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Hellström, K., Diószegi, A. & Diaconu, L. (2017). A broad literature review of density measurements of liquid cast iron. Metals, 7(5), Article ID 165.
Open this publication in new window or tab >>A broad literature review of density measurements of liquid cast iron
2017 (English)In: Metals, ISSN 2075-4701, Vol. 7, no 5, article id 165Article, review/survey (Refereed) Published
Abstract [en]

The literature on density measurements, with a particular interest in methods suitable for liquid cast iron, is reviewed. Different measurement methods based on a number of physical properties are highlighted and compared. Methods for the calculation of density are also reviewed, and the influence of alloying elements on density is, to some extent, discussed. The topic is of essence for the understanding of the material behaviour at solidification, which is pivotal in software applications for casting simulation. Since a deeper understanding of the relationship between the density of liquid cast iron and volume expansion is necessary, the conclusion that further research within the field is needed lies close at hand.

Place, publisher, year, edition, pages
MDPI, 2017
Keyword
Calculation, Density, Experimental methods
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-36608 (URN)10.3390/met7050165 (DOI)000404052600014 ()2-s2.0-85019918559 (Scopus ID)
Funder
VINNOVAKnowledge Foundation
Available from: 2017-07-04 Created: 2017-07-04 Last updated: 2017-11-13Bibliographically approved
Svidró, P., Diószegi, A., Pour, M. S. & Jönsson, P. (2017). Investigation of dendrite coarsening in complex shaped lamellar graphite iron castings. Metals, 7(7), Article ID 244.
Open this publication in new window or tab >>Investigation of dendrite coarsening in complex shaped lamellar graphite iron castings
2017 (English)In: Metals, ISSN 2075-4701, Vol. 7, no 7, article id 244Article in journal (Refereed) Published
Abstract [en]

Shrinkage porosity and metal expansion penetration are two casting defects that appear frequently during the production of complex-shaped lamellar graphite iron components. These casting defects are formed during the solidification and usually form in the part of the casting which solidifies last. The position of the area that solidifies last is dependent on the thermal conditions. Test castings with thermal conditions like those existing in a complex-shaped casting were successfully applied to provoke a shrinkage porosity defect and a metal expansion penetration defect. The investigation of the primary dendrite morphology in the defected positions indicates a maximum intradendritic space, where the shrinkage porosity and metal expansion penetration defects appear. Moving away from the defect formation area, the intradendritic space decreases. A comparison of the intradendritic space with the simulated local solidification times indicates a strong relationship, which can be explained by the dynamic coarsening process. More specifically, long local solidification times facilitates the formation of a locally coarsened austenite morphology. This, in turn, enables the formation of a shrinkage porosity or a metal expansion penetration.

Place, publisher, year, edition, pages
MDPI, 2017
Keyword
Coarsening, Dendrite morphology, Lamellar cast iron, Metal expansion penetration (MEP), Primary austenite, Shrinkage porosity (SP)
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-37108 (URN)10.3390/met7070244 (DOI)000407365900015 ()2-s2.0-85022339105 (Scopus ID)
Funder
Knowledge Foundation
Available from: 2017-08-31 Created: 2017-08-31 Last updated: 2017-08-31Bibliographically approved
Svidró, J. T., Diószegi, A., Svidró, J. & Ferenczi, T. (2017). The effect of different binder levels on the heat absorption capacity of moulding mixtures made by the phenolic urethane cold-box process. Journal of thermal analysis and calorimetry (Print), 130(3), 1769-1777
Open this publication in new window or tab >>The effect of different binder levels on the heat absorption capacity of moulding mixtures made by the phenolic urethane cold-box process
2017 (English)In: Journal of thermal analysis and calorimetry (Print), ISSN 1388-6150, E-ISSN 1588-2926, Vol. 130, no 3, p. 1769-1777Article in journal (Refereed) Published
Abstract [en]

