Gray Cast Research Articles

A comparative study of flake graphite iron and compacted graphite iron in austempered condition for directional control valves

Demand for lighter materials with the right qualities is unavoidable in the present era of engineering. Compacted graphite iron is a type of cast iron gaining momentum nowadays in foundries due to its distinct characteristics that fall between gray cast iron/flake graphite iron and spheroidal graphite iron. It becomes the right candidate to replace flake graphite iron in many applications. In this research, flake graphite iron (FC −30) and compacted graphite iron-300 grades were studied to enhance its properties through austempering heat treatment process. Initially, the as-cast (non-austempered) flake graphite iron and compacted graphite iron were subjected to microstructural study and mechanical testing. Subsequently, the flake graphite iron and compacted graphite iron were subjected to austempering heat treatment. The various austempering temperatures selected are 270, 320, and 370 °C for different soaking time periods of 30, 60, 90, and 120 min. As cast flake graphite iron specimen (FC-30) exhibited lesser tensile strength (293 N/mm2) than as cast compacted graphite iron (528 N/mm2) and austempered compacted graphite iron (652 N/mm2). With respect to hardness measurement, austempered compacted graphite iron specimens yielded higher hardness of up to 415 BHN. However, the compacted graphite iron specimen austempered at 370 °C for 90 min measured an optimum hardness value of 373 BHN and tensile strength of 630 N/mm2 with less retained austenite (0.3%). This hardness value is considered to be more suitable in machining operation for making hydraulic directional control valves exposed to constant abrasion.

Comparative Wear Resistance of Existing and Prospective Materials of Fast-Wearing Elements of Mining Equipment

The results of tests for resistance to abrasive wear on highly abrasive hard rock white electrocorundum are presented. The main material of fast-wearing elements of mining and processing equipment-110G13L steel (Gadfield steel) in comparison with other 9 grades of steel and cast iron, including specially developed wear-resistant foreign steels such as Hardox and Miiluks, is analyzed. The studies were carried out using an experimental stand for studying the material wearing process. On the stand the sample was fixed in a holding device and, after being brought into contact with the abrasive, it was rotated under a constant load. As a result of the experiments, it was confirmed that the order of placement of the tested materials in terms of increasing wear resistance coincides with their placement in terms of increasing hardness. At the same time, the wear resistance of the most resistant material – U8A steel after quenching – is about 4 times higher than this indicator for the least resistant components – low-carbon steel 25L, including gray and high-strength cast iron SCH21, VCH35. The wear resistance of 110G13L steel, as well as 65G, U8 steels in the hardened state, is from 1.5 to 2 times higher than that of foreign steels M400, H450, M500, H500. The results of the conducted studies allow us to evaluate the analyzed materials on the basis of their wear resistance and hardness indicators on the feasibility of using them in the manufacture of fast-wearing parts of mining equipment. Based on the research data, it seems promising to develop new ways to increase the wear resistance of domestic steel, including 110G13L steel traditionally used in mining.

Одержання гідрощільних виливків із синтетичного сірого та високоміцного чавуну за моделями, що газифікуються

Одержання гідрощільних виливків із синтетичного сірого та високоміцного чавуну за моделями, що газифікуються

Study on Growth of Corrosion Scale on Various Iron Based Materials (Grey cast iron/Carbon steel/Ductile Iron) in Water Distribution Systems

Study on Growth of Corrosion Scale on Various Iron Based Materials (Grey cast iron/Carbon steel/Ductile Iron) in Water Distribution Systems

Simultaneous thermal and contraction/expansion analyses of cast iron solidification process

