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Publications (10 of 150) Show all publications
Domeij, B. & Diószegi, A. (2024). A review of dendritic austenite in cast irons. Paper presented at 7th Keith Millis symposium on Ductile Iron, October 18–20, 2023, Atlanta, GA, USA. International Journal of metalcasting
Open this publication in new window or tab >>A review of dendritic austenite in cast irons
2024 (English)In: International Journal of metalcasting, ISSN 1939-5981, E-ISSN 2163-3193Article, review/survey (Refereed) Epub ahead of print
Abstract [en]

Solidification of cast irons usually involves dendritic growth of austenite. This article presents a literature survey about the dendrites in cast irons, their consequences and how they may be manipulated. The literature review is supplemented with relevant micrographs from our research. While austenite usually transforms into ferrite or pearlite, the dendrites limit where liquid flows, where eutectic grows, and where segregated elements go. The amount and shape of dendrites show correlations with tensile strength in pearlitic gray and compacted graphite irons. There are also indications that a coarse dendrite grain structure may be beneficial to tensile strength. The dendrite grain structure depends on melting process parameters and shows sensitivity to melt treatment. The evolution of scale of dendrite arms and their spacing under isothermal condition is by now fairly well-understood; however, work remains to better understand its evolution during cooling and its interaction with the eutectic. The amount and shape of dendrites are less understood in irons of near-eutectic and hypereutectic composition, in particular mixtures of dendrites of distinct scales, associated with regions of distinct graphite morphology. While significant advances have been made in recent years, the role and control of dendrites remain a relatively unexplored area of research with potential to improve production and properties of cast irons.

Place, publisher, year, edition, pages
Springer, 2024
Keywords
austenite grains, cast iron, component casting, dendrites, microstructure control, primary austenite, Austenite, Casting, Crystal microstructure, Dendrites (metallography), Eutectics, Grain size and shape, Graphite, Morphology, Pearlite, Solidification, Tensile strength, Austenite grain, Dendrite, Dendritic growth, Dendritics, Liquid flow, Literature reviews, Literature survey
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-63445 (URN)10.1007/s40962-023-01239-8 (DOI)001144162400001 ()2-s2.0-85182437766 (Scopus ID)HOA;;933680 (Local ID)HOA;;933680 (Archive number)HOA;;933680 (OAI)
Conference
7th Keith Millis symposium on Ductile Iron, October 18–20, 2023, Atlanta, GA, USA
Funder
Knowledge Foundation, 20210082
Note

Acknowledgements: "This paper is an invited submission to IJMC selected from presentations at the 7th Keith Millis symposium on Ductile Iron held October 18–20, 2023, at the Crown Plaza Atlanta Perimeter at Ravinia, Atlanta, GA. It is published in the IJMC by permission of the DIS (Ductile Iron Society)".

Available from: 2024-01-30 Created: 2024-01-30 Last updated: 2024-02-07
Belov, I., Matsushita, T., Fourlakidis, V., Sundaram, D. & Diószegi, A. (2023). A simulation and experimental methodology to evaluate conditions for gas penetration from FURAN sand core into a cast iron melt. In: : . Paper presented at 17th European Congress and Exhibition on Advance Materials and Processes, FEMS EUROMAT 2023, 03-07 September 2023, Germany.
Open this publication in new window or tab >>A simulation and experimental methodology to evaluate conditions for gas penetration from FURAN sand core into a cast iron melt
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2023 (English)Conference paper, Oral presentation only (Refereed)
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-63231 (URN)
Conference
17th European Congress and Exhibition on Advance Materials and Processes, FEMS EUROMAT 2023, 03-07 September 2023, Germany
Available from: 2024-01-09 Created: 2024-01-09 Last updated: 2024-01-10Bibliographically approved
Belov, I., Fourlakidis, V., Domeij, B., Matsushita, T. & Diószegi, A. (2023). A thermal conductivity model for grey iron. International Journal of metalcasting
Open this publication in new window or tab >>A thermal conductivity model for grey iron
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2023 (English)In: International Journal of metalcasting, ISSN 1939-5981, E-ISSN 2163-3193Article in journal (Refereed) Epub ahead of print
Abstract [en]

