| 1. |
- Diószegi, Attila, 1962-, et al.
(författare)
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Defect formation mechanisms in lamellar cast iron related to the casting geometry
- 2015
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Ingår i: Advances in the science and engineering of casting solidification. - Hoboken, NJ : John Wiley & Sons. - 9781119082385 - 9781119093367 ; , s. 251-259
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Konferensbidrag (refereegranskat)abstract
- 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.
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| 2. |
- Svidró, Peter, et al.
(författare)
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Characterization of primary dendrite morphology in complex shaped lamellar cast iron castings
- 2014
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Ingår i: The 10<sup>th</sup> International Symposium on the Science and Processing of Cast Iron, SPCI10, November, 2014, Mar del Plata, Argentina. - : The Institute for Research in Materials Science and Technology (INTEMA). ; , s. 1-7
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Konferensbidrag (refereegranskat)abstract
- 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.
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| 3. |
- Bagni, T., et al.
(författare)
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Modeling Results of the Quench Behavior of a Nb-Ti Canted-Cosine-Theta Corrector Magnet for LHC
- 2024
-
Ingår i: IEEE transactions on applied superconductivity (Print). - : IEEE. - 1051-8223 .- 1558-2515. ; 34:5
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Tidskriftsartikel (refereegranskat)abstract
- A newly designed superconducting magnet of the Canted-Cosine-Theta (CCT) type was developed as a result of a collaboration between Swedish universities (Uppsala and Linneaus) and Swedish industries. This magnet was designed to function as a replacement of the present LHC orbit corrector magnets, which are approaching their end of life due to the radiation load. As a result, the new CCT magnet was developed to be more radiation tolerant and to constitute a one-to-one replacement to the currently installed version, which is a 1 m long 70 mm double aperture dipole magnet. The final magnet, which is currently under construction, will be tested at FREIA laboratory at Uppsala University and generate a magnetic field of 3.3 T and an integrated field of 2.8 Tm at about 85 A. To examine the magnet quench behavior and to identify a suitable quench protection system, the 3D electro-magnetic and thermal behavior of the coil was modeled using the RAT-Raccoon software. Based on the simulation results, a Metrosil varistor was selected to protect the magnet during the test. In this article, we report the results of the numerical analysis. The magnet model is equipped with a spot heater to initialize the quench and the temperature and voltages are monitored during the avalanche effect. The simulated current decay and the hot-spot temperature are analyzed with a focus on the impact of quench-back on the magnet protection.
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| 4. |
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| 5. |
- Diószegi, Attila, et al.
(författare)
-
Defect formation mechanisms in lamellar graphite iron related to the casting geometry
- 2016
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Ingår i: International Journal of Cast Metals Research. - : Taylor & Francis. - 1364-0461 .- 1743-1336. ; 29:5, s. 279-285
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 6. |
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| 7. |
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| 8. |
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| 9. |
- Dugic, Izudin, 1962-, et al.
(författare)
-
An investigation of the effect of five different inoculants on the metal expansion penetration in grey cast iron
- 1999
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The production of quality castings requires the casting surface to be clean and free from defects. In some grey cast iron components which are cast in sand moulds, the metal sometimes penetrates into the mould, producing difficulties in cleaning the components. The defect causes very high costs due to component rejection and increased fettling in the casting industry. Most of the grey iron foundries around the world have problems with metal penetration on applicable components. In this work the problem of metal penetration has been studied using a commercial casting component. Eight castings were mounted on the pattern plate and five different inoculants were investigated. The experiments show that the inoculation of grey cast iron will influence the metal penetration in areas with late solidification times and where the melt is in contact with 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 obtained when using the inoculant which contained silicon, aluminium and zirconium. Using this inoculant, the average penetration area was only about 20 % of what was found using the worst 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 the beginning 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. From the measurements of penetration areas, one can draw the conclusion that the inoculant with the smallest grain size gives nuclei with the shortest lifetime. The coarser grains give a longer dissolution 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 be activated. If the hot spot is located close to the metal surface, the metal will expand into the mould; resulting in metal expansion penetration. The worst cases of metal penetration have been obtained using an inoculant containing titanium. A large number of small eutectic cells and high volume of the small cells were observed, which leads to severe penetration.
