Cast Iron Melt Research Articles

Alteration of the Graphite Morphology in Solid Solution-Strengthened Ductile Iron Due to High Contents of Cerium and Bismuth

The impact of combined addition of high levels of bismuth up to 120 wt ppm and cerium up to 2000 wt ppm on the graphite morphology in GJS 450-18 with 3.2 wt% carbon and 3.2 wt% silicon was studied. Experiments were conducted with insulated keel blocks with a solidification time of 40 min. Samples from the thermal centre of the castings were analysed by optical microscopy, and the forms and sizes of graphite particles were characterised. Bismuth addition, even at 25 wt ppm, resulted in an altered graphite form in the last-to-freeze regions resembling intercellular lamellar graphite (ILG). Additions of 45 wt ppm or more Ce to these Bi-containing melts prevented the formation of ILG and produced chunky graphite (CHG) instead. ILG did not appear for ratios Bi/Ce > 1.5, while CHG could not be found for ratios Bi/Ce < 0.7. Only one type of graphite degeneration (either ILG or CHG) was present in each sample, thus rendering their formation mutually exclusive. Larger amounts of Ce between 300 and 500 wt ppm resulted in the formation of predominantly graphite form V, while no degenerations could be observed. The addition of Ce to a Bi-contaminated cast iron melt to avoid ILG formation and achieve a regular graphite structure with mainly form VI graphite is not possible. Instead, form V replaces form VI as the predominantly formed morphology. Ce levels higher than 1000 wt ppm resulted in the formation of large areas of undercooled graphite in the last-to-freeze regions regardless of the Bi content in the cast iron melt.

PREPARATION OF MOLTEN CAST IRON FOR MODIFICATION BY MEANS OF REFINING TREATMENT IN THE FURNACE

Refining issues of molten metal are still actual in modern conditions of foundry. In manufacturing process of ductile and vermicular graphite iron castings with required microstructure and mechanical properties one of the essential conditions is the control of sulfur content in the base iron. Increased sulfur concentration (over 0,02%) can destabilize the production process of ductile and vermicular graphite iron castings and decrease the efficiency of modifying treatment. An additional factor reducing the efficiency of modification, which is not mostly controlled and not taken into account in foundry is oxidation of cast iron; average content is 1200–1600 ppb depending on charge materials. In this regard, in the production of ductile castings, the stage of metal pretreatment in the furnace, which consists in refin-ing the metal from sulfur and oxygen, is important. The iron foundry factories do not often have the opportunity to buy the modern equipment for refinement of liquid metal due to its high cost. In this case, in addition to existing traditional methods of refining, it is interesting to use specially developed compositions of complex materials and modifiers, improvement of methods of their input into the liquid metal. A possible variant of metal pretreatment for subsequent modification was presented. The complex briquetted material Refloy®F based on ferrosilicon FS45 has in its composition such active elements as alkaline-earth and rare-earth metals. The chemical composition of briquette Refloy®F and mechanism of its influence on cast iron melt was presented and practical experience of its application was provided. The technology of introducing briquettes depending on applied smelting unit, its consumption characteristics, results of reduction of oxygen and sulfur concentration in pig iron in the course of tests at different plants are presented. The advantages of iron desulfurization technology with Refloy®F briquettes are provided.

Study of aluminosilicate refractories after operation in the presence of fluorine-containing wastes

