The results presented in this article are part of the research on fatigue life of various foundry alloys carried out in recent years in the Lukasiewicz Research Network – Institute of Precision Mechanics and AGH University of Science and Technology, Faculty of Foundry Engineering. The article discusses the test results obtained for the EN-GJS-600-3 cast iron in an original modified low-cycle fatigue test (MLCF), which seems to be a beneficial research tool allowing its users to evaluate the mechanical properties of materials with microstructural heterogeneities under both static and dynamic loads. For a comprehensive analysis of the mechanical behaviour with a focus on fatigue life of alloys, an original modified low cycle fatigue method (MLCF) adapted to the actually available test machine was used. The results of metallographic examinations carried out by light microscopy were also presented. From the analysis of the results of the conducted mechanical tests and structural examinations it follows that the MLCF method is fully applicable in a quick and economically justified assessment of the quality of ductile iron after normalizing treatment.
The paper presents the initial results of investigation concerning the abrasion resistance of cast iron with nodular, vermicular, or flake graphite. The nodular and vermicular cast iron specimens were cut out of test coupons of the IIb type with the wall thickness equal to 25 mm, while the specimens made of grey cast iron containing flake graphite were cut out either of special casts with 20 mm thick walls or of the original brake disk. The abrasion tests were carried out by means of the T-01M tribological unit working in the pin-on-disk configuration. The counterface specimens (i.e. the disks) were made of the JT6500 brand name friction material. Each specimen was abraded over a distance of 4000 m. The mass losses, both of the specimens and of the counterface disks, were determined by weighting. It was found that the least wear among the examined materials was exhibited by the nodular cast iron. In turn, the smallest abrasion resistance was found in vermicular cast iron and in cast iron containing flake graphite coming from the brake disk. However, while the three types of specimens (those taken from the nodular cast iron and from grey cast iron coming either from the special casts or from the brake disk) have almost purely pearlitic matrix (P95/Fe05), the vermicular cast iron matrix was composed of pearlite and ferrite occurring in the amounts of about 50% each (P50/Fe50). Additionally, it was found that the highest temperature at the cast iron/counterface disk contact point was reached during the tests held for the nodular cast iron, while the lowest one occurred for the case of specially cast grey iron.
This paper presents matters related to production of ceramic and cast iron composite. The composite was made with the use of a foam structured ceramic insert. The tests included measuring of hardness, impact strength and resistance to abrasive wear of the composite produced. On the basis of obtaining results was stated that the use of foamed ceramic filters provides good conditions of filling a ceramic framework with molten grey or chromium cast iron. The growth of hardness of the ceramic- grey cast iron composite is ca. 60% as compared to the grey cast iron hardness. The growth of hardness of the ceramic- chromium cast iron composite is slight and does not exceed 5 % in comparison to the chromium cast iron. Introduction of the ceramic inserts deteriorates the cast iron impact strength by ca. 20 - 30 %. The use of ceramic inserts increases the resistance to abrasive wear in case of grey cast iron by ca. 13% and in case of the chromium cast iron by ca. 10 %.
Results of a research on influence of chromium, molybdenum and aluminium on structure and selected mechanical properties of Ni-Mn-Cu cast iron in the as-cast and heat-treated conditions are presented. All raw castings showed austenitic matrix with relatively low hardness, making the material machinable. Additions of chromium and molybdenum resulted in higher inclination to hard spots. However, a small addition of aluminium slightly limited this tendency. Heat treatment consisting in soaking the castings at 500 °C for 4 h resulted in partial transformation of austenite to acicular, carbon-supersaturated ferrite, similar to the bainitic ferrite. A degree of this transformation depended not only on the nickel equivalent value (its lower value resulted in higher transformation degree), but also on concentrations of Cr and Mo (transformation degree increased with increasing total concentration of both elements). The castings with the highest hard spots degree showed the highest hardness, while hardness increase, caused by heat treatment, was the largest in the castings with the highest austenite transformation degree. Addition of Cr and Mo resulted in lower thermodynamic stability of austenite, so it appeared a favourable solution. For this reason, the castings containing the highest total amount of Cr and Mo with an addition of 0.4% Al (to reduce hard spots tendency) showed the highest tensile strength.
