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  • 1.
    Almaari, Firas
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Aljbban, Essam
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Strain Rate Effect on Fracture Mechanical Properties of Ferritic-Pearlitic Ductile Iron.2018Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This study investigates the effect of strain rate on fracture properties of Ferritic-Pearlitic Ductile Iron.

    A series of dynamic three point bending tests, with various load application rates, are conducted on Charpy V-notch specimens, in room temperature and approximately -18 °C.

    The tests are performed in a custom-made fixture and during the tests, force and displacement data are recorded. A XFEM (Extended Finite Element Method) model of the test setup has been established and material data from the tests are used as input to the model.

    The test results show a strong dependency of the strain rate regarding the force needed for crack initiation. Moreover, it can be concluded that low temperature makes the material very brittle, even at low load application rates.

  • 2.
    Attila, Dioszegi
    et al.
    Jönköping University, Dept of Mechanical Engineering/Component Technology.
    Elmquist, Lennart
    Jönköping University, Dept of Mechanical Engineering/Component Technology.
    Orlenius, Jessica
    Jönköping University, Dept of Mechanical Engineering/Component Technology.
    Dugic, Izudin
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Defect Formation of Grey Cast Iron2009Conference paper (Refereed)
    Abstract [en]

    Cast iron is one of the oldest technical alloys used for creating objects. Foundrymen from the very beginning ofcasting was fighting to avoid casting defects. In the beginning a successfully performed casting was associated withwitchcraft. Cast component producers suffer yearly substantial expanses due to rejecting or repairing castings. Thepresent work will summarize research efforts to understand formation mechanisms of defects, performed incollaboration with Swedish foundries during the last years. The presented work will focus on defects, specific castingof gray iron components. Studied defects are gas porosity, shrinkage porosity and metal expansion penetration.Novell experimental set up has been developed or existing methods has been improved to study defect formationmechanisms. Today we can realize that casting without defects are possible only by approaching the defect formationmechanism with multidisciplinary science.

  • 3.
    Bocko, Jozef
    et al.
    Technical University of Košice, Slovakia.
    Dorn, Michael
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Nohajová, Viera
    Technical University of Košice, Slovakia.
    Application of Evolutionary Algorithm in Elasticity2015In: Applied Mechanics and Materials, ISSN 1660-9336, E-ISSN 1662-7482, Vol. 816, p. 363-368Article in journal (Refereed)
    Abstract [en]

    This article introduces evolutionary algorithms and their utilization in mechanicalengineering. First part of this work describes evolutionary algorithms and their characteristics. Themain body of evolutionary algorithms, the selection methods for parents and the types ofreproduction are explained in the next part of this article. Termination conditions are also discussed.Finally, the application of evolutionary algorithms to a problem in mechanical engineering isdescribed. Thereby, the material parameters for a Bodner-Partom model describing viscoelastoplasticmaterial behavior are determined by fitting data from experiments on Aluminum testsamples under tension load.

  • 4.
    Dioszegi, Attila
    et al.
    Jönköping University.
    Svidro, Peter
    Jönköping University.
    Elmquist, Lennart
    SinterCast AB, Katrineholm.
    Dugic, Izudin
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Defect formation mechanisms in lamellar graphite iron related to the casting geometry2016In: International Journal of Cast Metals Research, ISSN 1364-0461, E-ISSN 1743-1336, Vol. 29, no 5, p. 279-285Article in journal (Refereed)
    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.

  • 5.
    Diószegi, Attila
    et al.
    Jönköping University.
    Dugic, Izudin
    Jönköping University.
    The Mechanism of Metal Expansion Penetration in Gray Cast Iron2006Conference paper (Refereed)
  • 6.
    Diószegi, Attila
    et al.
    Jönköping University.
    Dugic, Izudin
    Jönköping University.
    Svensson, Ingvar L
    Jönköping University.
    Metal Expansion Penetration on Concave Casting Surfaces of Grey Cast Iron Cylinder Heads2007In: Transactions of the American Foundry Society, Vol. 115, p. 609-615Article in journal (Refereed)
  • 7.
    Diószegi, Attila
    et al.
    Jönköping University.
    Dugic, Izudin
    Jönköping University.
    Svensson, Ingvar L
    Jönköping University.
    Penetrationsfehler an konkaven Gussteiloberflächen von Grauguss-Zylinderköpfen (Penetration errors casting concave surfaces of grey cast iron cylinder heads)2007In: Giesserei-Praxis, ISSN 0016-9781, Vol. 58, no 11, p. 450-454Article in journal (Other academic)
  • 8.
    Diószegi, Attila
    et al.
    Jönköping University.
    Elmquist, Lennart
    Jönköping University.
    Orlenius, Jessica
    Högskolan i Jönköping, JTH. Forskningsområde Material och tillverkning - gjutning.
    Dugic, Izudin
    Jönköping University.
    Defect Formation at Casting of Gray Iron Components2009In: Proceedings of the Carl Loper Cast Iron Symposium, Madison, Wisconsin, US, 2009Conference paper (Refereed)
  • 9.
    Diószegi, Attila
    et al.
    Jönköping University.
    Elmquist, Lennart
    Jönköping University.
    Orlenius, Jessica
    Jönköping University.
    Dugic, Izudin
    Jönköping University.
    Defect Formation of Gray Iron Casting2009In: International Journal of metalcasting, ISSN 1939-5981, E-ISSN 2163-3193, Vol. 3, no 4, p. 49-58Article in journal (Refereed)
    Abstract [en]

    Cast iron is one of the oldest technical alloys used for creating objects. Foundrymen from the very beginning of casting was fighting to avoid casting defects. In the beginning a successfully performed casting was associated with witchcraft. Cast component producers suffer yearly substantial expenses due to rejecting or repairing castings. The present work will summarize research efforts to understand formation mechanisms of defects, performed in collaboration with Swedish foundries during the last years. The presented work will focus on defects, specific casting of gray iron components. Studied defects are gas porosity, shrinkage porosity and metal expansion penetration. Novell experimental set up has been developed or existing methods has been improved to study defect formation mechanisms. Today we can realize that casting without defects are possible only by approaching the defect formation mechanism with multidisciplinary science.

