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Prof. Pär Jönsson
Department of Materials Science and Engineering (MSE), KTH Royal Institute of Technology, Stockholm, Sweden

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0 Process Control
0 Reactor Design
0 Inclusion engineering
0 Precipitate engineering
0 Metallurgical process modeling

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Inclusion engineering

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Journal article
Published: 25 August 2021 in Materials
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Different stainless steel slags have been successfully employed in previous experiments, for the treatment of industrial acidic wastewaters. Although, before this technology can be implemented on an industrial scale, upscaled pilot experiments need to be performed. In this study, the parameters of the upscale trials, such as the volume and mixing speeds, are firstly tested by dispersing a NaCl tracer in a water bath. Mixing time trials are used to maintain constant mixing conditions when the volumes are increased to 70, 80 and 90 L, compared to the 1 L laboratory trials. Subsequently, the parameters obtained are used in pH buffering trials, where stainless steel slags are used as reactants, replicating the methodology of previous studies. Compared to laboratory trials, the study found only a minor loss of efficiency. Specifically, in previous studies, 39 g/L of slag was needed to buffer the pH of the acidic wastewaters. To reach similar pH values within the same time span, upscaled trials found a ratio of 43 g/L and 44 g/L when 70 and 90 L are used, respectively. Therefore, when the kinetic conditions are controlled, the technology appears to be scalable to higher volumes. This is an important finding that hopefully promotes further investments in this technology.

ACS Style

Mattia De Colle; Rahul Puthucode; Andrey Karasev; Pär G. Jönsson. A Study of Treatment of Industrial Acidic Wastewaters with Stainless Steel Slags Using Pilot Trials. Materials 2021, 14, 4806 .

AMA Style

Mattia De Colle, Rahul Puthucode, Andrey Karasev, Pär G. Jönsson. A Study of Treatment of Industrial Acidic Wastewaters with Stainless Steel Slags Using Pilot Trials. Materials. 2021; 14 (17):4806.

Chicago/Turabian Style

Mattia De Colle; Rahul Puthucode; Andrey Karasev; Pär G. Jönsson. 2021. "A Study of Treatment of Industrial Acidic Wastewaters with Stainless Steel Slags Using Pilot Trials." Materials 14, no. 17: 4806.

Journal article
Published: 09 July 2021 in Sustainability
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A six day industrial trial using hydrochar as part of the carbon source for hot metal production was performed in a production blast furnace (BF). The hydrochar came from two types of feedstocks, namely an organic mixed biosludge generated from pulp and paper production and an organic green waste residue. These sludges and residues were upgraded to hydrochar in the form of pellets by using a hydrothermal carbonization (HTC) technology. Then, the hydrochar pellets were pressed into briquettes together with commonly used briquetting material (in-plant fines such as fines from pellets and scraps, dust, etc. generated from the steel plant) and the briquettes were top charged into the blast furnace. In total, 418 tons of hydrochar briquettes were produced. The aim of the trials was to investigate the stability and productivity of the blast furnace during charging of these experimental briquettes. The results show that briquettes containing hydrochar from pulp and paper industries waste and green waste can partially be used for charging in blast furnaces together with conventional briquettes. Most of the technological parameters of the BF process, such as the production rate of hot metal (<1.5% difference between reference days and trial days), amount of dust, fuel rate and amount of injected coal, amount of slag, as well as contents of FeO in slag and %C, %S and %P in the hot metal in the experimental trials were very similar compared to those in the reference periods (two days before and two days after the trials) without using these experimental charge materials. Thus, it was proven that hydrochar derived from various types of organic residues could be used for metallurgical applications. While in this trial campaign only small amounts of hydrochar were used, nevertheless, these positive results support our efforts to perform more in-depth investigations in this direction in the future.

ACS Style

Tova Jarnerud; Andrey Karasev; Chuan Wang; Frida Bäck; Pär Jönsson. Utilization of Organic Mixed Biosludge from Pulp and Paper Industries and Green Waste as Carbon Sources in Blast Furnace Hot Metal Production. Sustainability 2021, 13, 7706 .

AMA Style

Tova Jarnerud, Andrey Karasev, Chuan Wang, Frida Bäck, Pär Jönsson. Utilization of Organic Mixed Biosludge from Pulp and Paper Industries and Green Waste as Carbon Sources in Blast Furnace Hot Metal Production. Sustainability. 2021; 13 (14):7706.

Chicago/Turabian Style

Tova Jarnerud; Andrey Karasev; Chuan Wang; Frida Bäck; Pär Jönsson. 2021. "Utilization of Organic Mixed Biosludge from Pulp and Paper Industries and Green Waste as Carbon Sources in Blast Furnace Hot Metal Production." Sustainability 13, no. 14: 7706.

