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Hernando, J. C., Elfsberg, J., Dahle, A. & Diószegi, A. (2019). Evolution of primary austenite and its influence on eutectic microstructures during coarsening of Fe-C-Si alloys. Materialia, 7, Article ID 100391.
Open this publication in new window or tab >>Evolution of primary austenite and its influence on eutectic microstructures during coarsening of Fe-C-Si alloys
2019 (English)In: Materialia, ISSN 2589-1529, Vol. 7, article id 100391Article in journal (Refereed) Published
Abstract [en]

The evolution of primary austenite morphology during isothermal coarsening has been studied in the three main Fe–C–Si alloys used in industry, LGI, CGI, and SGI. The dendritic microstructure increases length scale during coarsening accompanied by fragmentation and coalescence of austenite crystals. The morphological parameters, SDAS, Mγ, DhydID, and Dγ show a linear relation with the cube root of coarsening time, t1/3, with similar rates for the three different Fe–C–Si alloys. The eutectic microstructures after coarsening of primary austenite in CGI and SGI alloys are not significantly affected by the surface area of primary austenite and the size of the interdendritic regions. Fraction, nodularity, shape distribution of graphite particles and the number of nodules and eutectic cells are similar when studied as a function of coarsening time. These results suggest that the nucleation frequency in CGI and SGI, and the growth of eutectic microstructures in CGI, are not significantly influenced by the morphology of primary austenite.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Solidification; Coarsening; Dendrites; Austenite; Eutectic; EBSD; CGI; SGI
National Category
Materials Engineering
Identifiers
urn:nbn:se:hj:diva-43552 (URN)10.1016/j.mtla.2019.100391 (DOI)2-s2.0-85068795536 (Scopus ID)PP JTH 2019 embargo 24 (Local ID)PP JTH 2019 embargo 24 (Archive number)PP JTH 2019 embargo 24 (OAI)
Funder
VinnovaKnowledge Foundation
Note

Included in thesis in manuscript form with the title "Evolution of primary austenite and its influence on eutectic microstructures during coarsening of Fe-C-Si alloys".

Available from: 2019-04-29 Created: 2019-04-29 Last updated: 2019-08-06Bibliographically approved
Ghassemali, E., Hernando, J. C., Stefanescu, D. M., Diószegi, A., Jarfors, A. E. .., Dluhoš, J. & Petrenec, M. (2019). Revisiting the graphite nodule in ductile iron. Scripta Materialia, 161, 66-69
Open this publication in new window or tab >>Revisiting the graphite nodule in ductile iron
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2019 (English)In: Scripta Materialia, ISSN 1359-6462, E-ISSN 1872-8456, Vol. 161, p. 66-69Article in journal (Refereed) Published
Abstract [en]

The growth mechanism of graphite nodules in ductile iron was experimentally investigated using high-resolution 3D tomography of an individual graphite nodule in a near-eutectic ductile iron. The dual beam scanning electron microscopy (FIB-SEM) technique was used for this purpose. Iron particles elongated in the radial direction were observed inside a graphite nodule. Some micro-voids were detected inside the nodule, mostly located at the end of the iron particles. These observations were compared with established theories about the growth of graphite nodules and iron entrapment/engulfment in between the graphite sectors during solidification of ductile iron. 

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
3D reconstruction, FIB, Growth mechanism, Solidification, Ductility, Graphite, Iron, Scanning electron microscopy, 3-d tomographies, Graphite nodules, Growth mechanisms, High resolution, Iron Particles, Micro voids, Radial direction, Cast iron
National Category
Materials Engineering
Identifiers
urn:nbn:se:hj:diva-41986 (URN)10.1016/j.scriptamat.2018.10.018 (DOI)000450375500015 ()2-s2.0-85055115924 (Scopus ID)JTHMaterialIS (Local ID)JTHMaterialIS (Archive number)JTHMaterialIS (OAI)
Available from: 2018-11-07 Created: 2018-11-07 Last updated: 2019-04-29Bibliographically approved
Hernando, J. C., Elfsberg, J., Ghassemali, E., Dahle, A. & Diószegi, A. (2019). The effect of coarsening of primary austenite on the ultimate tensile strength of hypoeutectic compacted graphite Fe-C-Si alloys. Scripta Materialia, 168, 33-37
Open this publication in new window or tab >>The effect of coarsening of primary austenite on the ultimate tensile strength of hypoeutectic compacted graphite Fe-C-Si alloys
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2019 (English)In: Scripta Materialia, ISSN 1359-6462, E-ISSN 1872-8456, Vol. 168, p. 33-37Article in journal (Refereed) Published
Abstract [en]

