Induction Crucible Furnace Research Articles

FOUNDRY TRIBOTECHNICAL BRONZE BrO3A3 CORROSION RESISTANCE INVESTIGATION

Problem statement. Bronzes have been and remain the main material for friction bearings, anti-friction and corrosion-resistant parts manufacturing that work under high loads, chemically active aggression influence at low and elevated temperatures, in cavitation, erosion, etc. conditions. That is, technology continuous development requires from anti-friction bronzes constant their corrosion resistance increasing, as a factor that will allow to significantly expand their application scope and increase cast products from them durability and reliability. The purpose of the articles. Based on relationship between corrosion damages and chemical composition analysis, compare BrO3A3 bronze corrosion resistance with BrA5, BrA9Zh3L and BrO5Tz5C5 bronzes corrosion resistance as the materials most often used in industry for parts manufacturing that work in friction nodes and chemically active environments. Methodology. Alloys for samples production have been prepared by technical purity primary charge materials fusing. Melting has been carried out in induction crucible furnace using a graphite crucible and charcoal as a coating material. Cast bronze samples corrosion resistance studies have been carried out in accordance with ISO 7384:2001, ISO 11845:1995 and GOST 9.308-85 requirements. Studied samples corrosion resistance has been evaluated based on the results of their relative weight loss during exposure for 90 days in climate chamber at relative humidity of 93 ± 3 % and temperature of 40 ± 2 °С, in sea and fresh water with temperature of 20...22 °С. Conclusions. BrO3A3 bronze, among the studied foundry bronzes, is characterized by the best level of anti-corrosion properties in all environments used in this research. In this regard, it is a reason to recommend the studied bronze for tribotechnical purpose cast parts manufacturing, which work in air, fresh or sea water.

ENVIRONMENTAL ASPECTS OF PROCESSING GRANULAR FILTERS FOR PRIMARY ALUMINUM REFINING

This article presents the results of experimental studies on the involvement in the processing of used filters from ash and slag waste used in the refining of primary aluminum as a filler in the production of concrete for building products. The research was carried out within the framework of grant funding from the Science Committee of the Ministry of Science and Higher Education of the Republic of Kazakhstan under the competition «Zhas Galym» under the project IRN AR19175493 «Development of technology for refining primary aluminum with filters with an active surface». The recycling of used grain filters was carried out in three stages: preliminary processing of filter grains to remove aluminum scrap; metallurgical processing of separated aluminum scrap by remelting in an induction crucible furnace and refining using complex technology described by the authors in the work; obtaining a concrete mixture based on crushed waste filter grains, quartz sand and bauxite sludge, screenings from crushing rocks with a fraction of 20–30 mm and Portland cement to obtain samples of construction products. According to the test results, the tensile strength of concrete samples of building products is 20.89–37.75 MPa, depending on the content of Portland cement (from 20 to 40 %) and corresponds to the class of heavy concrete. Keywords: aluminum, granular filter, ash, waste, recycling.

Оцінка підходів до прогнозування властивостей синтетичного чавуну у ливарному виробництві

An overview of approaches to assessing the dependence of the mechanical properties of products made of synthetic iron smelted in induction crucible furnaces on the content of carbon and the content of silicon in its chemical composition, as well as on the carbon equivalent, the degree of eutecticity, and the ratio of the carbon content to the silicon content is given. The statistical parameters of the percentage distributions of the specified elements in the chemical composition of cast irons with lamellar graphite produced in accordance with the requirements of DSTU 8833-2019 were analyzed. The values ​​of the carbon equivalent of the chemical state of these cast irons and the values ​​of their degree of eutecticity were calculated according to common formulas for determining these indicators using the Monte Carlo method and using a probabilistic approach taking into account the content of each element in the chemical composition of cast iron. It is emphasized that, from a probabilistic point of view, the values ​​of the carbon equivalent and the degree of eutecticity may not coincide in different batches of cast iron, even with the same values ​​of the percentage content of chemical elements in its composition. It is shown that with an increase in the carbon equivalent and the degree of eutecticity, the strength and hardness of cast iron produced in accordance with DSTU 8833-2019 decrease. As the carbon content and carbon equivalent increase, the ratio of carbon content to silicon content decreases. In industrial batches of cast iron brake pads and «Khanin wedge» manufactured in accordance with GOST 30249-97 and GOST 34503-2018, the hardness of these products does not depend on the carbon equivalent due to the small range of the carbon equivalent values. Keywords: foundry products, cast iron, chemical composition, carbon equivalent, ratio of carbon content to silicon content, degree of eutecticity, hardness, strength