The phenolic urethane cold-box (PUCB) process was first introduced to the foundry industry in the late 1960s. Since then, it has become one of the most popular methods to make foundry purpose sand moulds and cores, utilized in the manufacturing of aluminium and cast iron cast components. The factors to be considered, affecting the general performance of a PUCB moulding mixture, are the temperature of sand, the moisture content, the mixing conditions, etc. Moreover, there are variable production parameters such as binder level, to improve certain properties of the mould and/or the core based on their specific area of application. These are mainly mechanical properties such as tensile or splitting strength. They have significant influences on the behaviour of the moulding material and are usually tested at room temperature. Although the production phases of the PUCB system are refined to a high extent today, the effect of binder content on the quality of the mould/core and the final casting should be supported by new approaches also in thermal sciences, interpreted in high-temperature environment. In this work, different PUCB mixtures were produced to evaluate the effect of various binder levels on the thermophysical properties of sand cores. Thermogravimetry, differential thermal analysis and a novel application of Fourier thermal analysis were used to study the decomposition processes of the PUCB mixture and to reveal the impact of binder level on the heat absorption (cooling) capacity of sand cores at temperatures relevant in the manufacturing of cast iron parts (1300 ± 10 °C).

Place, publisher, year, edition, pages
Springer, 2017
Keyword
Casting process; TG–DTA; Fourier thermal analysis; Heat absorption; Phenolic urethane resin
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-37099 (URN)10.1007/s10973-017-6611-y (DOI)000415619800056 ()2-s2.0-85028008121 (Scopus ID)JTHMaterialIS (Local ID)JTHMaterialIS (Archive number)JTHMaterialIS (OAI)
Available from: 2017-08-30 Created: 2017-08-30 Last updated: 2017-12-11Bibliographically approved
Svidró, J., Diószegi, A., Tóth, L. & Svidró, J. T. (2017). The influence of thermal expansion of unbonded foundry sands on the deformation of resin bonded cores. Archives of Metallurgy and Materials, 62(2), 795-798
Open this publication in new window or tab >>The influence of thermal expansion of unbonded foundry sands on the deformation of resin bonded cores
2017 (English)In: Archives of Metallurgy and Materials, ISSN 1733-3490, E-ISSN 2300-1909, Vol. 62, no 2, p. 795-798Article in journal (Refereed) Published
Abstract [en]

Depending on the preparation and the applied materials, moulds and cores can be of high rigidity or can be flexible. Although, chemically bonded moulding materials have relatively good flexibility, their high temperature behaviour determines the dimensional accuracy, the stresses in the castings and can induce several casting defects, such as rattail, veining, etc. The phenomenon is based on two major effects: the thermal expansion of the unbonded foundry sands and the deformation of the sand mixtures. The main objective of the present work was to study the relationship between these two effects, and to improve the knowledge related to the thermo-mechanical interactions between the casting and the mould. Dilatometric analysis of unbonded sand samples were performed and compared to the results of hot distortion tests of moulding mixture specimens. The results showed, that the thermal expansion of foundry sand largely influences the hot distortion behaviour, but depending on the type of binder used.

Place, publisher, year, edition, pages
De Gruyter Open, 2017
Keyword
foundry sand, hot distortion, moulding material, phenolic resin, thermal expansion
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-36936 (URN)10.1515/amm-2017-0118 (DOI)000406180900049 ()2-s2.0-85026783797 (Scopus ID)JTHMaterialIS (Local ID)JTHMaterialIS (Archive number)JTHMaterialIS (OAI)
Available from: 2017-08-21 Created: 2017-08-21 Last updated: 2017-08-21Bibliographically approved
Hernando, J. C., Ghassemali, E. & Diószegi, A. (2017). The morphological evolution of primary austenite during isothermal coarsening. Materials Characterization, 131, 492-499
Open this publication in new window or tab >>The morphological evolution of primary austenite during isothermal coarsening
2017 (English)In: Materials Characterization, ISSN 1044-5803, E-ISSN 1873-4189, Vol. 131, p. 492-499Article in journal (Refereed) Published
Abstract [en]