Research article
Published: 06 July 2021 in steel research international
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The characteristics of non-metallic inclusions (NMIs) in low-alloyed steel samples taken during ladle treatment before and after Ca-treatment were evaluated by using the Pulse Distribution Analysis Optical Emission Spectroscopy (PDA/OES) method, INCA-Feature investigations of inclusions on a polished surface of steel samples, and three-dimensional investigations of NMIs after electrolytic extraction (EE) of steel samples. The investigation results of NMIs by using different methods were compared. The PDA/OES results show a clear tendency of a change in the average composition and quantity of NMIs during the ladle treatment, which correlated well with the results obtained from the other two methods. Overall, it was found that the application of the PDA/OES method is appropriate to enable a fast online evaluation of inclusion compositions and their behaviors during steelmaking. This, in turn, provides the means for establishing an online control and correction of technological operations of the ladle treatment to implement necessary modification of NMIs in order to improve the cleanliness of steels and to avoid clogging problems during casting.

ACS Style

Hongying Du; Annika Yang; Andrey V. Karasev; Pär G. Jönsson. Characterization of Nonmetallic Inclusions in Low‐Alloyed Steels Using Pulse Distribution Analysis Optical Emission Spectroscopy and Offline Investigation Methods. steel research international 2021, 1 .

AMA Style

Hongying Du, Annika Yang, Andrey V. Karasev, Pär G. Jönsson. Characterization of Nonmetallic Inclusions in Low‐Alloyed Steels Using Pulse Distribution Analysis Optical Emission Spectroscopy and Offline Investigation Methods. steel research international. 2021; ():1.

Chicago/Turabian Style

Hongying Du; Annika Yang; Andrey V. Karasev; Pär G. Jönsson. 2021. "Characterization of Nonmetallic Inclusions in Low‐Alloyed Steels Using Pulse Distribution Analysis Optical Emission Spectroscopy and Offline Investigation Methods." steel research international , no. : 1.

Journal article
Published: 29 May 2021 in Metals
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A statistical model is developed in order to simulate the melt composition in electric arc furnaces (EAFs) with respect to uncertainties in (1) scrap composition, (2) scrap weighing and (3) element distribution factors. The tramp element Cu and alloying element Cr are taken into account. The model enables simulations of a charge program as well as backwards estimations of the element concentrations and their variance in scrap. In the backwards calculation, the maximum likelihood method is solved by considering three cases corresponding to the involved uncertainties. It is shown that the model can estimate standard deviations for elements so that the real values lie within the estimated 95% confidence interval. Moreover, the results of the model application in each target product show that the estimated scrap composition results in a melt composition, which is in good agreement with the measured one. The model can be applied to increase our understanding of scrap chemical composition and lower the charged material cost and carbon footprint of the products.

ACS Style

Niloofar Arzpeyma; Moudud Alam; Rutger Gyllenram; Pär Jönsson. Model Development to Study Uncertainties in Electric Arc Furnace Plants to Improve Their Economic and Environmental Performance. Metals 2021, 11, 892 .

AMA Style

Niloofar Arzpeyma, Moudud Alam, Rutger Gyllenram, Pär Jönsson. Model Development to Study Uncertainties in Electric Arc Furnace Plants to Improve Their Economic and Environmental Performance. Metals. 2021; 11 (6):892.

Chicago/Turabian Style

Niloofar Arzpeyma; Moudud Alam; Rutger Gyllenram; Pär Jönsson. 2021. "Model Development to Study Uncertainties in Electric Arc Furnace Plants to Improve Their Economic and Environmental Performance." Metals 11, no. 6: 892.

Journal article
Published: 18 May 2021 in Materials
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In this study, CaO-containing wastes from pulp and paper industries such as fly ash (FA) and calcined lime mud (LM) were utilized to neutralize and purify acidic wastewaters from the pickling processes in steel mills. The investigations were conducted by laboratory scale trials using four different batches of wastewaters and additions of two types of CaO-containing waste materials. Primary lime (PL), which is usually used for the neutralization, was also tested in the same experimental set up in the sake of comparison. The results show that these secondary lime sources can effectively increase the pH of the acidic wastewaters as good as the commonly used primary lime. Therefore, these secondary lime sources could be potential candidates for application in neutralization processes of industrial acidic wastewater treatment. Moreover, concentrations of metals (such as Cr, Fe, Ni, Mo and Zn) can decrease dramatically after neutralization by using secondary lime. The LM has a purification effect from the given metals, similar to the PL. Application of fly ash and calcined lime mud as neutralizing agents can reduce the amount of waste from pulp and paper mills sent to landfill and decrease the need for nature lime materials in the steel industry.

ACS Style

Tova Jarnerud; Andrey Karasev; Pär Jönsson. Neutralization of Acidic Wastewater from a Steel Plant by Using CaO-Containing Waste Materials from Pulp and Paper Industries. Materials 2021, 14, 2653 .

AMA Style

Tova Jarnerud, Andrey Karasev, Pär Jönsson. Neutralization of Acidic Wastewater from a Steel Plant by Using CaO-Containing Waste Materials from Pulp and Paper Industries. Materials. 2021; 14 (10):2653.

Chicago/Turabian Style

Tova Jarnerud; Andrey Karasev; Pär Jönsson. 2021. "Neutralization of Acidic Wastewater from a Steel Plant by Using CaO-Containing Waste Materials from Pulp and Paper Industries." Materials 14, no. 10: 2653.