Samples of aluminosilicate refractory after operation in the shaft and in the hearth of a coke-gas cupola were investigated; this cupola was used for smelting of cast iron with spheroidal graphite using carbon wastes from aluminium electrolysis production as a reducing agent. Use of only fluorine-containing carbon wastes as a solid fuel in cast iron production allows to utilize hazardous man-caused wastes, improves the economic performance of production and has influence on resistance of fireclay refractories. It was established that the products acquire a distinct zone features during the service, due to penetration of the components of gas and liquid phases and the effect of low-boiling components of carbon-containing wastes. Upon that, changes in the structure along the distance from the working space are complex ones in lining thickness and in concentration of volatile components in the &ldquo;cold&rdquo; parts of the lining. Permanent character of the mullite content in different zones of fireclay products can be traced, as well as a slight increase in the less altered zone, despite the different service conditions. Absence of alkaline and fluoride phases in the zones of refractory products in the pores and structure of the fireclay refractory was established, due to migration of these gaseous phases into the working space of the cupola with their subsequent removal with furnace gases. Additional development of mullite in certain zones of refractory was revealed, resulting by its synthesis from alumina that did not react during fireclay refractories manufacture under the mineralizing action of a fluorine compound. Use of fluorine-containing carbonaceous wastes as a solid fuel in cast iron production makes it possible to utilize hazardous man-caused wastes, improves the economic performance of production and has slight effect on resistance of aluminosilicate refractories in the conditions of a coke-gas cupola.

SPECIFIC FEATURES OF VECTOR OPTIMIZATION METHODS FOR SELECTING THE OPTIMAL COMPOSITION OF BLAST FURNACE CHARGE

Technological and mathematical formulation of the problem of optimizing the composition of multicomponent blast furnace charge, which will ensure the melting of cast iron of the required composition and the given technical and economic indicators of the melting is formulated. The features of the developed algorithm for solving the problem of multicriteria conditional nonlinear optimization with the use of modified simplex methods (Box, Nedler - Mead) are outlined. As a result, an optimal compromise solution in a given area of constraints is found, taking into account a special class of technological constraints, which makes it possible to form scientifically valid recommendations for choosing a rational composition of charge materials in modern conditions of blast furnace production.

RARE EARTH METALS IN ROLLED CAST IRON

The effect of the additive value of three rare earth metals individually (lanthanum, cerium, and yttrium) on the crystallization parameters of cast iron was studied. The study was carried out using a differential scheme for measuring cooling temperatures using the ФПК -59 device. As a result of the conducted studies, a similar effect of experimental rare earth metals on the crystallization parameters of rolled cast iron was shown. Additives of rare earth metals, which led to the greatest changes in the crystallization parameters and the formation of spherical graphite inclusions in the structures of modified cast irons, were different. When modifying cast iron melt to produce spherical graphite, yttrium must be added less than cerium or lanthanum.

Iron production along the Great Wall Belt of the Han Empire: A metallurgical study of an iron smelting site in the Northern Shaanxi, China

AbstractIronworks of the Han dynasty in Yangqiaopan ancient city are so far the only discovered iron smelting site in Northern Shaanxi. A total of 27 slag samples from the site were analysed. The results of metallographic and elemental analyses suggest that both cast iron smelting and the fining process were employed at the site. In addition, this paper suggests that under the iron monopoly policy, iron production was carried out in prefectures along the Great Wall Belt where iron offices (tieguan) were not set up, and iron industry not only satisfied the local demands but also supplied iron to the neighbouring cities.

Оцінка параметрів занурення частинок реагенту з газом у розплав при інжекційній позапічній десульфурації чавуну

The aim of the work is to develop a mathematical model for estimating the immersion of reagent particles with gas in molten iron during desulfurization. The technologies of out-of-furnace injection ladle desulfurization of cast iron are based on the introduction of reagent particles into liquid cast iron with the help of high-speed gas jets. The patterns of behavior and interactions of two-phase jets (carrying gas+reagent) with cast iron melt are complex, as the individual dynamic characteristics of individual particles are lost. Also important is the question of the ratio of the number of particles that went deep into the metal and the particles that ended up in the floating bubble. In the work, a number of experimental studies were performed to evaluate the factors and parameters of the immersion of the reagent particle during ladle desulfurization of cast iron. Experiments have shown that the depth of immersion of a reagent particle with a radius of 0.5 mm in the presence of a cavern depends on the velocity of the particle. For an initial speed of 20 m/s, the length of the cavern is about 6 gauges, and for a speed of 140 m/s - about 10 gauges. However, as it follows from the calculations, the velocities of the reactant particles drop rapidly, which should lead to a change in the flow structure and the emergence of caverns. In this case, capillary forces will play a significant role in the penetration of the reagent into the melt. In the developed model, they are taken into account as an additional factor. It is shown that these effects have a rather weak character compared to the repulsive force of Archimedes.

