STUDY OF THE MICROSTRUCTURAL FEATURES OF HIGH-STRENGTH CAST IRON

Abstract

This study focuses on the structural and microstructural characteristics of high-strength spheroidal graphite cast iron and their relationship with the mechanical performance of the material. Particular attention is paid to the morphology, size, distribution, and degree of spheroidization of graphite nodules, as well as to the phase composition of the metallic matrix. The applicability of metallographic examination, optical microscopy, and digital image analysis for evaluating the microstructure of spheroidal graphite cast iron is discussed. The analysis demonstrates that the mechanical behavior of the material is strongly influenced by graphite morphology and nodularity, the spatial distribution of graphite particles, and the relative proportions of ferrite and pearlite in the matrix. A more uniform and highly spheroidized graphite structure contributes to a reduction in local stress concentration and promotes improved strength and plasticity. At the same time, an increase in pearlite content generally results in higher hardness and tensile strength, while a predominantly ferritic matrix provides greater ductility and impact resistance. The presence of compacted, irregular, vermicular, or other degenerated graphite forms may lead to deterioration of the mechanical characteristics. The obtained results emphasize the importance of controlling microstructural parameters during the production of high-strength spheroidal graphite cast iron.