INFLUENCE OF SILICON WHEN MODIFYING THE CRYSTALLIZATION OF CAST IRON WITH FRAKE GRAPHITE

The study objective is to evaluate the effect of silicon concentration on modifying cast iron with frake graphite from the point of view of melt heterogenization. The task to which the paper is devoted is to analyze the results of microstructural and electron probe microanalysis of gray antifriction cast iron samples of SHM and A-HMM grades, experimentally obtained using silicon-based modifiers of different concentrations of 68-72% and 73-75%. Research methods: theoretical analysis of the literature on the subject of the study, experimental studies of modifier compositions with different concentrations of silicon, practical determination of sample hardness, microstructural studies, microrentgenospectral analysis. The novelty of the work: the hypothesis of melt heterogeneity after modification and the formation of finely dispersed graphite in areas with high silicon content is experimentally confirmed. Research results: Practical results make it possible to prove that the silicon concentration has a significant effect on the crystallization of low-sulfur gray cast iron. Analysis of the characteristic X-ray spectrum of the graphite phase confirmed the presence of silicon on the spectrum in samples with the best structure and properties obtained using modifiers with a high silicon content of 73-75%, which confirms the hypothesis of melt heterogeneity after modification and the formation of finely dispersed graphite in areas with a high silicon content.