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Diaconu, Lucian Vasile
Publications (8 of 8) Show all publications
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)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: 2018-08-28Bibliographically approved
Diószegi, A., Diaconu, L. V. & Jarfors, A. E. .. (Eds.). (2018). Science and Processing of Cast Iron XI. Paper presented at 11th International Symposium on the Science and Processing of Cast Iron, SPCI-XI 2017, Jönköping, Sweden, 4-7 September 2017. Trans Tech Publications
Open this publication in new window or tab >>Science and Processing of Cast Iron XI
2018 (English)Conference proceedings (editor) (Refereed)
Abstract [en]

The goal of this book is to present for readers the articles from the 11th International Symposium on the Science and Processing of Cast Iron that was held in September 2017 in Jönköping, Sweden. The content of the book reflects the state of the art, research and development tendencies of cast iron as the main engineering cast material also in the 21st century.

Place, publisher, year, edition, pages
Trans Tech Publications, 2018. p. 546
Series
Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752 ; 925
Keywords
Cast Iron, Characterization, Defect Formation, Modelling, Properties, Simulation, Solidification, Structure Formation
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-41397 (URN)10.4028/www.scientific.net/MSF.925 (DOI)978-3-0357-1055-7 (ISBN)978-3-0357-2055-6 (ISBN)978-3-0357-3055-5 (ISBN)
Conference
11th International Symposium on the Science and Processing of Cast Iron, SPCI-XI 2017, Jönköping, Sweden, 4-7 September 2017
Available from: 2018-09-10 Created: 2018-09-10 Last updated: 2018-09-10Bibliographically approved
Fourlakidis, V., Diaconu, L. V. & Diószegi, A. (2018). Strength prediction of lamellar graphite iron: From Griffith’s to hall-petch modified equation. 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, 272-279
Open this publication in new window or tab >>Strength prediction of lamellar graphite iron: From Griffith’s to hall-petch modified equation
2018 (English)In: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 925, p. 272-279Article in journal (Refereed) Published
Abstract [en]

Traditionally, ultimate tensile strength (UTS) is used as the main property for the characterization of lamellar graphite iron (LGI) alloys under static loads. The main models found in the literature for predicting UTS of pearlitic lamellar graphite iron are based on either regression analysis on experimental data or on modified Griffith or Hall-Petch equation. In pearlitic lamellar graphite iron the primary austenite dendritic network, transformed to pearlite, reinforces the bulk material while the distance between those pearlite grains, defines the maximum continuous defect size in the bulk material. Recently the novel parameter of the Diameter of Interdendritic Space has been used to express the flow length in a modified Griffith equation for the prediction of the UTS in LGI. Nevertheless this model neglects the strengthening effect of the pearlite lamellar spacing within the perlite grains. A model based on modified Hall-Petch equation was developed in this work. The model considers the effect of both microstructure parameters and covers a broad spectrum of microstructure sizes typical for complex shape castings with various wall thicknesses. 

Place, publisher, year, edition, pages
Trans Tech Publications, 2018
Keywords
Lamellar graphite iron, Pearlite spacing, Primary austenite, Tensile strength, Austenite, Forecasting, Graphite, Materials handling equipment, Microstructure, Pearlite, Regression analysis, Graphite iron, Interdendritic space, Micro-structure parameters, Strength prediction, Strengthening effect, Ultimate tensile strength, Cast iron
National Category
Materials Engineering
Identifiers
urn:nbn:se:hj:diva-41295 (URN)10.4028/www.scientific.net/MSF.925.272 (DOI)2-s2.0-85050010996 (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: 2018-08-29 Created: 2018-08-29 Last updated: 2018-08-29Bibliographically approved
Skoglund, P., Elfsberg, J., Ipek, N., Diaconu, L. V., Larsson, M. & Schmidt, P. (2018). Thermo-mechanical fatigue of grey cast iron for cylinder heads - Effect of niobium, molybdenum and solidification time. 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, 377-384
Open this publication in new window or tab >>Thermo-mechanical fatigue of grey cast iron for cylinder heads - Effect of niobium, molybdenum and solidification time
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2018 (English)In: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 925, p. 377-384Article in journal (Refereed) Published
Abstract [en]

Grey iron alloyed with molybdenum and niobium in seven different compositions has been casted using three, in industrial components viable, solidification times which resulted in 21 different samples. The samples have been investigated with respect to microstructure, static properties and thermo-mechanical fatigue performance. It was found that the solidification time is very important for both the static and thermo-mechanical performance. If the solidification time is long the properties are controlled entirely by the large graphite flakes and there is no influence of the alloying elements. On the other hand if the solidification time can be kept short the need for alloying elements may be removed. For the shorter solidification times an influence from the matrix and thus the alloying elements can be seen. It was found that molybdenum enhances TMF-life while no such effect was found for niobium. Niobium, on the other hand, has a larger effect on static strength than molybdenum and also on the cyclic stress in the thermo-mechanical fatigue experiments. 

