On the stable eutectic solidification of iron–carbon–silicon alloys

Stefanescu, Doru M.; Alonso, G.; Larrañaga, P.; Súarez, Ramón

doi:10.1016/j.actamat.2015.09.043

Cited by 57 publications

(30 citation statements)

References 13 publications

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“…The classical literature consider the case where the graphite sphere is encapsulated by a uniform shell of austenite, however, more recent research shows that primary dendrites significantly influence graphite growth so that the proximity of a dendrite to a nodule, whether it is encapsulated or un-encapsulated, will change the carbon concentration field so that it is no longer symmetrical. [20,27] In the present investigation it is found that graphite continues to grow while it is encapsulated and that the growth rate is restricted by the presence of neighbouring particles. Recent work [9] has shown that Mg can influence the growth mode of graphite when it grows in austenite to become less spherical.…”

Section: Encapsulated Growthsupporting

confidence: 49%

“…Later Stefanescu et al [20] describes similar structures and suggests that it is a transitional stage between spheroidal graphite and flake graphite. It is well established in the literature that contamination of elements like O, S and others influence graphite growth and that also local segregation of said elements will lead to local variations in growth morphology.…”

Section: Resultsmentioning

confidence: 93%

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Analysis of Local Conditions on Graphite Growth and Shape During Solidification of Ductile Cast Iron

Tiedje

Bjerre

Azeem

et al. 2018

Trans Indian Inst Met

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Analysis of local conditions on graphite growth and shape during solidification of ductile cast iron.Abstract 3D X-Ray tomography recordings have been used to study graphite growth during solidification of ductile cast iron. Using data from such recordings, it is shown how local growth conditions influence growth rate and morphology of nodules during solidification. The experiments show that it is common for nodules to gradually change shape during solidification so that sphericity decreases. It is also shown that different shapes of nodules can evolve in direct contact with liquid iron and also after when they are encapsulated in austenite.It is observed that a significant proportion of originally complete spherical nodules become less spherical via formation of protrusions on the surface, these new surfaces are observed to grow relatively faster.It is shown that encapsulation of the graphite nodule by austenite may be incomplete, and that at the end of solidification, partial encapsulation and the effect of the number of nearest graphite nodules play a crucial role in determining the final graphite morphology.

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Section: Encapsulated Growthsupporting

confidence: 49%

Section: Resultsmentioning

confidence: 93%

Analysis of Local Conditions on Graphite Growth and Shape During Solidification of Ductile Cast Iron

Tiedje

Bjerre

Azeem

et al. 2018

Trans Indian Inst Met

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“…7) or TiCS plates were found. 30 Graphite nuclei for SIG, other than sporadic titanium compounds, were not identified in this research or in previous research (e.g. Ref.…”

Section: Nucleationmentioning

confidence: 87%

Solidification of superfine graphite iron revealed by interrupted solidification experiments

Alonso

Stefanescu

Larrañaga

et al. 2016

International Journal of Cast Metals Research

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The tensile strength of near-eutectic grey iron can be increased from 230-300 to 300-345 MPa, without a significant increase in hardness, through 0.3-0.4%Ti addition to low sulphur (<0.01%S) iron. This is due to the combination of higher primary austenite/eutectic ratio and the precipitation of superfineinterdendritic-graphite (SIG), characterised by a fine (10-20 μm) and highly branched fibrous structure. To reveal the influence of the %Ti on graphite shape evolution during solidification and its relationship to the solid fraction, quenching experiments at successive solidification stages were carried out on hypoeutectic alloys with 0.18% and 0.32%Ti. The graphite shape factors were measured, and their evolution as a function of the titanium content and the solid fraction was analysed. SEM was used to evaluate the change in graphite shape during early solidification, as well as its nucleation and growth. The correlation between the oxygen in the melt and SIG formation was also explored. It was concluded that nucleation of graphite in SIG irons occurs on carbon rich regions at the austenite/liquid interface and, sometimes, on titanium carbides. Solidification velocity-undercooling curves were used to explain the transition from lamellar (type-A), to interdendritic (type-D), to SIG, and then to coral graphite.

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“…The model accounts for gray and white eutectics nucleation and their growth as grains with spherical shape [44]. The gray eutectic is formed by austenite and graphite, while the white eutectic is formed by austenite and cementite.…”

Section: Solidification Modelmentioning

confidence: 99%

Modeling and Simulation of the Gray-to-White Transition during Solidification of a Hypereutectic Gray Cast Iron: Application to a Stub-to-Carbon Connection Used in Smelting Processes

Urrutia

Celentano

Gunasegaram

2017

Metals

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This work reports on experimental and numerical results of the gray-to-white transition (GWT) during solidification of a hypereutectic gray cast iron (GCI) in a casting test using a stub-to-carbon (STC) connection assembly. Since in this process non-uniform cooling rates are produced, the mechanical properties are expected to spatially vary due to the development of different microstructures along the thimble. The twin aims of this work were to (1) experimentally validate the GWT prediction capabilities of the microstructural model proposed earlier by the authors in the rodding process of a hypereutectic GCI-STC, and (2) estimate, from the numerically obtained microstructure and ultimate tensile strength (UTS), the local hardness of the alloy after the numerical predictions of the microstructure were experimentally validated. To this end, the final microstructure at different points of the thimble and the hardness profile along its radial direction were measured for validation purposes. Moreover, this rodding process was simulated using an extension of a thermal microstructural model previously developed by the authors and the GWT was superimposed on that simulation. The computed results encompass cooling curves, the evolution of gray and white fractions, eutectic radii and densities and, in addition, the hardness profile. A detailed discussion of the experimental and numerical results is presented. Finally, the computed GWT was found to adequately reproduce the experimental data.

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On the stable eutectic solidification of iron–carbon–silicon alloys

Cited by 57 publications

References 13 publications

Analysis of Local Conditions on Graphite Growth and Shape During Solidification of Ductile Cast Iron

Analysis of Local Conditions on Graphite Growth and Shape During Solidification of Ductile Cast Iron

Solidification of superfine graphite iron revealed by interrupted solidification experiments

Modeling and Simulation of the Gray-to-White Transition during Solidification of a Hypereutectic Gray Cast Iron: Application to a Stub-to-Carbon Connection Used in Smelting Processes

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