Browsing by Subject "eutectic transformation"

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Access status: Open Access ,
Analysis of cooling curves of nodular cast iron
(AGH University of Science and Technology Press, 2018) Bartošová, Marianna; Pribulová, Alena; Futáš, Peter; Eperješi, Štefan
The solidification of cast iron is a complex process with characterized entrance and marginal conditions. Thermal analysis is one of the processes that allows us to observe the solidification of alloys. There is a possibility of gaining information about the melted cast iron quality and predicting the final properties of the cast by evaluating the scanned cooling curves by solidification (stable and metastable system). This article deals with the study and analysis of cooling curves taken from production conditions of a foundry during ductile cast iron production. The aim is to discover the reproduction and reliability of the thermal analysis results of cast iron. The study of the progress of the cooling curves and their first derivation to follow the reactions of the curves to changing factors in the production process.
Access status: Open Access ,
Eutectic transformation in ductile cast iron. Part 2 - Experimental verification
(2005) Fraś, Edward; Górny, Marcin; López, Hugo F.
In this work the predictions of a proposed analytical theory aimed at elucidating factors influencing on the nodule counts, the chill and the chilling tendency of nodular cast iron were experimentally verified. The experimental work was focussed on processing nodular cast iron under various inoculation conditions in order to achieve various physicochemical states of the experimental melts. In addition, plates of various wall thicknesses were cast and the resultant chilling tendency was established. Metallographic evaluations were made to determine the exhibited nodule counts in the experimental plates. Moreover, thermal analysis of these nodular cast irons was used to find out the degree of maximum undercooling for the graphite eutectic deltaTm. Finally, calculations were made using previously derived analytical expressions to determine graphite nodule counts, chilling tendency and critical wall thicknesses, below which the chill appears. From this analysis, it was found that there is good agreement between the theoretical predictions and the experimental outcome.
Access status: Open Access ,
Eutectic transformation in ductile cast iron. Part I - Theoretical background
(2005) Fraś, Edward; Górny, Marcin; López, Hugo F.
In the present paper, heat balance is incorporated in developing expressions for the solidiflcation kinetics of divorced eutectic in ductile cast iron taking into account nucleation and growth processes for spheroidal graphite. Accordingly, a new analytical equations were derived that describe the nodule count N and the chill and chilling tendency CT of ductile cast iron. From this analysis, it is viable to predict cast nodule counts as well as the chill and CT for ductile iron from experimental data on cooling rates, chemical composition and other factors. Finally, the effect of technological factors on the resultant nodule counts the chill and chilling tendency is considered in this work.