Browsing by Subject "chill"

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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 ,
Solidification conditions of gray and white cast iron. Part I, Theoretical background
(2005) Fraś, Edward; Górny, Marcin; López, Hugo F.
The present work is based on a heat balance during the solidification of cast iron. Accordingly. an analytical expression was derived to relate the chilling tendency (CT) of cast iron with nucleation and growth processes associated with eutectic graphite and cementite constituents. A relationship is found between the CT and factors such as the physical-chemical state of liąuid, the distribution of nucleation sites, and the density of nucleation sites for eutectic grains. In particular, it is found that the casting modulus (M), enabling determinations of minimum wali thickness for chilled castings or chill widths in wedge shaped castings can be related to the CT. Finally, the present work provides a rationa-lization for the effect of technological factors such as the chemistry of the melt, inoculation practice. holding temperaturę and time on the resultant CT and chill of the cast iron.
Access status: Open Access ,
Solidification conditions of gray and white cast iron. Part II, Experimental verification
(2005) Fraś, Edward; Górny, Marcin; López, Hugo F.
In this work, an experimental verification of the theoretical principles for the transition from gray to mottled and white cast iron solidification is presented. Experimental tests have been implemen-ted using plate and wedge shaped castings of various sizes. The experiments included inoculated and non-inoculated cast irons of different chemical compositions and time after the inoculation treatment. In addition, thermal analysis tests were employed to determine the degree of undercooling of graphite eutectic ATm. This included microstructural evaluations in order to establish the density of eutectic grain (cells). This procedurę enabled the calculation of the theoretical grain density (celi count) TV, the wedge value w, as well as the chilling tendency CT of cast iron. It was found that the predictions of the theoretical analysis are in good agreement with the experimental outcome for the chill exhibited in wedge and plate shaped castings.