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- Dugic, Izudin, 1962-, et al.
(författare)
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Metal Expansion Penetration on Concave Casting Surfaces of Grey Cast Iron Cylinder Heads
- 2006
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Rapport (övrigt vetenskapligt/konstnärligt)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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- Dugic, Izudin, 1962-, et al.
(författare)
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The Influence of Inoculation on the Metal Expansion Penetration With Respect to the Primary and Eutectic Solidification
- 2005
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- 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.
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- Elmquist, Lennart, et al.
(författare)
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Characterizing shrinkage porosity in gray cast iron using microstructure investigation
- 2008
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Ingår i: Transactions of the American Foundry Society. - Schaumburg, Ill : The American Foundry Society. - 9780874333183 ; , s. 691-703-
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Konferensbidrag (refereegranskat)abstract
- The presence of shrinkage porosity in gray cast iron cylinder heads is a common reason for rejected castings. Therefore, an investigation was carried out to characterize the microstructure around these defects in order to achieve a better understanding of their origin. Cylinder heads from two different foundries, producing cylinder heads with different design, were examined. Despite the differences, shrinkage porosity was found to appear at similar positions. Color etsching technique was used to reveal the microstructure and the characteristic features of the porosity. Besides, also solidification simulation was used to compare thermal distribution at the positions of interest. The investigation shows that there are similarities, as well as differences, and these will be discussed in detail together with the characteristic features found. In both cases, the simulations shows a thermal center crossing the interface between mould and casting. This leads to a discussion of how the solidification is progressing and the importance of the solidification skin, or columnar zone, as well as the equiaxed zone on shrinkage porosity formation.
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