Increasing the Efficiency of Synthetic Iron Production by the Use of New Kit Lining

The production of synthetic iron castings in Russia comprises 50% of all alloys produced; therefore, increasing their smelting efficiency is an urgent task in the industry. This process depends primarily on the efficiency of industrial frequency induction crucible furnaces using acid lining. In the present study, the properties of quartzite, which forms the basis of such a lining, were investigated. An analysis of the proposed variants for changing the composition of the acid lining for use at temperatures of 1550–1600 °C was conducted. Following the preliminary temperature treatment of raw quartzite, which was then subjected to a sintering regime, we determined the conditions under which it was possible to obtain a phase state, allowing for the operation of the lining at temperatures above 1450 °C. We determined the use of an electrocorundum of two fractions as an additive to the traditional composition of the acid lining. The industrial testing of a new liner composition for the smelting of synthetic cast iron in an induction crucible melting furnace with a single steel scrap-metal filling was assessed, which required the use of an increased amount of carburizing agent. The positive results obtained can be explained by the study of the spent lining, which withstood 345 smelting methods of genophasic rent analysis. The results of the test are based on the results obtained in a study conducted on the finished coating of the product.

Synthesis of B<sub>4</sub>C–TiB<sub>2</sub> composition powder mixtures by carbidobor reduction using nanofibrous carbon for ceramic fabrication

The results of the researching process of obtaining composition powder material B4C–TiB2 by carbide reduction of titanium dioxide, using carbon reducing agent – carbon nanofibers, are presented. Furthermore, the results of studying of some properties of ceramics made using the synthesized powder are presented. The synthesis of composite materials was carried out in an induction crucible furnace for 20 min in the temperature range of 1200–1900 °C in an argon atmosphere. It has been established that the optimum temperature of the synthesis is 1650 °C, irrespective of the batch composition. The characteristics of the composite powders containing 10–30 mol. % of the TiB2 phase have been studied. X-ray electron microscopy has revealed that the particles of the powder are predominantly aggregated. There are two peaks in the particle size distribution histograms. The part of the histogram with a smaller particle size mainly characterizes the B4C phase. The part of the histogram with a larger particle size characterizes the TiB2 phase. The average particle size of the B4C phase is in the range of 5.3–5.5 µm, and that of the TiB2 phase is in the range of 33.6–41.9 µm. The average size of 50 % of composite powder’s particles for these contents does not exceed 13.4 μm. The surface area of the samples does not exceed 5 m2/g. The oxidation of the composite powder materials by atmospheric oxygen begins at a temperature of approximately 500 °C. At the same time, when the temperature reaches 1000 °C, no more than 45 wt. % of the studied powders is oxidized. Ceramics made with the synthesized powder mixture B4C + 30 mol. % TiB2 by hot pressing has shown rather high values of relative density (99.0±1.1 %) and fracture toughness (5.0±0.2 MPa∙m0.5).

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.

Steeling of synthetic cast iron in induction crucible furnace taking into account consumption rate of carburizers

In an article about the importance of the choice of materilas, harmful impurities in synthetic cast iron, amd improving the strength characteristics of cast iron, which requires a new method of smelting synthetic cast iron using steel scrap as charge in the corrresponding crucible furnaces, the presences of a charge of metal charge, together with pig iron, the return of own production, carburetors, and ferroalloys for the purpose of carburizing and alloying to the required chemical composition.