The article presents results of pitting corrosion studies of selected silicon cast irons. The range of studies included low, medium and high silicon cast iron. The amount of alloying addition (Si) in examined cast irons was between 5 to 25 %. Experimental melts of silicon cast irons [1-3] were conducted in Department of Foundry of Silesian University of Technology in Gliwice and pitting corrosion resistance tests were performed in Faculty of Biomedical Engineering in Department of Biomaterials and Medical Devices Engineering of Silesian University of Technology in Zabrze. In tests of corrosion resistance the potentiostat VoltaLab PGP201 was used. Results obtained in those research complement the knowledge about the corrosion resistance of iron alloys with carbon containing Si alloying addition above 17 % [4-6]. Obtained results were supplemented with metallographic examinations using scanning electron microscopy. The analysis of chemical composition for cast irons using Leco spectrometer was done and the content of alloying element (silicon) was also determined using the gravimetric method in the laboratory of the Institute of Welding in Gliwice. The compounds of microstructure were identify by X-ray diffraction.
The results of studies on the use of magnesium alloy in modern Tundish for production of vermicular graphite cast irons were described. This paper describes the results of using a low-magnesium ferrosilicon alloy for the production of vermicular graphite cast irons. The paper presents a vermicular (and nodular) graphite in different walled castings. The results of trials have shown that the magnesium Tundish process can produce high quality vermicular graphite irons under the specific industrial conditions of Foundries - Odlewnie Polskie S.A. in Starachowice. In this work describes too preliminary studies on the oxygen state in cast iron and their effect on graphite crystallization.
The paper presents the issue of synthetic cast iron production in the electric induction furnace exclusively on the steel scrap base. Silicon carbide and synthetic graphite were used as carburizers. The carburizers were introduced with solid charge or added on the liquid metal surface. The chemical analysis of the produced cast iron, the carburization efficiency and microstructure features were presented in the paper. It was stated that ferrosilicon can be replaced by silicon carbide during the synthetic cast iron melting process. However, due to its chemical composition (30% C and 70% Si) which causes significant silicon content in iron increase, the carbon deficit can be partly compensated by the carburizer introduction. Moreover it was shown that the best carbon and silicon assimilation rate is obtained where the silicon carbide is being introduced together with solid charge. When it is thrown onto liquid alloy surface the efficiency of the process is almost two times less and the melting process lasts dozen minutes long. The microstructure of the cast iron produced with the silicon carbide shows more bulky graphite flakes than inside the microstructure of cast iron produced on the pig iron base.
Steel and cast-iron products, due to their low price and beneficial properties, are the most widely used among metals; their consumption has become an indicator of the economic development of countries. The characteristics of iron raw materials, in relation to current metallurgical requirements, are presented in the present this article. The globalization of the trade and development of steelmaking technologies have caused significant changes in the quality of raw materials in the last half-century forcing improvements in processing technologies. In many countries, standard concentrates (at least 60% Fe) are almost twice as rich as those processed in the mid-20th century. Methods of quality assessment have been improved and quality standards tightened. The quality requirements for the most important raw materials ‒ iron ores and concentrates, steel scrap, major alloy metals, coking coal, and coke, as well as gas and other energy media ‒ are reviewed in the present paper. Particular attention is paid to the quality testing methodology. The quality of many raw materials is evaluated multi-parametrically: both chemical and physical characteristics are important. Lower-quality parameters in raw materials equate to significantly lower prices obtained by suppliers in the market. The markets for these raw materials are diversified and governed by separate sets of newly introduced rules. Price benchmarks (e.g. for standard Australian metallurgical coal) or indices (for iron concentrates) apply. Some raw materials are quoted within the framework of the commodity market system (certain alloying components and steel scrap). The abandonment of the long-established system of multi-annual contracts has led to wide fluctuations in prices, which have reached a scale similar to that of other metals.
The purpose of this paper is to focus on the loss separation of non-grain-oriented electrical steels used for speed-variable rotating electrical machines. The impact of laser-cutting, used in prototype manufacturing and of flux density harmonics, occurring locally in the lamination, on the loss distribution is studied in detail. Iron losses occurring under operation can physically be separated in different loss components. In this paper, a frequency-based loss model with parameters identified for single-sheet tester specimens, cut in strips of different widths, is therefore used. Moreover, a time-domain approach considers loss distributions occurring from higher harmonics. Hysteresis losses having high sensitivity to cut edge effects are calculated by the well-known Jiles-Atherton model adapting the frequency-based loss parameters. The model is validated by free-curve measurements at a single-sheet tester. It has been shown that the studied elliptical hysteresis model becomes inaccurate particularly for specimens with small strip widths with similar dimensions as teeth of electrical machine laminations. The incorrect mapping of losses occurring from minor hysteresis loops due to higher harmonics is concluded. The results showconsequently that both, the impact of a cut edge effect and local distributions of flux density harmonics need to be considered in terms of accurate iron loss prediction of electrical machine design.