The morphological evolution of primary austenite in an industrial hypoeutectic lamellar cast iron was studied under isothermal conditions for coarsening times varying from 0 min to 96 h. The dendritic austenite structure formed during the primary solidification suffered major morphological changes during the isothermal coarsening process. After a sufficient coarsening time, dendrite fragmentation, globularization, and coalescence of austenite were studied using electron backscatter diffraction (EBSD) technique. This study confirmed that the secondary dendrite arm spacing (SDAS) is an inappropriate length scale to describe the primary austenite coarsening process for longer times. The application of shape independent quantitative parameters confirmed the reduction of the total interfacial area during microstructural coarsening. The modulus of the primary austenite, Mγ, which represents the volume-surface ratio for the austenite phase, and the spatial distribution of the austenite particles, measured as the nearest distance between the center of gravity of neighboring particles, Dγ, followed a linear relation with the cube root of coarsening time during the whole coarsening process. The mean curvature of the austenite interface, characterized through stereological relations, showed a linear relation to Mγ and Dγ, allowing the quantitative characterization and modeling of the complete coarsening process of primary austenite.

Place, publisher, year, edition, pages
Elsevier, 2017
Keyword
Dendrite fragmentation, Dendritic coarsening, EBSD, Microstructure evolution, Primary austenite, Austenite, Cast iron, Isotherms, Microstructure, Dendrite fragmentations, Electron backscatter diffraction technique, Micro-structure evolutions, Microstructural coarsening, Quantitative characterization, Secondary dendrite arm spacing, Coarsening
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-36890 (URN)10.1016/j.matchar.2017.07.030 (DOI)000411535600054 ()2-s2.0-85026387205 (Scopus ID)
Note

Included in licentiate thesis in submitted form.

Available from: 2017-08-16 Created: 2017-08-16 Last updated: 2017-10-19Bibliographically approved
Svidró, J. T., Diószegi, A., Svidró, J. & Ferenczi, T. (2017). Thermophysical aspects of reclaimed moulding sand addition to the epoxy-SO2 coremaking system studied by Fourier thermal analysis. Journal of thermal analysis and calorimetry (Print), 130(3), 1779-1789
Open this publication in new window or tab >>Thermophysical aspects of reclaimed moulding sand addition to the epoxy-SO2 coremaking system studied by Fourier thermal analysis
2017 (English)In: Journal of thermal analysis and calorimetry (Print), ISSN 1388-6150, E-ISSN 1588-2926, Vol. 130, no 3, p. 1779-1789Article in journal (Refereed) Published
Abstract [en]

The most important advantage of foundry purpose moulding sand is that it can be reclaimed and reused through the casting manufacturing process. Supplying the foundry with a new source of material, sand reclamation brings along both environmental and economic advantages. Utilization of used sand can be considered as a common technological routine in the production of most types of chemically bound moulding materials. The epoxy-SO2 process is prevalent in the processing of cast iron engine components worldwide. Based on its excellent properties, it is mainly suitable for producing internal sand cores with complex geometry. Even though reclaimed sand addition is an active and well-functioning feature in ferrous foundries, the scientific and thermophysical background of its effects on the casting process is yet to be explored. In this work, the thermal aspects of different reclaimed sand levels in the epoxy-SO2 moulding system were examined. Thermogravimetry and differential thermal analysis of the epoxy-SO2 and reclaimed sand in focus were carried out to obtain basic understandings about their high-temperature behaviour. A state-of-the-art Fourier thermal analysis method presented in a recent paper was used at temperatures corresponding to actual cast iron production (1300 ± 10 °C), contrary to the previous tests at the typical temperature range of aluminium melt processing (660 ± 10 °C). By the right of the method, the effects of reclaimed sand addition on the heat absorption (cooling) capacity of the epoxy-SO2 moulding mixtures were investigated.