Особливості початкового етапу взаємодії компонентів стопу Cu–Fe під час топлення в індукційній тиґельній печі

Особливості початкового етапу взаємодії компонентів стопу Cu–Fe під час топлення в індукційній тиґельній печі

Comparative Analysis of Lead Removal from Liquid Copper by ICF and CCF Refining Technologies.

Innovative technologies require the use of materials that meet increasingly high requirements; one such requirement is the purity of metals. In the case of copper, this translates into a parameter related to electrical conductivity. Traditional metal refining technologies have some limitations that can be eliminated through the use of modern melting aggregates. Such solutions include vacuum induction furnaces, comprising an induction furnace with a cold crucible. As part of this work, the possibilities of refining copper and lead alloys were investigated. In addition, the research was carried out with the use of two induction vacuum aggregates, allowing us to compare their effectiveness. The tests were carried out in a pressure range of 10–1000 Pa and at temperatures of 1273–1473 K. The results obtained made it possible to determine the mass transport coefficient of lead from an alloy with copper, and to determine the share of resistance in individual stages of the process. For experiments conducted inside an induction crucible furnace, lowering the working pressure inside the furnace chamber from 1000 to 10 Pa while increasing the temperature from 1323 to 1473 K was accompanied by a drop in the lead concentration inside the alloy of 69 to 96%, compared to its initial mass. For experiments conducted inside a cold crucible furnace, approximate values of lead removal appeared for lower temperatures (1273 to 1323 K), confirming that the analyzed process happens faster in this aggregate.

Influence of Moisture in Quartzite on the Lining Properties and Efficiency of Industrial-Frequency Induction Crucible Furnaces

The main purpose of industrial frequency induction crucible smelters (IGM) is the smelting of synthetic cast iron, using metal filling scrap in the amount of 30–35%, at a temperature not exceeding 1450 OZ C. The basis of the lining used is quartzite, which undergoes polymorphic transformations in the pre-treatment process to form tridimite. The efficiency of using these furnaces is significantly increased when using a metal casting consisting of a single steel scrap, but for this purpose, the melting mode has to be raised to 1550–1600 °C, which will reduce the resistance of the lining. The structural transformation of quartzite is strongly influenced by the state of water in it. In this work, studies have been carried out for changes in the water condition in the quartzite of the brand PCMVI-3 under the action of temperatures of 200–1550 °C. The Shimadzu XRF-1800 spectrometer established the actual chemical composition of the investigated quartzite and found that the amount of impurities in it is 0.66%. A derivative study of STA 449 F1 Jupiter found two endothermic effects. The first, at 170 °C, relates to the loss of adsorbed water. The second, at a temperature of 570 °C, passes without the loss of mass of the sample, and it is accompanied by the beginning of the process of the destruction of point defects in the form of Al-OH groupings. From a temperature of 620–630 °C, no mass changes associated with water removal were detected. The BRUKER D8 ADVANCE diffractometer investigated phase changes during the removal of moisture from the quartzite at temperatures of 200 and 800 °C and subsequent cooling and then during the heating used to sinter the lining. As a result, it has been established that the sheet in which the quartzite contains only chemically bound moisture, after sintering, turns into cristobalite and provides a more stable exposure to sudden temperature changes. This makes it possible to use up to 90% of the steel scrap in metal filling, which increases the efficiency of the melting furnace and the production of castings in general.

Increasing the Efficiency of Foundry Production by Changing the Technology of Pretreatment with Quartzite