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| 10. |
- Dugic, Izudin, 1962-, et al.
(författare)
-
An investigation of the effect of inoculants on the metal expansion penetration in grey iron
- 1999
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Ingår i: International Journal of Cast Metals Research. - 1364-0461 .- 1743-1336. ; 11:5, s. 333-338
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 11. |
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| 12. |
- Dugic, Izudin, 1962-
(författare)
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Ductile iron for the wind power industry
- 2013
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Konferensbidrag (refereegranskat)abstract
- 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.
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| 13. |
- Dugic, Izudin, 1962-
(författare)
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Effect of Casting Temperature on the Surface Finish of Grey Iron Castings
- 2019
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Ingår i: Materials Processing Fundamentals 2019. - Cham : Springer. - 9783030057275 - 9783030057282 ; , s. 87-95
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Konferensbidrag (refereegranskat)abstract
- 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.
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| 14. |
- Dugic, Izudin, 1962-
(författare)
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Effect of cooling rate on the casting defects of high chromium white cast iron for the impellers
- 2015
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Ingår i: Zbornik povzetkov referatov 55. mednarodnega livarskega posvetovanja, Portorož 2015. - Ljubljana : Društvo livarjev Slovenije. - 9789619372319 ; , s. 35-
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Konferensbidrag (refereegranskat)abstract
- 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.
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| 15. |
- Dugic, Izudin, 1962-
(författare)
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Effect of molybdenum content and pouring temperature on the casting defects of high chromium white cast iron for the impellers
- 2014
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Ingår i: Proceeding book of the 14th international foundrymen conference. - Sisak, Croatia : University of Zagreb, Faculty of Metallurgy. - 9789537082178 ; , s. 17:1-17:8
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- 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.
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| 16. |
- Dugic, Izudin, 1962-
(författare)
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Effect of Molybdenum Content, Pouring Temperature and Cooling Rate on the Casting Defects of High Chromium White Cast Iron
- 2017
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Ingår i: TMS 2017 146TH ANNUAL MEETING & EXHIBITION SUPPLEMENTAL PROCEEDINGS. - Cham : Springer. - 9783319514932 - 9783319514925 ; , s. 475-482
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Konferensbidrag (refereegranskat)abstract
- 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.
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| 17. |
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| 18. |
- Dugic, Izudin, 1962-, et al.
(författare)
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GIFA 2011 – New opportunities
- 2011
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Ingår i: Swedish Foundry Technical Association Conference. - Nyköping, Sweden.
-
Konferensbidrag (populärvet., debatt m.m.)
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| 19. |
- Dugic, Izudin, 1962-
(författare)
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How to Prevent Gas Porosity Defects in Castings of Stator Housing in Grey Cast Iron
- 2020
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Ingår i: TMS 2020 149th Annual Meeting & Exhibition Supplemental Proceedings. - Cham : Springer. - 9783030362959 ; , s. 1139-1148
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Konferensbidrag (refereegranskat)abstract
- Grey cast iron is one of the easiest metals to cast in a foundry, and of ferrous metals, it has the lowest pouring temperature, high fluidity, and very low shrinkage during the transformation from the liquid to solid phase. One of the disadvantages of this grade of cast iron is the presence of the different types of defects produced in green sand casting. Cast defects are, at a higher proportion, caused by evolution of gases. Pinholes and blowholes are major casting defects caused by gases. This experimental work has focused on reducing gas defects on casting component, stator housing, at a production scale using the green sand casting process. The casting component produced was strongly affected by gas defects. A series of simulations were performed using the casting simulation program MAGMASOFT® in order to investigate the solidification characteristics as well as the porosity formation in the casting component.