  • 10.
    Diószegi, Attila
    et al.
    Jönköping University, Sweden.
    Svidró, Peter
    Jönköping University, Sweden.
    Elmquist, Lennart
    Jönköping University, Sweden.
    Dugic, Izudin
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Defect formation mechanisms in lamellar cast iron related to the casting geometry2015In: 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, Hoboken, NJ: John Wiley & Sons, 2015, p. 251-259Conference paper (Refereed)
    Abstract [en]

    Although lamellar cast iron has been used in advanced applications for about twenty years, our knowledge about the mechanisms affecting microstructure and defect formation is relatively limited. The present paper summarizes 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 mold material is seen. Material transport occurs across the casting-mold interface where the existence of or the permeability of the primary columnar zone determines if material transport can take place.

  • 11.
    Dugic, Izudin
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Ductile iron for the wind power industry2013Conference paper (Refereed)
    Abstract [en]

    The generation of electricity in the Europe from wind-powered turbines is increasing and the most important challenges for the wind turbine manufacturers are linked to the development of larger and more effective wind turbines. Cast iron is today used in central parts of a wind turbine construction and this is a growing market for Swedish foundries. The specifications and requirements applied for the cast iron components are among the most stringent used within the iron foundry branch. A problem for the production of these large components can be too high pearlite content in the metal matrix, thereby deteriorating mechanical properties. Because of this reason there are just a few iron foundries in Sweden that are able to cast the required high quality cast iron components.

    The project work has focused on reducing the pearlite stabilizing blanks into the melt and to improve the inoculation process. The project has shown that systematic work with the melt composition and inoculation may provide a much improved structure and thus better properties.

  • 12.
    Dugic, Izudin
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Effect of Casting Temperature on the Surface Finish of Grey Iron Castings2019In: Materials Processing Fundamentals 2019 / [ed] Lambotte G., Lee J., Allanore A., Wagstaff S., Springer, 2019, p. 87-95Conference paper (Refereed)
    Abstract [en]

    One of the most common surface defects in sand casting of grey cast iron is caused by metal penetration into the sand mould. Metal penetration is a surface condition in which metal or metal oxides have filled the voids between sand grains to various depth without displacing them, thus yielding a phase of sand grains surrounded by metal and frequently by mould–metal reaction products. The penetration is often so severe that casting components are beyond the point of economical rework and must be scrapped. This experimental work has focused on reducing metal penetration on casting component on a production scale. The casting component produced has strongly affected by sand sintering metal penetration. A series of simulations were performed with the casting simulation program MagmaSoft® in order to investigate the solidification characteristics as well as the porosity formation in the casting component. 

  • 13.
    Dugic, Izudin
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Effect of cooling rate on the casting defects of high chromium white cast iron for the impellers2015In: Zbornik povzetkov referatov 55. mednarodnega livarskega posvetovanja, Portorož 2015 / [ed] Alojz Križman; Mirjam Jan-Blažič; Martin Debelak; Peter Schumacher; Rüdiger Deike, Ljubljana: Društvo livarjev Slovenije , 2015, p. 35-Conference paper (Refereed)
    Abstract [en]

    One of the oldest high alloys white cast irons is produced commercially when the chromium content is between 23 and 28 %. The high-chromium white irons have excellent abrasion resistance and are used effectively in slurry pumps, brick molds, coal-grinding mills, rolling mill rolls, shot blasting equipment, and components for quarrying, hard-rock mining and milling.

    The specifications and requirements applied for the white cast iron components are among the most stringent used within the iron foundry branch. One of the biggest problems for the production of these components is hot tearing or hot cracking, or hot shortness. Irrespective of the name, this phenomenon represents the formation of an irreversible failure (crack) in the still semisolid casting.

    This paper will show a study of the effect of cooling rate on the cracks. The procedure to achieve this was to study one casting component, impeller, in a production scale using different cooling rate after pouring.

    In this work it has been shown that the solidification rate has a strong effect on the hot cracking.

  • 14.
    Dugic, Izudin
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Effect of molybdenum content and pouring temperature on the casting defects of high chromium white cast iron for the impellers2014In: Proceeding book of the 14th international foundrymen conference / [ed] Unkić, Faruk, Sisak, Croatia: University of Zagreb, Faculty of Metallurgy , 2014, , p. 10p. 17:1-17:8Conference paper (Other academic)
    Abstract [en]

    White cast iron components are today used in central parts for pumps. The specifications and requirements applied for the white cast iron components are among the most stringent used within the iron foundry branch. One of the problems for the production of these components can be cracks. Because of this reason there are just a few iron foundries in Sweden that are able to cast the required high quality white cast iron components.

    The project work has focused on reducing the cracks and to improve the machining properties of the casting. The experiments showed that molybdenum content and pouring temperature had an important influence on casting defects and machining of the casting components behaviour.

  • 15.
    Dugic, Izudin
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Effect of Molybdenum Content, Pouring Temperature and Cooling Rate on the Casting Defects of High Chromium White Cast Iron2017In: TMS 2017 146TH ANNUAL MEETING & EXHIBITION SUPPLEMENTAL PROCEEDINGS, Springer, 2017, p. 475-482Conference paper (Refereed)
    Abstract [en]

    High chromium white cast are commonly used in application requiring excellent abrasion resistance, as central parts for pumps. The specifications and requirements applied for the white cast iron components are among the most stringent used within the iron foundry branch. One of the biggest problems for the production of these components is hot tearing. Irrespective of the name, this phenomenon represents the formation of an irreversible failure (crack) in the still semisolid casting. This paper aims to investigate the effect of molybdenum content, pouring temperature and cooling rate on the casting defect hot tearing. The procedure to achieve this was to study one casting component, impeller, in a production scale. The experiments showed that molybdenum content and pouring temperature had an important influence on casting defects. It was also observed that the solidification rate has a strong effect on the hot cracking.

