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The 10 kg induction furnace experiments were carried out to investigate the oxidation and decarburization behaviour and melting characteristics of the steel bars with different carbon contents. In ...

In this study, ternary Al-12Si-0.6Mg material was manufactured by gravity die casting method in induction melting furnace. Microstructure images of alloy were taken on optical microscope after T6 h...

In the present study, interactions between Fe-2.1 wt-%Al and Fe-5.1 wt-%Al alloys and different tundish refractories, and a spinel generation in the Fe–Al alloys were investigated in laboratory experiments at 1550°C in an alumina crucible using a high-frequency induction furnace. The results indicated that the formation of a spinel layer at the interface was owing to both the oxidation–reduction reactions and the phase transformation at the interface according to initial phases in refractories. The thickness of the interface layer increased with increasing the content of the [Al] in Fe–Al alloys, the SiO2 content in the refractory and the immersion time, however, the [Al] content was a dominant factor. Both experimental results and thermodynamic calculations concluded that MgO·Al2O3 spinel inclusions along with a small amount of CaO–MgO–Al2O3 were the main inclusions in Fe–Al alloys. MgO·Al2O3 inclusions were mainly formed at the interface by alloy/refractory interactions and then mechanically tra...

Local atomic configuration, phase composition and atomic intermixing in Fe-rich Fe1−xCrx and Fe1−xMox ribbons (x = 0.05, 0.10, 0.15), of potential interest for high-temperature applications and nuclear devices, are investigated in this study in relation to specific processing and annealing routes. The Fe-based thin ribbons have been prepared by induction melting, followed by melt spinning and further annealed in He at temperatures up to 1250 °C. The complex structural, compositional and atomic configuration characterisation has been performed by means of X-ray diffraction (XRD), transmission Mossbauer spectroscopy and differential scanning calorimetry (TG-DSC). The XRD analysis indicates the formation of the desired solid solutions with body-centred cubic (bcc) structure in the as-quenched state. The Mossbauer spectroscopy results have been analysed in terms of the two-shell model. The distribution of Cr/Mo atoms in the first two coordination spheres is not homogeneous, especially after annealing,...

Laboratorial study was carried out to reduce the rates of sulphide inclusions in rail steel. Rail steel was re-melted in an induction furnace with the addition of titanium to 0.0098wt%. The cast in...

The equilibrium condition between molten steel and slag during manganese-ore carbon-reduction was studied using both resistance furnaces and induction furnaces. The resistance furnace experiment shows that it is difficult to further increase the yield of manganese (maintained at around 37%) without stirring. The bottom blowing and top slag stirring were strengthened in the induction furnace test, where white slag was continuously produced to promote the carbon reduction of manganese dioxide in slag between molten steel and slag. Under these conditions, the yield of manganese between molten steel and slag can reach greater than 90%. The main factors affecting the manganate capacity are the carbon and silicon content in molten steel. The limiting process of manganese mass transfer is mainly the mass transfer of manganese in molten steel. Under carbon reduction in molten steel the limiting factor affecting the mass transfer of manganese is the mass transfer of manganese in slag.

Monolithic materials with a strong thermal insulating effect are required by the foundry industry for further energy savings, meanwhile possible premature wear of refractory linings caused by over-insulation should be avoided. A monolithic insulating material containing lightweight aggregates possessed strong thermal insulation and was proposed to replace the traditional insulating material made of chamotte currently used in a channel induction furnace. To evaluate the new lining concept, creep of the working lining was considered in the finite element modelling and followed the classical von Mises creep model, which was defined with the Norton–Bailey strain hardening creep equation. The results showed that the lightweight design of the insulating lining reduces the heat loss from the steel shell and material consumption. Moreover, the thermomechanical loads in the refractory linings and steel shell remain within a reasonable range when compared with the currently in-use refractory lining concept.

Large amounts of dust produced in basic oxygen steelmaking not only reduce the yield of metal, but also increases the dedusting load. Based on the different vapour pressure of Mn, Fe, V, Mo, disparate alloys were added into induction furnace with various carbon content, and different portions of mixed gas of CO2 and O2 were blown into the furnace. Through laboratory investigation of the production behaviour of dust in basic oxygen steelmaking, the dust production mechanism was studied. The experiments prove that the production of dust in basic oxygen steelmaking depends on both entrainment of the bubbles and evaporation of elements. As the reactions proceed, the dust particle size shows a tendency to become larger. With the increasing of CO2 blowing rate, the amount of dust produced by entrainment of the bubble increases, while which produced by evaporation of elements decreases, and dust size diminishes. Blowing a certain portion of CO2 into the bath not only contribute to the utilisation of CO2, but als...