An attempt to summarize the primary iron raw materials and steel market’s hundred years history as well as influence of economic indicators on the iron ore deposit qualification for extraction has been undertaken in the paper. Steel products are crucial to the world economy, and their production has a major impact on the environment. The main factor is the huge scale of the production and growth rate, unprecedented among minerals. Iron ore and concentrates production has increased more than thirty times over the past century, and the geological resource base at the current level of consumption has provided almost 250 years of sufficiency. There have been tremendous changes in the world geography of the ore and steel industry. The iron ore mining industry is the driver of other economic activities (land transport, freight, metallurgy) and involves huge capital and human resources. The consumption of iron raw materials is also considered as an important indicator of the countries development and current or even future economic situation. Population growth remains one of the key stimulating factors. The prices of ore and iron concentrates depend on the quality of the raw material, delivery conditions, market balance and the weight of the ordered cargo. They are usually the subject of negotiations. In the past, they were long-term contracts, while short-term (yearly, quarterly) and current spot transactions are now significant. The prices of ores and concentrates in relation to steel prices are showing a strong correlation. The average iron content of the reserves has been reduced in the largest producers in the 21st century, however it does not translate into the quality of mining output. Exploitation of the richer parts of the mineral deposit is usually carried out. The high content of iron in the output is a response to the technological requirements of the metallurgy where the blast furnace charge should contain at least 56% Fe and 5–8% FeO. The current surplus of geological-mining supply (large resource base) justifies that a mineral deposit choice, destined for excavation, is economic profit maximization as well as social and environmental considerations.
Copper slag is a by-product obtained during smelting and refining of copper. Copper smelting slag typically contains about 1 wt.% copper and 40 wt.% iron depending upon the initial ore quality and the furnace type. Main components of copper slag are iron oxide and silica. These exist in copper slag mainly in the form of fayalite (2FeO ·SiO2). This study was intended to recover pig iron from the copper smelting slag by reduction smelting method. At the reaction temperature of below 1400°С the whole copper smelting slag was not smelted, and some agglomerated, showing a mass in a sponge form. The recovery behavior of pig iron from copper smelting slag increases with increasing smelting temperature and duration. The recovery rate of pig iron varied greatly depending on the reaction temperature.
Group of steel balls with different chemical composition, diameters and nitriding treatment parameters were investigated with using magnetic resonance and magnetization methods. Emerging nitrided regions consists of diffusion and surface layer of iron nitrides. The thickness of the individual layers depends on the type of steel and process parameters. Resonance signal shape and position were successfully described in the ferromagnetic resonance regime expected for dense iron magnetic system. Influence of the sample size, thermal treatment and carbon content on the absorption signal has been analyzed. Significant magnetic anisotropy has been revealed, as well as non-usual increasing of the magnetization as a function of temperature. It suggests, that overall antiferromagnetic ordering, destroyed by thermal movement, lead to increasing of the ferromagnetic region.
The combination of the austempered ductile iron mechanical properties strongly depend on the parameters used on the austempering cycle. On this study, the influence of austempering time and austenitizing temperature on the properties of a ductile iron were evaluated. A metallic bath of Zamak at 380°C was used as an austempering mean. A set of ductile iron blocks were austenitized at 900°C for 90 minutes and submitted to different austempering times in order to determine the best combination of microstructural and mechanical properties. After the definition of the time of austempering, the reduction of the austenitizing temperature was evaluated. The best combination of properties was obtained with austenitizing at 860°C and austempering during 60 minutes.
Magnetic properties of Fe nanowire arrays (NWs) electrodeposited in anodic alumina membranes have been studied. The influence of nanowire geometry (length, pore diameter) and an external magnetic field applied during electrodeposition process on the magnetic properties of nanowire arrays was investigated. With the use of the X-ray diffraction analysis the structure of iron wires was determined. The iron wires have the regular Body Centered Cubic structure. Magnetic measurements show that shape anisotropy aligns the preferential magnetization axis along the wire axis. It was found that the application of an external magnetic field in a parallel direction to the sample surface induces magnetic anisotropy with an easy axis of magnetization following the nanowire axis. The dependence of the height of Fe wires on the electrodeposition time was determined.
