On problems of volume change measurements in lamellar cast iron

Svidró, Péter; Diószegi, Attila

doi:10.1179/1743133613y.0000000075

Cited by 18 publications

(9 citation statements)

References 9 publications

(7 reference statements)

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“…Some of the authors of the present paper have published a review on the problems of volume change measurement [14]. Based on that study, an idea for a new experimental arrangement was developed.…”

Section: Methodsmentioning

confidence: 99%

Determination of pressure in the extradendritic liquid area during solidification

Svidró

Diószegi

Jönsson

et al. 2018

J Therm Anal Calorim

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Complex-shaped lamellar graphite iron castings are susceptible to casting defects related to the volume change during solidification. The formations of these recurring defects are caused by the flow of the liquid in the intradendritic area, between the austenite dendrite arms, and in the extradendritic area between the austenite grains. The conditions for the liquid flow, in turn, are determined by the solidification behavior. The present study suggests a new measurement method and a novel calculation algorithm to determine the pressure of the extradendritic liquid during solidification. The method involves a spherical sample suspended in a measurement device, where the temperature and the volume changes are measured during solidification. The calculation algorithm is based on the numerical interpretation of the ClausiusClapeyron equation where the temperature variation, the volume change and the released latent heat are processed to determine the local pressure of the extradendritic liquid area during solidification.

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Section: Methodsmentioning

confidence: 99%

Determination of pressure in the extradendritic liquid area during solidification

Svidró

Diószegi

Jönsson

et al. 2018

J Therm Anal Calorim

Self Cite

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“…The second wave curve was rarely investigated in similar studies. In previous studies, the dendritic coherency phenomenon of critical point for transition from the primary austenite precipitation stagnation zone to the precipitation cooling zone on the cooling curve and relevant solidification mechanism have not been reasonably explained [7][8] . The prediction of this wave curve is positive to the analysis of the problems encountered in the process of casting solidification.…”

Section: Materials and Casting Processmentioning

confidence: 93%

Construction and analysis of dynamic solidification curves for non-equilibrium solidification process in lost-foam casting hypoeutectic gray cast iron

Xie

Zhu

2017

China Foundry

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P ioneer studies of the dynamic solidification curve (DSC) of castings date back to the late 1940s, when Ruddle from the British Institute of Metals measured the temperature field to analyze the solidification process of nonferrous alloy castings [1] . R. P. Dunphy et al from the Naval Research Laboratory in US [2] constructed the DSC of hypoeutectic gray cast iron based on thermodynamics. The changes of the liquidus temperature, eutectic temperature, and the solidus temperature of the castings Abstract: Most lost-foam casting processes involve non-equilibrium solidification dominated by kinetic factors, while construction of a common dynamic solidification curve is based on pure thermodynamics, not applicable for analyses and research of non-equilibrium macro-solidification processes, and the construction mode can not be applied to nonequilibrium solidification process. In this study, the construction of the dynamic solidification curve (DSC) for the nonequilibrium macro-solidification process included: a modified method to determine the start temperature of primary austenite precipitation (T AL ) and the start temperature of eutectic solidification (T ES ); double curves method to determine the temperature of the dendrite coherency point of primary austenite (T AC ) and the temperature of eutectic cells collision point (T EC ); the "technical solidus" method to determine the end temperature of eutectic reaction (T EN ). For this purpose, a comparative testing of the non-equilibrium solidification temperature fields in lost-foam casting and green sand mold casting hypoeutectic gray iron was carried out. The thermal analysis results were used to construct the DSCs of both these casting methods under non-equilibrium solidification conditions. The results show that the transformation rate of non-equilibrium solidification in hypoeutectic gray cast iron is greater than that of equilibrium solidification. The eutectic solidification region presents a typical mushy solidification mode. The results also indicate that the primary austenite precipitation zone of lost-foam casting is slightly larger than that of green sand casting. At the same time, the solid fraction (f s ) of the dendrite coherency points in lost-foam casting is greater than that in the green sand casting. Therefore, from these two points, lost-foam casting is more preferable for reduction of shrinkage and mechanical burntin sand tendency of the hypoeutectic gray cast iron. Due to the fact that the solidification process (from the surface to center) at primary austenite growth area in the lost-foam cylinder sample lags behind that in the green sand casting, the mushy solidification tendency of lost-foam casting is greater and the solidification time is longer. were used to describe the corresponding solidification process. So far, the DSC is widely adopted in studies of the characteristics of the macro-solidification process of cast iron, especially in the analysis of the difference between solidification and process characteristics of ductile cast iro...

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“…Further, the solidification time locally, the undercooling, and the number of eutectic cells are all factors that will have an influence. Moreover, it has also been reported that cylindrical samples display an anisotropic behaviour when volume change has been measured in axial and radial directions [84].…”

Section: Expressions Based On Morphologymentioning

confidence: 99%

A Broad Literature Review of Density Measurements of Liquid Cast Iron

Hellström

Diószegi

Diaconu

2017

Metals

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Abstract:The literature on density measurements, with a particular interest in methods suitable for liquid cast iron, is reviewed. Different measurement methods based on a number of physical properties are highlighted and compared. Methods for the calculation of density are also reviewed, and the influence of alloying elements on density is, to some extent, discussed. The topic is of essence for the understanding of the material behaviour at solidification, which is pivotal in software applications for casting simulation. Since a deeper understanding of the relationship between the density of liquid cast iron and volume expansion is necessary, the conclusion that further research within the field is needed lies close at hand.

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On problems of volume change measurements in lamellar cast iron

Cited by 18 publications

References 9 publications

Determination of pressure in the extradendritic liquid area during solidification

Determination of pressure in the extradendritic liquid area during solidification

Construction and analysis of dynamic solidification curves for non-equilibrium solidification process in lost-foam casting hypoeutectic gray cast iron

A Broad Literature Review of Density Measurements of Liquid Cast Iron

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