  • 16.
    Dugic, Izudin
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Inoculation of Grey Cast Iron and the Influence on Metal Expansion Penetration2011In: Proceedings book of the 11th International foundrymen conference Foundry Industry – Significance and Future Challenges / [ed] Unkić, Faruk, Croatia: University of Zagreb , 2011, , p. 12p. 378-389Conference paper (Refereed)
    Abstract [en]

    One of the most important factors which influence the microstructure evolution of cast iron is nucleation. Nucleation of eutectic phase in grey cast is assumed to take place heterogeneously. Inoculation is the most common method to influence the heterogeneous nucleation. The choice of inoculants used in grey cast iron production today is probably one of the most important parameters to obtain good quality of castings component. In some grey cast iron components which are cast in sand moulds, the metal some time penetrates into the mould producing surface defects and causes difficulties when cleaning the components. 

    The present work utilizes the latest development of primary austenite inoculation in combination with classic eutectic inoculation to limit the metallurgical contribution to metal expansion penetration. A solid shell containing the primary austenite dendrite network constitutes the barrier between the liquid metal and mould interface. Inoculants of both the primary- and eutectic phase control the permeability of the dendrite network

  • 17.
    Dugic, Izudin
    Linköping University.
    Metal Expansion Penetration During Solidification of Grey Cast Iron1999Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The meta! expansion penetration has been examined experimentally. The whole casting process was simulated using a commercial software, in order to investigate the solidification characteristics and the pore formation in the casting studied. In order to do this, a special module for cast iron was used, where nucleation and growth of all relevant phases are considered. During simulation it is possible to detect the areas where porosities are likely to be formed. The results of the experiments show that expansion penetration generally occurs in the same areas as detected in the simulation depending on the solidification path. The inoculation and solidification behaviour will result in an excess or deficiency of meta! at the end of solidification. This will lead to either meta! penetration or the formation of pores.

    A series of test castings were produced at a foundry. They were used to study the influence of chemical composition, the type and amount of inoculant and the casting temperature. The results show that the carbon and phosphorus content had an influence on meta! penetration. The tendency for meta! penetration decreased whit decreasing carbon content as well as with increasing phosphorus content.

    The experiments show that the type and amount of inoculant and casting temperature for grey cast iron influence the meta! expansion penetration in areas with late solidification and where the melt is in contact with the sand mould. The worst cases of meta! penetration were obtained with uninoculated melt. A !arge number of small eutectic cells making up a !arge fraction of the volume were observed, resulting in a !arge penetration.

  • 18.
    Dugic, Izudin
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Metal Expansion Penetration on Concave Casting Surfaces of Cylinder Heads Cast in Grey Cast Iron2009Conference paper (Refereed)
    Abstract [en]

    Cylinder heads have an extremely complex shape with large areas of concave casting surfaces. The concave casting surfaces are often associated with metal expansion penetration problems or other surface defects, e. g. surface shrinkage. The defects cause high production costs due to component rejection and increased fettling time. This report presents an investigation of the microstructure in grey cast iron close to the sand-metal interface affected by metal penetration in a complex shaped casting. The dominant penetration defect observed in the cylinder heads was expansion penetration. Even pre-solidification penetration and sand crack defects were observed. The microstructure found in the non penetrated areas is typical for solidification of grey iron cast in sand moulds.

  • 19.
    Dugic, Izudin
    Linköping University.
    The mechanisms of metal expansion penetration during solidification of grey cast iron2006Doctoral thesis, monograph (Other academic)
    Abstract [en]

    The production of high quality castings requires the casting surface to be clean and free from defects. One type of defect often found is caused by metal penetration into the sand mould. Metal penetration is a casting surface condition resulting from either physical, mechanical and/or thermochemical reactions or a combination of these at the mould–metal interface. The metal penetrates into the voids between the sand grains to various depths without displacing the grains, thus yielding a phase of sand grains surrounded by metal and frequently by mould-metal reaction products. The present work is devoted to investigating the mechanisms of metal expansion penetration during solidification of grey cast iron.

    The phenomenon of metal expansion penetration has been examined experimentally. A series of test castings were produced at two foundries, to study the influence of chemical composition, the casting temperature and the addition of inoculants with respect to both primary and eutectic phases.

    The experiments show that the type and amount of inoculant, the casting temperature and the chemical composition influence the metal expansion penetration.

    Two major types of metal expansion penetration mechanisms are suggested with respect to the nucleation and growth of the primary and eutectic phases. The expansion penetration mechanisms found in the experimental work were also identified on complex shaped industrial castings such as clutch components and cylinder heads.

    The entire casting process was simulated using commercial software, and in which nucleation and growth of all relevant phases was considered in order to investigate the solidification characteristics and porosity formation in the casting. A good correlation between the simulation and experiments on real castings was found.

    Density and volume change in grey cast iron seem to play a decisive roll in the occurrence of metal expansion penetration. Laboratory measurements of density variations are difficult. A novel method of modeling the density variation in cast iron has been introduced.

  • 20.
    Dugic, Izudin
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    White Cast Iron for the Impellers2014In: Conference Proceedings of the 54th International Foundry Conference Portorož 2014 / [ed] Križman, A. ; Debelak, M, Ljubljana: Društvo livarjev Slovenije , 2014, , p. 8p. 71-72Conference paper (Other academic)
    Abstract [en]

    High chromium white cast iron are commonly used in applications requiring excellent abrasion resistance, as central parts for pumps. Their excellent abrasion resistance is mainly due to their solidification microstructures. The specifications and requirements applied for the white cast iron components are among the most stringent used within the iron foundry branch. One of the problems for the production of these components can be cracks. Because of this reason there are just a few iron foundries in Sweden that are able to cast the required high quality white cast iron components.