The effect of 0.5 wt-% SiC nanoparticle addition on microstructure and brazeability of Al–9Si–20Cu alloys has been investigated. The brazing is performed using the filler at 550°C for 30 min. Microstructural observations reveal the refinement of Si and CuAl2 in Al–9Si–20Cu–0.5SiC composite. The average size of Si particles decreases from ∼9 to ∼4 μm. It has been shown that SiC nanoparticles improve the filler brazeability; the spreading ratio increases up to 88.4% as compared to 76.67% over Al–9Si–20Cu alloy. The tensile strength and ductility of Al–9Si–20Cu–0.5SiC are also enhanced by 47 and 53% respectively. The melting point shows a depression ∼4°C in Al–9Si–20Cu–0.5SiC and thus can be a potential filler candidate for brazing industries.

A series of small iron specimens with minor additions of C, Si and Mn were manufactured via induction melting and characterised using a high throughput methodology. The aim was to analyse the high throughput approach itself, not the effects of minor additions to steel. Despite their small size, the trends in measured standard mechanical properties were consistent with published data, and target alloy compositions were achieved to a sufficient degree of accuracy. This is most encouraging as the experimental approaches described here delivered results in a very short time frame, with time per composition estimated to be

Melting plays a critical role in cast parts production, and an electromagnetic field can affect heat transfer in the induction melting process. This paper studied a mathematical model of coupled electromagnetic and temperature fields based on a simplified physical model of the induction melting process. The ‘’ method was applied to solve the electromagnetic governing equations, while the finite difference method of the uneven mesh was used to discretise all the control equations. The simulation results of the self-developed program and ANSYS software for electromagnetic fields had the same distribution trend and both demonstrated a good agreement of current skin effect and magnetic edge effect. However, the result comparisons illustrated that the simulation results of this program were more accurate. The simulation results explained the heat transfer mechanism of cast steel in the induction melting process, and the impact of current and frequency on heat transfer was also discussed.

To clarify the operating conditions for the homogenization of metallic low-level radioactive wastes (LLW), melting tests were conducted in the metal melting system of the Advanced Volume Reduction Facilities at the Japan Atomic Energy Agency (JAEA). Simulated metallic LLW with a non-radioactive tracer were melted in the induction furnace of the metal melting system. Regardless of the chemical composition or amounts of the simulated wastes, the tracer distribution in the solidified products was nearly homogeneous when the simulated wastes were completely melted in the range from 1550 °C to 1638 °C.

The effect of carbon on the microstructure and mechanical properties of lightweight steel based on Fe–7 wt-%Al produced by air induction melting with flux cover is investigated. The ingots were hot worked to plates and were characterised. Steel containing 0.02 wt-%C exhibited a single phase microstructure Fe–Al(α), whereas steel containing 0.5 and 1.0 wt-% carbon exhibited a two-phase microstructure containing significant amounts of Fe3AlC0.5 precipitates in Fe–Al(α) matrix. Microhardness of the matrix decreases with increasing carbon content due to depletion of aluminium from the matrix to form Fe3AlC0.5 carbides. The bulk hardness, room temperature strength increases and tensile elongation decreases with increasing carbon content. However, at 873 K the improvement in strength as well as creep properties with increasing carbon content is marginal.

Temperature measurements of liquid pig iron coming out of a blast furnace are essential for estimating the thermal condition in the hearth. The temperature is generally monitored by a disposable th...

Experimental research on smelting vanadium steel by direct alloying with self-reduction briquettes of V2O5 has been conducted in a medium frequency induction furnace of the laboratory and in a 60 t ladle of Shijiazhuang Iron and Steel Co. Ltd. The result indicates that the amount of the reductant (FeSi) and the flux (CaO) inside the self-reduction briquette of V2O5 have effects on the yield of vanadium during the direct alloying, and the optimum composition of the self-reduction briquette of V2O5 is 23·88V2O5–29·75FeSi–15·93CaO–30·44CaF2. When smelting vanadium steel by direct alloying in a 60t ladle, the average yield of V is 96·54%. Meanwhile, the steel product could achieve the required quality level.

