Similarities of nucleation and growth of spheroidal and compacted graphite

Tartera, J.; Llorca-Lsern, N.; Marsal, M.; Rojas, José Luis Vázquez

doi:10.1080/13640461.2003.11819571

Cited by 18 publications

(18 citation statements)

References 5 publications

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“…In the present work, a third-order polynomial relation can be derived, Eq. [6], correlating nodularity according to ISO standard as a function of the residual Mg at the beginning of the solidification. The regions giving result to CGI and SGI can clearly be limited in Figure 9 by comparison with Figure 8.…”

Section: E Relation Between Magnesium Fading and Nodularitymentioning

confidence: 99%

“…[2] This concept assumes that graphite particles nucleate on a pre-existing inclusion in the liquid. [3][4][5][6][7] In the case of lamellar graphite iron (LGI), these inclusions are complex sulfides (Mn,X)S that at the same time have nucleated on complex oxides of Al, Si, Zr, Mg, and Ti. [3][4][5] On the other hand, graphite in SGI and CGI is observed to have similar nuclei, formed by complex Mg silicates (MgO.SiO 2 ) which are nucleated on the external layer of MgS and CaS sulfides.…”

mentioning

confidence: 99%

“…[3][4][5] On the other hand, graphite in SGI and CGI is observed to have similar nuclei, formed by complex Mg silicates (MgO.SiO 2 ) which are nucleated on the external layer of MgS and CaS sulfides. [6] The subsequent growth of graphite nuclei is primarily affected by two factors: the presence of surface-active impurities in the melt, and the cooling rate during solidification of the alloy. [1] The effect of the latter is widely accepted; higher cooling rates promote the formation of SGI.…”

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confidence: 99%

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New Experimental Technique for Nodularity and Mg Fading Control in Compacted Graphite Iron Production on Laboratory Scale

Hernando

Domeij

González

et al. 2017

Metall Mater Trans A

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The narrow production window for compacted graphite iron material (CGI) drastically reduces the possibilities to produce it in small batches outside an industrial environment. This fact hinders laboratory-scale investigations on CGI solidification. This work presents a solution to that issue by introducing an experimental technique to produce graphitic cast iron of the main three families. Samples of a base hypereutectic spheroidal graphite iron (SGI) were re-melted in a resistance furnace under Ar atmosphere. Varying the holding time at 1723 K (1450°C), graphitic irons ranging from spheroidal to lamellar were produced. Characterization of the graphite morphology evolution, in terms of nodularity as a function of holding time, is presented. The nodularity decay for the SGI region suggests a linear correlation with the holding time. In the CGI region, nodularity deterioration shows a slower rate, concluding with the sudden appearance of lamellar graphite. The fading process of magnesium, showing agreement with previous researchers, is described by means of empirical relations as a function of holding time and nodularity. The results on nodularity fade and number of nodules per unit area fade suggest that both phenomena occur simultaneously during the fading process of magnesium.

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Section: E Relation Between Magnesium Fading and Nodularitymentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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New Experimental Technique for Nodularity and Mg Fading Control in Compacted Graphite Iron Production on Laboratory Scale

Hernando

Domeij

González

et al. 2017

Metall Mater Trans A

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“…Tartera et al [27] reported that graphite nuclei in CGI contained MgS and CaS similar to nuclei found in SGI. In SGI, graphite nodules are nucleated which then freely grow in the liquid (Fig.…”

Section: Solidification Pathmentioning

confidence: 75%

General Characteristic of the Ductile and Compacted Graphite Cast Iron

Górny

2015

Microstructure and Properties of Ductile Iron and Compacted Graphite Iron Castings

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This section provides basic information about the spheroidal graphite cast iron (SGI) and compacted graphite cast iron (CGI) which belong to the group of high-quality cast iron. The classification of SGI and CGI according to ISO standards, their characteristics and the use of modern types such as ADI or Si-Mo were provided. The solidification path was shown, pointing to the important role of surface active elements in shaping the form of graphite. Models presenting eutectic grain growth in SGI and CGI were also described. It was also shown that in this connection, the main surface active elements (O and S) cause changes in the growth direction, and additionally, the so-called anti-spheroidizers, such as Ti, Bi, Zr, P and N, characterized by strong normal segregation, lower the liquidus temperature of the melt, thus creating the liquid channels that characterize CGI, which then stimulate the formation of compacted graphite. The issues of the number of eutectic grains, the cooling rate and the occurrence of defects in castings were raised. Finally the spheroidizing/compacting treatments have been shown along with the general scheme of the SGI/CGI preparation process.Spheroidal graphite cast iron (SGI) and compacted graphite cast iron (CGI) belong to the group of high-quality cast iron, the production of which is continually increasing. The general classification of cast iron is shown in Fig. 6.1.Currently, SGI and CGI, belongs to a group of the most important engineering materials, in view of its:• high mechanical properties, • significant savings in cost and weight (compared to equivalent steel and aluminum alloys), • excellent combination of good castability and machinability, • less sensitive to the cooling rate compared to cast iron (FGI), • provides the starting material for the production of "high tech" austempered ductile iron (ADI) and austempered vermicular cast iron (AVCI),

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“…the graphite is nucleated on a pre-existing inclusion in the melt. [15][16][17][18][19][20][21] In LGI the graphite has its origin at (Mn,X)S where X can be several active available elements, e.g. Fe, Si, Al, Zr, Ti, Ca, Sr or P. 15 Graphite in SGI nucleates on complex magnesium silicates, of the type MgO.SiO 2 , which surrounds a sulphide core, containing MgS and CaS.…”

Section: Introductionmentioning

confidence: 99%

Literature review of microstructure formation in compacted graphite Iron

König

2010

International Journal of Cast Metals Research

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The literature concerning microstructure formation in compacted graphite iron is reviewed. Compacted graphite iron has an intermediate graphite morphology between lamellar graphite iron and spheroidal graphite iron. The formation of compacted graphite morphology is controlled by small changes in alloy composition. Several important factors influencing the formation of the as solidified microstructure, as well as the microstructure formation during the eutectoid transformation are also reviewed. The focus of this review is to compare mechanisms in which compacted graphite iron differs from lamellar graphite iron and spheroidal graphite iron. The effects of microstructure on some properties that are relevant in commercial applications are included in the study. Additionally the relatively few models for microstructure formation are also summarised.

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Similarities of nucleation and growth of spheroidal and compacted graphite

Cited by 18 publications

References 5 publications

New Experimental Technique for Nodularity and Mg Fading Control in Compacted Graphite Iron Production on Laboratory Scale

New Experimental Technique for Nodularity and Mg Fading Control in Compacted Graphite Iron Production on Laboratory Scale

General Characteristic of the Ductile and Compacted Graphite Cast Iron

Literature review of microstructure formation in compacted graphite Iron

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