    This work has been carried out on a foundry where an impeller for pumps has been analyzed. The project work has focused on reducing cracks on casting component in a production scale using different type of shell moulding sand. The experiments showed that the shell moulding sand had an important influence on the cracks

  • 21.
    Dugic, Izudin
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Diozegi, A
    Svensson, I. L.
    Metal Expansion Penetration on Concave Casting Surfaces of Grey Cast Iron Cylinder Heads2010In: International Foundry Research/Giessereiforschung, ISSN 0046-5933, Vol. 62, no 1, p. 38-23Article in journal (Other academic)
    Abstract [en]

    Cylinder heads have an extremely complex shape withlarge areas of concave casting surfaces. The concavecasting surfaces are often associated with metalexpansion penetration problems or other surfacedefects, e. g. surface shrinkage. The defects cause highproduction costs due to component rejection andincreased fettling time. This report presents aninvestigation of the microstructure in grey cast ironclose to the sand-metal interface affected bymetal penetration in a complex shaped casting.The dominant penetration defect observedin the cylinder heads was expansion penetration.Even pre-solidification penetration and sandcrack defects were observed. The microstructurefound in the non penetrated areas is typicalfor solidification of grey iron cast in sand moulds.

  • 22.
    Dugic, Izudin
    et al.
    Jönköping University.
    Diozegi, A
    Jönköping University.
    Svensson, Ingvar L.
    Metal Expansion Penetration on Concave Casting Surfaces of Grey Cast Iron Cylinder Heads2010In: International Foundry Research/Giessereiforschung, ISSN 0046-5933, Vol. 62, no 1, p. 38-23Article in journal (Other academic)
    Abstract [en]

    Cylinder heads have an extremely complex shape withlarge areas of concave casting surfaces. The concavecasting surfaces are often associated with metalexpansion penetration problems or other surfacedefects, e. g. surface shrinkage. The defects cause highproduction costs due to component rejection andincreased fettling time. This report presents aninvestigation of the microstructure in grey cast ironclose to the sand-metal interface affected bymetal penetration in a complex shaped casting.The dominant penetration defect observedin the cylinder heads was expansion penetration.Even pre-solidification penetration and sandcrack defects were observed. The microstructurefound in the non penetrated areas is typicalfor solidification of grey iron cast in sand moulds.

  • 23.
    Dugic, Izudin
    et al.
    Jönköping University.
    Diószegi, Attila
    Jönköping University.
    Svensson, Ingvar L.
    Jönköping University.
    The Influence of Inoculation on the Metal Expansion Penetration With Respect to the Primary and Eutectic Solidification2005Report (Other academic)
    Abstract [en]

    The mechanism of metal expansion penetration of grey cast iron components is dependent on both solidification anomalies at the metal – mould interface and the inclination of the sand mould to permit the metal liquid to penetrate between the sand grains. The present work utilizes the latest development of primary austenite inoculation in combination with classic eutectic inoculation to limit the metallurgical contribution to metal expansion penetration. A solid shell containing the primary austenite dendrite network constitutes the barrier between the liquid metal and mould interface. Inoculants of both the primaryand eutectic phase control the permeability of the dendrite network.

  • 24.
    Dugic, Izudin
    et al.
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Henriksson, Felix
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Strebel, Conrad
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Kosmaz, Ozkan
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Seifeddine, Salem
    Jönköping University.
    On the Effects of Alloying Element Range on the Mechanical Properties of Recycled Aluminium Alloy EN AB-460002016In: Light Metals 2016 / [ed] Edward Williams, John Wiley & Sons, 2016Conference paper (Refereed)
    Abstract [en]

    Aluminium can be produced from the raw material bauxite or by recycling aluminium scrap. When aluminium is being recycled, the material strength is then depending on the alloying and trace elements in the aluminium scrap. This paper aims to investigate the sole effect of the alloying element range of Si, Cu, Mg, Mn and Fe on the mechanical properties of the recycled aluminium alloy EN AB-46000 by producing directional solidified samples with low defect levels.

  • 25.
    Dugic, Izudin
    et al.
    Jönköping University.
    Svensson, Ingvar L
    Jönköping University.
    An investigation of the effect of inoculants on the metal expansion penetration in grey iron1999In: International Journal of Cast Metals Research, ISSN 1364-0461, E-ISSN 1743-1336, Vol. 11, no 5, p. 333-338Article in journal (Refereed)
    Abstract [en]

    The production of quality castings requires the casting surface to be clean and free fromdefects. In some grey cast iron components which are cast in sand moulds, the metalsometimes penetrates into the mould, producing difficulties in cleaning the components. Thedefect causes very high costs due to component rejection and increased fettling in the castingindustry. Most of the grey iron foundries around the world have problems with metalpenetration on applicable components.In this work the problem of metal penetration has been studied using a commercial castingcomponent. Eight castings were mounted on the pattern plate and five different inoculantswere investigated. The experiments show that the inoculation of grey cast iron will influencethe metal penetration in areas with late solidification times and where the melt is in contactwith the sand mould. In all experiments 0.14 % inoculant was added in the pouring ladle.The experiments show that the best results to reduce metal penetration have been obtainedwhen using the inoculant which contained silicon, aluminium and zirconium. Using thisinoculant, the average penetration area was only about 20 % of what was found using theworst inoculant. However, this inoculant also gave rise to a large tendency to formation sinks.The experiments also show two main classes of eutectic cell size. One class nucleated at thebeginning of the eutectic solidification and one at the end of the solidification.Two other inoculants, both containing Al and Si have about the same base composition. Fromthe measurements of penetration areas, one can draw the conclusion that the inoculant withthe smallest grain size gives nuclei with the shortest lifetime. The coarser grains give a longerdissolution time and this promotes the survival of the nuclei. At the end of solidification, a larger amount of graphite will precipitate at higher temperatures if new nuclei can beactivated. If the hot spot is located close to the metal surface, the metal will expand into themould; resulting in metal expansion penetration.The worst cases of metal penetration have been obtained using an inoculant containingtitanium. A large number of small eutectic cells and high volume of the small cells wereobserved, which leads to severe penetration.