Thermal conductivity is an important property for many iron cast components, and the lack of widely accepted thermal conductivity model for cast iron, especially grey cast iron, motivates the efforts in this research area. The present study contributes to understanding the effects alloy microstructure has on thermal conductivity. A thermal conductivity model for a pearlitic cast iron has been proposed, based on the as-cast alloy composition and microstructural parameters obtained at different solidification rates. According to the model, available parallel heat transfer paths formed by connected graphite flakes across eutectic cells are determined by the space between dendrite arms. The uncertainties both for model inputs and for validation measurements have been estimated. Sensitivity analysis has been conducted to result in better understanding of the model behaviour. The agreement between modelled and measured thermal conductivities has been achieved within 5% on the average for the investigated samples.

Place, publisher, year, edition, pages
Springer, 2023
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-62560 (URN)10.1007/s40962-023-01157-9 (DOI)001073921500002 ()2-s2.0-85172984032 (Scopus ID)HOA;;907155 (Local ID)HOA;;907155 (Archive number)HOA;;907155 (OAI)
Funder
Knowledge Foundation, 20210082, 20180033
Available from: 2023-10-02 Created: 2023-10-02 Last updated: 2024-01-10
Diószegi, A. & Diaconu, L. V. (2023). Advances in metallography and stereology of cast iron. In: : . Paper presented at New Trends in Metallic Material Processing: 4th Edition, Special Edition: SGI 80 years / Iulian Riposan 75 years, 16–18 May 2023, Bucharest, Romania.
Open this publication in new window or tab >>Advances in metallography and stereology of cast iron
2023 (English)Conference paper, Oral presentation only (Refereed)
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-63278 (URN)
Conference
New Trends in Metallic Material Processing: 4th Edition, Special Edition: SGI 80 years / Iulian Riposan 75 years, 16–18 May 2023, Bucharest, Romania
Available from: 2024-01-10 Created: 2024-01-10 Last updated: 2024-01-10Bibliographically approved
Matsushita, T., Belov, I., Svidró, J. T., Svidró, J. & Diószegi, A. (2023). Analysis of the penetration behavior of molten cast iron into the sand mold. International Journal of metalcasting
Open this publication in new window or tab >>Analysis of the penetration behavior of molten cast iron into the sand mold
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2023 (English)In: International Journal of metalcasting, ISSN 1939-5981, E-ISSN 2163-3193Article in journal (Refereed) Epub ahead of print
Abstract [en]

An evaluation method for the initial penetration of molten cast iron into the sand mold was suggested based on the laboratory-scale penetration experiments for the cast iron. The horizontal penetration depth of the molten cast iron into the sand core was analyzed using the capillary model. The early stage of the penetration was discussed, and it was clarified that the penetration is not stopped by the solidification but is stopped by the decreasing of the equivalent pore radius. It was explained that the equivalent pore radius decreases with increasing the penetration depth, and the penetration is stopped when the critical pressure, i.e., the pressure required for the penetration, becomes higher than the pressure which is acting on the penetration front. Based on the analysis, an evaluation method of the penetration of depth at the early stage of the penetration was suggested. The analysis method was applied for the other type of metals (mercury and steel) as well, and reasonable results were obtained. A simplified finite-element model of liquid iron penetration into a sand core was developed, accounting for heat exchange between the melt and the porous medium, at different pore geometries.

