A new unidirectional solidification method to study gray cast iron

Abstract

A new unidirectional solidification (US) method to study gray cast iron was developed. It is based on the combination of the classical Bridgman-type technique and the directional casting technique. By means of this method, it is possible to achieve, among others, the following aims: (a) changes in chemical composition of the melt during the experiment without modifying G/R (G: thermal gradient and R: solidification rate); (b) US of modified (compacted/vermicular) gray-cast iron, avoiding equiaxal nucleation in front of the solid/liquid (S/L) interface; and (c) quenching of the S/L interface retaining the microstructure of the growing solid.

From flake to nodular: A new theory of morphological modification in gray cast iron

“…All these experimental details were described elsewhere. [20] with the liquid is observed. On the contrary, when the graphite crystal is equilibrated with a pure Fe-C melt, faceted (singular*) interfaces are observed.…”

“…The transition was provoked by a change in chemical composition, maintaining G/R constant. [20] As was previously indicated, the addition of commercial alloys to the remainder of the liquid was made in such an amount that the calculated final concentration was 1.5 to 5 wt pct. In such a case, the maximum bulk concentration of added foreign elements (as, for example, Mg of CG559) would only be 0.0025 pct.…”

“…As was described in our previous work, [20] in order to retain the microstructure of the solid/liquid interface, the solidification can be interrupted by quick quenching of the liquid at 1 to 2 mm ahead of the growing solid. Figure 8 is a low-magnification SEM photograph of the microstructure obtained by this procedure.…”

“…In a previous work, [20] a new technique of directional solidification, which allows the performance of the experiments mentioned previously, was depicted. In this work, the results that support a new model which explains morphological modification are presented.…”

Development of compacted vermicular graphite cast iron for railway brake discs

“…V. graphite cast iron has recently gained renewed popularity owing to its price competitiveness and excellent mechanical and thermal characteristics [6][7][8]. On the basis of its outstanding processibility, thermal conductivity, and wear characteristics [7,9], it has been applied to automobile and railway brake discs.…”