  • 26.
    Dugic, Izudin
    et al.
    Högskolan i Jönköping.
    Svensson, Ingvar L
    Högskolan i Jönköping, JTH. Forskningsområde Material och tillverkning - gjutning.
    An investigation of the effect of inoculants on the metal expansionpenetration in grey iron1998Report (Other academic)
  • 27.
    Dugic, Izudin
    et al.
    Jönköping University.
    Svensson, Ingvar L
    Jönköping University.
    The effect of chemical composition on the metal expansion penetration in grey cast iron1999Report (Other academic)
    Abstract [en]

    In some grey cast iron components which are cast in sand moulds, the metal sometimes penetrates into the mould producing defects and causing difficulties when cleaning the components. To improve knowledge of the metal penetration mechanism a series of test castings was performed at ITT Flygt’s foundry where the influence of chemical composition was studied. The chemical composition of the melt was changed in the ladle before pouring. The result showed that the carbon and phosphorus content had an influence on metal penetration. The metal penetration tendency decreased when decreasing the carbon content as well as when increasing the phosphorus content. The penetration areas were analysed in a Scanning Electron Microscope (SEM) with Energy Dispersive Analysis (EDS). The analysis showed that the average chemical composition in the penetration zones was close to the initial composition of the alloy. Consequently, no significant macro segregation of carbon or phosphorous could be observed. The whole casting process was simulated with the software MAGMAsoftTM, in order to investigate the solidification characteristics as well as the porosity formation in the casting studied. For this, a special module for cast iron was used, MAGMAironTM, where nucleation and growth of all relevant phases are considered. During simulation it is possible to detect the areas where porosities are likely to be formed. The results show that expansion penetration generally occurs in the same areas depending on the mode of solidification. The inoculation and solidification behaviour will result in excess or deficiency of the metal at the end of solidification, which will lead to either metal penetration or formation of porosities.

  • 28.
    Ericsson, Mikael
    et al.
    Högskolan Väst, Sweden.
    Bolmsjö, Gunnar
    University West, Sweden.
    Nylén, Per
    Högskolan Väst, Sweden.
    Three-dimensional simulation of robot path and heat transfer of a TIG-welded part with complex geometry2002In: 11th International Conferences on Computer Technology in Welding: Colombus, Ohio December 6-7, 2001, Society of Manufacturing Engineers, North American Manufacturing Research Institution, 2002, p. 309-316Conference paper (Other academic)
    Abstract [en]

    The application of commercial software (OLP) packages for robot simulation, and programming, use interactive computer graphics, provide powerful tools for creating welding paths off-line. By the use of such software, problems of robot reach, accessibility, collision and timing can be eliminated during the planning stage. This paper describes how such software can be integrated with a numerical model that predicts temperature-time histories in the solid material. The objective of this integration is to develop a tool for the engineer where robot trajectories and process parameters can be optimized on parts with complex geometry. Such a tool would decrease the number of weld trials, increase productivity and reduce costs. Assumptions and principles behind the modeling techniques are presented together with experimental evaluation of the correlation between modeled and measured temperatures.

  • 29.
    Holmgren, Magnus
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Rening av väte vid återvinning av aluminium: Purification of hydrogen in aluminum recycling2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Detta examensarbete har utförts på Stena Aluminium (SA) i Älmhult. Undersökningen handlar om att mäta vätgashalten genom densitetsindexprover på smält aluminium, för att kartlägga hur vätgashalten påverkas av processtegen vid återvinning av aluminium i SAs produktions-anläggning. I arbetet ingick att undersöka vätgashalten för två olika legeringstyper (EN-AB 43400 och 46000), utvärdera avgasningseffektivitet för de utvalda legeringstyperna och att utvärdera den befintliga utgjutningssystemet. Mätningar för undersökningen är utförda i SAs smältverk, vid processtegen raffinering och utgjutning.

  • 30.
    Holmgren, Magnus
    et al.
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Dugic, Izudin
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Liljenfors, Tomas
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Purification of hydrogen in aluminium recycling2014In: Proceeding book of the 14th international foundrymen conference / [ed] Unkić, Faruk, Sisak, Croatia: University of Zagreb Faculty of Metallurgy , 2014, , p. 9p. 17:1-17:8Conference paper (Other academic)
    Abstract [en]

    Second to steel, aluminium is the most widely used metal and its applications are manifold. It is available in all forms; such is wire, bars, extrusions, power, forging and casting. One of the major characteristics of aluminium is that it is very well suited for recycling. Recycled aluminium is known as secondary aluminium, but maintains the same physical properties as primary aluminium.

     The Company XY is a cast house in the Nordic countries supplying aluminium cast products. Customers today are placing greater demands on the products strength and quality. An important quality parameter of aluminium is its purity from contaminants, where hydrogen is one of the major issues with impact on the strength of the final product.

     The hydrogen content has been measured by Density Index for two different types of alloys (EN AB-43400 and EN AB-46000), at specific locations, at different stages in the process and with different degassing methods. Density Index is a measure for measuring and comparing the samples with respect to the internal porosity. As the air contains moisture, along with the melt temperature, the solubility of hydrogen in the melt is affected.

     The project work has focused on reducing the hydrogen content and to improve the strength of the final product. 

  • 31.
    Ivarsson, Tom
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Nytt material i kontaktröret vid MAG-svetsning2016Independent thesis Basic level (professional degree), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [sv]

    Svetsning är idag den mest använda sammanfogningsmetoden för metaller, och pågrund av metodens relativt enkla utförande och höga produktivitet är MIG/MAG-svetsning idag den mest använda svetsmetoden industriellt i hela världen. En viktig del av svetsutrustningen till MIG/MAG är svetspistolen. Strömöverföringen från pistol till tillsatsmaterial sker genom en komponent som kallas kontaktrör. Kontaktröret är traditionellt tillverkat av koppar.

    Målet med detta examensarbete är att fastställa huruvida det nya materialet i ett kontaktrör påverkar grundmaterialet och svetsgodset negativt vid svetsning.

    Slutsatsen som drogs var att det nya materialet i kontaktröret inte har en negativ påverkan på grundmaterialet eller svetsgodset vid svetsning. Produkten kaneventuellt leda till stora ekonomiska och ekologiska vinster för svetsindustrin i framtiden.