Place, publisher, year, edition, pages
Trans Tech Publications, 2018
Keywords
Grey cast iron, Static mechanical properties, Thermomechanical fatigue, Alloying, Alloying elements, Molybdenum, Niobium, Solidification, Thermal fatigue, Effect of niobium, Industrial components, Solidification time, Static properties, Thermo mechanical fatigues (TMF), Thermo-mechanical performance, Cast iron
National Category
Materials Engineering
Identifiers
urn:nbn:se:hj:diva-41296 (URN)10.4028/www.scientific.net/MSF.925.377 (DOI)2-s2.0-85050010392 (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: 2018-08-29 Created: 2018-08-29 Last updated: 2018-08-29Bibliographically approved
Diószegi, A. & Diaconu, L. V. (2017). Microstructures and Characterization of Gray Irons. In: Doru M. Stefanescu (Ed.), ASM Handbook, Volume 1A: Cast Iron Science and Technology (pp. 583-589). Materials Park, Ohio: ASM International
Open this publication in new window or tab >>Microstructures and Characterization of Gray Irons
2017 (English)In: ASM Handbook, Volume 1A: Cast Iron Science and Technology / [ed] Doru M. Stefanescu, Materials Park, Ohio: ASM International, 2017, p. 583-589Chapter in book (Refereed)
Place, publisher, year, edition, pages
Materials Park, Ohio: ASM International, 2017
Series
ASM Handbook ; 1A
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-41374 (URN)978-1-62708-133-7 (ISBN)1-62708-133-X (ISBN)978-1-62708-134-4 (ISBN)
Available from: 2018-09-06 Created: 2018-09-06 Last updated: 2018-09-06Bibliographically approved
Diaconu, L. V., Sjögren, T., Skoglund, P. & Diószegi, A. (2013). A molibdén hatása az öntöttvasak termomechanikus hőfárasztási tulajdonságaira.. Banyaszati es Kohaszati Lapok - Kohaszat, 146(1), 13-17
Open this publication in new window or tab >>A molibdén hatása az öntöttvasak termomechanikus hőfárasztási tulajdonságaira.
2013 (Hungarian)In: Banyaszati es Kohaszati Lapok - Kohaszat, ISSN 0005-5670, Vol. 146, no 1, p. 13-17Article in journal (Refereed) Published
Place, publisher, year, edition, pages
Budapest: , 2013
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:hj:diva-23143 (URN)
Available from: 2014-01-17 Created: 2014-01-17 Last updated: 2015-10-27Bibliographically approved
Diaconu, L. V., Sjögren, T., Skoglund, P. & Diószegi, A. (2013). Stress relaxation of compacted graphite iron alloyed with molybdenum. International Journal of Cast Metals Research, 26(1), 51-57
Open this publication in new window or tab >>Stress relaxation of compacted graphite iron alloyed with molybdenum
2013 (English)In: International Journal of Cast Metals Research, ISSN 1364-0461, E-ISSN 1743-1336, Vol. 26, no 1, p. 51-57Article in journal (Refereed) Published
Abstract [en]

In a previous study, the thermomechanical fatigue resistance of four compacted graphite irons (CGIs) and one grey cast iron was investigated. The molybdenum content of the four CGIs varied between 0 and 1.01 wt-%. It was observed that during thermal cycling, the maximum value of the compressive stress continuously decreased while the value of the maximum tensile stress continuously increased. The continuous decrease in compressive stresses showed that stress relaxation occurs at elevated temperatures during thermal cycling. The goal of the present investigation was to investigate the phenomenon of stress relaxation at elevated temperatures. The tests were performed at 350 and 600°C respectively. The results of the stress relaxation tests performed at 600°C showed the same trend observed at thermomechanical fatigue testing. The tests showed that additions of molybdenum improved the fatigue resistance of CGI by lowering the stress relaxation rate.

Place, publisher, year, edition, pages
Taylor & Francis, 2013
Keywords
Molybdenum alloying, Stress relaxation, Thermomechanical fatigue, Compacted graphite iron
National Category
Engineering and Technology
Identifiers
urn:nbn:se:hj:diva-19446 (URN)10.1179/1743133612Y.0000000036 (DOI)000313743800007 ()2-s2.0-84872693720 (Scopus ID)JTHMaterialIS (Local ID)JTHMaterialIS (Archive number)JTHMaterialIS (OAI)
Available from: 2012-09-17 Created: 2012-09-17 Last updated: 2018-10-15Bibliographically approved
Diaconu, L. V., Sjögren, T., Skoglund, P. & Diószegi, A. (2012). Influence of molybdenum alloying on thermomechanical fatigue life of compacted graphite irons. International Journal of Cast Metals Research, 25(5), 277-286
Open this publication in new window or tab >>Influence of molybdenum alloying on thermomechanical fatigue life of compacted graphite irons
2012 (English)In: International Journal of Cast Metals Research, ISSN 1364-0461, E-ISSN 1743-1336, Vol. 25, no 5, p. 277-286Article in journal (Refereed) Published
Abstract [en]

In this study four compacted graphite irons (CGIs) and one grey cast iron (FGI) were produced and tested in the laboratory. The molybdenum content of the four CGI grades was varied between 0 and 1··01 wt-%. The purpose of the investigations was to examine the effect of the different molybdenum contents of the CGI on the thermomechanical fatigue (TMF) behaviour. The TMF tests were performed by cycling a constrained specimen between 110 and 600°C. For every material three tests were performed on specimens machined from a ∅20 mm cylinder. Other tests were performed on specimens machined from ∅55 mm and ∅85 mm cylinders respectively. The tests showed that additions of molybdenum improved the fatigue resistance of CGI. It was observed that additions of molybdenum refined the pearlite and that the specimens with a finer metallic matrix had a higher TMF resistance.

Place, publisher, year, edition, pages
Maney Publishing, 2012
National Category
Engineering and Technology
Identifiers
urn:nbn:se:hj:diva-19445 (URN)10.1179/1743133612Y.0000000021 (DOI)000309578500004 ()2-s2.0-84867282037 (Scopus ID)JTHMaterialIS (Local ID)JTHMaterialIS (Archive number)JTHMaterialIS (OAI)
Available from: 2012-09-17 Created: 2012-09-17 Last updated: 2018-10-15Bibliographically approved
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