FEATURES FORMATION ZONE OF WAVES AND BURSTS ON THE SURFACE LADLE BATH

The results studies influence physicochemical properties and thickness cover slag, formed during ladle desulfurization pig iron by blowing a mixture of lime and magnesium, features formation a breaker on the surface bath and the level of metal losses with emissions outside ladle from this zone are presented. The necessity creating conditions for ensuring height breaker, which would not exceed thickness slag layer on the surface bath, has been substantiated. Using results of the high-temperature simulation blowing the cast iron melt with a neutral gas supplied through the nozzles tips stationary and rotating submersible lances, features development of counter waves and metal splashes in the absence and during formation slag cover with thickness of 30—80 mm on the surface bath are determined. The features change in the height and area breakers are determined depending on the gas flow rate for blowing bath and thickness slag. Based on the analysis results low-temperature modeling bath blowing, scientific ideas about the combined effect of the bath blowing intensity, speed of rotation submerged lance and thickness slag layer on the diameter bubbling zone, gas saturation of the bath and features wave formation on its surface in the slag-free zone were further developed (so-called «eye»). The nature relationship between length of the gas jet from lance nozzle, diameter «eye», and geometric parameters breaker has been established. It is shown that dependence profile breaker on speed of rotation lance and thickness slag layer is nonlinear. So, blowing bath through tip of a rotating lance with one nozzle at 240 rpm. with a gas flow rate of 2.2 l/min. creates conditions for raising top breaker to a height that is 33 % higher than the current thickness slag layer and contributes to the intensification formation of waves and bursts on the surface bath. With a decrease in the gas flow rate to 1.0 l/min., Under other unchanged conditions, height breaker is already 2/3 of the height slag layer, and as thickness slag decreases proportionally decreases. The smallest, recorded in the experiments, relative height breaker was 33.3% of the slag thickness at a lance rotation speed in the range of 90—120 rpm. Mathematical models are proposed that are suitable for calculating height breakers depending on the thickness slag layer, speed of rotation lance and intensity of gas injection into the bath. Taking into account established mutually opposite effect thickness of the cover slag layer and speed of rotation submerged lance on the «eye» area and height of the breaker, it is advisable to continue search for ways to improve design tip submerged lance and slag mode of ladle desulfurization.

Various Aspects of Application of Silicon Carbide in the Process of Cast Iron Melting

Various Aspects of Application of Silicon Carbide in the Process of Cast Iron Melting

Mechanical properties of ductile cast iron relation to the charge elements

SummaryIn many recent publications on the optimisation of alloys in terms of, among other things, their strength and resistance to wear, a trend can be observed to look for new alloying additives to improve these properties. This paper presents the results of a study on the effect of changes in the chemical composition of EN-GJS-500-7 ductile alloy cast iron on its mechanical properties. In order to confirm the effect of alloying additives on the mechanical properties of the alloys, industrial melting of cast iron was carried out and samples were taken for testing. The smelts were not subjected to heat treatment, but were carried out differently in terms of the feedstock used and based on the analysis of the cooling curve using an automated smelting technology enabling the elimination of degraded Chunky graphite. The influence of the shape of graphite precipitates on tensile strength and hardness was determined, and spectroscopic studies of the microstructure of cast irons were carried out.