The efficiency of the production of foundry products depends on the reliable operation of the melting furnace including, therefore, the durability of its lining. The most common material adopted for the production of an acid furnace crucible lining is quartzite, in which during the pretreatment (heating to 800 °C followed by holding), a tridymite phase appears that maintains a constant volume at 840–1470 °C for a long time and provides high lining durability of 300–350 melts, but only when using melting temperature regimes not exceeding 1500 °C. However, the absence of iron scrap leads to the smelting of synthetic iron from only one steel scrap using higher melting temperatures (1550–1570 °C), which sharply reduces the lifetime of the lining to 220 melts. This work is devoted to research aimed at establishing technology for the pretreatment with the original quartzite, which ensures the formation of a phase state that successfully withstands elevated temperatures for a long time. The studies were carried out using a Bruker D8 ADVANCE diffractometer and a Shimadzu XRF-1800 X-ray wave-dispersive spectrometer. The work consisted of drying samples of the original quartzite at temperatures of 200 and 800 °C with subsequent exposure to temperatures of 200, 400, 600, 870, 1000, 1200, 1470 and 1550 °C. As a result, the conditions for pretreatment of quartzite were established, during which during its further use, a cristobalite phase can be obtained, which makes it possible manufacture a high-temperature lining that ensures its high durability. The introduction of this technology will ensure the efficiency of the production of foundry products for enterprises operating induction crucible furnaces at industrial frequency.

Optimization of tin and aluminum content in tin bronze according to mechanical properties indicators

Problem statement. New compositions of foundry bronzes in which the best levels of properties inherent in both tin and aluminum bronzes are combined need to be developed. Purpose of research. Regularities between mechanical properties indicators and alloying components content in bronze of Cu−Sn−Al system with tin and aluminum content up to 6 % each are obtained. Methodology. Alloys for investigation was prepared by technical purity primary charge materials melting in induction crucible furnace using graphite crucible and charcoal as a coating material. Investigated alloys mechanical properties was calculated based on tests results of corresponding samples during their static elongation and impact bending at room temperature according to actual standards. Alloys chemical composition control was carried out on precision analyzer EXPERT 4L on samples cut from cross-shaped samples. Investigated multicomponent system response surfaces plotting was performed by H. Scheffe simplex-planning method with models of fourth and third degree. Results and discussion. According to Cu−Sn−Al alloys research results, functional dependences between mechanical properties vs. Sn and Al content from 1 to 6 % by weight of each are determined. This makes it possible to predict the level of mechanical properties according to chemical composition of such bronze during casting. Conclusions. It was found that within tin and aluminum content in investigated limits the best combination of mechanical properties has bronze BrO3A3 with content of Sn = (3…4) % and Al (3…4) %. Bronze BrO3A3 has higher (including plastic) mechanical properties values compared to the properties of tin bronzes, which are most often used in industry. This gives the reason to recommend such bronze for shaped castings and friction bearings manufacturing.

Functional dependences between indicators of mechanical properties and tin-aluminum bronze chemical composition

Problem statement. Statistically significant relationships establishing between cast tin-aluminum bronze properties, as well as between bronze properties and its chemical composition will predict the level of its mechanical properties when poured into dry sand-sodium-silicate mold. Purpose. Functional relationships determination between mechanical properties of tin-aluminum bronze with tin and aluminum content of up to 6% each. Material and methods. Alloys for investigation have been prepared by melting of technical purity primary charge materials in crucible induction furnace using graphite crucible and charcoal as coating material. Studied alloys mechanical proper-ties have been calculated based on experimental samples tests results during their static expansion and impact bending at room temperature in accordance with actual stand-ards. Alloys chemical composition control has been carried out using precision analyzer EXPERT 4L on samples cut from club-shaped samples. Relationships between mechani-cal properties indicators, as well as mechanical properties and alloys chemical compo-sition have been built using EXEL computer program. Results and discussion. According to Cu-Sn-Al alloys examination results, functional dependences between mechanical properties and Sn and Al content from 1 to 6% by weight of each have been established. This makes it possible to predict mechanical properties level according to chemical composition of such bronze during casting. Conclusions. For the first time, relationships between cast tin-aluminum bronze mechanical properties have been established. This is at the stage of Cu-Sn-Al system bronze designing, with tin and aluminum up to 6% each content, allows predicting its mechanical properties level when pouring bronze in dry sand-sodium-silicate mold.

