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The range of graphite forms observed in vacuum-treated Fe-C-Si alloys was studied using synthetic and commercial alloys (Sorel F-10, S-125) in order to attain a better understanding of the thermal and chemical conditions governing the growth of the various graphite forms. High-purity Fe-C-Si alloys were further treated by 3-h vacuum-refining and allowed to solidify in situ as well as in an unheated ceramic mold under vacuum. The effects of various foreign elements such as sulphur, oxygen, argon, nitrogen and hydrogen were studied by adding them singly to the vacuum-refined high purity Fe-C-Si alloys. The results are reported.There appeared to be some confusion in the literature, particularly regarding the vermicular/coral and the compacted forms, both in the terminology used to describe them and in their sequential order in the graphite morphology "spectrum". Hence an attempt has been made to clarify the situation in order to develop a clearer understanding of graphite morphology control.

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An attempt has been made to develop forgeability criteria based on data obtained from local strain measurements. Nodular case iron has been used as the modelling material because its microstructure may be manipulated to contain near-spherical graphite nodules which are suitable for the study of deformation, foregeability, etc. Cracking will occur under certain deformation conditions which may be determined by following the changes in spherulite/nodule shape and habit. Local strain in any area of interest may be determined by measuring the shape change of the previously spherical nodules in terms of an aspect ratio b/a (a = major axis, b = minor axis of the deformed nodules) from specimens sectioned after deformation. A wide variety of forgeabilities can be obtained by changing the microstructure and composition of the matrix.

A method is described for the preparation of Charpy impact specimens suitable for screening purposes for a series of small experimental cast austenitic manganese steel heats. The process involves the investment casting of test specimens and notching by means of a computer controlled electrical-discharge-machining (EDM) unit.