Prospects for using boron in metallurgy. Report 1

On the basis of literature and our own data, the effect of boron on characteristics of all stages of metallurgical processes (from sintering, smelting of cast iron and ferroalloys, to steel production) and on the properties of the resulting slag and metal was studied. To intensify the pellets hardening at the stage of liquid-phase sintering and to improve their metallurgical properties, it is sufficient to have 0.20 – 0.35 % of boron oxide in them. According to the laboratory studies, the presence of boron oxide in pellets increases their compressive strength by 1.5 – 1.7 times and hot strength by 3 – 4 times. While studying the mechanism and kinetics of sulfur removal, it was shown that the presence of boric anhydride significantly intensifies processes of pellets desulfurization. Their intensive progress goes to the zones of lower temperatures of 1050 – 1100 °С. To increase the sinter strength characteristics, it is possible to add B2O3 to the charge. The introduction of 0.44 % of B2O3 does not affect the sinter abrasion. The content of fines (0 – 5 mm) in comparison with the base sample is reduced by 1.5 times. The use of boron pellets in blast-furnace smelting makes it possible to increase the basicity of the final slag from 1.10 to 1.16. In this regard, the sulfur distribution coefficient increases from 48 to 74. The sulfur content in cast iron decreases by 0.005 %. The possibility of using boron and its compounds to improve the technical and economic indicators of production and the quality of pellets, sinter and cast iron is shown on the base of the presented theoretical, laboratory-experimental and industrial data.

Adjustment of a technology of cast iron smelting in the blast furnace of jsc "ural steel" w ith a volume of 1232 см&lt;sup&gt;3&lt;/sup&gt; with charge h a v in g 95% share of Mikhailovskii GOK pellets

To use effectively internal raw material base, JSC “Ural Steel” accomplished I category major overhaul of the blast furnace No. 2. The main purpose of the overhaul was to design a rational profile which could ensure an ability to operate with a charge containing 95 % of Mikhailovskii GOK (mining and concentrating plant) pellets having basicity of 0.5 by CaO/SiO2. The blast furnace No. 2 having useful volume of 1232 m3, was constructed by design of Danieli Corus, the Netherlands, and was blown in on December 30, 2020. In the process of guarantee tests, step-by-step increase of Mikhailovskii GOK pellets (Fetotal = 60.5 %, CaO/SiO2 = 0.5) content in the charge iron ore part was being accomplished from 55 to 95.1%. Charging of the blend containing pellets in the amount of 55% of iron ore part, was done by charging system 4OOCC + 1COOCC (Ore - Coke) with filling level 1.5 m. Under conditions of pellets part increase in the blend, the charging system was changed to decrease their content at the periphery, to increase it in the ore ridge zone and make it intermediate between periphery and the ore ridge. At the pellets share in the iron ore raw materials 0.75 the charging system was used as the following: 3OOCC + 1COOC + 1COOCC, while at the content 95.1% the following charging system was used: 2COOC + 2COOC + 1COOCC. It was noted that in the period of guarantee tests the furnace running was smooth. The average silicon content in the hot metal was 0.70% at the standard deviation 0.666. Sulfur content in the hot metal did not exceed 0.024%, the blowing and natural gas consumption figures were 2100 m3/min and 11000 m3/min correspondently, oxygen content in the blowing 26.5%, hot blowing and top smoke pressure figures were 226.5 and 109.8 KPa correspondently. The productivity of the furnace was reached as high as 2358 t/day at the specific coke rate 433 kg/t of hot metal. After guarantee tests completion, the pellets content in the iron ore part was decreased gradually from 95 down to 50%. The decreasing was made by 5% in every 6 hours of operation. Application of the mastered technology of the blast furnace No. 2 with the increased share of pellets will enable to stably supply the blast furnaces No. 1, 3 and 4 by iron ore raw materials in the proportion of 30-35% of pellets and 65-70% of sinter.

