STATISTICAL ANALYSIS OF THE CHEMICAL COMPOSITION AND PROPERTIES OF DUCTILE IRON

It is shown that the current task in foundry production is the scientific support of technical solutions for the introduction into industrial practice of non-destructive methods for determining the mechanical properties of cast iron castings based on the results of the analysis of their chemical composition. The chemical composition and properties of cast iron castings of various classes and grades were analyzed using the method of assessing its carbon equivalent and degree of eutecticity using the probabilistic approach and the Monte Carlo method. The parameters of the arrays of probable values of the carbon equivalent, degree of eutecticity, and the ratio of the percentage content of silicon to the carbon content of malleable iron were determined. Histograms of the distributions of the values of these indicators in cast iron were presented. The probable ranges of the dispersion of the values of the carbon equivalent, degree of eutecticity, and the ratio of the content of silicon to the carbon content were established. The values of carbon equivalent, degree of eutecticity, other indicators of chemical composition and properties of malleable iron compared with similar characteristics of cast irons with lamellar, vermicular and spheroidal graphite. It is shown that taking into account the limitations of the total content of carbon and silicon in the chemical composition of malleable iron does not significantly affect the numerical values of its carbon equivalent and degree of eutecticity. The dependence of hardness, other mechanical properties of malleable iron castings on the values of its carbon equivalent and degree of eutecticity was not revealed. The influence of heat treatment on the properties of malleable iron is considered. The possibilities of improving the quality of malleable iron castings by their heat treatment are revealed. Recommendations are summarized for the selection of heat treatment modes for cast iron castings for various purposes to increase the level of their operational characteristics.