3Ti, and a phosphide phase.

Place, publisher, year, edition, pages
MDPI, 2019
Keywords
A286 superalloy, cast structure, continuous casting, porosity, intermetallic phases, dendrite arm spacing
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-255576 (URN)10.3390/met9060711 (DOI)000475356500095 ()2-s2.0-85070474292 (Scopus ID)
Note

QC 20190802

Available from: 2019-08-02 Created: 2019-08-02 Last updated: 2019-10-04Bibliographically approved
Bölke, K., Ersson, M., Andersson, N. A. I., Imris, M. & Jönsson, P. (2019). Experimental Determinations of Mixing Times in the IronArc Pilot Plant Process. METALS, 9(1), Article ID 101.
Open this publication in new window or tab >>Experimental Determinations of Mixing Times in the IronArc Pilot Plant Process
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2019 (English)In: METALS, ISSN 2075-4701, Vol. 9, no 1, article id 101Article in journal (Refereed) Published
Abstract [en]

IronArc is a newly developed technology and an emerging future process for pig iron production. The long-term goal with this technology is to reduce the CO2 emissions and energy consumption compared to existing technologies. The production rate of this process is dependent on the stirring, which was investigated in the pilot plant process by measuring the mixing time in the slag bath. Moreover, slag investigations were done both based on light optical microscope studies as well as by Thermo-Calc calculations in order to determine the phases of the slag during operation. This was done because the viscosity (which is another important parameter) is dependent on the liquid and solid fractions of the slag. The overall results show that it was possible to determine the mixing time by means of the addition of a tracer (MnO2 powder) to the slag. The mixing time for the trials showed that the slag was homogenized after seconds. For two of the trials, homogenization had already been reached in the second sample after tracer addition, which means <= 8 s. The phase analysis from the slag indicated that the slag is in a liquid state during the operation of the process.

Place, publisher, year, edition, pages
MDPI, 2019
Keywords
IronArc process, Ironmaking, pig iron production, mixing time, CO2 reduction, slag investigation
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-246292 (URN)10.3390/met9010101 (DOI)000459738500100 ()2-s2.0-85060686372 (Scopus ID)
Note

QC 20190325

Available from: 2019-03-25 Created: 2019-03-25 Last updated: 2019-05-13Bibliographically approved
Pirouznia, P., Andersson, N. A. I., Tilliander, A. & Jönsson, P. (2019). The Impact of the Gas Inlet Position, Flow Rate, and Strip Velocity on the Temperature Distribution of a Stainless-Steel Strips during the Hardening Process. METALS, 9(9), Article ID 928.
Open this publication in new window or tab >>The Impact of the Gas Inlet Position, Flow Rate, and Strip Velocity on the Temperature Distribution of a Stainless-Steel Strips during the Hardening Process
2019 (English)In: METALS, ISSN 2075-4701, Vol. 9, no 9, article id 928Article in journal (Refereed) Published
Abstract [en]

A non-uniform temperature across the width of martensitic stainless-steel strips is considered to be one of the main reasons why the strip exhibits un-flatness defects during the hardening process. Therefore, the effect of the gas inlet position in this process, on the temperature distribution of the steel strip was investigated numerically. Furthermore, an infrared thermal imaging camera was used to compare the model predictions and the actual process data. The results showed that the temperature difference across the width of the strip decreased by 9% and 14% relative to the calculated temperature and measured values, respectively, when the gas inlet position was changed. This temperature investigation was performed at a position about 63 mm from the bath interface. Moreover, a more symmetrical temperature distribution was observed across the width of the strip. In addition, this study showed that by increasing the amount of the hydrogen flow rate by 2 Nm(3)/h, a 20% reduction of temperature difference across the width of strip was predicted. Meanwhile, the results show that the effect of the strip velocity on the strip temperature is very small.

Place, publisher, year, edition, pages
MDPI, 2019
Keywords
continuous hardening process, martempering, heat transfer, numerical modelling, computational fluid dynamics
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-262979 (URN)10.3390/met9090928 (DOI)000489129800014 ()2-s2.0-85073350992 (Scopus ID)
Note

QC 20191031

Available from: 2019-10-31 Created: 2019-10-31 Last updated: 2019-10-31Bibliographically approved
Kadrolkar, A., Andersson, N. Å. I. & Dogan, N. (2017). A Dynamic Flux Dissolution Model for Oxygen Steelmaking. Metallurgical and materials transactions. B, process metallurgy and materials processing science, 48(1), 99-112
Open this publication in new window or tab >>A Dynamic Flux Dissolution Model for Oxygen Steelmaking
2017 (English)In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 48, no 1, p. 99-112Article in journal (Refereed) Published
Abstract [en]

A modified model for prediction of flux dissolution in oxygen steelmaking process is presented in this study. The aim of this paper is to introduce a procedure for simulating the amount of dissolved lime with respect to the saturation concentration of CaO by coupling the existing thermodynamic and kinetic models simultaneously. The procedure is developed to calculate the saturation concentrations/solubility of CaO in slag using thermodynamic models namely FactSage (TM), Cell Model, and Thermo-Calc (TM). Total amount of dissolved lime is evaluated by integrating solubility values in the rate equation of lime dissolution over time taking into account the effects of physical properties and temperature of slag and particle size of flux additions and validated against industrial data available in literature. Comparison between measured and calculated undissolved lime shows a good agreement between them using any thermodynamic models even though there are some differences in the predictions of saturation concentration of CaO in slag. It has been shown that two distinct control mechanisms for lime dissolution in BOF slags exist and consideration of the free lime-controlled mechanism is essential for accurate prediction of dissolution rate of lime in slag.