A new fractional melting process using an induction furnace and a centrifugal system has been developed for metallurgical-grade silicon (MG-Si) refining. An induction furnace enables rapid heating and therefore reduces the total refining process time. Impurity-rich liquids can be ejected effectively from the MG-Si by the centrifugal force induced by a motor. The impurity behaviors of the refined samples are observed by scanning electron microscope (SEM). The refining efficiency, which depends on sample size and centrifugal force, is evaluated using inductively coupled plasma atomic emission spectroscopy (ICP-AES) and inductively coupled plasma mass spectroscopy (ICP-MS). The purity of the refined silicon increases with the centrifugal force. The correlation between the centrifugal force and silicon purity is rationalized using the surface tension of impurity-rich liquids. In spite of the rapid heating rate by induction furnace, the MG-Si is refined and 96.7% of the impurities are removed at rotation speed...

In this paper, comprehensive utilisation of hydrometallurgy zinc residue, goethite especially, was proposed. The raw material used in this study was mixed residue while the mass ratio of goethite and lead–silver residue was fixed at 4∶1. Based on the characters of mixed residue, the top blowing fuming method was taken by using induction furnace. The effects of parameters such as CaO/SiO2 (0·61–0·91), C/feed mass ratio (18–26%) and reduction time (20–60 min) had been studied. Under the optimum conditions (CaO/SiO2 = 0·71; C/feed mass ratio of 24%; reduction time of 50 min), the average fuming efficiency of zinc, lead and sliver in the mixed residue could reach up to 97·2, 98·1 and 82% respectively.

The current industrial production of aluminum from alumina is based on the electrochemical Hall-Heroult process, which has the drawbacks of high-greenhouse gas emissions, reaching up to 0.70 kg CO2-equiv/kg Al, and large energy consumption, about 0.055 GJ/kg Al. An alternative process is the carbothermic reduction of alumina. Thermodynamic equilibrium calculations and experiments by induction furnace heating indicated that this reaction could be achieved under atmospheric pressure only above 2200°C. Lower required reaction temperatures can be achieved by alumina reduction under vacuum. This was experimentally demonstrated under simulated concentrated solar illumination and by induction furnace heating. By decreasing the CO partial pressure from 3.5 mbar to 0.2 mbar, the temperature required for almost complete reactant consumption could be decreased from 1800°C to 1550°C. Deposits condensed on the relatively cold reactor walls contained up to 71 wt% of Al. Almost pure aluminum was observed as Al drops, wh...

The effect of alloying elements including aluminium, chromium, cobalt, indium, molybdenum, titanium and vanadium on the corrosion behaviour of a synthetic 90/10 Cu–Ni alloy in natural sea water and in artificial saline solutions (containing 2·86 wt-%NaCl and 0 or 2260 ppm sulphate) was investigated. Synthetic alloys were prepared in an induction furnace, under an Ar/7 vol.-%H2 atmosphere in cylindrical boron nitride crucibles and were heat treated in a tube furnace. The electrochemical measurements were conducted using aerated electrolytes at room temperature using a potential range between −1·5 and +2·5 V(SCE). Tafel extrapolation, cyclic polarisation, cyclic voltammetry and linear polarisation electrochemical techniques were applied in this investigation. It was concluded that the corrosion behaviour of the synthetic alloys depends on the alloying element added to the alloy. Cobalt was detected to be the most effective alloying element and aluminium may be used as an alloying element only in the...

Solid state and smelting reduction of ilmenite is an important process of upgrading ilmenite to high titania feedstock. In this study, an ilmenite concentrate supplied by Panzhihua Iron and Steel (Group) Co. was first reduced at solid state in an electric resistance furnace, followed by smelting reduction in an induction furnace. The effects of reducing agent (carbon) amount on the chemical composition of the solid state reduction sample and the titania slag reduced from them, were analysed. It was found that the metallisation of iron in the solid reduction samples and the grade of titania slag generally increased with increasing carbon amount from 8 to 12%, and then remained constant when the carbon amount was increased above 12%. The content of metallic iron in the titania slag increased with increasing carbon amount, because the slag viscosity and liquidus temperature increased with decreasing FeO content. It was also known that the content of Ti2O3 increased with decreasing the content of FeO ...