  • 32.
    Josefsson, Simon
    et al.
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Berndt, Robin
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Icke-metalliska defekters inverkan på utmattningshållfasthet för sätthärdade kolstål i kugghjul2017Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [sv]

    Inom fordonsindustrin arbetas det kontinuerligt med att utveckla mer miljövänliga och ekonomiska produkter. Genom att undersöka material och förbättra utmattningshållfastigheten på befintliga material kan växellådor bli mer kompakta, ekonomiska och starkare samtliga parter. Syftet och målet med detta arbete är att få en generell förståelse för icke-metalliska inneslutningar och hur de påverkar ett materials utmattningshållfasthet, samt att ge förslag på förbättringar till den nuvarande materialspecifikationen. Genom tester på ultraljud kan en klar skillnad mellan storleken på defekter ses mellan stål tillverkade med olika processer. Genom undersökande av tidigare utförda tester på roterande böj kan en ökning av utmattningshållfastigheten på 37.5% ses mellan ett götgjutet stål och ett stränggjutet. Vid studerande av internationella och Europeiska standarder kan korrigeringar till den nuvarande materialspecifikationen föreslås.

  • 33.
    Kroon, Martin
    et al.
    Royal Institute of Technology.
    Faleskog, Jonas
    Royal Institute of Technology.
    A probabilistic model for cleavage fracture with a length scale: influence of material parameters and constraint2002In: International Journal of Fracture, ISSN 0376-9429, E-ISSN 1573-2673, Vol. 118, no 2, p. 99-118Article in journal (Refereed)
    Abstract [en]

    A probabilistic model for the cumulative probability of failure by cleavage fracture with a material related length scale is developed in this study. The model aims at describing the random nature of fracture in ferritic steels in the brittle-to-ductile transition temperature region. The model derives from use of an exponential function to describe the distribution of microstructural entities eligible to take part in the fracture initiation process, where also a dependence on effective plastic strain is incorporated. A nonlocal stress measure, calculated as the average stress in a spherical volume, drives the contribution to failure probability of an infinitesimal material volume. The radius of the spherical volume enters as the material length in this model. This length has a significant influence on failure probability predictions in geometries exposed to strong stress gradients as found ahead of cracks. The material length is associated with a fracture toughness threshold value. In a fracture application three model parameters need to be estimated based on testing; a parameter directly related to the mean fracture toughness, a parameter that primarily is related to crack-tip constraint effects and the material length parameter. The model is explored in a parametric study showing model features in concord with typical features found in toughness distributions from fracture mechanics testing in the transition region.

  • 34.
    Kroon, Martin
    et al.
    Royal Institute of Technology.
    Faleskog, Jonas
    Royal Institute of Technology.
    Influence of crack deflection into the carbide/ferrite interface on cleavage fracture initiation in ferritic steels2008In: Mechanics of materials (Print), ISSN 0167-6636, E-ISSN 1872-7743, Vol. 40, no 8, p. 695-707Article in journal (Refereed)
    Abstract [en]

    In this and a companion study (Kroon, M., Faleskog, J., 2005. Micromechanics of cleavage fracture initiation in ferritic steels by carbide cracking. J. Mech. Phys. Solids 53, 171–196), the initiation of cleavage fracture in ferritic steels is studied. The initiation is modelled explicitly in the form of a microcrack, which nucleates in a brittle carbide and propagates into the surrounding ferrite. The carbide is modelled as an elastic cylinder and the ferrite as an elastic viscoplastic material. The crack growth is modelled using a cohesive surface, in which the tractions are governed by a modified exponential cohesive law. The advancing microcrack, which has nucleated in the carbide, may either continue into the ferrite or deflect into the interface between the carbide and the ferrite. Special attention is given to the influence of the mode mixity factor ββ, which is defined as the ratio between the shear and tensile strength of the interface between the carbide and the ferrite. Crack growth in the interface occurs in shear mode and is driven by a fibre loading mechanism. For mode mixity values β⩽0.2β⩽0.2, the crack deflects into the interface. The results indicate that crack growth in the interface can have a profound influence on the macroscopic fracture toughness of ferritic steels.

  • 35.
    Kroon, Martin
    et al.
    Royal Institute of Technology.
    Faleskog, Jonas
    Royal Institute of Technology.
    Micromechanics of cleavage fracture initiation in ferritic steels by carbide cracking2005In: Journal of the mechanics and physics of solids, ISSN 0022-5096, E-ISSN 1873-4782, Vol. 53, no 1, p. 171-196Article in journal (Refereed)
    Abstract [en]

    Cleavage fracture in ferritic steels is often initiated in brittle carbides randomly distributed in the material. The carbides break as a result of a fibre loading mechanism in which the stress levels in the carbides are raised, as the surrounding ferrite undergoes plastic deformation. The conditions in the vicinity of the nucleated micro-crack will then determine whether the crack will penetrate or be arrested by the ferrite. The ferrite is able to arrest nucleated cracks through the presence of mobile dislocations, which blunt and shield the microcrack and thus lowers the stresses at the crack tip. Hence, the macroscopic toughness of the material directly depends on the ability of the ferrite to arrest nucleated micro-cracks and in turn on the plastic rate sensitivity of the ferrite. The initiation of cleavage fracture is here modelled explicitly in the form of a micro-crack, which nucleates in a brittle carbide and propagates into the surrounding ferrite. The carbide is modelled as an elastic cylinder or in a few cases an elastic sphere and the ferrite as an elastic viscoplastic material. The crack growth is modelled using a cohesive surface, where the tractions are governed by a modified exponential cohesive law. It is shown that the critical stress, required to propagate a microcrack from a broken carbide, increases with decreasing plastic rate sensitivity of the ferrite. The results also show that a low stress triaxiality and a high aspect ratio of the carbide promote the initiation of cleavage fracture from a broken carbide.

