Cast Iron Melt Research Articles

INVESTIGATION OF THE MECHANICAL AND TRIBOLOGICAL BEHAVIOURS OF CUPOLA SLAG AND MWCNT-REINFORCED EPOXY HYBRID NANOCOMPOSITES: A SUSTAINABLE APPROACH FOR ENVIRONMENTAL PRESERVATION

This experimental investigation explores the mechanical and tribological characteristics of cupola slag (CS) and multiwall carbon nanotubes (MWCNTs) reinforced hybrid nanofiller epoxy composites. Cupola slag is an industrial by-product that is generated during the melting of cast iron. The disposal of slag residues in landfills results in environmental pollution. In the context of environmental preserving as well developing new engineering composites material from waste to resource. MWCNTs possess an excellent strength-to-weight ratio, high stiffness, and thermal properties. The mechanical and tribological characteristics of the hybrid nanocomposites comprising epoxy were examined by varying the weight fraction of fillers composed of CS and MWCNTs. The experimental results indicated that the ECSM3 hybrid nanocomposites have superior tensile strength and the flexural modulus improved by 92 % and 78 % respectively when compared with epoxy. Similarly, the tribology performance of the ECSM3 exhibited improved specific wear resistance of 97 %, 106 % and 88 % on the dry-sliding loads of 10 N, 20 N and 30N, respectively. A morphological analysis was carried out on fractured and worn surfaces of the specimen to understand the homogeneous dispersion and matrix-interlocking mechanism between the hybrid nanofillers and the epoxy matrix. The integration of CS alongside MWCNTs for the fabrication of epoxy hybrid nanocomposites represents a stride towards sustainable and eco-friendly technology in the production of multifunctional composite materials for diverse engineering applications.

ВАРИАНТ КОМПАКТИРОВАНИЯ МЕЛКОДИСПЕРСНЫХ ЖЕЛЕЗОСОДЕРЖАЩИХ МАТЕРИАЛОВ ДЛЯ МЕТАЛЛУРГИЧЕСКОГО ПЕРЕДЕЛА

The paper presents the results of a study of options for compacting fine iron-containing materials for metallurgical processing. The authors have proposed a method that involves the use of, in addition to an iron-containing material, a thermoplastic binder material. In this case, aggregation of the mixture and strengthening of the resulting aggregates is carried out simultaneously in a closed mold under the influence of pressure and temperature not lower than the softening temperature of the thermoplastic material. It is possible to obtain a compact unit, convenient for storage and transportation, that successfully performs the functions of a charge component during cupola and blast furnace melting of cast iron.

Development and implementation of technological measures to extend the campaign of blast furnace No. 5 of PJSC Severstal

The work presents generalized experience in the development and implementation at PJSC Severstal of technological measures to extend the campaign of blast furnace No. 5. The authors carried out an analysis, identified and described the problem areas, generalized the principles for ensuring the safety of the shaft lining, boshes and metal receiver of the blast furnace. The results of a study of the working space of blast furnace No. 5 in 2006 are also presented. The identified technological factors ensure an increase in duration of the unit campaign. Technolo­gical measures are given for: washing the blast furnace hearth, reducing chemical erosion of the carbon blocks of the hearth and flange, forming a protective skull in the blast furnace shaft, special methods for loading solid coke substitutes, and organizing an effective structure of the charge column in the blast furnace. It is necessary to use digital models integrated into the blast furnace expert system for operational control of blast furnace technology. The results of the current blast furnace campaign were compared with previous ones. It was proven that the systematic use of all elements of the developed technology makes it possible to achieve high economic indicators while exceeding the standard duration of the campaign by 1.75 times. Experience in technology development made it possible to increase the furnace campaign duration to 17.46 years, achieve a reduction in specific coke consumption by 15.9 %, and increase the specific consumption of natural gas for cast iron smelting by 46.4 %; reduce the specific carbon consumption for cast iron smelting by 6.3 %.