Duplex stainless steel with varying nitrogen contents of 0.22% (alloy 1) and 0.18% (alloy 2) were produced using a conventional induction furnace under normal ambient atmosphere. The samples were subsequently rolled under hot (1,000–1,100°C) conditions to various thickness reductions (15–75%). Both the hot rolled alloy samples were examined for the changes in microstructure and mechanical properties. The alloy 1 with higher nitrogen content opens out while deforming above 15%, whereas the alloy 2 deformation in the hot working zone is perfect without any defects. The crack initiation parameter for the alloy 1 is the secondary phase formation in the austenite area, which is brittle. The temperature range of 1,050 to 1,100°C is not desirable for hot rolling of alloy 1 and the same temperature range is suitable for hot rolling of alloy 2.

Thermochemical equilibrium calculations are carried out to elucidate improved conditions for the production of Al, Si, FeSi, Ti, Mg, Hf, Zr, Be, and Ge by the high-temperature carbothermic reduction of their oxides, and for the production of Mg by the silicothermic reduction of MgO–CaO. The onset temperature for the formation of free Al, Be, Si, Ti, Mg, Hf, and Zr in the gas phase is considerably lowered by decreasing the total pressure, enabling their vacuum distillation. An important prediction of vacuum operation is the suppression of undesired by-products, such as Al-carbide, Al4C3, and the Al-oxycarbides Al2OC and Al4O4C. These species considerably interfere in the carbothermic Al production at an ambient pressure, as shown in preliminary experiments using induction furnace irradiation. CO coproduced in these reactions may be water-gas shifted to syngas and further processed to hydrogen and liquid fuels.

In the present paper, the clogging tendency of aluminium or silicon killed low carbon and stainless steel grades has been investigated using pilot scale equipment. Steel was melted and deoxidised in a 600 Hz induction furnace, then teemed through a temperature controlled nozzle into a mould situated on a scale measuring the teemed mass. The steel and nozzle temperatures could be adjusted within ±1°C. It was found that the clogging rate, when teeming through a hot nozzle, increased with an increasing amount of alumina phase present in the steel melt. This, in combination with composition analysis and a detailed crystallographic investigation using electron backscatter diffraction, suggested that the clogging was created by deoxidation products from the steel melt. Furthermore, it was found that the freezing effect onto the nozzle wall when teeming non‐clogging steel through a cold nozzle was of the same order of magnitude as the clogging rate of the aluminium killed steels teemed through a hot nozzle. Succ...

In this study a Fe-Cr-W-V alloy was prepared by induction melting and hot rolling. To precipitate carbide particles in the matrix structure, this alloy was heat treated at 1000°C for 30 min, and then subjected to tempering treatment at 700°C for 2h. These particles were extracted from matrix of this alloy and identified by XRD, DTA and TEM analyses and the stoichiometry, size and shape of them were determined. Results were shown mainly two types of carbide precipitated as M7C3 and M23C6 that were spherical and blocky shapes. In addition, very fine precipitates as MC were only detected by TEM. Also, measuring of particle size showed that average diameter of spherical particles and thickness and length of blocky particles were about 80, 60 and 140 nm, respectively.

Laboratory trials were performed in an induction furnace to study droplet formation during lance blowing. Oxygen was blown on a molten iron bath consisting of iron alloyed with carbon and silicon. Iron droplets were collected using a specially designed sampler. The average iron droplet composition and the oxide layer thickness were determined using scanning electron microscopy combined with energy dispersed spectroscopy. In addition, the concentration gradient of elements was determined using electron probe microanalysis. It should be noted that a special technique had to be developed in order to prepare the droplet sample. The size distribution and composition of the droplets were also determined using the microprobe. The carbon was found to be homogeneously distributed throughout the droplet independently of the size of the droplet. For the experiments using both carbon and silicon it was found that the silicon in most droplets could be found in the periphery of the droplets. It was also found that the tendency was that both the carbon content as well as the silicon content in the droplets decreased with a decreased droplet size. Thus, it was concluded that it is necessary to modify top blown decarburisation processes so that a maximum area between droplet and atmosphere is obtained.