Визначення вуглецевого еквівалента і ступеня евтектичності чавуну в ливарному виробництві

The issues related to the essence of the concepts of carbon equivalent, an indicator of the degree of eutecticity and the ratio of carbon content to silicon content for characterizing the chemical composition and properties of gray cast iron were analyzed. The results of studies of the carbon equivalent value, the degree of eutecticity and the C/Si ratio of the chemical composition of synthetic cast iron, which is used for the manufacture of brake pads and the «Khanin wedge» of railway rolling stock, are presented. Examples of different approaches and formulas for determining the limits and methods of using the carbon equivalent of the chemical composition of cast iron to characterize the weldability of steels, coefficient of friction, wear, other operational indicators of cast iron brake pads, and evaluation of the quality of cast iron as a whole are given and analyzed. Within the standards-regulated ranges of the content of chemical elements in cast iron, the value of its carbon equivalent in individual smelting batches of products can differ significantly (by 30 %). With certain ratios of the main elements in the chemical composition of cast iron, the values of the carbon equivalent can be the same, but the mechanisms of crystallization of cast iron and its properties do not coincide. The parameters of the distribution of the content of carbon, silicon, manganese, phosphorus, sulfur, carbon equivalent, and the degree of eutecticity in cast iron СЧ350, from which the friction «Khanin wedge» for railway rolling stock is made, were analyzed. Cleaning the factory arrays of indicators of chemical composition, hardness, carbon equivalent, degree of eutecticity of cast irons intended for the production of brake pads and the friction «Khanin wedge» from gross erroneous values practically did not affect the general characteristics of the statistical analysis, which indicates the reliability of the results. It is shown that when smelting in induction crucible furnaces gray synthetic cast iron intended for the production of brake pads and the «Khanin wedge», the ranges of variation in the content of C, Si, Mn, P, S are much narrower than those regulated by the standards for these foundry products. The fundamental possibility of introducing appropriate clarifications to the requirements of the standards regarding the content of chemical elements in synthetic gray cast iron intended for the production of brake pads of the «M» type and the friction «Khanin wedge» for railway rolling stock was noted, in particular, reducing the sulfur content to 0,05 % to increase stability of its quality. Keywords: cast iron, chemical composition, carbon equivalent, degree of eutecticity, properties, castings, brake pads, operational characteristics.

Investment casting wastes suitability assessment for obtaining of acid lining of induction crucible furnace

The prerequisites for the use of ceramic shells scrap of steel investment casting as an acid lining of induction crucible furnaces are presented. Research tasks are set, the solution of which will make it possible to obtain an inexpensive and high-quality lining material from these wastes.

Increasing the Efficiency of Production of Synthetic Cast Iron Castings

The main factor that determines the content of the development strategies of a modern foundry is the use of modern technological processes, especially melting technology. First of all, this applies to the production of iron castings, which make up 65% of the mass of all alloys. Since 2000, in Russia, there has been a sharp decrease in the amount of pig iron scrap, the cost of foundry and pig iron and the cost of their transportation have increased significantly. This led to an increase in material costs in the production of castings from synthetic iron, which was mainly obtained in crucible induction furnaces of industrial frequency (ICT). In addition, problems began to arise with the use of acidic lining as the cheapest and most durable, since an increased amount of steel scrap began to be used in the metal charge, and for this reason the melting temperature was raised above 1450 ° C. The durability of the lining has sharply decreased, and downtime associated with its replacement has increased. All this had a negative impact on the efficiency of the production of synthetic iron castings.

Kinetics of Zinc Evaporation from Aluminium Alloys Melted Using VIM and ISM Technologies.