Механизм влияния электрического поля на процесс модифицирования серого чугуна

A diagram of an experimental installation for measuring the electrical resistance of a gray cast iron melt is presented, where a gauge based on a Kelvin double bridge is used. It is shown that the value of the specific electrical resistance of gray cast iron varies depending on the type of conditioning agent. Experimental data on the difference in specific resistivity values for various gray cast iron nucleating agents are presented. Changes in the values of electrical resistance under the influence of electric field treatment of inoculated cast iron melt are also given. Comparison of the strength values of gray cast iron with its values of the electrical resistivity of the cast iron melt after the electrical field exposure showed their simultaneous change. The decrease in the values of the electrical resistance of hot iron due to the electric field exposure is shown and it corresponds to an increment in the strength of inoculated cast iron. The effectiveness of the electric field exposure on the process of inoculation is determined by thermal ionization of the chemical elements included in the conditioning agent. The maximum increase of these parameters after electric field exposure when using FS75 nucleating agent is shown. The mechanism of the influence of an electric field on the cast iron solidification for the inoculation process of FS75, containing 75 % silicon in its composition, is described. The dependence of the efficiency of electric field exposure on the composition of the nucleating agent for gray cast iron is shown. A physical model of the effect of an electric field exposure on the process of cast iron inoculation is found. The possibility of influencing the hydrodynamic situation in the melt of gray cast iron and changing the rate of dissolution of nucleating agent particles by means of electric field exposure is given

Study on the effect of ultrasonic treatment for fabricating nodular cast iron with improved mechanical properties

In this paper, a novel ultrasonic treatment technique was proposed in nodular cast iron melt with the aim of improving the microstructure and mechanical properties of nodular cast iron. The effects of ultrasound on the microstructures and properties were investigated by comparing experiments with and without ultrasound. The results showed that compared with the NO UT specimen, the mean equivalent diameter of graphite nodules was reduced by 46% in the UT 105 s specimen, while the mean roundness and nodule count per unit area were increased by 33.9% and 43.6%, respectively. In addition, the ultrasonic treatment of melt could increase the pearlite content, refine the matrix microstructure and reduce the pearlite interlamellar spacing from 392.7 nm to 231.3 nm. Compared with the NO UT specimen, the mechanical properties of the UT specimen were improved significantly, and could up to UTS of 739 MPa, YS of 579 MPa and El of 9.4% in the UT 105 s specimen. In this work, the mechanism of ultrasonic action on nodular cast iron also was discussed in detail.

Study on Dissolution of Ba-Containing Inoculant in Ductile Cast Iron Melt and Nucleation of Graphite

The production of high quality ductile cast iron requires different and complex inoculants. Besides iron and silicon, they also contain alloying elements such as zirconium, strontium, barium, calcium and rare earth metals. The addition of these elements reduces carbide solidification and increases the number of eutectic cells, which improves the quality of the cast iron produced. This study investigates the process of incipient melting of a complex barium inoculant and its effects on graphite nucleation. In the study, the sample was prepared by introducing the inoculant grain into the melt of the ductile iron. The region between the inoculant grain and the less inoculated matrix was examined metallographically using light and scanning electron microscopy. We used energy dispersion spectroscopy to determine the phases in the microstructure formed. It was found that graphite particles can already nucleate and grow in solid particles when the inoculant is still dissolving and also from the melt where the Ba and Ca concentrations are high and form BaO·CaO phases that serve as nuclei for graphite growth.

