BUILDING MODELS OF STRUCTURE FORMATION OF UNAL-LOYED HYPOEUTECTIC CAST IRON USING THERMAL ANALYSIS

HGMGRY

Abstract

The article presents the results of research in the field of thermal analysis of the solidification of hypoeutectic unalloyed cast iron with various types of microstructures. The importance of primary crystallisation as a key stage in the formation of the microstructure of the future casting is noted. It details the materials, methods, and equipment used in the implementation of the thermal analysis method in the authors' experiments. The parameters of the structural formation model are provided, which include a list of key temperature points of phase transformations, theoretical indicators of eutectic crystallisation, and theoretical quality indicators of the cast iron melt. Microstructures of four samples, investigated using light microscopy, are presented. The patterns of the cooling curve behaviour are described in relation to the technological features of sample production. It is experimentally demonstrated that the crystallisation models of both hypoeutectic and near-eutectic cast irons exhibit different behaviours associated with the differences in the mechanisms of their phase transformations during primary crystallisation. Conclusions are drawn indicating that the parameters of the primary crystallisation models can be used to predict the structural formation processes during the crystallisation of hypoeutectic melts.