Revisiting Models for Spheroidal Graphite Growth

Bjerre, Mathias Karsten; Azeem, Mohammed Abdul; Lee, Peter; Hattel, Jesper Henri; Tiedje, Niels Skat

doi:10.4028/www.scientific.net/msf.925.118

Cited by 7 publications

(7 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…X-ray imaging using synchrotron radiation has allowed observation of the solidification behavior in various metallic alloys such as Sn alloys, [7][8][9][10][11][12][13][14][15][16] Al alloys, 9,10,17,18) cast iron, [19][20][21][22][23] Fe-C steels, 11,[24][25][26][27][28] and stainless steels. 29) Installing a deformation device in the observation apparatus, in-situ observation of semisolid deformation by X-ray transmission imaging (referred to as 2D observation hereinafter) was achieved with a high spatial resolution with respect to grain size.…”

Section: Introductionmentioning

confidence: 99%

Time-resolved and <i>in-situ</i> Observation of Semisolid Deformation in Al–Cu Alloys with Equiaxed and Columnar Grain Structures by Using a Combination Technique of 4D-CT and 3DXRD

et al. 2021

View full text Add to dashboard Cite

Time-resolved combined absorption tomography and three-dimensional X-ray diffraction was developed to study semisolid deformation of metallic alloys, which combined time-resolved tomography and threedimensional X-ray diffraction microscopy (3DXRD). The combined technique allowed observation of configuration and crystallographic orientation of solid grains, whereby translation and rotation of solid grains induced by interaction between solid grains during semisolid deformation was analyzed. During the compression tests of a semisolid Al-10mass%Cu alloy with the equiaxed grain structure, translation and rotation of solid grains rather than the plastic deformation played a dominant role in the deformation until strain reached − 0.04. In a portion of the specimen, a gap between solid grains expanded owing to the interaction between solid grains, and consequently apparent volume expansion (dilatancy) occurred. The solid grains around the expanded region possessed similar rotational axis directions, which were perpendicular to the normal direction of the expanded region. As the compression proceeded, both translation/ rotation and the plastic deformation of solid grains occurred owing to an increase in physical contact between solid grains. For a semisolid Al-10mass%Cu alloy with the columnar grain structure, solid grain comprised a single crystallographic domain. Inflection of the dendrite arms was confirmed by 3DXRD, where the compression of strain at − 0.25 caused the grain to be inflected up to 12 degrees. The strain distribution in the grain was estimated using the inflection angle. In-situ observation revealed that the behaviors of solid grains and the liquid phase in semisolid alloys during the compression tests differed according to the structure.

show abstract

Section: Introductionmentioning

confidence: 99%

Time-resolved and <i>in-situ</i> Observation of Semisolid Deformation in Al–Cu Alloys with Equiaxed and Columnar Grain Structures by Using a Combination Technique of 4D-CT and 3DXRD

et al. 2021

View full text Add to dashboard Cite

show abstract

“…The final volume of N2 and N3 is overestimated while it is underestimated for N1 and well predicted for N4. This is not a 18 surprise given the individual differences in growth conditions which result in growth rate variations between otherwise similar nodules as discussed by Bjerre et al [34]. The current investigation only considers growth of regular nodules to ensure a relevant experimental basis for comparison to simulated results.…”

Section: Nodule Growthmentioning

confidence: 80%

“…By comparing growth rates of neighbouring nodules and taking into account the arrangement of graphite, austenite and liquid, Boeri et al [34] found that proximity of a nodule to the last-to-solidify regions contribute to high growth rates even during late stages of solidification. Nodules situated among several neighbours exhibited sluggish growth and the overall growth plateaued relatively early.…”

mentioning

confidence: 99%

A graphite nodule growth model validated by in situ synchrotron x-ray tomography

Bjerre

Azeem

Tiedje

et al. 2018

Modelling Simul. Mater. Sci. Eng.

View full text Add to dashboard Cite

An accurate prediction of ductile cast iron microstructures is crucial for a science-based optimisation of cast component design. The number density and distribution of graphite nodules critically influence the mechanical performance of a component in service. Although models predicting nodule growth have been researched for many years, recent improvements have been impeded by lack of detailed experimental data on nodule growth kinetics for validation. This data has now been made available through in situ observations of the solidification of ductile cast iron using synchrotron X-ray tomography in combination with a high temperature environmental cell. In the present investigation, a new sphere of influence model for spheroidal graphite growth is proposed. It inherently incorporates the competition for carbon between neighbouring nodules and the depletion of carbon in the matrix.Comparing simulation results to the in situ observations of graphite growth, the sphere of 2 influence model successfully predicts both growth of individual nodules as well as the size distribution of a large nodule population during solidification.

show abstract

“…The two graphite particles shown in Figure 1a and g form at approximately the same time, but their shapes and final sizes become significantly different during the course of solidification. The final size of the particles appears to be determined by local variations in carbon concentrations, determined by distance to nearest neighbours and growth of austenite in adjacent regions [15,16]. Graphite particles forming early in solidification are not impinged by their neighbouring particles, and even though they are encapsulated in austenite they grow relatively fast.…”

Section: Resultsmentioning

confidence: 99%

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

Self Cite

View full text Add to dashboard Cite

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.

show abstract

Revisiting Models for Spheroidal Graphite Growth

Cited by 7 publications

References 14 publications

Time-resolved and <i>in-situ</i> Observation of Semisolid Deformation in Al–Cu Alloys with Equiaxed and Columnar Grain Structures by Using a Combination Technique of 4D-CT and 3DXRD

Time-resolved and <i>in-situ</i> Observation of Semisolid Deformation in Al–Cu Alloys with Equiaxed and Columnar Grain Structures by Using a Combination Technique of 4D-CT and 3DXRD

A graphite nodule growth model validated by in situ synchrotron x-ray tomography

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

Contact Info

Product

Resources

About