Контроль прочности серого чугуна электрографическим способом

The experimental procedure carried out on a test installation to determine the electrical resistance value in the process of crystallization of cast iron is presented. A scheme of a test installation using a measuring circuit based on the Wheatstone bridge circuit to determine the electrical resistance value of crystallized cast iron is given. Recording measured data over time allowed constructing a graphical dependence of the change in the values of specific electrical resistance during the crystallization of gray cast iron. Experimental data on changes in the values of the specific electrical conductivity of a sample of gray cast iron during crystallization and their relationship to the amount of supercooling of the melt of this alloy are presented. The obtained dependence made it possible to identify on the curve of specific electrical resistivity change under supercooling of cast-iron test sample those areas, which were exposed to the cast-iron melt supercooling. The ratio of the initial and final values of the electrical resistivity under supercooling of cast iron allowed calculating the values of the relative electrical resistivity. Measurements of cast iron strength have shown that they are functionally related to the value of the relative electrical resistivity of gray cast iron, determined by the degree of supercooling of the cast iron melt. The use of this method will make it possible to predict gray cast iron strength and will allow reducing the amount of castings defective in terms of mechanical properties and at the same time increasing foundry production profitability.

Effect of Carbon and Cooling Rate on the Structure of Hypereutectic High Chromium Cast Iron in the Cast State and after Heat Treatment

The article presents experimental data on the changes in the structural parameters and properties of castings from high-chromium cast iron G-X300CrMo27-1 depending on the carbon content, which ranged from 2.8 to 4.5 wt. %. Castings were obtained under cooling conditions with two cooling rates—0.083–0.117 °C/s and 4.67–5 °C/s. Changes in the structure and properties of these castings after destabilizing annealing and subcritical heat treatment were assessed. Changes in carbon concentration and cooling rate in the crystallization interval have a significant effect on the sizes of primary carbides (Cr, Fe)7C3, and on the fraction of eutectic carbides. The microprobe analysis results indicating the effects of cooling rate on the composition of phases in cast iron castings with carbon contents of 4.2 wt. % are presented. The offset value of the crystallization onset temperature and eutectic point with an increase in the cast iron melt cooling rate from 0.083 to 0.83 °C/s is shown. The changes found in the properties of castings with increases in carbon concentration and cooling rate cannot be unambiguously explained by the transformation of the structure of primary and eutectic carbides and changes in the elemental composition of phases. The composition and condition of the matrix has a significant effect on the hardness, bending strength and abrasion resistance of castings. It is suggested that internal stresses arising in primary and eutectic carbides affect the properties of castings in the cast and heat-treated state.

APPLICATION OF VACUUM SUCTION CASTING OF IRON-CARBON ALLOYS FOR THE PRODUCTION OF ENGINE PARTS

The use of vacuum suction casting technology for iron-carbon alloys for the production of internal combustion engine parts will improve their quality and wear resistance, preserve metal, and reduce emissions. The technology is widely used for non-ferrous alloys. At the same time, its implementation for iron-carbon alloys (including cast iron) in modern engine construction requires careful scientific and practical preparation. Problematic tasks arise when improving the pneumatic system of vacuum suction (large volumes of gas release), the stability of the metal pipeline (thermal overload in a high-temperature cast iron melt), and the stabilization of the casting microstructure (high-speed crystallization). The authors suggest using a specialized titanium alloy VT3-1 for the metal pipeline, for which the article calculates thermal loads during cyclic operation in the “Deep – take-out” mode for the use of cast irons of the SCH25 and VCH50-1.5 grades. For reliable operation of the metal pipeline and the absence of solidification of the melt on its inner surface, a thermal calculation method was develop, which allows determining the time of heat removal of overheating of the melt according to the diameter of the metal pipeline. The pneumatic system of the vacuum unit is supplement with a patented gas jet ejector, which, in combination with a powerful shop compressed air system, provides a full gas outlet. Applying the developed law of change in the discharge between atmospheric pressure and pressure in the mold cavity, the authors of the article regulate the rate of crystallization of castings, which makes it possible to form much smaller phases of perlite in the microstructure and reduce the presence of Ferrite. At the Enterprise "Pervomaiskdizelmash" using vacuum casting technology, blanks of guide bushings of engine valves 6CHN25/34 made of cast iron SCH25 and VCH50-1,5, as well as oils of piston rings made of cast iron VCH50-1,5 were obtained. The obtained parts showed an increased service life by 15-30%. Vacuum casting technology is recommend for iron-carbon alloys in the production of engine parts.