Simultaneous thermal and contraction/expansion analysis of hypoeutectic grey (lamellar graphite) and ductile (nodular graphite) cast irons solidification is recorded, using an equipment with a special designed ceramic cup, incorporating a thermocouple and contraction/expansion measuring device. Both cooling and contraction/expansion curves and their specific parameter values are displayed in a real time. The two compared cast irons occupy different and opposite positions during solidification process evolution: lower level of temperatures at the beginning and especially at the end of solidification, but higher level during the eutectic reaction for ductile cast irons. In the tested conditions, solidification of hypoeutectic cast irons with lamellar graphite is characterized by a greater undercooling during the eutectic reaction (lower ΔT1 and ΔT2, referring to the metastable eutectic temperature), with higher value for eutectic recalescence (ΔTr) and the maximum recalescence rate. Iron castings, including nodular graphite (ductile irons), show an end of solidification at higher undercooling (ΔT3), with less negative pick level of the first derivative of cooling curve. More graphitic initial expansion [edi(gr)], which favours the shrinkage formation, characterized nodular graphite iron castings. There is a good relationship between some parameters on the cooling curves and corresponding events on the contraction/expansion curves, such as solidification undercooling degrees, comparing to metastable eutectic temperature, and graphitic expansion [edi(gr)] for both tested cast irons: higher the level of ΔTr, and of ΔT1, ΔT2, ΔT3 (less negative) and GRF1 (graphitic factor), higher the [edi(gr)] level is.

The effects of different engine material properties on the performance of a diesel engine at maximum combustion temperatures

In this study, the influences of various engine materials such as palladium, titanium, thorium, zirconium, vanadium, alumina, aluminum bronze, copper, iron (gray cast), manganese, nickel, cobalt, and carbon steel on the effective efficiency and effective power with respect to the variation of equivalence ratio at the maximum combustion temperatures. In-cylinder gas temperatures have been determined with respect to the melting temperatures and the performance values have been calculated with respect to the variation of the gas temperatures. The results indicated that alumina provides the maximum performance values as aluminum bronze gives the minimum performance values due to the combustion temperatures. Further-more, the equivalence ratios which give the maximum performance characteristics have been parametrically described. The obtained results can be assessed by engine designers and manufacturers to choose suitable engine material.

Integrated System of Thermal/Dimensional Analysis for Quality Control of Metallic Melt and Ductile Iron Casting Solidification

The main objective of the present work is to introduce a specific experimental instrument and technique for simultaneously evaluating cooling curves and expansion or contraction of cast metals during solidification. Contraction/expansion analysis illustrates the solidification parameters progression, according to the molten cast iron characteristics, which are dependent on the melting procedure and applied metallurgical treatments, mold media rigidity and thermal behavior [heat transfer parameters]. The first part of the paper summarizes the performance of this two-mold device. Its function is illustrated by representative shrinkage tendency results in ductile cast iron as affected by mold rigidity (green sand and furan resin sand molds) and inoculant type (FeSi-based alloys), published in part previously. The second part of the paper illustrates an application of this equipment adapted for commercial foundry use. It conducts thermal analysis and volume change measurements in a single ceramic cup so that mold media as well as solidification conditions are constants, with cast iron quality as the variable. Experiments compared gray and ductile cast iron solidification patterns. Gray iron castings are characterized by higher undercooling at the beginning and at the end of solidification and lower graphitic expansion. Typically, ductile cast iron exhibits higher graphitic, initial expansion, conducive for shrinkage formation in soft molds.

Cast Iron Inoculation Enhanced by Supplementary Oxy-sulfides Forming Elements

Inoculation is one of the most important metallurgical treatments applied to the molten cast iron immediately prior to casting, to promote solidification without excessive eutectic undercooling, which favors carbides formation usually with undesirable graphite morphologies. The paper focused on the separate addition of an inoculant enhancer alloy [S, O, oxy-sulfides forming elements] with a conventional Ca-FeSi alloy, in the production of gray and ductile cast irons. Carbides formation tendency decreased with improved graphite characteristics as an effect of the [Ca-FeSi + Enhancer] inoculation combination, when compared to other Ca/Ca, Ba/Ca, RE-FeSi alloy treatments. Adding an inoculant enhancer greatly enhances inoculation, lowers inoculant consumption up to 50% or more and avoids the need to use more costly inoculants, such as a rare earth bearing alloy. The Inoculation Specific Factor [ISF] was developed as a means to more realistically measure inoculant treatment efficiency. It compares the ratio between the improved characteristic level and total inoculant consumption for this effect. Addition of any of the commercial inoculants plus the inoculant enhancer offered outstanding inoculation power [increased ISF] even at higher solidification cooling rates, even though the total enhancer addition was at a small fraction of the amount of commercial inoculant used.