The effect of primary austenite morphology on the ultimate tensile strength (UTS) of hypoeutectic compacted graphite Fe-C-Si alloys (CGI) is studied by isothermal coarsening experiments. Secondary dendrite arm spacing (SDAS) and the morphological characteristics related to the surface area of primary austenite, M γ and D ID Hyd , increase with the cube root of coarsening time. UTS decreases linearly with increasing coarseness of primary austenite. The eutectic and eutectoid microstructures are unaffected by the primary austenite morphology. These observations demonstrate the strong influence of primary austenite morphology on the mechanical properties of hypoeutectic CGI alloys.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Coarsening, Compacted graphite iron, Dendrites, Mechanical properties, UTS, Austenite, Dendrites (metallography), Graphite, Morphology, Ostwald ripening, Silicon alloys, Tensile strength, Morphological characteristic, Primary austenite, Secondary dendrite arm spacing, Si alloys, Surface area, Ultimate tensile strength, Iron alloys
National Category
Materials Engineering
Identifiers
urn:nbn:se:hj:diva-43550 (URN)10.1016/j.scriptamat.2019.04.010 (DOI)000470798400008 ()2-s2.0-85064563538 (Scopus ID)PP JTH 2019 embargo 24 (Local ID)PP JTH 2019 embargo 24 (Archive number)PP JTH 2019 embargo 24 (OAI)
Funder
Vinnova, 2013-03303; 2013-04720Knowledge Foundation, 2018-0033
Available from: 2019-04-29 Created: 2019-04-29 Last updated: 2019-08-06Bibliographically approved
Svidró, J. T. & Diószegi, A. (2018). A novel measurement method to study the thermal aspects of moulding mixture decomposition. In: 73rd World Foundry Congress "Creative Foundry", WFC 2018 - Proceedings: . Paper presented at 73rd World Foundry Congress "Creative Foundry", 23-27 September 2018, Kraków, Poland (pp. 113-114). Stowarzyszenie Techniczne Odlewnikow Polskich/Polish Foundrymen's Association
Open this publication in new window or tab >>A novel measurement method to study the thermal aspects of moulding mixture decomposition
2018 (English)In: 73rd World Foundry Congress "Creative Foundry", WFC 2018 - Proceedings, Stowarzyszenie Techniczne Odlewnikow Polskich/Polish Foundrymen's Association , 2018, p. 113-114Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

A wide variety of moulding mixtures are extensively used in the process of sand casting of metal components. The sector is continuously developing in production volume, moreover the expectations from the customers are increasing on monthly basis, also from the quality point of view. Even though mould and core manufacturing are well-organized processes in most foundries, technological problems still appear which may lead to casting defects. These trends are forcing metal casters to come up with fitting strategies to solve their daily production challenges, while their suppliers are expected to keep up the continuous development of their existing foundry products and to find innovative solutions. Research on moulding materials and their properties must also take the step forward accordingly to generate the necessary new knowledge. This paper summarizes the latest results of a novel measurement method suitable for studying the degradation characteristics of different moulding materials from a new perspective. The fundamentals of the method are based on thermal analysis, focusing on the heat absorption behaviour of sand mixtures regardless of binder type/amount or manufacturing process. 

