Shape Of Graphite Inclusions Research Articles

The structure and shape of graphite inclusions in cast iron, affecting the durability of molds. Part 4

The structure and shape of graphite inclusions in cast iron, affecting the durability of molds. Part 4

КОРРЕЛЯЦИОННАЯ ЗАВИСИМОСТЬ ВЛИЯНИЯ СТРУКТУРЫ И ФОРМЫ ВКЛЮЧЕНИЙ ГРАФИТА ЧУГУНА СТАЛЕРАЗЛИВОЧНЫХ ИЗЛОЖНИЦ НА ИХ СТОЙКОСТЬ

The resistance of cast irons to destruction is largely determined by the shape of graphite inclusions, the size of graphite inclusions, the number of graphite inclusions, and the nature of the distribution of graphite inclusions. Studies of the stress-strain state, performed on models of gray and modified cast iron for bending, allow us to evaluate the advantages and disadvantages of the obtained structure and shape of graphite inclusions. The application of the method of mathematical statistics with obtaining an empirical dependence of the influence of the structure and form of the graphite inclusion of cast iron on the durability of the molds will allow optimizing the chemical composition of cast iron and increasing the number of fillings. The use of the method of analytical statistics in research, such as correlation analysis performed on physical models of cast iron, established the correlation dependence of the influence of the structure and shape of graphite inclusions of cast iron in steel casting molds on their durability.

ОПРЕДЕЛЕНИЕ РАЗМЕРНО-ТОПОЛОГИЧЕСКИХ ПАРАМЕТРОВ ГРАФИТОВОЙ ФАЗЫ В ЧУГУНАХ МЕТОДОМ ФРАКТАЛЬНОГО АНАЛИЗА ИЗОБРАЖЕНИЙ ЕГО МИКРОСТРУКТУРЫ

The basics of metallography and modern systems used for studying and analyzing the structures of materials are described. Special attention is paid to the techniques of quantitative microscopy, as a kind of ancestress of modern microstructure analysis systems. The analysis of modern computer programs used to analyze images of microstructures obtained from digital microscopes is presented. The basics of fractal analysis as a highly effective tool for calculating numerical values of parameters of geometrically complex objects are outlined. Using the example of the analysis of graphitized cast iron structure, the application of the fractal analysis method to determine such characteristics of the graphite phase as the shape of graphite inclusions and their distribution in the alloy volume is demonstrated. As part of the study, various classes of cast iron have been studied, such as graphitic pig iron with flaked graphite, cast iron with vermicular graphite, and high-grade cast iron with spheroidal graphite. To determine the shape of graphite inclusions, a fractal dimension has been proposed to be used, and the unevenness of the distribution has been estimated using such a function as lacunarity. The individual stages of determining these characteristics using a specialized FracLac module applied in the structure of the ImageJ program are presented. The obtained results showed high adequacy. Despite positive assessment, the shortcomings identified during the research on the use of fractal analysis methods for identifying geometrically complex dimensional and topological parameters inherent in the graphite phase in cast iron are noted. The ways for further improvement of these methods for solving a wide range of problems in metallography of alloys are proposed.

Using Computer Microscopy Methods to Control the Microstructure of Malleable Cast Iron Product with Spherical Graphite

The method of identification of objects on images of the microstructure of cast iron with spherical graphite of the correct shape with uniform distribution is presented. Morphological analysis techniques were used to identify shrinkage pores and graphite inclusions in microstructure images. Geometric features of the shape of graphite inclusions were used as methods for identifying graphite, in particular, particle size analysis, which is widely used to identify various objects in computer microscopy. The computer analysis of the image was performed with the program ImageJ. To determine the pores against the background of graphite inclusions, two characteristics were used - the shape and size of the objects themselves. The pores, presented on the image, differ from graphite inclusions by a complex, fractal border and comparatively large areas. For the visualization of the research results, the combination of the graphite part with the calculation and analytical part was used. Such presentation of the results is the most significant and allows to perform the most correct evaluation of the graphitized cast iron microstructure in accordance with GOST 3443-87.

The use of technogenic dispersed waste engineering to obtain compact forms of graphite in the materials of the system Fe-C-Al

Currently, the significant problem of domestic engineering is to improve the quality level of products based on efficient resource-saving technologies. In the paper the main emphasis has been placed on using in such a significant procurement industry of engineering, which is foundry, dispersed iron-containing with a different degree of oxidation of the designated waste element. Moreover, this use of waste is proposed to carry out both at the stage of preparation of the melt for blanks, and in the manufacture of a mold. We are talking about blanks of materials based on the system Fe-C-Al, the quality of which is largely determined by the shape of graphite inclusions.

Interaction of modifiers with liquid cast iron

The effects of some chemical elements and complex modifiers and certain technological operations (gas blowing, the sequence of introduction of additions, etc.) on the oxygen activity in and the surface tension of iron-carbon melts are studied. Correlations between these characteristics and the shape of graphite inclusions in cast iron are found.

Effect of “melt-crystal” interphase surface energy in iron on its structure in castings

Problems of the influence of “melt-graphite” interphase energy in iron on formation of graphite inclusions of different shapes are considered. The effect of the content of elements surface-active with respect to graphite in the melt on the shape of graphite inclusions is considered. The direction of their action on the variation of the “melt-graphite” interphase energy, which is the main factor of shaping of graphite inclusions in cast iron, is shown and the intensity of this action is evaluated.

On the mechanism of the effect of plastic deformation on the corrosion resistance of high-strength cast iron

The mechanism of the effect of preliminary plastic deformation on the corrosion resistance of high-strength cast iron is analyzed. Based on the experimental results, a scheme of the mechanism considering the contribution of the variation in the number and shape of graphite inclusions to the anisotropy of corrosion rate of strained cast iron is proposed.

Formation of the microstructure and properties in deformation heat treatment of high-strength cast iron with globular graphite

1. VChShG can be subjected to different kinds of plastic deformation without failure. 2. In the process of plastic deformation of cast VChShG, graphite inclusions irreversibly lose their globular shape, extending along the direction of metal flow in the deformation source. Subsequent heat treatment affects only the microstructure and the morphology of the phases that compose the metallic matrix and does not affect the shape of graphite inclusions. This determines the level and the isotropic nature of the mechanical properties of semifinished products of VChShG fabricated by plastic deformation of cast preforms and imposes certain constraints on the production process and the quality parameters of ready articles. 3. VChShG are susceptible to decarburization of the surface layer in heat treatment or heating for deformation in a furnace with an oxidizing atmosphere, which should be taken into account in designing the method of their deformation.

Effect of the shape of graphite inclusions on the properties of magnesium cast iron

Effect of the shape of graphite inclusions on the properties of magnesium cast iron

The shape of graphite inclusions in Fe?C and Fe?C?Si alloys

The shape of graphite inclusions in Fe?C and Fe?C?Si alloys