Place, publisher, year, edition, pages
Springer, 2017
Keyword
Cast iron; TG–DTA; Fourier thermal analysis; Epoxy resin; Heat absorption; Reclaimed foundry sand
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-37098 (URN)10.1007/s10973-017-6612-x (DOI)000415619800057 ()2-s2.0-85027969356 (Scopus ID)JTHMaterialIS (Local ID)JTHMaterialIS (Archive number)JTHMaterialIS (OAI)
Available from: 2017-08-30 Created: 2017-08-30 Last updated: 2017-12-11
Hernando, J. C. & Diószegi, A. (2016). An overview of isothermal coarsening in hypoeutectic lamellar cast iron. In: Laurentiu Nastac, Baicheng Liu, Hasse Fredriksson, Jacques Lacaze, Chun-Pyo Hong, Adrian Catalina, Andreas Buhrig-Polaczek, Daan M. Maijer, Charles Andrew Monroe, Adrian Sabau, Roxana Ruxanda, Alan A. Luo, Subhayu Sen, Attila Diószegi (Ed.), Advances in the science and engineering of casting solidification: An MPMD symposium honoring Doru Michael Stefanescu. Paper presented at The honorary symposium "Advances in the Science and Engineering of Casting Solidification" (TMS2015, Orlando, Florida, March 15-19, 2015) held in honor of Professor Doru Michael Stefanescu, Emeritus Professor, Ohio State University and the University of Alabama, USA. (pp. 295-302). Cham: Springer
Open this publication in new window or tab >>An overview of isothermal coarsening in hypoeutectic lamellar cast iron
2016 (English)In: Advances in the science and engineering of casting solidification: An MPMD symposium honoring Doru Michael Stefanescu / [ed] Laurentiu Nastac, Baicheng Liu, Hasse Fredriksson, Jacques Lacaze, Chun-Pyo Hong, Adrian Catalina, Andreas Buhrig-Polaczek, Daan M. Maijer, Charles Andrew Monroe, Adrian Sabau, Roxana Ruxanda, Alan A. Luo, Subhayu Sen, Attila Diószegi, Cham: Springer, 2016, p. 295-302Conference paper, Published paper (Refereed)
Abstract [en]

A complete qualitative characterization of the isothermal coarsening process in hypoeutectic lamellar cast iron is presented for the first time in this work. Interrupted solidification experiments were used to study the evolution of the dendritic austenite network under long term isothermal conditions. Cylindrical samples were re-melted and isothermally coarsened for times from 2 minutes to 6 days at 1175°C after dendritic coherence was reached. Micrographs from horizontal and vertical sections of the coarsened samples are presented. Complete fragmentation of the dendrite network and further rearrangement of the solid phase are reported as new behaviors in the coarsening process in lamellar cast iron. A linear increase in secondary dendrite arm spacing in agreement with the literature is observed in the first several samples confirming qualitative observations. A new model is proposed which describes the entire coarsening process observed in this investigation.

Place, publisher, year, edition, pages
Cham: Springer, 2016
Keyword
Lamellar Cast Iron; Coarsening; Ripening; Dendrite Morphology; Solidification
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-37536 (URN)10.1007/978-3-319-48117-3_35 (DOI)9783319486055 (ISBN)9783319481173 (ISBN)
Conference
The honorary symposium "Advances in the Science and Engineering of Casting Solidification" (TMS2015, Orlando, Florida, March 15-19, 2015) held in honor of Professor Doru Michael Stefanescu, Emeritus Professor, Ohio State University and the University of Alabama, USA.
Available from: 2017-10-03 Created: 2017-10-03 Last updated: 2017-10-03Bibliographically approved
Diószegi, A., Svidró, P., Elmquist, L. & Dugic, I. (2016). Defect formation mechanisms in lamellar graphite iron related to the casting geometry. International Journal of Cast Metals Research, 29(5), 279-285
Open this publication in new window or tab >>Defect formation mechanisms in lamellar graphite iron related to the casting geometry
2016 (English)In: International Journal of Cast Metals Research, ISSN 1364-0461, E-ISSN 1743-1336, Vol. 29, no 5, p. 279-285Article in journal (Refereed) Published
Abstract [en]

Although lamellar cast iron has been used in advanced applications for about 20 years, our knowledge about the mechanisms affecting microstructure and defect formation is relatively limited. The present paper summarises some solidification-related phenomena from a series of recently published peer-reviewed papers and scientific theses and suggests a mechanism of defect formation which is dependent on the shape of the solidifying casting geometry. When shrinkage porosity or metal expansion penetration occurs, evidence of material transport in the intergranular zone of primary equiaxed austenite grains in the casting and in the intergranular regions between the sand grains in the mould material is seen. Material transport occurs across the casting-mould interface, where the existence of or the permeability of the primary columnar zone determines if material transport can take place.

