Mathematical Modeling of the Graphitization Process Applied to Nodular Cast Iron Parts

Used mainly in the construction of automobiles as a substitute for steel, or in the metallurgical industry, mainly in the manufacture of rolling mill cylinders, the mechanical properties of nodular cast iron depend largely on their structure, consisting of a ferritic metal mass, ferrite - pearlitic mass or pearlitic and graphite formations (graphite nodules) of maximum compactness. The modification of the structure in the desired direction of use properties, possible by applying appropriate heat treatments, can be achieved in conditions of technical and economic efficiency by applying the optimal heat treatment variant, in which the technological parameters temperature - time have a decisive influence. The paper summarizes some research results that aimed to establish the influence of annealing temperature and maintenance time to determine the optimal variant of graphite annealing heat treatment. Process modeling by statistical methods, indicated in the analysis of complex technological processes, has allowed, based on a preliminary experiment and then on the factorial experiment, the establishing of the degree of connection between the technological parameters of the process, as well as the technological parameter with the greatest influence on the process.