Journal article
Published: 07 May 2021 in Metals
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Wrought nickel-based Alloy 825 is widely used in the oil and gas industries, attributed to its high strength at temperatures up to 540 °C. However, differences in mechanical properties arise in finished components due to variations in both grain size and dislocation density. Numerous experimental studies of the strengthening mechanisms have been reported and many models have been developed to predict strengthening under thermomechanical processing. However, there are debates surrounding some fundamental issues in modeling and the interpretation of experimental observations. Therefore, it is important to understand the evolution of strain within the material during the hot-forging process. In addition, there is a lack of research around the behavior during hot deformation and subsequent stabilization of Alloy 825. This article investigates the origin of this strength and considers a variety of strengthening mechanisms, resulting in a quantitative prediction of the contribution of each mechanism. The alloy is processed with a total forging strain of 0.45, 0.65, or 0.9, and subsequent annealing at a temperature of 950 °C, reflecting commercial practice. The microstructure after annealing is similar to that before annealing, suggesting that static recovery is dominant at this temperature. The maximum yield strength and ultimate tensile strength were 348 MPa and 618 MPa, respectively, obtained after forging to a true strain of 0.9, with a ductility of 40%. The majority of strengthening was attributed to grain refinement, the dislocation densities that arise due to the large forging strain deformation, and solid solution strengthening. Precipitate strengthening was also quantified using the Brown and Ham modification of the Orowan bowing model. The results of yield strength calculations are in excellent agreement with experimental data, with less than 1% difference. The interfacial energy of Ti(C,N) in the face-centered cubic matrix of the current alloy has been assessed for the first time, with a value of 0.8 mJm−2. These results can be used by future researchers and industry to predict the strength of Alloy 825 and similar alloys, especially after hot-forging.

ACS Style

Munir Al-Saadi; Fredrik Sandberg; Pär Jönsson; Christopher Hulme-Smith. Modelling of Strengthening Mechanisms in Wrought Nickel-Based 825 Alloy Subjected to Solution Annealing. Metals 2021, 11, 771 .

AMA Style

Munir Al-Saadi, Fredrik Sandberg, Pär Jönsson, Christopher Hulme-Smith. Modelling of Strengthening Mechanisms in Wrought Nickel-Based 825 Alloy Subjected to Solution Annealing. Metals. 2021; 11 (5):771.

Chicago/Turabian Style

Munir Al-Saadi; Fredrik Sandberg; Pär Jönsson; Christopher Hulme-Smith. 2021. "Modelling of Strengthening Mechanisms in Wrought Nickel-Based 825 Alloy Subjected to Solution Annealing." Metals 11, no. 5: 771.

Journal article
Published: 21 April 2021 in Energy
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Pyrolysis of municipal solid waste (MSW) represents one of the most promising solutions to recycle materials and recover energy. Two of the main components of MSW are waste cardboard and plastic. In this study, the pyrolysis of cardboard and polyethylene (PE) and the co-pyrolysis of their mixtures were conducted to investigate the synergistic effect by using thermogravimetric analysis. The whole reaction process was divided into four pseudoreactions, namely, hemicellulose, lignin, cellulose, and PE, by using the Frazer-Suzuki deconvolution method. It was found that the co-pyrolysis of cardboard and PE could promote the decomposition degrees of cardboard from 70.28% to 75.31%, when the PE fraction increased from 0 to 75%. However, the presence of cardboard can hinder the heat adsorption of PE, which shifts the peak of the PE reaction to a higher temperature. This results in higher Ea and ΔH‡ values for PE pyrolysis with an increasing fraction of cardboard. On the other hand, the Ea and ΔH‡ values of cellulose pyrolysis have their lowest values when the mixing rate is around 50%. This research deepens the understanding of the synergistic effect of co-pyrolysis of cardboard and PE, which supports the potential application of pyrolysis of MSW.

ACS Style

Yuming Wen; Ilman Nuran Zaini; Shule Wang; Wangzhong Mu; Pär Göran Jönsson; Weihong Yang. Synergistic effect of the co-pyrolysis of cardboard and polyethylene: A kinetic and thermodynamic study. Energy 2021, 229, 120693 .

AMA Style

Yuming Wen, Ilman Nuran Zaini, Shule Wang, Wangzhong Mu, Pär Göran Jönsson, Weihong Yang. Synergistic effect of the co-pyrolysis of cardboard and polyethylene: A kinetic and thermodynamic study. Energy. 2021; 229 ():120693.

Chicago/Turabian Style

Yuming Wen; Ilman Nuran Zaini; Shule Wang; Wangzhong Mu; Pär Göran Jönsson; Weihong Yang. 2021. "Synergistic effect of the co-pyrolysis of cardboard and polyethylene: A kinetic and thermodynamic study." Energy 229, no. : 120693.

Journal article
Published: 11 April 2021 in Materials
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Natural convection of molten steel flow in a tundish occurs due to the temperature variation of the inlet stream and heat losses through top surface and refractory walls. A computational fluid dynamics (CFD) model was applied to study the effect of thermal buoyancy on fluid flow and residence-time distribution in a single-strand tundish. The CFD model was first validated with the experimental data from a non-isothermal water model and then applied to both scale-down model and prototype. The effects of flow control devices, including weir, dam and turbulence inhibitor, were compared and analyzed. Parameter studies of different heat losses through the top surface were performed. The results show that thermal buoyancy has a significant impact on the flow pattern and temperature distributions of molten steel in the tundish. The increase of heat loss through the top surface shortens the mean residence time of molten steel in the tundish, leading to an increase in dead volume fraction and a decrease in plug flow volume fraction.