Influence of Temperature Regimes of Synthetic Iron Smelting on Casting Production Efficiency

The purpose of the foundry is to provide the consumer with blanks for general machine-building (special) purposes which are as close as possible to the size of the future part in full compliance with the requirements. The competitiveness of these products is primarily dependent on the use of efficient and reliable smelting equipment which meets the necessary cost. The replacement of high-value ironworks and ironworks iron with steel scrap using induction melting furnaces (ICFs) reduces the cost of producing synthetic cast iron. However, this results in temperatures greater than 1500 °C, reduced lining stability and increased downtime of the smelter. As a result of the research carried out, a technology for the use of quartzite is proposed. Thereby, the purpose of this work is to establish temperature regimes for the smelting of synthetic pig iron, allowing the use in metal filling up to 70–90% of steel scrap; this leads to a reduction in the cost of purchasing bulk materials (depending on the brand of cast iron) up to 50% and, thus, increases the efficiency of synthetic cast iron smelting and castings production in general. After removal of the original moisture and the subsequent sintering of the manufactured lining, it provides the possibility of melting using the melting temperatures 1550–1600 °C. It increases the efficiency of the operation of the melting furnaces and eliminates the consumption of the ironworks and the melting of the cast iron in the blast furnace, as well as the cost of the lost alloy. As a result, metallurgical production will be able to reduce the volume of production and supply of cast iron for ironworks, which will improve their environmental situation during the production and processing of necessary raw materials.

Effect of Mn Content on Fatigue Limit of Various Flake Graphite Cast Irons

In recent years, with the active use of Mn-containing high-tensile strength steels as an automotive body material, it has become increasingly difficult to recycle Mn-containing high tensile strength steel scrap as raw material to produce cast iron, due to the fact that Mn is known as an element promoting the chilling tendency of cast iron melt. Therefore, in this study, the effect of Mn on the fatigue limit of flake graphite cast iron was investigated for the purpose of increasing the strength of cast iron and recycling high tensile strength steel. Flake graphite cast irons with different Mn contents (0.5 mass % and 2.0 mass %, the carbon equivalent corresponding to FC200, FC300 and FC400 of JIS specification (G 5501)) were prepared for plane bending fatigue test.

On modification of eutectic cast iron graphite

It has been shown that elementary crystalline cells of graphite and basic products of iron modification do not correspond to the principle of structural and dimensional correspondence of Dankov –Konobeevsky. Modifying elements Al, Ca, Mg, Ba, Ce increase the phase tension melt‑graphite by binding surface‑active oxygen and sulfur. Modifying cast iron eutectic graphite is a nanostructured process in which modifying elements refine elemental graphite nanocrystals from adsorbed oxygen and sulfur atoms. This contributes to an increase in the concentration of graphite nuclei upon solidification of the cast iron melt. The modification reduces the concentration of dissolved hydrogen, which increases the effectiveness of the modifying effect. Reduced concentrations of demodifying surface‑active elements, melt degassing, increased heat removal contribute to increasing the degree of branching and compactness of graphite dendrites during iron crystallization. The strongest modifying element of eutectic cast iron graphite is magnesium.

Iron production in the ancient Xianyang city of the Qin state: A perspective on iron smelting slags

The ancient Xianyang city was the capital city of the Qin state and Qin empire during the 4th century BCE to the 3rd century BCE. In the past decades, several archaeological excavations and surveys have carried out in the city site and two ironworks have been discovered. The present paper reports the iron production technology applied in one of the ironworks in the ancient Xianyang city site through metallographic and elemental analyses of collected slags. The analytical results provide evidence that both cast iron smelting and fining process were applied in the ancient Xianyang city.