Place, publisher, year, edition, pages
Taylor & Francis, 2016
Keyword
Columnar to equiaxed transition, Columnar zone, Defect formation mechanisms, Equiaxed zone, Lamellar graphite iron, Metal expantion penetrayion, Primary austenite grains, Shrinkage porosity, Austenite, Cast iron, Graphite, Interfaces (materials), Iron, Molds, Porosity, Shrinkage, Textures, Defect formation, Graphite iron, Primary austenite, Defects
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-31287 (URN)10.1080/13640461.2016.1211579 (DOI)000386206200006 ()2-s2.0-84980349450 (Scopus ID)
Available from: 2016-08-19 Created: 2016-08-19 Last updated: 2017-11-28Bibliographically approved
Tóth, J., Svidró, J. T., Diószegi, A. & Stevenson, D. (2016). Heat absorption capacity and binder degradation characteristics of 3D printed cores investigated by inverse fourier thermal analysis. International Journal of metalcasting, 10(3), 276-288
Open this publication in new window or tab >>Heat absorption capacity and binder degradation characteristics of 3D printed cores investigated by inverse fourier thermal analysis
2016 (English)In: International Journal of metalcasting, ISSN 1939-5981, E-ISSN 2163-3193, Vol. 10, no 3, p. 276-288Article in journal (Refereed) Published
Abstract [en]

The application of 3D printing techniques is a recently developing area used within foundry technology. Digital production of sand molds and cores eliminates the need for hard tooling, drastically reduces lead times and offers design freedoms not possible in the traditional pattern making. Even though mold and core making technologies are refined from both scientific and practical points of view, casting defects may still occur in the final products. Thus, molding material related casting research is required to generate state-of-the-art methods and understandings to avoid the formation of casting defects. In this paper, a pioneering method is presented which is suitable to determine novel thermophysical and heat transfer properties of various types of molding materials. These properties are strongly connected to the cooling capacity and the gas evolution features of the cores used in casting production. The method is based on temperature measurements inside spherical shaped core sand specimens and evaluated by a special application of Fourier thermal analysis. Temperature measurements were performed in test samples produced by two different 3D core printing systems. The registered temperature data were processed by Fourier thermal analysis to calculate the thermal properties and the decomposition characteristics of the 3D printed cores. The experiments were executed under different heating conditions analogous to aluminium and cast iron production.

Keyword
3d printing, Aluminium, Cast iron, Casting defect, Core, Decomposition, Foundry, Molding material, Sand, Spherical, Temperature, Thermal analysis, Thermophysical, Aluminum, Coremaking, Defects, Foundries, Foundry sand, Fourier transforms, Heat transfer, Inverse problems, Iron, Molding, Molds, Printing, Temperature measurement, Thermoanalysis, 3-D printing, Molding materials, 3D printers
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-31242 (URN)10.1007/s40962-016-0043-5 (DOI)2-s2.0-84978042712 (Scopus ID)JTHMaterialIS (Local ID)JTHMaterialIS (Archive number)JTHMaterialIS (OAI)
Available from: 2016-08-15 Created: 2016-08-15 Last updated: 2017-11-28Bibliographically approved
Domeij, B. & Diószegi, A. (2016). Inferring the development of microsegregation and microstructure in Spheroidal and Compacted Graphite Iron using EPMA‐WDS. , 5(1)
Open this publication in new window or tab >>Inferring the development of microsegregation and microstructure in Spheroidal and Compacted Graphite Iron using EPMA‐WDS
2016 (English)Manuscript (preprint) (Other academic)
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-35531 (URN)
Available from: 2017-05-16 Created: 2017-05-16 Last updated: 2017-05-16Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-3024-9005

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