Place, publisher, year, edition, pages
Springer, 2017
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-202427 (URN)10.1007/s11663-016-0777-8 (DOI)000392295500013 ()2-s2.0-84982293205 (Scopus ID)
Note

QC 20170306

Available from: 2017-03-06 Created: 2017-03-06 Last updated: 2017-11-29Bibliographically approved
Schmidt, C., Andersson, N. A. I., Tilliander, A., Jönsson, P. & Ljungqvist, P. (2017). Measurement techniques for meltdown control in a stainless steel AC electric arc furnace. In: ESSC and DUPLEX 2017 - 9th European Stainless Steel Conference - Science and Market and 5th European Duplex Stainless Steel Conference and Exhibition: . Paper presented at 9th European Stainless Steel Conference: Science and Market, ESSC 2017 and 5th European Duplex Stainless Steel Conference and Exhibition, DUPLEX 2017, 25 May 2017 through 27 May 2017. Associazione Italiana di Metallurgia
Open this publication in new window or tab >>Measurement techniques for meltdown control in a stainless steel AC electric arc furnace
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2017 (English)In: ESSC and DUPLEX 2017 - 9th European Stainless Steel Conference - Science and Market and 5th European Duplex Stainless Steel Conference and Exhibition, Associazione Italiana di Metallurgia , 2017Conference paper, Published paper (Refereed)
Abstract [en]

A method for vibrational evaluations of spectrogram data from pilot plant measurements was established for obtaining a consistent analysis of the molten scrap state. Not knowing the meltdown progress inside the furnace results in an inefficient power scheduling, which affects refractory life, process time and energy losses. Hence, there exists potential to control the furnace power so that it is kept high while there is sufficient amounts of scrap inside furnace to absorb the input energy. Thus, harmonic distortions of the electric current and measurements of the sound and vibrations emitted from the furnace were correlated to the molten state of the scrap. By using this method, a reduction in melting time in the order of minutes per heat can be obtained. The method was found to give stable signals and it was judged to be a good candidate for implementation in industry. Furthermore, the developed method is universal and may be applied for other types of signals and combined into intelligent soft sensor systems. 

Place, publisher, year, edition, pages
Associazione Italiana di Metallurgia, 2017
Keywords
Flat bath, Process control, Scrap meltdown, Thd, Vibrations, Electric arcs, Electric furnaces, Energy dissipation, Furnaces, Pilot plants, Vibration analysis, Consistent analysis, Electric arc furnace, Measurement techniques, Plant measurement, Power Scheduling, Soft sensor system, Stainless steel
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-236817 (URN)2-s2.0-85049263456 (Scopus ID)9788898990122 (ISBN)
Conference
9th European Stainless Steel Conference: Science and Market, ESSC 2017 and 5th European Duplex Stainless Steel Conference and Exhibition, DUPLEX 2017, 25 May 2017 through 27 May 2017
Funder
Swedish Energy Agency
Note

QC 20190107

Available from: 2019-01-07 Created: 2019-01-07 Last updated: 2019-01-07Bibliographically approved
Gauffin, A., Andersson, N. A. I., Storm, P., Tilliander, A. & Jönsson, P. G. (2016). The Global Societal Steel Scrap Reserves and Amounts of Losses. Resources, 5(3), Article ID 27.
Open this publication in new window or tab >>The Global Societal Steel Scrap Reserves and Amounts of Losses
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2016 (English)In: Resources, E-ISSN 2079-9276, Vol. 5, no 3, article id 27Article in journal (Refereed) Published
Abstract [en]

In this study a newly developed method called the Progressing and Backcasting models were used to evaluate the annual resource utilizations of steel scrap in Sweden and globally. The model results show that it is possible to assess the amounts of steel scrap available for steelmaking at a given point in time, based on statistical dynamic material flow models. By a better mapping of the available amounts of steel scrap reserves on a country basis, it is possible to ease the trade of scrap across country boarders. This in turn can optimize the supply of recyclable metals as a raw material used in the industry. The results for Swedish steel consumption show that export bans used to secure the domestic market of steel scrap do damage the internal market due to increased amounts of losses. This suggests that export bans should be lifted to optimize recycling in countries. The model results also show that the global losses of steel are higher than for an industrialized country such as Sweden. Furthermore, the results show that the Backcasting and Progressing models can be used to calculate robust forecasts on the long term availability of steel scrap assets. This information could be used for future structural plans of scrap consuming steelmaking mills and waste management facilities. Hence, it is possible to contribute to a sustainable industrial development and a circular economy.

Place, publisher, year, edition, pages
MDPI AG, 2016
Keywords
scrap reserve, scrap generation, steel stock, recycling, losses, forecast, scarcity, dynamic material flow modelling, sustainability
National Category
Environmental Management
Identifiers
urn:nbn:se:kth:diva-196443 (URN)10.3390/resources5030027 (DOI)000385526200005 ()2-s2.0-85018228816 (Scopus ID)
Note

QC 20161129

Available from: 2016-11-29 Created: 2016-11-14 Last updated: 2018-09-19Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0002-2109-3731

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