Place, publisher, year, edition, pages
Stowarzyszenie Techniczne Odlewnikow Polskich/Polish Foundrymen's Association, 2018
Keywords
Cold-box, Greensand, Moulding mixture, Thermal analysis, Cold boxes, Continuous development, Degradation characteristics, Innovative solutions, Manufacturing process, Measurement methods, Mixture decomposition, Foundries, Mixtures, Thermoanalysis, Molding
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-43375 (URN)2-s2.0-85062275328 (Scopus ID)9788390430638 (ISBN)
Conference
73rd World Foundry Congress "Creative Foundry", 23-27 September 2018, Kraków, Poland
Available from: 2019-03-22 Created: 2019-03-22 Last updated: 2019-03-22Bibliographically approved
Hellström, K., Svidró, P., Diaconu, L. V. & Diószegi, A. (2018). Density variations during solidification of grey cast Iron. Paper presented at 11th International Symposium on the Science and Processing of Cast Iron, SPCI-XI 2017, Jönköping, Sweden, 4-7 September 2017. Materials Science Forum, 155-162
Open this publication in new window or tab >>Density variations during solidification of grey cast Iron
2018 (English)In: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, p. 155-162Article in journal (Refereed) Published
Abstract [en]

As part of moving towards a sustainable production of diesel engines for heavy vehicle applications, the ability to predict casting defects has become ever so important. In order to model the solidification process for cast components correctly, it is of essence to know how the material will actually behave. To produce sound castings, often of complex geometry, the industry relies on various simulation software for the prediction and avoidance of defects. Thermophysical properties, such as density, play an important part in these simulations. Previous measurements of how the volume of liquid grey iron changes with temperature has been made with a conventional dilatometer. Measurements have also been made in the austenitic range, then on iron-carbon-silicon alloys with a carbon content lower than 1.5 wt%. Based on these measurements the density variations during solidification were calculated. The scope for this paper is to model the volume changes during solidification with the control volume finite difference method, using data from the density measurements. 

Place, publisher, year, edition, pages
Trans Tech Publications, 2018
Keywords
Density, Grey cast iron, Measurement, Modelling, Simulation, Casting, Computer software, Defects, Density (specific gravity), Diesel engines, Finite difference method, Models, Silicon alloys, Solidification, Technology transfer, Thermodynamic properties, Complex geometries, Control volume finite difference methods, Density variations, Simulation software, Solidification process, Sustainable production, Cast iron
National Category
Materials Engineering
Identifiers
urn:nbn:se:hj:diva-41280 (URN)10.4028/www.scientific.net/MSF.925.155 (DOI)XYZ ()2-s2.0-85050011430 (Scopus ID)9783035710557 (ISBN)
Conference
11th International Symposium on the Science and Processing of Cast Iron, SPCI-XI 2017, Jönköping, Sweden, 4-7 September 2017
Available from: 2018-08-28 Created: 2018-08-28 Last updated: 2019-01-25Bibliographically approved
Svidró, P., Diószegi, A., Jönsson, P. G. & Stefanescu, D. M. (2018). Determination of pressure in the extradendritic liquid area during solidification. Journal of thermal analysis and calorimetry (Print), 132(3), 1661-1667
Open this publication in new window or tab >>Determination of pressure in the extradendritic liquid area during solidification
2018 (English)In: Journal of thermal analysis and calorimetry (Print), ISSN 1388-6150, E-ISSN 1588-2926, Vol. 132, no 3, p. 1661-1667Article in journal (Refereed) Published
Abstract [en]

Complex-shaped lamellar graphite iron castings are susceptible to casting defects related to the volume change during solidification. The formations of these recurring defects are caused by the flow of the liquid in the intradendritic area, between the austenite dendrite arms, and in the extradendritic area between the austenite grains. The conditions for the liquid flow, in turn, are determined by the solidification behavior. The present study suggests a new measurement method and a novel calculation algorithm to determine the pressure of the extradendritic liquid during solidification. The method involves a spherical sample suspended in a measurement device, where the temperature and the volume changes are measured during solidification. The calculation algorithm is based on the numerical interpretation of the Clausius-Clapeyron equation where the temperature variation, the volume change and the released latent heat are processed to determine the local pressure of the extradendritic liquid area during solidification.