ACS Style

Dong-Yuan Sheng; Pär Jönsson. Effect of Thermal Buoyancy on Fluid Flow and Residence-Time Distribution in a Single-Strand Tundish. Materials 2021, 14, 1906 .

AMA Style

Dong-Yuan Sheng, Pär Jönsson. Effect of Thermal Buoyancy on Fluid Flow and Residence-Time Distribution in a Single-Strand Tundish. Materials. 2021; 14 (8):1906.

Chicago/Turabian Style

Dong-Yuan Sheng; Pär Jönsson. 2021. "Effect of Thermal Buoyancy on Fluid Flow and Residence-Time Distribution in a Single-Strand Tundish." Materials 14, no. 8: 1906.

Journal article
Published: 26 March 2021 in Metals
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The characteristics of elongated MnS have a critical effect on fatigue anisotropy and all mechanical anisotropies. A comparative investigation of nonmetallic inclusions in both stainless steels and tool steels has been carried out in this study. The inclusion characteristics were investigated using electrolytic extraction (EE) followed by scanning electron microscopy combined with energy-dispersive spectroscopy (SEM-EDS). Overall, three types of MnS inclusions (type I (regular), type II (irregular) and type III (Rod)) were found in tool steels in as-cast samples, which had not been heat-treated. Furthermore, three types of MnS inclusions (Rod-like sulfide (RS), Plate-like sulfide (PS) and Oxysulfide (OS)) were found in samples taken after rolling. Based on the breakability of the elongated MnS, three types of inclusions, Type UU, UB and BB, where U represents the undamaged or unbroken edge of an inclusion and B represents the fragment or broken edge of an inclusion, were studied in both stainless steels and tool steels both before and after additional heat treatment. The effect of heat treatment and dissolving the metal layer during the EE process is also discussed. The results show that both processes have a limited effect on the breakability of inclusions in steels with carbon contents <0.42 mass%.

ACS Style

Shuo Guo; Andrey Karasev; Anders Tilliander; Pär Jönsson. Evaluation of Sulfide Inclusions before and after Deformation of Steel by Using the Electrolytic Extraction Method. Metals 2021, 11, 543 .

AMA Style

Shuo Guo, Andrey Karasev, Anders Tilliander, Pär Jönsson. Evaluation of Sulfide Inclusions before and after Deformation of Steel by Using the Electrolytic Extraction Method. Metals. 2021; 11 (4):543.

Chicago/Turabian Style

Shuo Guo; Andrey Karasev; Anders Tilliander; Pär Jönsson. 2021. "Evaluation of Sulfide Inclusions before and after Deformation of Steel by Using the Electrolytic Extraction Method." Metals 11, no. 4: 543.

Journal article
Published: 09 March 2021 in Metals
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In this study, a complete and comprehensive analysis of non-metallic inclusions (NMI) in an Fe-10%Ni alloy was done by using two modern analytical methods that complement each other: Electrolytic Extraction (EE) of inclusions from metal samples followed by investigations by using Scanning Electron Microscopy (SEM) and Fractional Gas Analysis (FGA). The composition, morphology, size and number of different NMIs and clusters were investigated in metal samples taken after deoxidation by additions of Ti, Ti/Zr and Ti/Mg. The obtained results were discussed with respect to formation, modification and removal of NMIs and clusters depending on the type of deoxidations and the holding time. It was found that the peaks of oxygen reduced from different oxide inclusions obtained by the FGA measurements corresponded well to the main types of inclusions and clusters observed by using the EE + SEM method. More specifically, the total O content in oxide inclusions (ONMI) increases by 10% after a Zr addition and then decreases linearly by 40% during 5 min of holding due to flotation of NMIs and clusters. However, after a Mg addition in the melt deoxidized by Ti, the ONMI content decreases drastically by 63% during 5 min of holding, due to a fast floatation of NMIs caused by bubbles of vaporized Mg.

ACS Style

Andrey Karasev; Dmitry Gorkusha; Konstantin Grigorovich; Pär Jönsson. Application of Some Modern Analytical Techniques for Characterization of Non-Metallic Inclusions in a Fe-10mass%Ni Alloy Deoxidized by Ti/Zr and Ti/Mg. Metals 2021, 11, 448 .

AMA Style

Andrey Karasev, Dmitry Gorkusha, Konstantin Grigorovich, Pär Jönsson. Application of Some Modern Analytical Techniques for Characterization of Non-Metallic Inclusions in a Fe-10mass%Ni Alloy Deoxidized by Ti/Zr and Ti/Mg. Metals. 2021; 11 (3):448.

Chicago/Turabian Style

Andrey Karasev; Dmitry Gorkusha; Konstantin Grigorovich; Pär Jönsson. 2021. "Application of Some Modern Analytical Techniques for Characterization of Non-Metallic Inclusions in a Fe-10mass%Ni Alloy Deoxidized by Ti/Zr and Ti/Mg." Metals 11, no. 3: 448.