The present study analyses different boron contents (between 10 and 160 ppm) on the structure of a 0·2C–2Mn–1Si (wt-%) steel deformed at a starting temperature of 1050°C in a T. J. Pigott laboratory rolling mill. The steel was made in a laboratory open induction furnace using high purity raw materials and cast into metallic moulds. This experimental steel has proved to have tribological properties, under dry rolling/sliding contact, as good as those for the 0·8% pearlitic steels used in railway applications. Before thermomechanical processing, the steel ingots (70 × 70 × 70 mm) were homogenised at 1100°C for 1·5 h. The thermomechanical treatment was carried out by a reversed multipass process to reach a level of deformation of 60%. Plastic deformation was finished at ∼920°C for all the rolled steels and the plates (70 × 150 × 20 mm) were then water quenched and/or air cooled to room temperature. Results show more bainitic structures as boron content increases in the air cooled steel after hot rol...

With growing importance of smelting reduction processes, experimental research to understand reduction of FeO in molten slag and the foaming behaviour associated therein have assumed greater relevance. In a previous paper, experimental data on reduction of FeO in molten slag in a 30 kW capacity induction furnace have been reported. The present study used around 250 g slag in each experiment was concerned with influence of FeO concentration in molten slag and temperature on foaming and kinetics. The present paper describes a study on the same system carried out using the sessile drop technique (SDT) which, although it uses very small (∼25 mg) sample size, is extremely versatile. Moreover, SDT allows one to actually see the reaction occur. An attempt has been made to correlate kinetic data obtained using the present set-up with the data where much larger sample sizes were used. Both solid carbon and solute carbon have been employed in reduction studies.

High speed tool steels are high alloyed high carbon steels. The processing of these grades is affected to a large extent, by the behaviour of the alloying elements. In this work, the effect of nitrogen alloying, physical properties and chemical composition of fluxes used in electroslag refining (ESR) on hardness, microstructure and alloying elements recovery and homogeneity of two grades, conventional and nitrogen alloyed AISI M41 high speed tool steel, were studied. One melt of each selected grade was melted in an induction furnace. The ingots were then used as consumable electrodes in ESR, where each steel grade was remelted under three different prefused CaF2 based fluxes. The alloying element behaviour was investigated. The highest recovery was obtained using ESR flux of high viscosity and low metal/slag interfacial tension. Increasing the nitrogen content of the steel results in an increase in alloying element recovery. Furthermore, the ESR process improved the shape, size and distribution of...

Laboratory research has been conducted to investigate the effect of strong deoxidising elements such as Al, Zr or Ti in preconditioning of uninoculated and inoculated grey irons. Experimental heats were performed in an acid lined crucible induction furnace at 3˙7–3˙9% carbon equivalent, 5˙5–6˙5 Mn/S ratio and

Effects of alloying elements Cr, Mn, Si, Cu and Zr on the microstructure and mechanical properties of Fe3Al (Fe–16Al) based alloy containing ∼0·5 wt-%C have been investigated. Six alloys were prepared by a combination of air induction melting with flux cover and electroslag refining (ESR). ESR ingots were hot forged and hot rolled at 1373 K and were further characterised with respect to microstructure and mechanical properties. The base alloy and the alloys containing Cr, Mn, Si and Cu exhibit a two phase microstructure of Fe3AlC0·5 precipitates in Fe3Al matrix whereas the alloy containing Zr exhibits a three phase microstructure, the additional phase being Zr rich carbide precipitates. Cr and Mn have high solubility in Fe3AlC0·5 precipitates as compared to Fe3Al matrix whereas Cu and Si have very high solubility in Fe3Al matrix compared to Fe3AlC0·5 precipitate and Zr has very low solubility in both Fe3Al matrix and Fe3AlC0·5 precipitate. No significant improvement in room and high temperature (a...

Effect of quaternary alloying elements Ti, W, Mn, Mo and Si on the microstructure and mechanical properties of Fe–10·5Al–0·7C (wt-%) alloy has been investigated. Six different alloys were prepared by a combination of air induction melting with flux cover and electroslag remelting (ESR). The composition of the quaternary alloying element was ∼2 wt-% and was substituted for iron. The ESR ingots were hot forged and hot rolled at 1375 K. The hot rolled alloys were characterised with respect to microstructure and mechanical properties. Alloys containing W, Mn and Si exhibited two phase microstructure of Fe3AlC0·5 precipitates in α Fe–Al matrix. Whereas alloys containing Mo and Ti exhibited three phase microstructures, the additional phase being the respective carbides. Both α Fe–Al matrix and Fe3AlC0·5 precipitates have considerable amount of solubility for W, Mn and Mo whereas Si has very high solubility in α Fe–Al matrix as compared with Fe3AlC0·5 precipitates and titanium has very low solubility in ...

