New Comprehensive Approach to Mathematical Modeling of Metallographic Images of Tool Structures

Author

Svitlana P. Romaniuk, Kharkiv National Technical University of Agriculture named after P. Vasylenko (44, Alchevskykh St., Kharkiv, 61002, Ukraine), e-mail: romaniuk.khntusg@gmail.com, ORCID: 0000-0002-9226-2205

Abstract

To increase the operational durability of tools in production and operation, this paper proposes an integrated approach for processing metallographic images of tool structures at various stages of their life cycle. It is based on the use of the Thixomet Pro software and a specially developed optical-mathematical method, which supplements standard programs for searching for optimal properties and production parameters. The metallographic structural images, obtained by using both optical and electron microscopes, were evaluated with the analysis of pixels in photos. Changes in the structural components of the metal in the two zones (in the main part and at the edge of the working surface of a tool) were comparatively analyzed.  During operation, the decomposition of less stable structural components occurs, and a decrease in the proportion of special carbides from 14.4% to 8.15% can be observed. This is caused by the influence of deformation localization, which leads to the fragmentation and alignment of dispersed carbides at an angle of 45° relative to the working surface of a tool deep into the tool under the action of stresses, which during operation are the centers of crack nucleation and development. At the same time, carbide decomposition as well as diffusion of carbon and chromium can be observed. Using the mathematical method for describing structural changes, it was found that under the influence of external factors at the edge of the working surface of a tool, the intensity of the resulting diffusion of chemical components is higher. In addition, zones of damage and maximum local heterogeneity associated with the presence of pores and cracks were identified. This technique made it possible to identify an increase in the anisotropy of properties, formed during operation and associated with metal degradation, and determine the degree of structural heterogeneity.

Keywords: optical-mathematical method, image, structural heterogeneity, defects, carbide phase, diffusion.

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References

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Received 13 November 2019

Published 30 December 2019