Journal article
Published: 02 March 2021 in Applied Energy
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Anaerobic digestion is a practical process for recovering energy and materials from sewage sludge. However, land disposal of the derived digestate results in environmental problems, such as eutrophication and salinization. Copyrolysis of sewage sludge digestate and lignocellulosic biomass produces a high-quality oil, a diluted hazardous component of biochar. This study investigates the copyrolysis behavior of lignocellulosic biomass and sludge digestate with different blending ratios using bench-scale experiments. Compared to individual feedstock pyrolysis, copyrolysis shows a higher energy distribution in the liquid product and a lower energy distribution in the char and gas product. The highest energy yield with respect to the organic fraction of liquid product is observed in the copyrolysis case, corresponding to 36.4% of the total energy in the feedstock. The interaction between the sludge digestate and lignocellulosic biomass is studied through product characterizations, mechanistic investigations and char stability assessments. The liquid products in the copyrolysis cases show a relatively high abundance of esters, aliphatic hydrocarbons, pyridines and pyrroles. The reaction pathways of proteins, lipids and carbohydrates are investigated. Two synergistic reaction pathways are proposed. The char stability and nitrogen distribution are investigated. According to the results, the synergistic interaction between feedstocks enhances the quality and energy yield of the liquid biofuel. The char product from copyrolysis has higher potential for use as a carbon sink and fertilizer.

ACS Style

Shule Wang; Per Mandfloen; Pär Jönsson; Weihong Yang. Synergistic effects in the copyrolysis of municipal sewage sludge digestate and salix: Reaction mechanism, product characterization and char stability. Applied Energy 2021, 289, 116687 .

AMA Style

Shule Wang, Per Mandfloen, Pär Jönsson, Weihong Yang. Synergistic effects in the copyrolysis of municipal sewage sludge digestate and salix: Reaction mechanism, product characterization and char stability. Applied Energy. 2021; 289 ():116687.

Chicago/Turabian Style

Shule Wang; Per Mandfloen; Pär Jönsson; Weihong Yang. 2021. "Synergistic effects in the copyrolysis of municipal sewage sludge digestate and salix: Reaction mechanism, product characterization and char stability." Applied Energy 289, no. : 116687.

Journal article
Published: 02 March 2021 in Metals
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This study focuses on the impact of solidification on the inclusion morphologies in different sizes of production-scale electro-slag remelting (ESR) and electro-slag remelting under a protected pressure-controlled atmosphere, (PESR), ingots, in a common martensitic stainless steel grade. The investigation has been carried out to increase the knowledge of the solidification and change in inclusion morphologies during ESR and PESR remelting. In order to optimize process routes for different steel grades, it is important to define the advantages of different processes. A comparison is made between an electrode, ESR, and PESR ingots with different production-scale ingot sizes, from 400 mm square to 1050 mm in diameter. The electrode and two of the smallest ingots are from the same electrode charge. The samples are taken from both the electrode, ingots, and rolled/forged material. The solidification structure, dendrite arm spacing, chemical analyzes, and inclusion number on ingots and/or forged/rolled material are studied. The results show that the larger the ingot and the further towards the center of the ingot, the larger inclusions are found. As long as an ingot solidifies with a columnar dendritic structure (DS), the increase in inclusion number and size with ingot diameter is approximately linear. However, at the ingot size (1050 mm in diameter in this study) when the center of the ingot converts to solidification in the equiaxial mode (EQ), the increase in number and size of the inclusions is much higher. The transition between a dendritic and an equiaxial solidification in the center of the ingots in this steel grade takes place in the region between the ingot diameters of 800 and 1050 mm.

ACS Style

Ewa Persson; Sofia Brorson; Alec Mitchell; Pär Jönsson. Impact of Solidification on Inclusion Morphology in ESR and PESR Remelted Martensitic Stainless Steel Ingots. Metals 2021, 11, 408 .

AMA Style

Ewa Persson, Sofia Brorson, Alec Mitchell, Pär Jönsson. Impact of Solidification on Inclusion Morphology in ESR and PESR Remelted Martensitic Stainless Steel Ingots. Metals. 2021; 11 (3):408.

Chicago/Turabian Style

Ewa Persson; Sofia Brorson; Alec Mitchell; Pär Jönsson. 2021. "Impact of Solidification on Inclusion Morphology in ESR and PESR Remelted Martensitic Stainless Steel Ingots." Metals 11, no. 3: 408.

Journal article
Published: 29 January 2021 in Materials
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The flow behavior of gas in compressible and incompressible systems was investigated at an ambient temperature in an air–water system and at an operating process temperature in the IronArc system, using computational fluid dynamics. The simulation results were verified by experiments in the air–water system and established empirical equations to enable reliable predictions of the penetration length. The simulations in the air–water system were found to replicate the experimental behavior using both the incompressible and compressible models, with only small deviations of 7–8%. A lower requirement for the modified Froude number of the gas blowing to produce a jetting behavior was also found. For gas blowing below the required modified Froude number, the results illustrate that the gas will form large pulsating bubbles instead of a steady jet, which causes the empirical equation calculations to severely underpredict the penetration length. The lower modified Froude number limit was also found to be system dependent and to have an approximate value of 300 for the studied IronArc system. For submerged blowing applications, it was found that it is important to ensure sufficiently high modified Froude numbers of the gas blowing. Then, the gas penetration length will remain stable as a jet and it will be possible to predict the values using empirical equations.

