The Structure of Cast Irons

John Campbell

doi:10.4028/www.scientific.net/MSF.925.86

Paper Titles

Crystallography of Growth Blocks in Spheroidal Graphite
p.54

Degenerated Graphite Growth in Ductile Iron
p.62

Effect of Si and Ni Addition on Graphite Morphology in Heavy-Section Spheroidal Graphite Iron Parts
p.70

The Influence of Trace Elements on the Nature of the Nuclei of the Graphite in Ductile Iron
p.78

The Structure of Cast Irons
p.86

On the Primary Solidification of Compacted Graphite Iron: Microstructure Evolution during Isothermal Coarsening
p.90

Stereological Analysis of the Statistical Distribution of the Size of Graphite Nodules in DI
p.98

X-Ray Imaging of Formation and Growth of Spheroidal Graphite in Ductile Cast Iron
p.104

Evolution of the Macrostructure of Gray Cast Iron from Eutectic to Hypereutectic Composition
p.110

HomeMaterials Science ForumMaterials Science Forum Vol. 925The Structure of Cast Irons

The Structure of Cast Irons

Abstract:

There appear to be two main growth mechanisms for graphite in cast iron i) Coupled eutectic growth forms of gray irons which are classical growth modes of simultaneous parallel growth of graphite and austenite, not reliant on a bifilm mechanism. These are necessarily fine structures as a result of their control by the rate of diffusion of carbon in the liquid. These structures are well understood. (ii) Uncoupled eutectic mechanisms which appear to be much less well understood, including (a) growth of graphite on silica bifilm substrates floating freely in the melt, forming such structures as A-type graphite flakes. This prediction appears to have now been confirmed by direct observation. The transition to (b) nodular morphology occurs by Mg eliminating the silica bifilms by an exchange reaction. In this way the substrates for flake growth are instantly removed, and graphite can now wrap completely around nuclei, thereby growing as a nodule. Graphite structures in heavy sections such as chunky graphite may now be understandable in terms of the reorganisation by flotation of bifilms and/or nuclei.

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Periodical:

Materials Science Forum (Volume 925)

Pages:

86-89

DOI:

https://doi.org/10.4028/www.scientific.net/MSF.925.86

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Online since:

June 2018

Authors:

John Campbell*

Keywords:

Bifilm, Cast Iron, Ductile Iron, Oxide Film

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References

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