The influence of aluminium added in amounts of about 1.6%, 2.1%, or 2.8% on the effectiveness of cast iron spheroidization with magnesium was determined. The cast iron was melted and treated with FeSiMg7 master alloy under industrial conditions. The metallographic examinations were performed for the separately cast rods of 20 mm diameter. They included the assessment of the shape of graphite precipitates and of the matrix structure. The results allowed to state that the despheroidizing influence of aluminium (introduced in the above mentioned quantities) is the stronger, the higher is the aluminium content in the alloy. The results of examinations carried out by means of a computer image analyser enabled the quantitative assessment of the considered aluminium addition influence. It was found that the despheroidizing influence of aluminium (up to about 2.8%) yields the crystallization of either the deformed nodular graphite precipitates or vermicular graphite precipitates. None of the examined specimens, however, contained the flake graphite precipitates. The results of examinations confirmed the already known opinion that aluminium widens the range of ferrite crystallization.
In modern times, there are increasing requirements for products quality in every part of manufacturing industry and in foundry industry it is not different. That is why a lot of foundries are researching, how to effectively produce castings with high quality. This article is dealing with search of the influence of using different types of risers or chills on shrinkage cavity production in ductile iron castings. Differently shaped risers were designed using the Wlodawer´s modulus method and test castings were poured with and without combination of chills. Efficiency of used risers and chills was established by the area of created shrinkage cavity using the ultrasound nondestructive method. There are introduced the production process of test castings and results of ultrasound nondestructive reflective method. The object of this work is to determine an optimal type of riser or chill for given test casting in order to not use overrated risers and thus increase the cost effectiveness of the ductile iron castings production.
The paper proposes a methodology useful in verification of results of dilatometric tests aimed at determination of temperatures defining the start and the end of eutectoid transformation in the course of ductile cast iron cooling, based on quenching techniques and metallographic examination. For an industrial melt of ductile cast iron, the effect of the rate of cooling after austenitization at temperature 900°C carried out for 30 minutes on temperatures TAr1 start and TAr1 end was determined. The heating rates applied in the study were the same as the cooling rates and equaled 30, 60, 90, 150, and 300°C/h. It has been found that with increasing cooling rate, values of temperatures TAr1 start and TAr1 end decrease by several dozen degrees.
A cast iron is gradient material. This means that depending on the cooling rate it is possible, at the same chemical composition and the physicochemical state of molten metal, to obtain material with a different structure. The connection between the wall thickness of the casting and the speed of its cooling expresses the casting module. Along with the module escalation a cooling rate of the casting is reducing what can cause changes of the microstructure and the increased tendency to the crystallization of distorted graphite forms. Inspections of experimental castings from nodular cast iron with different modules were conducted to the graphite form.
The work determined the influence of aluminium in the amount from about 1% to about 7% on the graphite precipitates in cast iron with relatively high silicon content (3.4% to 3.90%) and low manganese content (about 0.1%). The cast iron was spheroidized with cerium mixture and graphitized with ferrosilicon. The performed treatment resulted in occurring of compact graphite precipitates, mainly nodular and vermicular, of various size. The following parameters were determined: the area percentage occupied by graphite, perimeters of graphite precipitates per unit area, and the number of graphite precipitates per unit area. The examinations were performed by means of computer image analyser, taking into account four classes of shape factor. It was found that as the aluminium content in cast iron increases from about 1.1% to about 3.4%, the number of graphite precipitates rises from about 700 to about 1000 per square mm. For higher Al content (4.2% to 6.8%) this number falls within the range of 1300 – 1500 precipitates/mm2 . The degree of cast iron spheroidization increases with an increase in aluminium content within the examined range, though when Al content exceeds about 2.8%, the area occupied by graphite decreases. The average size of graphite precipitates is equal to 11-15 μm in cast iron containing aluminium in the quantity from about 1.1% to about 3.4%, and for higher Al content it decreases to about 6 μm.
The paper presents an analysis of factors affecting the wear of cylinder liners. The effect of the graphite precipitation morphology on the cylinder liner wear mechanism is presented. Materials used to cast cylinder liners mounted in a number of engines have been examined for their conformity with requirements set out in applicable Polish industrial standard. A casting for a prototype cylinder liner has been made with a microstructure guaranteeing good service properties of the part.