Using a vacuum during the smelting and refining of alloys removes dissolved gasses, as well as impurities with high vapour pressure. When smelting is carried out in vacuum induction furnaces, the intensification of the discussed processes is achieved by intensive mixing of the bath, as well as an enhanced mass exchange surface (liquid metal surface) due to the formation of a meniscus. This is due to the electromagnetic field applied to the liquid metal. This study reports the removal of zinc from the Al-Zn alloy containing 6.3 wt.%. Zn. The experiments were carried out with the use of two types of metallurgical devices: the VIM and ISM furnaces. For the experiments carried out in the crucible induction furnace, reduction in the operating pressure in the furnace from 1000 Pa to 10 Pa, together with the increase in temperature from 953 K to 1103 K, is accompanied by a decrease in zinc content in the alloy from 6 to 96%, compared with the initial value. Simultaneously, the overall mass transfer coefficient kZn increases from 5.15 × 10−6 to −1.49 × 10−4 ms−1. For the experiments carried out in the furnace with a cold crucible (T = 953 K), a reduction in the operating pressure in the furnace from 1000 Pa to 10 Pa resulted in a decrease in zinc content in the alloy from 18 to 80%, compared with the initial value. For comparison, the experiments carried out in the crucible induction furnace at 953 K showed a reduction in zinc content in the alloy from 6 to 50%, which means that more intense zinc evaporation is seen in the furnace with a cold crucible. Comparison of ISM and VIM technologies in the removal efficiency of the Al-Zn alloy indicates a higher removal efficiency using the first technology, which, using the same conditions, achieves 80% of the removal efficiency of the component.

Numerical Investigation of the Combined Effect of Reactive Cleaning and Active Filtration on Inclusion Removal in an Induction Crucible Furnace

The cover image presents the melt flow inside the induction crucible furnace utilized under the frame of the Collaborative Research Centre (CRC 920) to investigate melt filtration and inclusion removal. The results of the numerical simulations indicate the importance of reactive cleaning and formation of carbon monoxide bubbles to remove inclusions from steel melt and enhance steel quality. Further details can be found in the article number 2100122 by Amjad Asad and co-worker.

FEATURES OF ALUMINUM DISC PRODUCTION TECHNOLOGY

The technology features of cast aluminum discs production in the conditions of «Vector» LLP are presented. Aluminum alloy AK-12 smelting process in induction crucible furnaces is described in detail. Results of industrial experiments conducted to reduce the melting time are presented. Initially, the task was set to find the optimal permissible metal residue (swamp) in the furnace after the melting was drained. Based on the results obtained, the optimal mass of the swamp was revealed to be 100 kg. A series of experimental melting was also carried out in order to identify the difference in the melting duration of the heated billet and the billet at room temperature. In the conditions of production of the enterprise «Vector» LLP, a reduction in the duration of melting by 25 minutes was achieved by using the melting method «in the swamp». Also, the preheating of charge materials in the space of the heating furnace contributed to the reduction of the melting time by 10–15 minutes. Before making changes to the technology, a maximum of 12 melts were carried out per day, taking into account the time for cleaning the furnace crucible and the process of draining metal from the furnace space. After the changes were made, the melts number and volume being metal smelted increased almost twice. This allowed the company to simultaneously put into operation four casting machines, which are supplied with metal by only one induction furnace with a capacity of 700 kg.

Numerical Investigation of the Combined Effect of Reactive Cleaning and Active Filtration on Inclusion Removal in an Induction Crucible Furnace

Herein, the combined influence of reactive cleaning and active filtration on inclusion removal is investigated using numerical simulations. Carbon‐bonded ceramic foam filters with active and reactive effect are inserted into the steel melt to remove nonmetallic inclusions. In case of reactive cleaning, carbon can dissolve from the filters into the melt. As a result, carbon reacts with oxygen on inclusion surface to form carbon monoxide bubbles. The filters can capture inclusions in terms of its active effect. A numerical model is developed in the open source library OpenFOAM to study the efficiency of the combined effect of filters. The results of the numerical simulations show that the flow field and the concentration of carbon are affected considerably by the position and the number of the used filters. Moreover, the results highlight the significant positive effect of reactive cleaning on the level of melt cleanliness despite the short time of the reactive phase of the filters. Moreover, it is apparent from the results that reactive cleaning dominates active filtration. The findings of the article prove the importance of reactive cleaning in the steel casting industry to enhance inclusion removal and improve steel quality.