Peculiarities of Cast Iron Smelting in Blast Furnaces with a Volume of 1232 and 1648 m3 of Ural Steel JSC with Different Share of Pellets

Peculiarities of Cast Iron Smelting in Blast Furnaces with a Volume of 1232 and 1648 m3 of Ural Steel JSC with Different Share of Pellets

New concept of cast iron melting technology in induction crucible furnace

The article considers methods for reducing harmful impurities in the composition of synthetic cast iron (SCI) and improving the strength characteristics of cast iron. A new method for smelting SCI using steel scrap as charge materials in induction crucible furnaces is proposed, including filling of metal charge, together with transfer cast iron, return of own production, carburetors, and ferroalloys to carburize and alloy up to the required chemical composition. It is revealed that with an increase in steel scrap in the metal charge, the melting time, specific power consumption, melting duration, hardness of the experimental sample increase, and the yield of usable liquid cast iron decreases. To achieve the required hardness of the experimental sample, it is necessary to have мeтaллoшихтefrom 10 to 40% of steel scrap in the metal charge.

До питання структуроутворення високоміцного чавуну при використанні діаграм стану систем «Fe-Si», «Mg-Si» та «Fe-Si-Mg»

The purpose of the work is to establish the patterns of structural formation of high-strength cast iron using the thermodynamic theory of phase transformations and to analyze state diagrams of the components of Fe-Si-Mg ligatures. The article presents the results of the analysis of patterns of structural formation of high-strength cast iron when using state diagrams of the "Fe-Si", "Mg-Si" and "Fe-Si-Mg" systems. The concept of graphite formation in high-strength cast iron is considered. The structure formation scheme of high-strength cast iron is presented. Disclosure of the mechanism of processes of formation of spherical and vermicular graphite opens wide opportunities for controlling the structure and properties of high-strength cast iron and contributes to the development of effective technological processes for obtaining cast products for various purposes. It has been established that during the modification of cast iron melt, as a result of a significant redistribution of all elements dissolved in it, purification of impurities (sulfur, phosphorus, etc.) takes place, which allows obtaining the structure of cast iron with nodular graphite with the use of modifiers. Diagrams of the "Fe-Si", "Mg-Si" and "Fe-Si-Mg" systems for the development of the composition of high-strength cast iron are given. After analyzing the data of the given state diagrams, it was concluded that in the composition of spheroidizing ligatures, all compounds of elements are low-melting (tpl < 1300 °С) in relation to the melting temperature of cast iron. During the crystallization of cast iron with the release of austenite, a direct microliquation of silicon with a distribution coefficient less than unity is characteristic, manganese is more evenly distributed in the metal, and carbide stabilizing elements are treated in the liquid phase. The regularities of structure formation of modified cast iron under different crystallization conditions have been established. The analysis of the study of the regularities of the process of the formation of spherical and vermicular graphite and the analysis of state diagrams of the "Fe-Si-Mg" liga-tur components were performed.

Analyzing the effect of inoculant addition on the solidification of ductile cast irons using thermal analysis

PurposeThe final properties of ductile iron are decided by the inoculant processing while pouring the melt. The shape and size of nodules generated during solidification are of paramount importance in solidification of ductile cast iron. The purpose of this study is to examine the effect of different inoculant addition on the solidification of ductile cast iron melt through thermal analysis.Design/methodology/approachThermal analysis has recently grown as a tool for modeling the solidification behavior of ductile cast irons. Iron properties will be predicted by analyzing the cooling curve patterns of the melts and predicting the related effectiveness of inoculant processing. In this study, thermal analysis is used to evaluate the need for inoculation.FindingsThe amount and type of inoculation will affect the amount of undercooling during the solidification of ductile cast iron. It is found that the addition of 0.1 to 0.4 Wt.% inoculant lowers the austenite dendrite formation starting temperature while increasing the eutectic freezing temperature. Microstructure analysis revealed that the addition of inoculation increases the nodule count from 103 to 242 nodules. The beneficial effects of inoculation are sustained by an improved graphitization factor, which shows the formation of graphite nodules in the second phase of the eutectic reaction.Originality/valueThe inoculation treatment has improved metallurgical occurrences such as carbide to graphite conversion, graphite microstructure control, graphite nodule count at the start of solidification and the last stage of solidification, which determines the soundness of casting. The foundry industry can follow these steps for monitoring the solidification of ductile iron castings.