General Process for <i>In Situ</i> Formation of Iron-Matrix Surface Composites Reinforced by Carbide Ceramic

Ceramic particles with high hardness and thermal stability can be used to fabricate in situ carbide particulate-reinforced iron-matrix surface composites with high macro-hardness while retaining high toughness. This paper describes a general process by which in situ carbide particulate-reinforced iron-matrix surface composites with hard ceramic particles are readily formed by a novel in situ synthesis process that combines an infiltration casting process with subsequent heat treatment. The basis of our approach is integrating selected plates of different alloys that can form carbide easily into a metal matrix with a certain amount of carbon such as gray or ductile cast iron by casting to form alloy plates reinforced iron-matrix surface composites. Subsequent thermal treatment of resulting composites leads to alloy elements of plate reacting to the carbon in the matrix to form carbide particles. This approach is applicable to a wide range of materials and morphologies, and can be used in composites and machining tools, as well as in the wear-resistant component industry.

Effect of chill formation on the mechanical properties and microstructure of grey and nodular cast irons used in automotive industry

Otomobillerde kullanilan kam milleri dokme demirden (gri dokme demir, kuresel dokme demir) veya celikten uretilmektedir. Bu calismada gri ve kuresel grafitli dokme demirin yuzeylerinde cil olusumunun sertlik, asinma, darbe toklugu ve mikro yapi uzerine etkisi incelenmistir. Bu amacla, gri ve kuresel dokme demirlerden cilli ve cilsiz olmak uzere dort farkli kam mili hazirlanmistir. Kam milleri dokum yontemiyle uretildikten sonra mekanik testler yapilmistir. Yuzeyde olusan cilin dokme demirin sertligini ve asinma direncini artirdigi, gri cil ve kuresel cil dokme demirin asinma miktarinin hemen hemen ayni oldugu tespit edilmistir. Maksimum sertlik gri cil dokme demirde elde edilmistir. Gerceklestirilen darbe toklugu testi sonucunda darbe toklugunun cil olusumu ile azaldigi tespit edilmistir. Maksimum darbe toklugu Kuresel dokme demirde elde edilmistir. Dokme demirlere ait mikro yapi optik mikroskopta incelendi ve asinma yuzeyleri ise taramali elektron mikroskobu ile incelenerek asinma mekanizmalari degerlendirildi. Anahtar Kelimeler: Kam mili, Dokme demir, Cil olusumu, Mekanik ozellik, Mikro yapi

Microstructure and Properties of Cast Iron with Semi-Solid Process Using Cooling Plate Technique

Semi-solid metal processing with the cooling plate technique is one of the key technologies for producing advanced materials. The multitude of cast iron families with their wide range of mechanical properties, and relatively low costs combined with the advantage of semi-solid processing allow production of high quality cast components from cast iron. The effect of semi-solid processing using the cooling plate technique on the microstructure and the properties of cast iron is studied. The investigated material is hypo-eutectic, hyper-eutectic gray iron, compacted graphite and ductile cast iron. The results indicated that the microstructure (primary austenite and graphite) becomes finer and more globular by increasing the fraction of solid. The tensile strength of semi-solid processed cast iron is relatively high compared with ordinary cast iron. The values of both the tensile strength and the elongation depend on the fraction of solid. The total fracture strength is observed to depend on the graphite morphology as well as the matrix contribution that mainly depends on fraction of solid. The wear resistance and damping capacity of cast iron were investigated as a function of the relative amount of primary fraction of solid.