ACS Style

Jonas Svantesson; Mikael Ersson; Pär Jönsson. Effect of Froude Number on Submerged Gas Blowing Characteristics. Materials 2021, 14, 627 .

AMA Style

Jonas Svantesson, Mikael Ersson, Pär Jönsson. Effect of Froude Number on Submerged Gas Blowing Characteristics. Materials. 2021; 14 (3):627.

Chicago/Turabian Style

Jonas Svantesson; Mikael Ersson; Pär Jönsson. 2021. "Effect of Froude Number on Submerged Gas Blowing Characteristics." Materials 14, no. 3: 627.

Journal article
Published: 26 December 2020 in Metals
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Alloy 825 is widely used in several industries, but its useful service life is limited by both mechanical properties and corrosion resistance. The current work explores the effect of the addition of magnesium on the recrystallization and mechanical behavior of alloy 825 under hot compression. Compression tests were performed under conditions representative of typical forming processes: temperatures between 1100 and 1250 °C and at strain rates of 0.1–10 s−1 to a true strain of 0.7. Microstructural evolution was characterized by electron backscattered diffraction. Dynamic recrystallization was found to be more prevalent under all test conditions in samples containing magnesium, but not in all cases of conventional alloy 825. The texture direction 〈101〉 was the dominant orientation parallel to the longitudinal direction of casting (also the direction in which the samples were compressed) in samples that contained magnesium under all test conditions, but not in any sample that did not contain magnesium. For all deformation conditions, the peak stress was approximately 10% lower in material with the addition of magnesium. Furthermore, the differences in the peak strain between different temperatures are approximately 85% smaller if magnesium is present. The average activation energy for hot deformation was calculated to be 430 kJ mol−1 with the addition of magnesium and 450 kJ mol−1 without magnesium. The average size of dynamically recrystallized grains in both alloys showed a power law relation with the Zener–Hollomon parameter, DD~Z−n, and the exponent of value, n, is found to be 0.12. These results can be used to design optimized compositions and thermomechanical treatments of alloy 825 to maximize the useful service life under current service conditions. No experiments were conducted to investigate the effects of such changes on the service life and such experiments should now be performed.

ACS Style

Munir Al-Saadi; Wangzhong Mu; Christopher N. Hulme-Smith; Fredrik Sandberg; Pär G. Jönsson. Effect of Trace Magnesium Additions on the Dynamic Recrystallization in Cast Alloy 825 after One-Hit Hot-Deformation. Metals 2020, 11, 36 .

AMA Style

Munir Al-Saadi, Wangzhong Mu, Christopher N. Hulme-Smith, Fredrik Sandberg, Pär G. Jönsson. Effect of Trace Magnesium Additions on the Dynamic Recrystallization in Cast Alloy 825 after One-Hit Hot-Deformation. Metals. 2020; 11 (1):36.

Chicago/Turabian Style

Munir Al-Saadi; Wangzhong Mu; Christopher N. Hulme-Smith; Fredrik Sandberg; Pär G. Jönsson. 2020. "Effect of Trace Magnesium Additions on the Dynamic Recrystallization in Cast Alloy 825 after One-Hit Hot-Deformation." Metals 11, no. 1: 36.

Journal article
Published: 02 December 2020 in Metals
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The focus of the study was to define the origin of the inclusions in production-scale electro-slag remelting, (ESR) and electro-slag remelting under a protected pressure controlled atmosphere, (PESR), ingots. The inclusion characteristics in production samples were studied using both polished sample surfaces (two-dimensional (2-D) investigations) and inclusions extracted from steel samples by electrolytic extraction (three-dimensional (3-D) investigations) using SEM in combination with EDS. The results were compared to results from previously reported laboratory-, pilot-, and production-scale trials including electrode, remelted, and conventional ingots. The results show that primary, semi-secondary, and secondary inclusions exist in the remelted ingots. The most probable inclusion to survive from the electrode is a MgO-Al2O3 (spinel). It was also found that the ESR/PESR process slag acts in a similar way to a calcium treatment modification of alumina inclusions. On the whole, the most significant finding is that the overall cleanliness of the electrode including the inclusions in the electrode has an influence on the inclusion content of the ESR and PESR ingots.

ACS Style

Ewa Sjöqvist Persson; Andrey Karasev; Alec Mitchell; Pär G. Jönsson. Origin of the Inclusions in Production-Scale Electrodes, ESR Ingots, and PESR Ingots in a Martensitic Stainless Steel. Metals 2020, 10, 1620 .

AMA Style

Ewa Sjöqvist Persson, Andrey Karasev, Alec Mitchell, Pär G. Jönsson. Origin of the Inclusions in Production-Scale Electrodes, ESR Ingots, and PESR Ingots in a Martensitic Stainless Steel. Metals. 2020; 10 (12):1620.