Place, publisher, year, edition, pages
Springer, 2018
Keywords
Volume change measurement; Fourier thermal analysis; Clausius-Clapeyron equation; Extradendritic liquid pressure; Lamellar graphite iron
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-41094 (URN)10.1007/s10973-018-7088-z (DOI)000432215600022 ()2-s2.0-85042940249 (Scopus ID)JTHMaterialIS (Local ID)JTHMaterialIS (Archive number)JTHMaterialIS (OAI)
Available from: 2018-08-03 Created: 2018-08-03 Last updated: 2019-03-05Bibliographically approved
Svidró, P., Diószegi, A. & Jönsson, P. G. (2018). Extended method of volume change measurements during solidification of lamellar graphite iron. Paper presented at 11th International Symposium on the Science and Processing of Cast Iron, SPCI-XI 2017, Jönköping, Sweden, 4-7 September 2017. Materials Science Forum, 925, 163-170
Open this publication in new window or tab >>Extended method of volume change measurements during solidification of lamellar graphite iron
2018 (English)In: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 925, p. 163-170Article in journal (Refereed) Published
Abstract [en]

Lamellar graphite iron (LGI) is an important technical alloy used to produce cast components for the automotive and the marine industry. The performance of the component is defined by the solidification sequence. Therefore, a lot of research work has been done in the field of solidification. The present work introduces a new measurement approach that combines advanced dilatation measurements with thermal analysis to investigate the solidification of LGI. The method involves a thermally balanced spherical sample. The temperature values are measured in the geometrical center and on the surface of the sample. The released heat of solidification is calculated by using the Fourier Thermal Analysis (FTA) method. The displacement values are measured on the surface of the sample. The volume change is calculated from the displacement data. The dilatation results clearly shows the advantage of the multidirectional measurement. 

Place, publisher, year, edition, pages
Trans Tech Publications, 2018
Keywords
Lamellar graphite iron, Thermal analysis, Volume change, Graphite, Marine industry, Solidification, Thermoanalysis, Cast components, Displacement value, Graphite iron, Solidification sequence, Technical alloys, Temperature values, Volume change measurement, Cast iron
National Category
Materials Engineering
Identifiers
urn:nbn:se:hj:diva-41283 (URN)10.4028/www.scientific.net/MSF.925.163 (DOI)XYZ ()2-s2.0-85050010354 (Scopus ID)9783035710557 (ISBN)
Conference
11th International Symposium on the Science and Processing of Cast Iron, SPCI-XI 2017, Jönköping, Sweden, 4-7 September 2017
Funder
Knowledge Foundation
Available from: 2018-08-28 Created: 2018-08-28 Last updated: 2019-01-25Bibliographically approved
Diószegi, A. & Svidró, P. (2018). Method of and device for analysing a phase transformation of a material. us US2018284043.
Open this publication in new window or tab >>Method of and device for analysing a phase transformation of a material
2018 (English)Patent (Other (popular science, discussion, etc.))
Abstract [en]

A method of analyzing a phase transformation process of a material comprises providing a spherical sample of the material, measuring and recording a first data series of core temperature at the sample's center of gravity, measuring and recording a respective second data series of temperature at the sample's periphery, measuring and recording a respective third data series of radial displacements at the sample's periphery, and calculating a change in pressure in the sample at a plurality of points in time based on first, second and third said data series.

