Revealing the solidification structure of nodular iron

Rivera, Graciela Leonor; Boeri, Roberto Enrique; Sikora, Jorge Antonio

doi:10.1080/09534962.1995.11819186

Cited by 55 publications

(63 citation statements)

References 4 publications

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“…8), at the eutectic temperature, austenite dendrites and graphite spheroids nucleate independently in the liquid. This mechanism has been confirmed in the experiments 9,10) and modeling 11,12) by both-for hypo-eutectic and eutectic, as well as hyper-eutectic SGI. The non-stationary diffusion in nodular graphite iron casting has been presented in Ref.…”

Section: Introductionsupporting

confidence: 68%

Undercooling, Cooling Curves and Nodule Count for Near-eutectic Thin-walled Ductile Iron Castings

2014

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A solidification model for ductile iron, including Weibull formula for nodule count, has been presented. The principal assumptions of the kinetic nature of growth, depending on undercooling in respect of the eutectic equilibrium temperature and austenite liquidus line, have been adopted, disregarding the diffusion processes, which was justified by the rapid course of the crystallization process in a thin-walled casting. From this model, the following parameters can be determined: cooling curves, kinetics of austenite and eutectic nucleation, austenite and eutectic growth velocity, and volume fraction.The correctness of the mathematical model has been experimentally verified by comparison with literature data in the range of the most significant factors, which include temperature field, the value of maximum undercooling, the value of minimum and maximum temperature on a cooling curve, maximum undercooling, the recalescence and graphite nodule count interrelated with the casting cross-section.

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Section: Introductionsupporting

confidence: 68%

Undercooling, Cooling Curves and Nodule Count for Near-eutectic Thin-walled Ductile Iron Castings

2014

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“…The solidification structure size was determined using a metallographic colour technique developed by Rivera et al, 14,15) which qualitatively reveals microsegregation patterns and allows the observation and quantification of closed areas called "cells". This technique was applied to the as-cast samples of each "Y" block size and the results, given in number of cells per square millimeter, are listed in Table 3.…”

Section: Metallographymentioning

confidence: 99%

“…10,11,13) Nevertheless, other more specific metallographic analysis can be done in order to characterize the refinement of the primary structure. 14,15) Austempered Ductile Iron (ADI) is increasingly applied to replace structural steel parts of different machinery. During the last years, several papers about properties, applications, production practice, etc.…”

Section: Introductionmentioning

confidence: 99%

Low Temperature Impact Tests in Austempered Ductile Iron and Other Spheroidal Graphite Cast Iron Structures.

et al. 2001

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Impact tests at low temperatures were carried out, aimed at comparing the response of five spheroidal graphite (SG) cast iron with different microstructures and to analyze the influence of the solidification structure size. "Y" blocks with two different thicknesses (13 and 75 mm) were cast using the same industrial melt. The following matrix microstructures were obtained by applying different heat treatments: pearliticferritic (as-cast condition), fully ferritic (sub-critical annealing), fully pearlitic (normalizing) and two ausferritic matrices (ADI grades 2 and 4). Charpy impact tests were performed on unnotched specimens at temperatures ranging from Ϫ100°C to ϩ200°C. The results showed a little variation of the upper and lower shelf energy values with the solidification structure size for each matrix type. However, there was a strong displacement in the transition temperature towards increasing temperatures as the solidification structure size enlarged. This effect is also related to the matrix microstructure. The highest impact energy values were obtained on ADI grade 2 samples, and the lowest ones on the samples with pearlitic matrix.

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“…However, clear differences in the plastic behavior are identified, where the LTF zones show higher strength. These differences could be associated to differences in chemical composition between LTF and FTF during the solidification process, particularly, the microsegregation of Si [3]. …”

Section: Determination Of Elastic-plastic Propertiesmentioning

confidence: 99%

“…The first to freeze zones, coincident with the axes and arms of the austenite dendrites, are usually named FTF. As the solid phases grow and collide with neighboring growing units, the last portions of remaining melt locate between them, and are referred to as the Last To Freeze zones (LTF) [2,3]. Certain alloy elements and impurities may diffuse and concentrate or be depleted in these zones.…”

Section: Introductionmentioning

confidence: 99%

Mechanism of Damage of Ferritic Ductile Iron, Influence of Matrix Heterogeneity

Fernandino

Boeri

Massone

2018

MSF

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Abstract. Ferritic ductile cast iron (FDI) microstructure is composed by graphite nodules embedded in a ferritic matrix. It is usual to assume that the ferritic matrix is homogeneous. However, the experimental analysis shows impurities and in some cases a high degree of heterogeneity. It is necessary to investigate the influence of these heterogeneities on the mechanical properties of FDI. This work focusses on the characterization of the elastoplastic properties of different zones of the ferritic matrix of FDI and the identification of the sequence and extent of the damage mechanisms at the micro-scale under uniaxial tensile loading.The methodologies for the characterization of the material micro constituents and microsegregated zones involve nano-indentation and atomic force microscopy techniques in combination with computational modelling. The analysis is performed by applying inverse analysis algorithms proposed in the literature. The microsegregated zones are identified by using color etching. The assessment of the micro-scale damage mechanisms was performed by in-situ optical microscopy observation of tensile tests of very small specimens.The results led to the quantification of the differences in mechanical properties along the metallic matrix as a result of the existing heterogeneities and allow for a better understanding of the ductile iron damage mechanism.

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Revealing the solidification structure of nodular iron

Cited by 55 publications

References 4 publications

Undercooling, Cooling Curves and Nodule Count for Near-eutectic Thin-walled Ductile Iron Castings

Undercooling, Cooling Curves and Nodule Count for Near-eutectic Thin-walled Ductile Iron Castings

Low Temperature Impact Tests in Austempered Ductile Iron and Other Spheroidal Graphite Cast Iron Structures.

Mechanism of Damage of Ferritic Ductile Iron, Influence of Matrix Heterogeneity

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