Chicago/Turabian Style

Ewa Sjöqvist Persson; Andrey Karasev; Alec Mitchell; Pär G. Jönsson. 2020. "Origin of the Inclusions in Production-Scale Electrodes, ESR Ingots, and PESR Ingots in a Martensitic Stainless Steel." Metals 10, no. 12: 1620.

Research article
Published: 29 November 2020 in Ironmaking & Steelmaking
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The wear of industrial refractory materials was studied in contact with slag containing high amounts of FeO using the rotating finger technique. The thermodynamic equilibrium of the refractory slag systems was also determined in Thermo-calc® and FactSage™. The studied refractories were alumina spinel, zirconia, graphite, silicon carbide (SiC), magnesia-carbon (MgO-C), chromite (Cr2O3), and MgO-Spinel (MgO–Al2O3). The fingers were rotated in a FeOx (90wt%) – SiO2 (5wt%) – CaO (5wt%) slag for 3 hours in a molybdenum crucible at 100 RPM at 1700K. The wear of the refractory fingers was determined by dimensional changes and changes in composition of the slags. Only MgO-spinel refractories exhibited resistance to the slag. The thermodynamic equilibrium calculations were able to predict the experimental behavior when appropriate databases were used, with the exception of the chromite slag.

ACS Style

Jonas L. Svantesson; Björn Glaser; Mikael Ersson; Jesse F. White; Matej Imris; Pär G. Jönsson. Study of dynamic refractory wear by slags containing very high FeO contents under steelmaking conditions. Ironmaking & Steelmaking 2020, 48, 607 -618.

AMA Style

Jonas L. Svantesson, Björn Glaser, Mikael Ersson, Jesse F. White, Matej Imris, Pär G. Jönsson. Study of dynamic refractory wear by slags containing very high FeO contents under steelmaking conditions. Ironmaking & Steelmaking. 2020; 48 (5):607-618.

Chicago/Turabian Style

Jonas L. Svantesson; Björn Glaser; Mikael Ersson; Jesse F. White; Matej Imris; Pär G. Jönsson. 2020. "Study of dynamic refractory wear by slags containing very high FeO contents under steelmaking conditions." Ironmaking & Steelmaking 48, no. 5: 607-618.

Journal article
Published: 29 October 2020 in Energies
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The primary energy consumption and greenhouse gas emissions from nickel smelting products have been assessed through case studies using a process model based on mass and energy balance. The required primary energy for producing nickel metal, nickel oxide, ferronickel, and nickel pig iron is 174 GJ/t alloy (174 GJ/t contained Ni), 369 GJ/t alloy (485 GJ/t contained Ni), 110 GJ/t alloy (309 GJ/t contained Ni), and 60 GJ/t alloy (598 GJ/t contained Ni), respectively. Furthermore, the associated GHG emissions are 14 tCO2-eq/t alloy (14 tCO2-eq/t contained Ni), 30 t CO2-eq/t alloy (40 t CO2-eq/t contained Ni), 6 t CO2-eq/t alloy (18 t CO2-eq/t contained Ni), and 7 t CO2-eq/t alloy (69 t CO2-eq/t contained Ni). A possible carbon emission reduction can be observed by comparing ore type, ore grade, and electricity source, as well as allocation strategy. The suggested process model overcomes the limitation of a conventional life cycle assessment study which considers the process as a ‘black box’ and allows for an identification of further possibilities to implement sustainable nickel production.

ACS Style

Wenjing Wei; Peter Samuelsson; Anders Tilliander; Rutger Gyllenram; Pär Jönsson. Energy Consumption and Greenhouse Gas Emissions of Nickel Products. Energies 2020, 13, 5664 .

AMA Style

Wenjing Wei, Peter Samuelsson, Anders Tilliander, Rutger Gyllenram, Pär Jönsson. Energy Consumption and Greenhouse Gas Emissions of Nickel Products. Energies. 2020; 13 (21):5664.

Chicago/Turabian Style

Wenjing Wei; Peter Samuelsson; Anders Tilliander; Rutger Gyllenram; Pär Jönsson. 2020. "Energy Consumption and Greenhouse Gas Emissions of Nickel Products." Energies 13, no. 21: 5664.

Journal article
Published: 25 September 2020 in Metals
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Three CoCrFeMnNi high-entropy alloys (HEAs) were produced by vacuum induction melting, induction melting under inert gas atmosphere, and melting under inert gas atmosphere followed by air exposure, respectively. The different manufacturing conditions for the three investigated alloys resulted in different levels and types of inclusions. The alloys melted under vacuum or inert gas contained Al2O3 inclusions formed by impurity Al, due to its high oxidation tendency. The molten alloy exposed in air showed an excessive oxidation. During oxidation of the molten alloy in air, impurity Al was initially oxidized, and fine MnCr2O4 inclusions were formed rather than pure Al2O3 inclusions. This difference was analyzed based on thermodynamic calculations. Specifically, the influence of impurity content on the inclusion characteristics was investigated for the three HEAs. Moreover, the inclusion characteristics were found to have an influence on mechanical properties of the alloys also. In air-exposed HEA, smaller inclusions were formed, resulting in a higher dislocation density at the matrix/inclusion interface and thus strengthening of the HEA. Thus, it is proposed that atmospheric conditions could be an important factor to control the inclusion characteristics and to form fine inclusion particles, which could improve the mechanical properties of HEAs.