Stokes' Law Approach to Slag Formation Process to Increase the Effectiveness of Cleaning Metal Liquids in Cast Iron Smelting Process

The purpose of this study was to increase the effectiveness of slag cleaning in the cast iron smelting process using an induction furnace. This study resulted in the calculation of the terminal velocity of the slag emerging to the surface of the induction furnace based on Stokes' Law approach for each slag that appears during the cast iron smelting process. For each cast iron casting, three samples were taken based on the fastest time on the very light slag, the slag’s time for the heaviest slag, and the extreme time for comparison. The results of each sample are tested for characterization such as shape, size, and chemical composition of each sample which are then adjusted to the calculations that have been made. The characterization was analyzed using X-ray diffraction, scanning electroscope, and energy dispersive spectroscopy microanalysis. The results show that the Stokes law approach to predict the slag reaching the surface gets the appropriate result that all the slag reaches the surface at time t = 230 s. The slag that appears at time t = 300 s is the slag formed due to the interaction of the liquid with the surface which is not the slag that occurs from the raw material used. This study succeeded in minimizing the formation of slag in each casting of cast iron using an induction furnace.

Use a smaller cylindrical thermal analysis sample cup to rapidly predict carbon and silicon content in cast iron

ABSTRACT For the current, the thermal analysis sample cups used to predict the carbon and silicon content of cast iron melts are relatively large and take a long time for each measurement, a smaller cylindrical thermal analysis sample cup with an inner diameter of 25 mm and a height of 55 mm was studied for the analysis of carbon and silicon. The thermal analysis system can quickly measure the temperature characteristic values of the liquidus temperature TL and the eutectic temperature TE of the temperature curves related to carbon equivalent, carbon content and silicon content within 2 min, and mathematical models for the prediction of carbon equivalent CEL (3.2–4.7), carbon content C% (3.0–4.0%) and silicon content Si% (1.0–2.5%) was established by multiple linear regression in combination with optical emission spectroscopy: We had checked the accuracy, the average error of carbon equivalent and carbon content and silicon content did not exceed 0.05%.

Procedure for selecting a rational technological mode for the processing of cast iron melt on the basis of graph-analytical processing of the data of serial smeltings

The object of research: cast iron grade DSTU EN 1561 (EN-GJL-200), used for the manufacture of body parts for mechanical engineering.
 Investigated problem: the choice of the technological mode of the process of producing cast iron under conditions of multifactorial influence on the formation of its microstructure.
 The main scientific results: A procedure for truncation of the influencing factors on the formation of the microstructure is proposed, which is a consistent reduction of data from serial smeltings to uniform conditions allowed by the actual data set. Common conditions mean the closeness of the chemical composition of the melt, which makes it possible to compare the effectiveness of the applied modifiers in combination with microalloying in terms of cast iron microstructure indicators. The proposed data truncation procedure made it possible, by creating conditions for comparing the efficiency of FeSi75 and FeSi65CaBaSr2 modifiers, to develop a rational technological regime for melt processing.
 It has been established that the compared modifiers have the same effect on the size of graphite – its content is (50–51) μm, however, the use of FeSi65CaBaSr2 in combination with an alloying complex (0.27 %Cr+0.083 %Ni+0.048 %Ti+0.155 %Cu+0.018 %V ) makes it possible to obtain an average amount of pearlite of 96 % in the microstructure.
 The area of practical use of the results of the study: the results obtained can be used in foundries or metallurgical shops of industrial enterprises as part of a general technology for producing cast iron of various grades, developed for cases of incomplete control of the quality of charge materials. Such a situation occurs, for example, when the charge is formed from dismantled armored vehicles that cannot be restored due to destruction on the battlefield.
 Innovative technological product: iron smelting technology that allows the possibility of minimizing the cost of smelting in terms of the use of modifiers and alloying ferroalloys
 The scope of the technological innovative product: technological regimes for the production of cast iron.