Effect of aluminium and carbon content on the microstructure and mechanical properties of Fe–Al–C alloys has been investigated. Alloys were prepared by combination of air induction melting with flu...

Smelting reduction process technology is progressing rapidly, and research to understand the reduction of FeO in molten slag and the associated foaming behaviour has gained importance. The present paper reports experimental data on the reduction of FeO in molten slag generated in a 30 kW capacity induction furnace. The influence of FeO content in the slag and temperature on the foaming and kinetics is discussed. The foaming index, a parameter describing the travel time of gas in the reactor, is shown to decrease with an increase in the superficial gas velocity. The quantitative dependence of the foaming index on slag properties viscosity, surface tension and density has been studied. The data have also been analysed to give an estimation of the activation energy for the reduction reaction. The reduction reaction, initiated by direct slag–graphite contact, produces CO gas, which spreads into the molten slag bath causing foaming of the slag; further reduction of FeO proceeds mostly via indirect redu...

The dust generated during electric arc furnace (EAF) steelmaking contains zinc and lead. The dust can be injected into the furnace to enhance the zinc and lead grades in the dust; however, the kinetics of this operation is poorly understood. The kinetics was studied in experiments in which dust was injected into 70 kg heats of iron or steel in an induction furnace. Supplemental additions of carbon and oxygen to overcome the heat load on the system were also investigated. The zinc content increased from 16% Zn to 60 - 80% Zn. About 50% of the zinc in the dust dissolved in the iron or steel. The ZnO in the dust is shown to be reduced by dissolved carbon and the zinc vapour dissolved in the iron. The implications for EAF dust recycling are discussed.La poussiere engendree lors de la production d’acier dans un four a arc electrique contient du zinc et du plomb. On peut injecter la poussiere dans le four pour ameliorer la qualite du zinc et du plomb dans la poussiere; cependant, la cinetique de cette o...

Intermetallic TiAl was induction brazed to steel in an induction furnace with Ag-Cu-Ti filler metal at 1143 K for 0·2–2·4 ks. Microstructural analysis indicates that Ti, Al, and C atoms in base metal diffuse to the interface and react strongly with the filler metal during brazing. The interface structure of the joint can be divided into three distinct zones: the reaction layer near TiAl, composed of Cu-Al-Ti compounds and Ag based solid solutions; the central zone of the interface, consisting of Ag based solid solutions in which Ag-Cu eutectic phases are dispersed; a TiC reaction layer adjacent to the steel. The relationship between brazing parameters and tensile strength of the joints is discussed, and the optimum induction brazing parameters obtained. When brazed at 1143 K for 0.9 ks, the tensile strength of the joint is 298 MPa.

A low-temperature process for iron-making, using mixed pellets of magnetite and domestic coal with an organic binder was investigated. Reduction tests performed in an induction furnace resulted in a product direct reduced iron (DRI) containing 75–80% metallic iron. The coal energy consumption of 23.71 GJ/ton DRI compares favorably with current DRI processes, although the total energy consumption of 33.65 GJ/ton is relatively high for iron-making. The use of low-grade coal as a reductant may improve the economics of the process as high-grade coking coal supplies dwindle worldwide.

The basic knowledge of the physical and chemical properties of the electric arc furnace (EAF) and secondary dust (SD) obtained by the characterisation provides important information on the potential problems that could be encountered during the processing of such materials. EAF dust consists mainly of very fine spherical particles. The most common phases in the EAF dust are solid solution of iron spinels generally enclosed into a matrix of calcium–iron silicate glass. Leaching tests show that as the Zn/Fe ratio increases, there is an increase in the zinc extraction, whereas the iron extraction decreases as the Zn/Fe ratio increases. It was possible to produce a SD containing 55.8% zinc by means of charging EAF primary dust–coal composite pellets into an induction furnace. SD consists of very fine particles presenting a mean particle size of 0.26μm. In addition, SD contains significant levels of iron, chloride and fluoride. The iron content in the SD was identified as being iron droplets ejected f...