Prospects for Using Boron in Metallurgy. Report 1

Based on literature and our own data, the effect of boron on the characteristics of all stages of metallurgical processes (from sintering, smelting of cast iron and ferroalloys, to steel production) and on the properties of the resulting slag and metal was studied. To intensify hardening of the pellets at the stage of liquid-phase sintering and to improve their metallurgical properties, it is sufficient to have 0.20–0.35% of boron oxide in them. According to laboratory studies, the presence of boron oxide in pellets increases their compressive strength by 1.5–1.7 times and hot strength by 3–4 times. While studying the mechanism and kinetics of sulfur removal, it was shown that the presence of boric anhydride significantly intensifies processes of ±pellets desulfurization. Their intensive progress goes to the zones of lower temperatures of 1050–1100°C. To increase the sinter strength characteristics, it is possible to add B2O3 to the charge. The introduction of 0.44% of B2O3 does not affect the sinter abrasion. The content of fines (0–5 mm) in comparison with the base sample is reduced by 1.5 times. The use of boron pellets in blast-furnace smelting makes it possible to increase the basicity of the final slag from 1.10 to 1.16. In this regard, the sulfur distribution coefficient increases from 48 to 74. The sulfur content in cast iron decreases by 0.005%. The possibility of using boron and its compounds to improve the technical and economic indicators of production and pellet quality, sinter and cast iron is shown on the base of the presented theoretical, laboratory-experimental and industrial data.

Investigation of the Nodularisation Propensity of Calcined Cashew-Nut Shell-Ash in Cast-Iron Melt Graphite

Production of ductile iron using ferrosilicon-magnesium master alloy in melt treatment is currently fraught with challenges bothering on cost and availability. In this study the suitability of cashew nut shells ash (CNSA) as a viable alternative to magnesium master alloys employed in the treatment of molten cast iron for enhanced mechanical properties was studied. The carbonized CNSA used varied from 2-10 wt. % to treat different heat batches; CA1-CA5 containing varied amount of CNSA, CaO and FeSi in the molten cast iron. The cast samples were subjected to both mechanical characterisation (tensile, hardness and impact) and microstructural analysis using Instron electromechanical machine, impact tester and scanning electron microscope (SEM) coupled with energy dispersive spectroscope (EDS). Results show that the 8 wt. % CNSA addition demonstrated the best mechanical properties comparable to ASTM A536 ferritic ductile cast iron. Specifically, the 8 wt. % CNSA cast samples exhibited 433 MPa tensile strength, 144HRC hardness and ductility of 14.7%. Contributions to improved mechanical properties may be attributed to the development of sufficient fractions of graphite nodules during melt treatment with CNSA. These outcomes are a boost both to the production of quality ductile irons and a cleaner environment.&#x0D; Keywords: Nodularisation, ductile-iron, cashew-nut, ferrosilicon-magnesium alloy, mechanical properties

Invention of cast iron smelting in early China: Archaeological survey and numerical simulation

The earliest cast iron in China dates to the 8th century BC and pre-dates the earliest European evidence by about two millennia. The invention of cast iron smelting is closely related to the pre-existing and contemporary technologies of casting bronze and firing ceramics as well as the social and political context of early 1st millennium BC China. A series of early iron smelting furnaces were surveyed, excavated, and scientifically analysed. However, in order to understand how cast iron was initially produced, the evidence from one of the earliest production sites was digitally simulated. This modelling allowed different potential methods for the underlying production technology to be evaluated. The explanation for the invention of cast iron lies both in borrowing and developing of techniques found in other contemporary pyrotechnologies as well as a contemporary systemic philosophical approach.

Influence of melt treatment parameters on the characteristics of modified cast iron in the metallurgical industry using data mining methods

A study of the effect of holding the cast iron melt at temperatures of 1,300, 1,450 and 1,600 °C for 20, 55 and 90 minutes on the structure and properties of cast iron in a liquid state and after crystallization was carried out. The studies were carried out on samples with a diameter of 30 mm; cast iron containing 3.61–3.75 % carbon, 1.9–2.4 % silicon, 0.03 % manganese, 0.081–0.084 % phosphorus, 0.031–0.039 % sulfur was poured into green-sand molds. The samples were cast from the original cast iron (unmodified), modified with ferrosilicon 75 GOST 1415-93 (FS75), rare-earth metals (REM) and together with the REM+FS75 complex. The structure of cast iron was investigated by optical metallography, electron microscopy and X-ray structural analysis. An increase in the holding temperature and time of the cast iron melt leads to an increase in its hardness. An increase in temperature at a short holding time leads to an increase in strength in the entire investigated temperature range (1,300–1,600 °С). Holding for 90 minutes at a temperature of 1,450 °C corresponds to an extremum, after which, with a further increase in temperature, a sharp drop in strength is observed. The change in the toughness of cast iron is characterized in a similar way