Place, publisher, year, edition, pages
Springer, 2023
Keywords
penetration, molten metal, porous medium, casting, surface defects, cast iron, finite element simulation
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-62796 (URN)10.1007/s40962-023-01169-5 (DOI)001089876100004 ()2-s2.0-85174849547 (Scopus ID)HOA;;62796 (Local ID)HOA;;62796 (Archive number)HOA;;62796 (OAI)
Funder
Knowledge Foundation, 20180033, 20200057, 20210082
Available from: 2023-10-30 Created: 2023-10-30 Last updated: 2023-11-28
Diaconu, L. V. & Diószegi, A. (2023). Density variations at solidification of grey cast iron. In: : . Paper presented at New Trends in Metallic Material Processing: 4th Edition, Special Edition: SGI 80 years / Iulian Riposan 75 years, 16–18 May 2023, Bucharest, Romania.
Open this publication in new window or tab >>Density variations at solidification of grey cast iron
2023 (English)Conference paper, Oral presentation only (Refereed)
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-63279 (URN)
Conference
New Trends in Metallic Material Processing: 4th Edition, Special Edition: SGI 80 years / Iulian Riposan 75 years, 16–18 May 2023, Bucharest, Romania
Available from: 2024-01-10 Created: 2024-01-10 Last updated: 2024-01-10Bibliographically approved
Domeij, B., Elfsberg, J. & Diószegi, A. (2023). Evolution of Dendritic Austenite in Parallel With Eutectic in Compacted Graphite Iron Under Three Cooling Conditions. Metallurgical and materials transactions. B, process metallurgy and materials processing science, 54, 2395-2410
Open this publication in new window or tab >>Evolution of Dendritic Austenite in Parallel With Eutectic in Compacted Graphite Iron Under Three Cooling Conditions
2023 (English)In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 54, p. 2395-2410Article in journal (Refereed) Published
Abstract [en]

Shrinkage defects are common problems in industrially produced metal cast components. Local density changes occur during freezing, which demand material transport between parts of the casting, often involving flow of liquid through partially solid regions. Cast alloys typically freeze with a dendritic morphology, which large interface against the liquid restricts liquid flow. Recent research also indicates that this dendritic structure has an impact on the mechanical properties of the final material. For these reasons it is important to understand and predict the evolution of this structure through the solidification of cast alloys. In this work, the evolution of the dendritic austenite structure is investigated in a near-eutectic compacted graphite iron solidified under three different cooling conditions. The solidification was interrupted by water quenching, enabling characterization of the dendritic austenite structure at different stages of solidification. Higher cooling rate was found to promote a more coherent dendritic austenite structure which constituted a larger volume fraction. In parallel with growth of the eutectic, the amount of dendritic austenite in extra-eutectic regions continued to rise. This rise was associated with both tip growth of new dendrites and with growth by thickening of existing dendrites.

Place, publisher, year, edition, pages
Springer, 2023
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-62167 (URN)10.1007/s11663-023-02842-0 (DOI)001023412900001 ()2-s2.0-85164154670 (Scopus ID)HOA;;897178 (Local ID)HOA;;897178 (Archive number)HOA;;897178 (OAI)
Funder
Vinnova, 2013-04720Knowledge Foundation
Available from: 2023-08-16 Created: 2023-08-16 Last updated: 2024-01-09Bibliographically approved
Domeij, B., Belov, I., Fourlakidis, V. & Diószegi, A. (2023). Implementation and Validation of Casting Simulation Methodology for Diagnostics of Lamellar Graphite Iron. International Journal of metalcasting, 17, 1507-1517
Open this publication in new window or tab >>Implementation and Validation of Casting Simulation Methodology for Diagnostics of Lamellar Graphite Iron
2023 (English)In: International Journal of metalcasting, ISSN 1939-5981, E-ISSN 2163-3193, Vol. 17, p. 1507-1517Article in journal (Refereed) Published
Abstract [en]

This paper describes and validates a methodology for implementation of full-scale sand-casting simulation in a general-purpose finite element software, including mold filling, heat transport, solidification kinetics, chemical microsegregation and prediction of microstructure and material properties. The solidification model, customized for gray cast iron, includes novel methods for handling interaction between parallel dendritic and eutectic solidification modes and its impact of their interaction on the final microstructure. The validation involves a previously published gray iron casting experiment and involves comparison of simulated and experimental cooling curves, microstructure parameters and tensile strength. We believe that this is valuable to researchers and engineers seeking to improve the state of the art of casting simulation tools.