National Category
Materials Engineering
Identifiers
urn:nbn:se:hj:diva-41982 (URN)
Patent
US US2018284043 (2018-10-04)
Available from: 2018-11-06 Created: 2018-11-06 Last updated: 2018-11-06
Svidró, J. T. & Diószegi, A. (2018). New possibilities in the thermal analysis of moulding materials. In: 73rd World Foundry Congress "Creative Foundry", WFC 2018 - Proceedings: . Paper presented at 73rd World Foundry Congress "Creative Foundry", 23-27 September 2018, Kraków, Poland (pp. 25-26). Stowarzyszenie Techniczne Odlewnikow Polskich/Polish Foundrymen's Association
Open this publication in new window or tab >>New possibilities in the thermal analysis of moulding materials
2018 (English)In: 73rd World Foundry Congress "Creative Foundry", WFC 2018 - Proceedings, Stowarzyszenie Techniczne Odlewnikow Polskich/Polish Foundrymen's Association , 2018, p. 25-26Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

Moulding material related studies within research activities concerning foundry technology have always been limited, despite the significant effect of moulding mixtures on the quality of cast parts. One reason behind this trend is the difficulty in interpreting results of such complex systems like moulds and cores. This paper provides a new possibility to study the heat absorption performance of materials used as moulding media in metal casting processes. By further developing the Fourier thermal analysis method of cores and moulds introduced by earlier authors, the investigation of unbonded sand has become available. Heat absorption properties of the components can be hereby separated and studied respectively. Thermal analyses were performed on sphere shaped, resin bonded cores with various binder levels and on unbonded sand samples. The temperature data collected in two points of the samples were then used for the calculation of novel thermophysical properties. The results revealed not only quantitative but qualitative differences in the characteristics of binder decomposition processes, providing deeper understanding on the thermal behavior of moulding materials. The outcome of the research provides more accurate data, which is the key for improved simulation of casting processes.

Place, publisher, year, edition, pages
Stowarzyszenie Techniczne Odlewnikow Polskich/Polish Foundrymen's Association, 2018
Keywords
Casting, Foundry sand, Fourier thermal analysis, Heat absorption, Moulding material, Binders, Foundries, Metal casting, Metal castings, Molding, Molds, Thermoanalysis, Thermodynamic properties, Decomposition process, Foundry technology, Fourier, Heat absorption, Qualitative differences, Research activities, Temperature data, Thermal behaviors
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-43371 (URN)2-s2.0-85062269103 (Scopus ID)9788390430638 (ISBN)
Conference
73rd World Foundry Congress "Creative Foundry", 23-27 September 2018, Kraków, Poland
Available from: 2019-03-21 Created: 2019-03-21 Last updated: 2019-03-21Bibliographically approved
Svidró, J. T. & Diószegi, A. (2018). Novel Measurement Method to Study Thermal Aspects of Molding Mixture Decomposition. Journal of Casting & Materials Engineering, 2(3), 63-66
Open this publication in new window or tab >>Novel Measurement Method to Study Thermal Aspects of Molding Mixture Decomposition
2018 (English)In: Journal of Casting & Materials Engineering, E-ISSN 2543-9901, Vol. 2, no 3, p. 63-66Article in journal (Refereed) Published
Abstract [en]

A wide variety of molding mixtures are extensively used in the process of the sand casting of metal components today. The sector is continuously developing in production volume; moreover, the expectations of customers are increasing on a monthly basis (also from a quality point of view). Even though mold and core manufacturing are well-organized routines in most foundries, technological problems still appear that can lead to technological problems and casting defects. These trends are forcing metal casters to come up with fitting strategies to solve their daily production challenges, while their suppliers are expected to keep up the continuous development of their existing foundry products and to find innovative solutions as well as new material combinations. Research on molding materials and their properties must, therefore, take a step forward accordingly to generate the necessary new knowledge to understand the behavior of mold and core mixtures during casting.

This paper summarizes the latest results of a novel measurement method suitable for studying the degradation characteristics of different molding materials from a new perspective. The fundamentals of the method are based on a thermal analysis, focusing on the heat-absorption behavior of greensand and two types of chemically bonded sands regardless of the binder type and amount or the manufacturing process.

Place, publisher, year, edition, pages
AGH University of Science and Technology Pres, 2018
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-42097 (URN)10.7494/jcme.2018.2.3.63 (DOI)
Available from: 2018-11-20 Created: 2018-11-20 Last updated: 2018-11-20
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-3024-9005

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