The effects of zirconium additions on the structure and properties of high carbon Fe - 10.5 wt-%Al alloy have been investigated. Three different alloys with nominal compositions, Fe - 10.5Al - 0.7C (base), Fe - 10.5Al - 0.7C - 0.1Zr and Fe - 10.5Al - 0 7C - 0.17Zr were prepared. Processing of these alloys through a combination of air induction melting with flux cover (AIMFC) and electroslag remelting (ESR) yielded sound ingots free from gas and microporosity with very low levels of sulphur, oxygen, and nitrogen. This process route also resulted in excellent recovery of aluminium and zirconium. The ESR ingots were hot forged and hot rolled at 1375 K and the hot rolled alloys were examined using scanning electron microscopy, electronprobe microanalysis, and X-ray diffraction to understand the microstructure of these alloys. The ternary, Fe - 10.5Al - 0.7C (base) alloy exhibited a two phase microstructure consisting of a large volume fraction of Fe3AlC0.5 precipitates in an Fe - Al (α) matrix. Additi...

The remelting of steel scrap, in particular automobile scrap, in an electric arc furnace results in the production of a fine and highly contaminated zinc-rich dust which is known as electric arc furnace dust. A number of processes have been developed to recover the valuable metals from the dust, but there has been only limited commercial success. The majority of the processes tested have been pyrometallurgical or hydrometallurgical or hybrids. In the present research, the reaction of the dust with molten pig iron containing carbon was investigated as a possible treatment method. The effects of processing time, temperature, electric arc furnace dust to pig iron ratio and the carbon concentration of the pig iron on the process are discussed. The sample mass loss and the zinc, the iron and the lead contents of the reacted slag were determined. Almost 100% of the zinc was readily reduced from the dust. On the other hand, although the majority of the iron could be recovered, it was difficult to reduce ...

The mechanical failure of oxide scales in high temperature tensile tests has been investigated in the present work. The results of experimental tests and three-dimensional finite element modelling are presented. The cracking behaviour of oxide scales formed on mild steel has been studied using a high temperature tensile test technique at 800-870°C. Induction heating equipment has been used to construct a vertical cylindrical furnace. To imitate the surface conditions of the flat rolling process, a special geometry of specimens has been designed; the oxide scale forms on a gauge section with plane surfaces and a rectangular cross-section. A varying number of cracks have been detected, and the appropriate gauge geometry is defined for future investigations. A comparison between round and flat specimens is presented.

Non-metallic inclusions that originate from secondary metallurgy treatments may provoke nozzle clogging during continuous casting and lead more or less directly to surface defects on final products. The amount of these non-metallic inclusions (oxides or nitride) in the solid or liquid steel is governed by the steelmaking practice and in particular by the different slags used in ladle, tundish or mould. One of the functions of the slag is the entrapment of non-metallic inclusions contained in the liquid steel. To study the rate of entrapment, a new experimental technique has been developed. It consists of melting the top of a steel rod together with a slag droplet in an induction furnace. The phenomenon of inclusion entrapment is directly observed on the surface of the liquid steel and recorded with a video camera. The rate of entrapment is measured using image analysis. The original laboratory results obtained have shown that one of the physical-chemical parameters which modifies the kinetics of o...

The international process for immobilization of high-activity waste from aqueous fuel reprocessing is vitrification. In the United States joule-heated melter technology has been implemented at West...

In the present work, the electrochemical behaviour of Mg–xCe–1Zn (x = 3, 8 and 13 wt-%) alloys has been investigated. The alloys were fabricated using an induction melting method under an argon atmosphere. Potentiodynamic polarisation was carried out in 3·5%NaCl solution of pH 7·2 at room temperature to evaluate the corrosion properties of Mg–xCe–1Zn (x = 3, 8 and 13 wt-%) alloys. The microstructure of the Mg–(3, 8 and 13 wt-%)Ce–1Zn alloys mainly consisted of α-Mg and eutectic Mg12Ce phase. With the increase in Ce contents, the volume per cent and size of the eutectic Mg12Ce phase were increased. Results indicated that the corrosion rate of Mg–xCe–Zn alloy was increased by excessive Ce addition.