  • 36.
    Kroon, Martin
    et al.
    Royal Institute of Technology.
    Faleskog, Jonas
    Royal Institute of Technology.
    Öberg, Hans
    Royal Institute of Technology.
    A probabilistic model for cleavage fracture with a length scale: parameter estimation and predictions of growing crack experiments2008In: Engineering Fracture Mechanics, ISSN 0013-7944, E-ISSN 1873-7315, Vol. 75, no 8, p. 2398-2417Article in journal (Refereed)
    Abstract [en]

    A probabilistic model for the cumulative probability of failure by cleavage fracture was applied to experimental results where cleavage fracture was preceded by ductile crack growth. The model, introduced by Kroon and Faleskog [Kroon M, Faleskog J. A probabilistic model for cleavage fracture with a length scale – influence of material parameters and constraint. Int J Fract 2002;118:99–118], includes a non-local stress with an associated material related length scale, and it also includes a strain measure to account for the number of nucleated cleavage initiation sites. The experiments were performed on single edge cracked bend test specimens with three different crack lengths at the temperature 85 °C, which is in the upper transition region for the steel in question. The ductile rupture process is modelled using the cell model for nonlinear fracture mechanics. The original cleavage fracture model had to be modified in order to account for the substantial number of cleavage initiators being consumed by the ductile process. With this modification, the model was able to accurately capture the experimental failure probability distribution.

  • 37.
    Kroon, Martin
    et al.
    Royal Institute of Technology.
    Faleskog, Jonas
    Royal Institute of Technology.
    Öberg, Hans
    Royal Institute of Technology.
    A probabilistic model for cleavage fracture with a length scale: parameter estimation and predictions of stationary crack experiments2004In: Engineering Fracture Mechanics, ISSN 0013-7944, E-ISSN 1873-7315, Vol. 71, no 1, p. 57-79Article in journal (Refereed)
    Abstract [en]

    This study presents a large experimental investigation in the transition temperature region on a modified A508 steel. Tests were carried out on single-edge-notch-bend specimens with three different crack depth over specimen width ratios to capture the strong constraint effect on fracture toughness. Three test temperatures were considered, covering a range of 85 °C. All specimens failed by cleavage fracture prior to ductile tearing. A recently proposed probabilistic model for the cumulative failure by cleavage was applied to the comprehensive sets of experimental data. This modified weakest link model incorporates a length scale, which together with a threshold stress reduce the scatter in predicted toughness distributions as well as introduces a fracture toughness threshold value. Model parameters were estimated by a robust procedure, which is crucial in applications of probabilistic models to real structures. The conformity between predicted and experimental toughness distributions, respectively, were notable at all the test temperatures.

  • 38.
    Lindström, Per
    et al.
    University West ; DNV GL Materials Laboratory, Norway.
    Jonsson, Anders
    DYNAmore Nordic AB .
    Jernberg, Anders
    DYNAmore Nordic AB .
    Östby, Erling
    DNV GL Materials Laboratory, Norway.
    Non-linear fracture mechanics in LS-DYNA and LS-PrePost2015In: European LS-DYNA Conference 2015: Conference Papers, Würzburg: DYNAmore GmbH , 2015Conference paper (Other academic)
    Abstract [en]

    Fracture mechanics provides an engineering framework for assessing the consequences of defects instructures. In linear elastic fracture mechanics (LEFM), stress intensity factors KI, KII and KIII are usedfor characterizing the stress singularity at the crack tip, which arises from the theory of linear elasticity.Crack growth is assumed to occur when KI exceeds the fracture toughness KC. LEFM can be usefulfor brittle materials, or when the size of the plastic zone is small compared to global dimensions. In non-linear fracture mechanics (EPFM), an energy based criterion is used for assessing the risk forcrack growth: if the energy release rate at the crack tip exceeds what is required for creating newsurfaces in the material, crack growth will occur. Under certain assumptions the energy release rate atthe crack tip can be calculated by a path independent integral, the so-called J-integral. In modernFE-based fracture mechanics applied to practical design, the structure under consideration ismodelled, including cracks at specific locations, and the J-integral values are computed and used asdesign criteria. From a numerics viewpoint, the J-integral has many appealing properties: it can beevaluated from the far-field solution, which reduces numerical errors that may arise close to the cracktip, and the expected path-independence can to some extent be used as a quick check on solutionvalidity.Evaluation of the J-integral from LS-DYNA simulation results has been implemented as a postprocessingtool in LS-PrePost, including consistent treatment of residual stresses. The implementationcovers both 2D (plane stress / plane strain) and 3D applications, using the virtual crack-tip extension(VCE) method. The tool is accessible both via the LS-PrePost GUI and via command file interface.

  • 39.
    Olsson, P. A. T.
    et al.
    Malmö University.
    Kese, K.
    Studsvik Nuclear Corporation.
    Kroon, Martin
    Malmö University ; Royal Institute of Technology.
    Holston, A-M Alvarez
    Studsvik Nuclear Corporation.
    Ab initio-based fracture toughness estimates and transgranular traction-separation modelling of zirconium hydrides2015In: Modelling and Simulation in Materials Science and Engineering, ISSN 0965-0393, E-ISSN 1361-651X, Vol. 23, no 4, article id 045015Article in journal (Refereed)
    Abstract [en]

    In this work we report the results of an ab initio study of the transgranular fracture toughness and cleavage of brittle zirconium hydrides. We use the Griffith–Irwin relation to assess the fracture toughness using calculated surface energy and estimated isotropic Voigt–Reuss–Hill averages of the elastic constants. The calculated fracture toughness values are found to concur well with experimental data, which implies that fracture is dominated by cleavage failure. To investigate the cleavage energetics, we model the decohesion process. To describe the interplanar interaction we adopt Rose's universal binding energy relation, which is found to reproduce the behaviour accurately. The modelling shows that the work of fracture and ductility decreases with increasing hydrogen content.