ACS Style

Nuri Choi; Nokeun Park; Jin-Kyung Kim; Andrey V. Karasev; Pär G. Jönsson; Joo Hyun Park. Influence of Manufacturing Conditions on Inclusion Characteristics and Mechanical Properties of FeCrNiMnCo Alloy. Metals 2020, 10, 1286 .

AMA Style

Nuri Choi, Nokeun Park, Jin-Kyung Kim, Andrey V. Karasev, Pär G. Jönsson, Joo Hyun Park. Influence of Manufacturing Conditions on Inclusion Characteristics and Mechanical Properties of FeCrNiMnCo Alloy. Metals. 2020; 10 (10):1286.

Chicago/Turabian Style

Nuri Choi; Nokeun Park; Jin-Kyung Kim; Andrey V. Karasev; Pär G. Jönsson; Joo Hyun Park. 2020. "Influence of Manufacturing Conditions on Inclusion Characteristics and Mechanical Properties of FeCrNiMnCo Alloy." Metals 10, no. 10: 1286.

Journal article
Published: 01 September 2020 in Metals
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Inclusions in steels and alloys are known to lower the resistance to deformation, as well as to lower the mechanical, corrosion and other properties. Studies of inclusions in nickel-based alloys are important since these materials could suffer from corrosion degradation in harsh operational conditions. This, in fact, could lead to a pitting initiation around the inclusions. Two industrial Ni-based alloys (alloy 718 and EP718) were investigated to determine the harmful effects of different inclusions on the corrosion resistance of Ni-based alloys. Specifically, the inclusion characteristics (such as composition, morphology, size, number and location) were determined for inclusions collected on film filters after electrolytic extraction and dissolution of a metal matrix around different inclusions on surfaces of metal samples after electrolytic extraction (EE). It was found that both Ni-based alloys contain various inclusion types: carbides (large size NbTi-C and small multicomponent carbides), nitrides TiNb-N and sulphides (TiNb-S in EP718 alloy). The most harmful effects on the corrosion resistance of metal were detected around sulphides and small carbides containing Mo, W, Cr. Dissolution effects were also observed around large carbides and nitrides, especially around inclusions larger than 10 µm. Moreover, the dissolution of a matrix around inclusions and clusters located on the grain boundaries were found to be 2.1–2.7 times larger compared to inclusions found inside of grains of the given alloy samples.

ACS Style

Ekaterina Alekseeva; Andrey Karasev; Pär G. Jönsson; Aleksey Alkhimenko. Effect of Inclusions on the Corrosion Properties of the Nickel-Based Alloys 718 and EP718. Metals 2020, 10, 1177 .

AMA Style

Ekaterina Alekseeva, Andrey Karasev, Pär G. Jönsson, Aleksey Alkhimenko. Effect of Inclusions on the Corrosion Properties of the Nickel-Based Alloys 718 and EP718. Metals. 2020; 10 (9):1177.

Chicago/Turabian Style

Ekaterina Alekseeva; Andrey Karasev; Pär G. Jönsson; Aleksey Alkhimenko. 2020. "Effect of Inclusions on the Corrosion Properties of the Nickel-Based Alloys 718 and EP718." Metals 10, no. 9: 1177.

Journal article
Published: 26 August 2020 in Processes
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The melting time of scrap is a factor that affects the Electrical Energy (EE) consumption of the Electric Arc Furnace (EAF) process. The EE consumption itself stands for most of the total energy consumption during the process. Three distinct representations of scrap, based partly on the apparent density and shape of scrap, were created to investigate the effect of scrap on the accuracy of a statistical model predicting the EE consumption of an EAF. Shapley Additive Explanations (SHAP) was used as a tool to investigate the effects by each scrap category on each prediction of a selected model. The scrap representation based on the shape of scrap consistently resulted in the best performing models while all models using any of the scrap representations performed better than the ones without any scrap representation. These results were consistent for all four distinct and separately used cleaning strategies on the data set governing the models. In addition, some of the main scrap categories contributed to the model prediction of EE in accordance with the expectations and experience of the plant engineers. The results provide significant evidence that a well-chosen scrap categorization is important to improve a statistical model predicting the EE and that experience on the specific EAF under study is essential to evaluate the practical usefulness of the model.

ACS Style

Leo S. Carlsson; Peter B. Samuelsson; Pär G. Jönsson. Modeling the Effect of Scrap on the Electrical Energy Consumption of an Electric Arc Furnace. Processes 2020, 8, 1044 .

AMA Style

Leo S. Carlsson, Peter B. Samuelsson, Pär G. Jönsson. Modeling the Effect of Scrap on the Electrical Energy Consumption of an Electric Arc Furnace. Processes. 2020; 8 (9):1044.

Chicago/Turabian Style

Leo S. Carlsson; Peter B. Samuelsson; Pär G. Jönsson. 2020. "Modeling the Effect of Scrap on the Electrical Energy Consumption of an Electric Arc Furnace." Processes 8, no. 9: 1044.