Técnicas de carburação em fornos rotativos a óleo de xisto e gás natural para a produção de ferros fundidos

A indústria metalúrgica tem buscado empregar processos de fusão mais eficientes. Os fornos rotativos a gás natural e óleo de xisto surgem como uma alternativa interessante para a produção de ligas ferrosas. Durante a fusão no forno rotativo acontece uma maior queima de elementos químicos, exigindo a utilização de técnicas de carburação adequadas. No presente trabalho foram avaliadas diferentes formas de adição de carburantes durante a fusão de ferros fundidos cinzentos e nodulares, utilizando fornos rotativos a óleo de xisto e gás natural. Dois tipos de carburantes, com diferentes granulometrias, foram adicionados em diferentes estágios do processo de fusão. Os resultados mostram que o rendimento de carburação é fortemente afetado pelo estado da carga metálica. O melhor rendimento foi obtido pelo carburante de coque de petróleo calcinado com granulometria de 1-3 mm, por meio da adição à carga no estado pastoso.

Semisolid Forging of Cast Iron Using Rapid Resistance Heating

Feasibility of semisolid forging of cast iron using rapid resistance heating was experimentally investigated. Gray pig iron FC250 and spheroidal graphite cast iron FCD600, whose carbon equivalents are both 4.3% in mass, were used for the experiments. Since these cast irons have a narrow semisolid temperature range, an AC power supply with an input electric energy control function was used. In this study, the resistance heating characteristics of the cast irons were firstly examined, and then their semisolid forging experiments were conducted. In the forging experiments, the conditions of the forgings such as microstructures and hardness properties were examined, and the feasibility of the semisolid forging of cast iron using resistance heating was discussed. As a result, it was found that the method presented here is highly feasible.

Eutectic cell and nodule count in grey and nodular cast irons

In the present work the predictions of a proposed analytical theory were compared with the experimental outcome on metallographic determinations of eutectic cell count N and nodule count Nn. Accordingly, processing of flake graphite and ductile cast irons was carried out under various inoculation conditions in order to achieve a range of physicochemical states for the experimental melts. In addition, plates of various wall thicknesses s were cast and the resultant eutectic cell and nodule counts were established. Moreover, thermal analysis was employed for determinations of the maximum degree of undercooling for the graphite eutectic ΔTm. A relationship was found between the eutectic cell N or the nodule count and ΔTm. In addition, it was found that N and Nn can be related to the casting modulus M and hence to s in plate shaped castings. Finally, the present work provides insights into the effect of technological factors such as the melt chemistry, the inoculation practice and the holding temperature and time on the resultant N and Nn values. In general, it was found that the predictions of the present analysis are in good agreement with the experimental outcome.

Gray–blue Al 2O 3–MoO x ceramic pigments: Crystal structure, colouring mechanism and performance

Grayish-blue coloured alumina–molybdena was synthesized by high temperature reducing firing and experimented as ceramic pigment. Synchrotron light and conventional X-ray diffraction powder, ICP-OES and BET analyses proved that molybdenum spreads over alumina surface, without entering the corundum lattice, with a high superficial concentration (i.e. 27–99 Mo atoms nm −2) implying a prevailing octahedral coordination and a certain long-range order, eventually resulting in the formation of crystalline MoO 2. XPS and DRS suggested the occurrence of different valences, Mo(VI) being predominant over Mo(V) and Mo(IV). The colouring mechanism is mainly due to electronic absorption of Mo(V) in the red–orange region of the visible spectrum, giving rise to a characteristic blue shade; the gray cast is caused by extensive light absorption by Mo(IV) crystal field transitions and particularly Mo–O charge transfer. The colouring performance of Al 2O 3–MoO x in ceramic glazes and porcelain stoneware bodies for wall and floor tiles is excellent, being equivalent to the pigment coloration. Thermal stability in these matrices seems to be mostly affected by Na 2O and MgO. However, the distinctly blue shade of these pigments is much less intense than that of the most performant ceramic colorants. At all events, alumina–molybdena system develops a peculiar colour that cannot be reproduced unless utilising the most expensive blue and black cobalt-bearing ceramic pigments.