Kinetic experiments were performed in an induction furnace to investigate the reduction of chromite ore by carbon dissolved in a high carbon ferrochromium alloy melt under conditions of varying Cr2O3 concentration, slag basicity, and temperature. The results obtained show that chromite reduction by dissolved carbon in slag systems of the type MgO-CaO-SiO2-FeO-Cr2O3- Al2O3 occurs principally by a stagewise process encompassing an intermediate reaction in which the divalent chromium oxide species is involved. During the fast period, Cr2O3 reduction is controlled by the diffusion of oxygen species in the slag for which a mass transfer coefficient of 0·003 cm s-1 was calculated. An activation energy value of 117 kJ mol -1 obtained for the reduction of Cr2O3 implies the rate controlling step is mass transfer of Cr2O3 from the slag to the slag/metal interface, since activation energies for metal phase control are typically

Electromagnetic stirring using multiple induction coils has been investigated as a method of preparing semisolid FC20 alloy. The effects of additions of titanium, zirconium, and boron on the microstructure of the FC20 alloy have also been studied. The electromagnetic flux density increased with input voltage and was higher at the wall of the container than near the centre of the coil. The microstructure of the alloys varied with cooling rate: the higher the cooling rate, the smaller the particle size and the greater the degree of sphericity. The additions of titanium, zirconium, and boron also improved the alloy microstructure. (C) 2001 IoM Communications Ltd.

In this investigation a microstructural characterization of the phases obtained in ternary and quaternary alloys was undertaken. One of the main objectives of this study was to explore the possibility of quasicrystalline phases formation under normal casting conditions from the liquid melt. The alloys investigated, were melted in an induction furnace and subsequently cast into a wedge shaped copper mould, which resulted in different cooling velocities in the same ingot. The thick and thin sections of the ingots were characterized by: Optical microscopy, x-ray diffractometry, chemical analysis using EDS and atomic absorption spectroscopy.

Some of the tungsten and vanadium was replaced by titanium in the high speed steel M7 to achieve good casting properties. The microstructure and other characteristics of as cast and heat treated specimens of this experimental steel were investigated by means of optical and electron microscopy with the aid of energy dispersive X-ray (EDX) analysis. Several heat cycle routines were studied to determine the best mechanical properties. These properties have been compared with those of standard M7 and M2 high speed steels to reach a better understanding of the behaviour of the cast experimental steel.

Nickel-Titanium alloys with stoichiometric single phase and non-stoichiometric dual phase structures of NiTi and NiTi+Ni3Ti are produced through high speed induction melting and combustion synthesis of pure Ti/Ni elements. Both alloys are homogenized at 1273 K for two hours, rolled into thin strips of 0.3 mm thickness, solution treated at 1273 K for two hours under vacuum and finally quenched in water. Effect of ageing on austenite/martensite and intermediate phase transformation temperatures are investigated. Results show that transformation temperatures and reversible shape memory properties comparable with those required for bioengineering applications such as manufacturing of artificial hand prostheses can be obtained through careful control of the chemical composition and the heating processes.

Samples of atomised powder of Ti–48Al–2Mn–2Nb, produced using a bottom pouring cold wall induction furnace, have been examined using optical, scanning electron, and analytical transmission electron microscopy before and after hot isostatic pressing (hipping). It has been found that individual atomised powders sometimes contain Ti rich dendritic features which are on too coarse a scale to have formed during atomisation. Hipped samples are also found to contain regions up to 100 μm in size which can have Ti contents as low as 42 at. -%. The number density of these heterogeneities is very low, with typically one Ti rich region found in a 1 cm diameter sample. These Ti rich regions act as failure sites when hipped samples are tested in tension at room temperature. It is argued that these regions are formed because some of the mushy zone, which must be present in a cold wall furnace, passes through the nozzle during atomisation. Hipped atomised powder from other sources, also manufactured using a cold ...

The fatigue properties of Al-1OMg (wt-%) castings have been shown to be improved by hot isostatic pressing (hipping) with a level of improvement highly dependent on the initial quality of the castings. Only castings with low oxide inclusion levels were found to show a significant improvement infatigue propertiesjollowing hipping. To reduce the oxide inclusion content a casting technique has been developed in which the molten aluminium is tapped from the bottom of an induction melting furnace. The average fatigue life (at a test stress amplitude of 106 MN m−2) increased from 213×103 to 1016×103 cycles following adoption of the bottom tapping technique. Hipping of the bottom tapped castings produced a further increase in the average life to at least 15×106 cycles. These substantial improvements in fatigue properties can be attributed to a reduction in the size and quantity of oxide inclusions in the bottom tapped castings. Unless the oxide inclusion content of the castings can be maintained at a suf...