Correction to: 90 years of thermal analysis as a control tool in the melting of cast iron

Following the publication of the article by Stefanescu et al.[1], missing citation was discovered. To make the article more comprehensive and complete, the authors propose to publish a correction. And the authors would like to apologize for any inconvenience caused to the readers by these changes in the paper.

Analytical Study of the Process of Dissolution of Silicon from a Modifier Particle

The process of dissolution of a particle of a ferrosilicon modifier in a cast iron melt is considered, taking into account such a physical analogy as the distribution of heat from a point source in space (an infinite body).

ЗАБЕЗПЕЧЕННЯ ЕКОБЕЗПЕКИ МІКСЕРНИХ ВІДДІЛЕНЬ СТАЛЕПЛАВИЛЬНИХ ЦЕХІВ

Introduction. Mixer branches of metallurgical enterprises are an intermediate link between blast furnace and steelmaking workshops. They are equipped with mixers – footer containers for storing cast iron melt. In Ukraine, mixers with a capacity of 1300 or 2500 tons are used. Technological operations are accompanied by emissions of finely dispersed brown smoke and large-dispersed graphite dust into the atmosphere. Problem. Mixer compartments of Ukrainian factories are equipped with aspiration systems that dimity emissions from cast iron pouring and draining units with the help of fume tubes, then emissions pass the dust collector and discharge into the atmosphere through a chimney. The main impact of mixer compartments on the environment is: disorganized emission through an aerodynamic dust lamp, which is not allotted by the aspiration system; organized emission through a smoke pipe of dust not caught by a dust collector; solid waste from gas cleaning and dust hoppers settling on the floor and structures of the mixer compartment from the disorganized ejection that did not come out through the lantern. The main problems are insufficient aspiration (disorganized emission) and low emission purification efficiency (emission through the chimney). A separate problem is the disposal of caught dust. The degree of aspiration in the factories of Ukraine is about 0.7 for the filling unit in the mixer and 0.8 for the drain unit from the mixer at the power of the aspiration system 150-250 thousand tons. This does not meet modern requirements. Results. Cyclones are used as a dust collector in most factories, which completely capture graphite, but are not effective enough for brown smoke. Therefore, it is proposed to use sleeve filters or electro filters. It is also possible to introduce the suppression of brown smoke with nitrogen. The use of nitrogen is possible in accordance with cyclones (for existing systems) or compatible with filters (during reconstruction or new construction). The use of suppression of brown smoke with nitrogen allows to solve the problem of disposal of caught dust, because nitrogen supply leads to enrichment of dust with graphite. The content of graphite increases from 15% to more than 30%, which converts dust from care to commodity product. Keywords: mixer, cast iron pouring, cast iron drainage, dust suppression by nitrogen, aspirational mixer compartment system.

Research and features of preliminary graphitizing processing of melt of iron with silicon carbide on the structure and properties of cast iron castings

The materials used for preliminary graphitizing treatment of cast iron melt (pre-modification), of which silicon carbide has the greatest technical and economic advantage, are considered. The features of the graphitizing effect of silicon carbide during the preparation of a gray cast iron melt on its structure and properties in standard cylindrical samples and clutch plate castings are analyzed. It is shown that its graphitizing effect on the cast iron melt begins to partially manifest itself already at the stage of introduction into the furnace and enhances the action of the main graphitizing modifier during subsequent ladle treatment as a result of a decrease in the content of interdendritic graphite in the microstructure.