Austempering of spheroidal graphite cast iron

We study gray spherulitic cast iron, its microstructure, hardness ultimate strength in tension, elongation, and impact toughness as functions of the duration of isothermal austenitizing in the bainite region at 350 and 400°C after austenitizing at 900°C. As the temperature of quenching increases from 350 to 400°C, the microstructure of the analyzed cast iron changes from lower to higher bainite and the amount of retained austenite increases (its maximum is attained after 1 h). At the same time, the ultimate strength in tension and hardness decrease, whereas the elongation and fracture toughness increase.

Effect of Pulsed Current and Mold Material for Pulsed Current Sintering.

The effect of a pulsed current on heating in a pulsed current sintering (PCS) was examined. When a graphite mold was used for the PCS, the heating rate of the mold did not depend on a frequency of a pulsed current. The heating rate of graphite applying pulsed current was larger than that of graphite applying direct current, because of the difference of the input of energy between pulsed current and direct current.The heating rate of the mold in a PCS was determined by a mold material. The hard metal with free carbon was heated more quickly than a usual hard metal in the PCS. Moreover, the cast iron including the precipitation of carbon was obtained higher heating rate by applying pulsed current. The heating rate of cast iron was almost unchanged by the morphology of the carbon, such as nodular graphite cast iron and gray cast iron.The metal mold including carbon is suitable for the near net forming of the powder in the PCS because of its machinability.

Structure of laser remelted surface of cast irons

Grey and white cast irons were surface remelted using a high power CO2 laser with a scanning velocity in the range 0·5–200 mm s-1 and the resulting surface structures were investigated using optical microscopy and X-ray diffraction. The remelted surface of the white iron was composed of austenite dendrites, which decompose to pearlite at low cooling rates and martensite at medium cooling rates. The maximum volume fraction of martensite was obtained at 10 mm s-1. The lattice parameter of the austenite increased with increasing solidification velocity owing to solute trapping of carbon. The remelted surface of the grey iron was composed of cellular ledeburite and X-ray diffraction analyses of the grey specimen indicated the presence of austenite, martensite, graphite, cementite, and ɛ phases. The initial austenite partially transformed to martensite at high cooling rates and to ɛ phase at low cooling rates. The appearance of the ɛ phase is therefore linked to the decomposition of supersaturated austenite.

Un critère de rupture multiaxial pour matériaux fragiles

Most brittle materials show little straining at failure and an ultimate strength that depends upon loading geometry. The surface that defines failure in stress space has a characteristic shape that may be defined by an appropriate mathematical criterion. In this paper, the authors present a simple multiaxial criterion formulated from two quadric functions. Under conventional triaxial compression, the MSDP criterion reduces to the Mises-Schleicher criterion at low mean stress and it takes the shape of the conical Nadai-Drucker-Prager criterion at higher mean stress. The MSDP criterion can be expressed from the three principal stresses or from the usual invariantsI1, J2, and J3. It includes four characteristic parameters, each having a particular significance regarding material properties. The validity of the criterion is shown using experimental results taken from the literature on rock, concrete, and grey cast iron.Key words: failure, brittle materials, rock, concrete, cast iron.

NI-ROD FC 55

Abstract NI-ROD FC 55 cored wire is used for flux-cored-arc and submerged-arc welding of gray, malleable, and ductile cast irons. It is also used for surfacing of cast irons and for joining cast irons to various wrought materials such as carbon steels and low-alloy steels. The cored wire combines the desirable features of NI-ROD 55 Welding Electrode with the speed and economy of automatic or semiautomatic welding. Submerged-arc welding with the cored wire is done with INCOFLUX 5 submerged arc flux. This datasheet provides information on composition, hardness, and tensile properties. It also includes information on joining. Filing Code: Ni-538. Producer or source: Inco Alloys International Inc.