Place, publisher, year, edition, pages
Springer, 2023
Keywords
simulation, casting, solidification, gray cast iron, level-set method
National Category
Materials Engineering
Identifiers
urn:nbn:se:hj:diva-58657 (URN)10.1007/s40962-022-00892-9 (DOI)000864958100001 ()2-s2.0-85139516629 (Scopus ID)HOA;;837798 (Local ID)HOA;;837798 (Archive number)HOA;;837798 (OAI)
Funder
Knowledge Foundation
Available from: 2022-10-18 Created: 2022-10-18 Last updated: 2024-01-10Bibliographically approved
Domeij, B., Belov, I., Fourlakidis, V. & Diószegi, A. (2023). Metodik för kort väg mellan forskning och gjutsimuleringsverktyg. Gjuteriet (1), 12-13
Open this publication in new window or tab >>Metodik för kort väg mellan forskning och gjutsimuleringsverktyg
2023 (Swedish)In: Gjuteriet, E-ISSN 0017-0682, no 1, p. 12-13Article in journal (Other (popular science, discussion, etc.)) Published
National Category
Materials Engineering
Identifiers
urn:nbn:se:hj:diva-63280 (URN)
Available from: 2024-01-10 Created: 2024-01-10 Last updated: 2024-01-10Bibliographically approved
Fourlakidis, V., Hernando, J. C. & Diószegi, A. (2023). Primary Austenite Morphology and Tensile Strength in CGI for Different C Contents, Cooling Conditions and Nodularity. International Journal of metalcasting
Open this publication in new window or tab >>Primary Austenite Morphology and Tensile Strength in CGI for Different C Contents, Cooling Conditions and Nodularity
2023 (English)In: International Journal of metalcasting, ISSN 1939-5981, E-ISSN 2163-3193Article in journal (Refereed) Epub ahead of print
Abstract [en]

Compacted graphite iron (CGI) is a good option for the blocks and cylinder heads in heavy duty engines due to their well-balanced thermal and mechanical properties. In this work, a remelting technique has been utilized for the production of CGI with different nodularity (10 and 20%), C contents (CE=3.5, 3.8, 4.2) and under different solidification and cooling rates. The employed experimental parameters had a sizeable influence on the morphology and fraction of the inter-dendritic structure and resulted in ultimate tensile strength (UTS) that ranged from 335 to 456 MPa and 371 to 521 MPa for the 10 and 20% nodularity, respectively. The results show that the UTS is linearly related to the solidification time and the microstructural parameter that express the scale length of the inter-dendritic region. Different CE and nodularity provide different relationships between UTS, solidification time and microstructure. Finally, an empirical model has been developed for the prediction of the UTS.

Place, publisher, year, edition, pages
Springer, 2023
Keywords
tensile strength, nodularity, inter-dendritic region, compacted graphite iron (CGI), solidification time, remelting technique
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-63093 (URN)10.1007/s40962-023-01219-y (DOI)001127393800001 ()2-s2.0-85180253093 (Scopus ID)HOA;;1821782 (Local ID)HOA;;1821782 (Archive number)HOA;;1821782 (OAI)
Funder
Knowledge Foundation, 20210082
Note

This paper is an invited submission to IJMC selected from presentations at the 7th Keith Millis Symposium on Ductile Iron held October 18–20, 2023, at the Crown Plaza Atlanta Perimeter at Ravinia, Atlanta, GA. It is published in the IJMC by permission of the DIS (Ductile Iron Society).

Available from: 2023-12-21 Created: 2023-12-21 Last updated: 2024-01-10Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-3024-9005

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