Structural Reconstruction of Solidification Kinetics in Cast Iron with Spherical Graphite

Lekakh, Semen Naumovich

doi:10.2355/isijinternational.isijint-2015-655

“…This is in agreement with comparison between image analysis and automatic counting using scanning electron microscope and energy-dispersive spectrometry. [8,19] The third criterion aims to exclude graphite particles which are not spherical. Roundness was calculated in line with ISO 16112:2017 [2] as the area of the particle A divided by the area of a circle A circle with a diameter equal to the maximum Feret diameter l max , i.e.,…”

Section: A Size Distribution Of Graphite Nodulesmentioning

confidence: 99%

Size Distribution of Graphite Nodules in Hypereutectic Cast Irons of Varying Nodularity

Domeij

¹

,

Hernando

²

,

Diószegi

³

2018

Metall Mater Trans B

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An SGI was machined into 400 g cylindrical pieces and remelted in an electrical resistance furnace protected by Ar gas to produce materials ranging from SGI to CGI. The graphite morphology was controlled by varying the holding time at 1723 K (1450°C) between 10 and 60 minutes. The discrete sectional size distribution of nodules by number density was measured on cross sections of the specimens and translated to volumetric distribution by volume fraction. Subpopulations of nodules were distinguished by fitting Gaussian distribution functions to the measured distribution. Primary and eutectic graphite, were found to account for most of the volume of nodular graphite in all cases. For holding times of 40 minutes and greater, corresponding to nodularity roughly below 40 pct, the primary subpopulation was very small and difficult to distinguish, leaving eutectic nodules as the dominant subpopulation. The mode and standard deviation of the two subpopulations were roughly independent of nodularity. Moreover, the nodular and vermicular graphite were segregated in the microstructure. In conclusion, the results suggest that the parallel development of the vermicular eutectic had small influence on the size distribution of eutectic graphite nodules.

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“…• types of non-metallic inclusions to initiate heterogeneous nucleation of graphite nod ules; • topology of these precipitates (dimension, number, and shape) to become active nuclei • sequence of precipitate formation for prolongation of nucleation events until the end o solidification. Practical applications of the engineering of non-metallic inclusions in SGI to contro graphite nodule nucleation were described by the author with colleagues and students in the articles related to reducing shrinkage microporosity in casting [2,[9][10][11][12][13][14]. Graphite pre cipitation from the melt causes volume expansion during solidification; therefore, the con trol of the kinetics of graphite nodule precipitation could be used as an effective way t eliminate shrinkage microporosity.…”

Section: Control Solidification Kinetics For Self-healing Microporosi...mentioning

confidence: 99%

“…Practical applications of the engineering of non-metallic inclusions in SGI to control graphite nodule nucleation were described by the author with colleagues and students in the articles related to reducing shrinkage microporosity in casting [2,[9][10][11][12][13][14]. Graphite precipitation from the melt causes volume expansion during solidification; therefore, the control of the kinetics of graphite nodule precipitation could be used as an effective way to eliminate shrinkage microporosity.…”

Section: Control Solidification Kinetics For Self-healing Microporosi...mentioning

confidence: 99%

Engineering Heterogeneous Nucleation During Solidification of Multiphase Cast Alloys: An Overview

Lekakh¹,

Qing²

2023

Preprint

0

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The theory of heterogeneous nucleation was initially developed as a part of condensed matter physics and later it was used as an important engineering tool to design metallurgical processes. The success leads to wide applications of the theory in metallurgical practice. For example, engineering heterogeneous nucleation in ductile iron has been used to reduce shrinkage defects, suppress cementite formation, and modify size and shape of micro-structural constituencies. This demonstrates how theoretical knowledge could benefit industry practice. This overview aims to summarize the authors’ published studies in co-authorship with colleagues and students, which covered different aspects of engineering heterogeneous nucleation in multiphase cast alloys. Several approaches for engineering heterogeneous nucleation using thermodynamic simulation and practical methods for improving efficiency of nucleation using co-precipitation technique and a local transient melt supersaturation were suggested. Automated Scanning Electron Microscopy Energy-Dispersive-X-ray (SEM/EDX) analysis and a high-resolution Transmission Electron Microscopy (TEM) were used to verify simulation predictions. Practical examples of controlling micro-porosity shrinkage in cast irons with spheroidal graphite are presented to illustrate the power of engineering heterogenous nucleation. The authors appreciate the great efforts that the co-authors have made on the original, overviewed articles here.

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“…• types of non-metallic inclusions to initiate heterogeneous nucleation of graphite nod ules; • topology of these precipitates (dimension, number, and shape) to become active nuclei • sequence of precipitate formation for prolongation of nucleation events until the end o solidification. Practical applications of the engineering of non-metallic inclusions in SGI to contro graphite nodule nucleation were described by the author with colleagues and students in the articles related to reducing shrinkage microporosity in casting [2,[9][10][11][12][13][14]. Graphite pre cipitation from the melt causes volume expansion during solidification; therefore, the con trol of the kinetics of graphite nodule precipitation could be used as an effective way t eliminate shrinkage microporosity.…”

Section: Control Solidification Kinetics For Self-healing Microporosi...mentioning

confidence: 99%

“…Practical applications of the engineering of non-metallic inclusions in SGI to control graphite nodule nucleation were described by the author with colleagues and students in the articles related to reducing shrinkage microporosity in casting [2,[9][10][11][12][13][14]. Graphite precipitation from the melt causes volume expansion during solidification; therefore, the control of the kinetics of graphite nodule precipitation could be used as an effective way to eliminate shrinkage microporosity.…”

Section: Control Solidification Kinetics For Self-healing Microporosi...mentioning

confidence: 99%

Engineering Heterogeneous Nucleation during Solidification of Multiphase Cast Alloys: An Overview

Lekakh

¹

,

Qing

²

2023

Metals

1

0

View full text Add to dashboard Cite

The theory of heterogeneous nucleation was initially developed as a part of condensed matter physics, and later it was used as an important engineering tool to design metallurgical processes. This success has led to wide applications of the theory in metallurgical practice. For example, engineering heterogeneous nucleation in ductile iron has been used to reduce shrinkage defects, suppress cementite formation, and modify the size and shape of microstructural constituencies. This demonstrates how theoretical knowledge could benefit industry practice. This overview aims to summarize the authors’ published studies in co-authorship with colleagues and students, which covers different aspects of engineering heterogeneous nucleation in multiphase cast alloys. Several approaches for engineering heterogeneous nucleation using thermodynamic simulation as well as practical methods for improving efficiency of nucleation using the co-precipitation technique and a local transient melt supersaturation are suggested. Automated scanning electron microscopy/energy-dispersive X-ray (SEM/EDX) analysis and high-resolution transmission electron microscopy (TEM) were used to verify the simulation predictions. Practical examples of controlling microporosity shrinkage in cast irons with spheroidal graphite are presented to illustrate the power of engineering heterogenous nucleation.

show abstract

Structural Reconstruction of Solidification Kinetics in Cast Iron with Spherical Graphite

Cited by 9 publications

References 21 publications

Size Distribution of Graphite Nodules in Hypereutectic Cast Irons of Varying Nodularity

Size Distribution of Graphite Nodules in Hypereutectic Cast Irons of Varying Nodularity

Engineering Heterogeneous Nucleation During Solidification of Multiphase Cast Alloys: An Overview

Engineering Heterogeneous Nucleation during Solidification of Multiphase Cast Alloys: An Overview

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