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| 20. |
- Dugic, Izudin, 1962-
(författare)
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How to Prevent Porosity Defects in Steel Casting Component
- 2023
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Ingår i: Materials Processing Fundamentals 2023. TMS 2023. - Cham : Springer. - 9783031226564 - 9783031226571
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Konferensbidrag (refereegranskat)abstract
- The production of steel casting can in some cases be complicated and difficult. To produce quality castings, it requires the casting to be clean and free from any defects. One of the main casting defects is hot tearing, also known as a crack or shortness. This phenomenon represents the formation of an irreversible failure (crack) in the steel semisolid casting. The second defect that commonly occurs in casting is porosity. Porosity is often used to describe any void or hole found in a casting. To control the porosity, you need to understand its sources and causes. Porosity can occur either by gas formation, solidification shrinkage, or non-metallic compound formation, all while the metal is liquid. This experimental work is focused on reducing the porosity defects in steel casting components at a production scale. The produced casting component was strongly affected by porosity defects.
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| 21. |
- Dugic, Izudin, 1962-
(författare)
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How Various Inoculants and Their Amount Influence on the Metal Expansion Penetration in Grey Cast Iron Component
- 2024
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Ingår i: TMS 2024 153rd Annual Meeting & Exhibition Supplemental Proceedings. - : Springer Nature. - 9783031503481 - 9783031503511 - 9783031503498 ; , s. 1052-1066
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Konferensbidrag (refereegranskat)abstract
- In some grey cast ironGrey cast iron components, which are cast in sand moulds, the metalMetals sometimes penetrates into the mould producing defectsDefects and causes difficulties when cleaning the components. To improve knowledge of the metalMetals penetration mechanism, a series of test casting was performed in production scale where the influence of different inoculantsInoculant and different amounts was studied. Investigation of the various inoculantsInoculant shows that the inoculation of grey cast ironGrey cast iron will influence the metal expansion penetrationMetal expansion penetration in areas with late solidificationSolidification times. The amount of inoculantInoculant added shows a clear effect on the degree of metalMetals penetration. The whole casting processProcess was simulated with the software MagmaSoft® in order to investigate the solidificationSolidification characteristics as well as the porosityPorosity in the casting component. © The Minerals, Metals & Materials Society 2024.
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| 22. |
- Dugic, Izudin, 1962-
(författare)
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Inoculation of Grey Cast Iron and the Influence on Metal Expansion Penetration
- 2011
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Ingår i: Proceedings book of the 11th International foundrymen conference Foundry Industry – Significance and Future Challenges. - Croatia : University of Zagreb. - 9789537082130 ; , s. 378-389
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Konferensbidrag (refereegranskat)abstract
- 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
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| 23. |
- Dugic, Izudin, 1962-
(författare)
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Metal Expansion Penetration During Solidification of Grey Cast Iron
- 1999
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- 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.
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| 24. |
- Dugic, Izudin, 1962-
(författare)
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Metal Expansion Penetration on Casting Components of Grey Cast Iron
- 2010
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Konferensbidrag (refereegranskat)abstract
- Cast irons are a family of sophisticated design materials with precise engineering properties.In some grey cast iron components which are cast in sand moulds, the metal sometimes penetrates into the mould producing defects which cause difficulty when cleaning the components. Metal penetration is a casting surface condition resulting from either physical, mechanical and/or thermo chemical reactions or a combination of these at the mould–metal interface.The present work will summarize research efforts to understand the mechanisms of metal expansion penetration performed in collaboration with Swedish foundries. The main parts of the experimental works are based on some casting components.
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| 25. |
- Dugic, Izudin, 1962-
(författare)
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Metal Expansion Penetration on Concave Casting Surfaces of Cylinder Heads Cast in Grey Cast Iron
- 2009
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Konferensbidrag (refereegranskat)abstract
- 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.
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