DOI: 10.52150/2522-9117-2025-39-16

S. O. Fedoriachenko^1,*, Ph. D. (Tech.), Associate Professor, ORCID 0000-0002-8512-3493
K. A. Ziborov¹, Ph. D. (Tech.), Associate Professor, ORCID 0000-0002-4828-3762
D. V. Laukhin¹, D. Sc. (Tech.)., Professor ORCID 0000-0002-9842-499X
O. V. Shchukin², Ph. D. (Tech.), Associate Professor, ORCID 0000-0001-6332-1811
O. V. Orel², Ph. D. (Tech.), Associate Professor, ORCID 0000-0003-0265-7527
V. M. Korol¹, Ph. D. student, ORCID 0009-0004-6433-1797
D. V. Harkavenko¹, Ph. D. student, ORCID 0009-0004-5011-9015

¹Dnipro University of Technology, Dmytra Yavornytskoho Avenue, 19, Dnipro, 49005, Ukraine

²Kharkiv National Automobile and Highway University, Yaroslava Mudrogo St., 25, Kharkov, 61002, Ukraine

^*Corresponding author: fedoriachenko.s.o@nmu.one

MATHEMATICAL MODELING OF MICROCRACK PROPAGATION UNDER THE PRESENCE OF INTERNAL DEFECTS IN METAL CASTINGS

Abstract. The article addresses the problem of the formation and development of microdefects in cast products made of metallic alloys, in particular microporosity and microcracks, which determine the durability and reliability of structures. It is shown that micropores of about 10 μm in size are difficult to detect using traditional control methods, yet they significantly reduce fatigue resistance, plasticity, and the tensile and yield strengths. The spatial distribution and morphology of pores govern the mechanism of crack initiation, while their coalescence in stress concentration zones accelerates fracture. Modern research methods are summarized, including optical and electron microscopy, X-ray computed tomography, and morphometric image analysis, which make it possible to determine the volume fraction of microporosity, defect geometry, and their degree of connectivity. The significance of numerical modeling is highlighted through the use of software packages such as Thercast, where the application of the Niyama criterion enables the prediction of porosity formation during solidification and the optimization of casting parameters. Particular attention is given to additive manufacturing technologies, where microporosity, combined with microstructural anisotropy and lack-of-fusion defects, increases material sensitivity to crack formation. For cast irons and steels, the dependence of microporosity on the carbon equivalent and graphite spheroidization is shown, which determines the quality of castings. A mechanico-mathematical model is proposed, integrating the principles of elasticity theory, linear fracture mechanics, and microstructural factors. Effective parameters are introduced-elastic modulus, yield strength, and fracture toughness-with correction factors accounting for defects, inclusions, and thermo-kinetic conditions. A crack growth law under dynamic loading is formulated and numerically verified. The results obtained have practical significance for optimizing casting and additive manufacturing processes, predicting service life, and ensuring the operational safety of structures in critically loaded mechanical and energy systems.

Key words: microporosity, microcracks, cast alloys, mechanico-mathematical modeling, Niyama criterion, additive technologies, fracture toughness, Thercast.

For citation: Fedoriachenko, S. O., Ziborov, K. A., Laukhin, D. V., Shchukin, O. V., Orel, O. V., Korol, V. M., & Harkavenko, D. V. (2025). Mathematical modeling of microcrack propagation under the presence of internal defects in metal castings. Fundamental and applied problems of ferrous metallurgy, 39, 274-284. https://doi.org/10.52150/2522-9117-2025-39-16

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Received 26.07.2025
Accepted 21.10.2025
Published online 01.12.2025