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Thermodynamic analysis of cast irons solidification with various types of graphite

Elbel T., Hampl J.

Archives of Foundry Engineering

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2012

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Vol. 12, iss. 4

157-165

EN

The contribution summarises the results of oxygen activity determinations, which were measured and registered continuously in castings from cast irons with various types of graphite. The results were used to find the relationship between two variables: natural logarithm of oxygen activities and reverse value of thermodynamic temperature 1 /T. Obtained regression lines were used to calculate oxygen activity at different temperatures, to calculate Gibbs free energy \deltaG at the different temperatures and to calculate the single \deltaG value for significant temperature of the graphite solidification. The results were processed by a statistical analysis of data files for the different types of graphite with flake, vermicular and spheroidal graphite. Each material has its proper typical oxygen activities range and individual temperature function of Gibbs free energy for analysing and governing casting quality.

2

Estimation of boundary heat flux during cast iron solidification

Mendakiewicz J.

Prace Naukowe Instytutu Matematyki i Informatyki Politechniki Częstochowskiej

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2007

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Vol. 6, nr 1

191-198

EN

In the paper the inverse problem consisting in estimation of boundary heat flux during cast iron solidification is presented. In order to solve the inverse problem formulated it is assumed that the cooling curves at selected set of points from the casting domain are given. The algorithm bases on the gradient method coupled with the finite differences method. In the final part of the paper the results of computations are shown.

3

Model of cast iron solidification using the artificial mushy zone approach

Lara S., Szopa R.

Archiwum Odlewnictwa

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2006

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R. 6, nr 22

292-297

EN

The solidification of typical cast iron proceeds partially in an interval of temperature and partially at a constant temperature. In order to apply the simple and effective approach called the one domain method the substitute thermal capacity of material considered must be introduced. It is possible under the assumption that the temperature Te corresponding to the eutectic change will be substituted by a change proceeding in a certain interval [...]. In this way the subdomain of artificial mushy zone is introduced. The value of local substitute thermal capacity is defined according to concept presented by Hsiao [5] and modified by Lara et al [6]. In the paper the theoretical aspects of problem and also the example of numerical simulation are discussed.

PL

Krzepnięcie typowego żeliwa zachodzi częściowo w przedziale temperatury, a częściowo w stałej temperaturze. Jedną z prostych i efektywnych możliwości realizacji obliczeń jest wprowadzenie zastępczej pojemności cieplnej rozważanego materiału. Temperaturę Te odpowiadającą przemianie eutektycznej zastąpiono pewnym przedziałem temperatury [...]. W ten sposób wprowadzono podobszar nazywany sztuczną strefą dwufazową. Wartość lokalnej zastępczej pojemności cieplnej zdefiniowano zgodnie z podejściem prezentowanym przez Hsiao i zmodyfikowanym przez Larę i innych. W artykule przedyskutowano teoretyczne aspekty problemu, a także zaprezentowano przykład obliczeń numerycznych.