  • 40.
    Olsson, Pär A.T.
    et al.
    Malmö University.
    Mrovec, Matous
    b Fraunhofer Institute for Mechanics of Materials (IWM), Germany ; Karlsruhe Institute of Technology, Germany .
    Kroon, Martin
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering. Malmö University ; Royal Institute of Technology, (KTH).
    First principles characterisation of brittle transgranular fracture of titanium hydrides2016In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 118, p. 362-373Article in journal (Refereed)
    Abstract [en]

    In this work we have studied transgranular cleavage and the fracture toughness of titanium hydrides by means of quantum mechanical calculations based on density functional theory. The calculations show that the surface energy decreases and the unstable stacking fault energy increases with increasing hydrogen content. This is consistent with experimental findings of brittle behaviour of titanium hydrides at low temperatures. Based on Griffith-Irwin theory we estimate the fracture toughness of the hydrides to be of the order of 1 MPa⋅m1/2, which concurs well with experimental data. To investigate the cleavage energetics, we analyse the decohesion at various crystallographic planes and determine the traction-separation laws based on the Rose's extended universal binding energy relation. The calculations predict that the peak stresses do not depend on the hydrogen content of the phases, but it is rather dependent on the crystallographic cleavage direction. However, it is found that the work of fracture decreases with increasing hydrogen content, which is an indication of hydrogen induced bond weakening in the material.

  • 41.
    Svensson, Ingvar L
    et al.
    Jönköping University.
    Dugic, Izudin
    Jönköping University.
    Modelling of volumes in cast iron solidification to predict shrinkage and expansion defects1999In: International Journal of Cast Metals Research, ISSN 1364-0461, E-ISSN 1743-1336, Vol. 11, no 6, p. 489-494Article in journal (Refereed)
  • 42.
    Svidró, Peter
    et al.
    Jönköping University.
    Elmquist, Lennart
    SinterCast AB.
    Dugic, Izudin
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Diószegi, Attila
    Jönköping University.
    Characterization of primary dendrite morphology in complex shaped lamellar cast iron castings2014In: The 10th International Symposium on the Science and Processing of Cast Iron, SPCI10, November, 2014, Mar del Plata, Argentina, 2014, p. 1-7Conference paper (Refereed)
    Abstract [en]

    Shrinkage porosity and metal expansion penetration are two fundamental defects appearing during the production of complex shaped lamellar cast iron components. Simplified test models simulating the thermal and geometrical conditions existing in complex shaped castings have been successfully used to provoke shrinkage porosity and metal expansion penetration. A stereological investigation of the primary dendrite morphology indicates a maximum intra-dendritic space in connection with the casting surface where the porosity and the penetration defects appear. Away from the defect formation area the intra-dendritic space decreases. Comparison of the simulated local solidification times and measured intra-dendritic space indicates a strong relation which can be explained by the dynamic ripening process. The slow local solidification time situated at the boundary between the casting surface and its surrounding is explained to be the reason for the formation of an austenite morphology which can promote mass flow between dendrites, thereby provoking shrinkage porosity or metal expansion penetration.

  • 43.
    Svidró, Péter
    et al.
    Jönköping University.
    Elmquist, Lennart
    Jönköping University.
    Dugic, Izudin
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Diószegi, Attila
    Jönköping University.
    Investigation of cooling rate dependent dendrite morphology in hypoeutectic lamellar cast iron2013Report (Other academic)
    Abstract [en]

    Shrinkage porosity and metal expansion penetration are two fundamental defects appearing at production ofcomplex shaped lamellar cast iron components. In previous work it has been shown that both shrinkageporosity and metal expansion penetration are related to the primary austenite dendrite network and itsformation mechanisms. The purpose of the present work is to study the morphology of primary austenite intest casting with a high tendency to form shrinkage porosity and metal expansion penetration. Simplified testmodels simulating the thermal and geometrical conditions similar to the conditions existing in complex shapedcasting have been successfully used to provoke shrinkage porosity and metal expansion penetration.Stereological investigation of the primary dendrite morphology indicates a maximum interdendritic space inconnection to the casting surface where the porosity and the penetration defect appear. Away from the defectformation area the interdendritic space decreases. Furthermore the local solidification times of the investigatedsamples were calculated in a 3D simulation software. Comparison of the simulated local solidification timesand measured interdendritic space indicates a strong relation of the same shape as it is known from theliterature when dynamic coarsening mechanism is characterized. The main outcome of the present paper is theobserved gradient of increasing interdendritic space from sections with high local solidification to sectionswith low solidification time. The mechanism of increasing the interdendritic phase can be explained by thedynamic ripening process. The unfortunate thermal conditions with the slowest local solidification timesituated in the border between the casting surface and its surrounding are considered the reason to form anaustenite morphology which can promote the mass flow between dendrite provoking shrinkage porosity ormetal expansion penetration.

  • 44.
    Svidró, Péter
    et al.
    Jönköping University.
    Elmquist, Lennart
    Jönköping University.
    Dugic, Izudin
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Diószegi, Attila
    Jönköping University.
    Investigation of cooling rate dependent dendrite morphology inhypoeutectic lamellar cast iron2013Report (Other academic)
    Abstract [en]

    Shrinkage porosity and metal expansion penetration are two fundamental defects appearing at production ofcomplex shaped lamellar cast iron components. In previous work it has been shown that both shrinkageporosity and metal expansion penetration are related to the primary austenite dendrite network and itsformation mechanisms. The purpose of the present work is to study the morphology of primary austenite intest casting with a high tendency to form shrinkage porosity and metal expansion penetration. Simplified testmodels simulating the thermal and geometrical conditions similar to the conditions existing in complex shapedcasting have been successfully used to provoke shrinkage porosity and metal expansion penetration.Stereological investigation of the primary dendrite morphology indicates a maximum interdendritic space inconnection to the casting surface where the porosity and the penetration defect appear. Away from the defectformation area the interdendritic space decreases. Furthermore the local solidification times of the investigatedsamples were calculated in a 3D simulation software. Comparison of the simulated local solidification timesand measured interdendritic space indicates a strong relation of the same shape as it is known from theliterature when dynamic coarsening mechanism is characterized. The main outcome of the present paper is theobserved gradient of increasing interdendritic space from sections with high local solidification to sectionswith low solidification time. The mechanism of increasing the interdendritic phase can be explained by thedynamic ripening process. The unfortunate thermal conditions with the slowest local solidification timesituated in the border between the casting surface and its surrounding are considered the reason to form anaustenite morphology which can promote the mass flow between dendrite provoking shrinkage porosity ormetal expansion penetration.

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