The influence of aluminium (added in quantity from about 0.6% to about 2.8%) on both the alloy matrix and the shape of graphite precipitates in cast iron treated with a fixed amounts of cerium mischmetal (0.11%) and ferrosilicon (1.29%) is discussed in the paper. The metallographic examinations were carried out for specimens cut out of the separately cast rods of 20 mm diameter. It was found that the addition of aluminium in the amounts from about 0.6% to about 1.1% to the cast iron containing about 3% of carbon, about 3.7% of silicon (after graphitizing modification), and 0.1% of manganese leads to the occurrence of the ferrite-pearlite matrix containing cementite precipitates in the case of the treatment of the alloy with cerium mischmetal . The increase in the quantity of aluminium up to about 1.9% or up to about 2.8% results either in purely ferrite matrix in this first case or in ferrite matrix containing small amounts of pearlite in the latter one. Nodular graphite precipitates occurred only in cast iron containing 1.9% or 2.8% of aluminium, and the greater aluminium content resulted in the higher degree of graphite spheroidization. The noticeable amount of vermicular graphite precipitates accompanied the nodular graphite.
The publication presents the results of examination of selected carburizers used for cast iron production with respect to their electric resistance. Both the synthetic graphite carburizers and petroleum coke (petcoke) carburizers of various chemical composition were compared. The relationships between electrical resistance of tested carburizers and their quality were found. The graphite carburizers exhibited much better conductivity than the petcoke ones. Resistance characteristics were different for the different types of carburizers. The measurements were performed according to the authors’ own method based on recording the electric current flow through the compressed samples. The samples of the specified diameter were put under pressure of the gradually increased value (10, 20, 50, 60, and finally 70 bar), each time the corresponding value of electric resistance being measured with a gauge of high accuracy, equal to 0.1μΩ. The higher pressure values resulted in the lower values of resistance. The relation between both the thermal conductance and the electrical conductance (or the resistance) is well known and mentioned in the professional literature. The results were analysed and presented both in tabular and, additionally, in graphic form.
The paper presents selected granular ceramic materials available on the Polish market. Their characteristics have been determined in the aspect on application in the production of iron alloy-ceramic composite. The possibility of obtaining a composite layer by means of bulk grains in molds of plates were considered, which was the foundation for experimental molds to be used in service tests. On the basis of obtaining results was stated that the knowledge of the characteristics of bulk grains enables the calculation of their quantity necessary for the composite production. When using the bulk grains the thickness of the composite layer is restricted by the thermal relations (cooler) and the physical phenomena (buoyancy, metal static pressure). Increasing amount of grains above definite condition causes surface defects in the castings. Each casting, due to its weight, shape and place of composite layer production requires an individual approach, both at the stage of formation and that of calculation of the required quantity of ceramic grains.
An initial assessment of the effectiveness of cast iron inoculation, performed by the method of impulse introducing the master alloy into cast iron, is presented. The experiment was concerned with the hypoeutectic gray cast iron inoculated with either the Alinoc or the Barinoc master alloy by means of an experimental device for pneumatic transportation. Examinations involved pneumatic injection of the powdered inoculant carried in a stream of gaseous medium (argon) into the metal bath held in the crucible of an induction furnace. It was found that the examined process is characterised by both high effectiveness and stability.
In this study, a preliminary evaluation was made of the applicability ofthe signalsof the cutting forces, vibration and acoustic emission in diagnosis of the hardness and microstructure of ausferritic ductile iron and tool edge wear rate during its machining. Tests were performed on pearlitic-ferritic ductile iron and on three types of ausferritic ductile iron obtained by austempering at 400, 370 and 320⁰C for 180 minutes. Signals of the cutting forces (F), vibration (V) and acoustic emission (AE) were registered while milling each type of the cast iron with a milling cutter at different degrees of wear. Based on individual signals from all the sensors, numerous measures were determined such as e.g. the average or maximum signal value. It was found that different measures from all the sensors tested depended on the microstructure and hardness of the examined material, and on the tool condition. Knowing hardness of the material and the cutting tool edge condition, it is possible to determine the structure of the material .Simultaneous diagnosis of microstructure, hardness, and the tool condition is probably feasible, but it would require the application of a diagnostic strategy based on the integration of numerous measures, e.g. using neural networks.