Showing papers in "Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science in 1994"

A Simple but Realistic Model for Laser Cladding

Abstract: A model which takes into account the main phenomena occurring during the laser-cladding process is proposed. For a given laser power, beam radius, powder jet geometry, and clad height, this model evaluates two other processing parameters, namely, the laser-beam velocity and the powder feed rate. It considers the interactions between the powder particles, the laser beam, and the molten pool. The laser power reaching the surface of the workpiece is estimated and, assuming this power is used to remelt the substrate with the clad having been predeposited, the melt-pool shape is computed using a three-dimensional (3-D) analytical model, which produces mmediate results, even on personal computers. The predictions obtained with this numerical model are in good agreement with experimental results. Processing engineers may therefore use this model to choose the correct processing parameters and to establish cladding maps.

Simulation of Argon Gas Flow Effects in a Continuous Slab Caster

Abstract: Three-dimensional finite-volume-based numerical models of fluid, heat, and mass transport have been developed and applied to help explain the complex inter-related phenomena of multiphase fluid flow, superheat dissipation, and grade intermixing during the continuous casting of steel slabs. Gas bubbles are simulated using a continuum model, which calculates the volume fraction and velocities of the gas, and its effect on the liquid flow. Turbulence has been incorporated using the standardK-e turbulence model. Reasonable agreement has been achieved between predicted velocities and corresponding measurements and observations in full-scale water models, both with and without gas injection. The effects of argon gas bubble injection on flow-related phenomena are investigated with simulations of a typical steel slab caster. Argon bubbles alter the flow pattern in the upper recirculation zone, shifting the impingement point and recirculation zones upward. The effect increases with increasing gas fraction and decreasing bubble size. Argon injection also causes superheat to be removed higher in the caster, moves the hot spot upward, lowers the peak heat flux, and increases heat extraction from the wide face and meniscus regions. During a steel grade transition, argon injection slightly affects slab surface composition but has no effect on intermixing in the slab interior.

Estimation of the viscosities of binary metallic melts using Gibbs energies of mixing

Abstract: In the present work, information on the integral molar Gibbs energies of mixing is employed to calculate the viscosities of binary substitutional metallic melts. A correlation has been established between the second derivative of the integral molar Gibbs energy of mixing with respect to composition and the corresponding function for the Gibbs energy of activation for viscosity. The viscosities predicted from available thermodynamic data in the case of a number of binary metallic systems using this correlation show satisfactory agreement with the values reported from experimental measurements. The value of this correlation in predicting the viscosities of complex metallic melts is also examined.

A Model for Estimation of Viscosities of Complex Metallic and Ionic Melts

Abstract: In the present work, the viscosities of high-temperature melts, ionic as well as metallic, are estimated by means of a model, which is based on the absolute reaction-rate theory for the description of flow processes. The composition of ionic melts is represented in analogy with Temkin's theory. The model has been applied to some multicomponent systems. The results of the calculations illustrate that the model is successful in extrapolating the viscosity data for complex metallic and slag systems both as a function of temperature and composition.

Three-dimensional finite element modeling of gas metal-arc welding

Abstract: The modeling of the gas metal-arc (GMA) welding process in three dimensions for moving heat sources has been attempted using the finite element method. The occurrence of finger penetration in the weldment resulting from a streaming type of metal transfer at high contents is explained by assuming that the heat content of transferring droplets is distributed in a certain volume of the workpiece below the arc. Volumetric distribution of the heat content of transferring droplets has been considered as an internal heat-generation term, and the differences between penetration characteristics in two cases of globular and streaming conditions of metal transfer have been analyzed. It is shown that weld penetration depends on the depth at which the droplets distribute their energy inside the workpieces. Temperature dependence of thermophysical properties,i.e., thermal conductivity and specific heat, has been included. Latent heat is incorporated by a direct iteration method. Heat losses from the plate caused by convection and radiation are also considered. The model is validated by predicting the weld-bead dimensions and comparing them with experimental data.

Water-Modeling Study of the Surface Disturbances in Continuous Slab Caster

Abstract: The present work is based on four static molds using nozzles of different port diameter, port angle, and immersion depth. It has been observed that the meniscus is wavy. The wave amplitude shows a parabolic variation with the nozzle exit velocity. The dimensionless amplitude is found to vary linearly with the Froude number. Vortex formation and bubble entrainment by the wave occurs at the meniscus beyond a critical flow rate, depending upon the nozzle configuration, immersion depth, and the mold aspect ratio.

Modeling the thin-slab continuous-casting mold

Abstract: A three-dimensional mathematical model has been developed to compute the thermomechanical state in the mold of thin-slab continuous casters. The thin-slab mold differs from those used in conventional slab casters in that the upper portion of the broad side walls defines a funnel-shaped chamber which allows the nozzle to be submerged into the liquid metal. The chamber converges with distance down the mold, reducing to the rectangular cross section of the finished casting near the mold exit. The new mold, along with casting speeds up to 6 m/min, allows slabs to be cast 50–60 mm thick, compared with 150 to 350 mm in conventional continuous slab casting. However, the mold shape and high casting speed lead to higher mold temperatures and shorter mold life than are found in conventional slab casters. In this article, we develop mathematical models of the process to determine the role of various process parameters in determining the mold life. Finite-element analysis is used to determine the temperatures in the mold and cast slab, and these data are then used in an elastic-viscoplastic analysis to investigate the deformation of the mold wall in service. Cyclic inelastic strains up to 1.75 Pct are found in a region below the meniscus along the funnel edge. These large strains result from the combination of locally high temperatures coupled with geometric restraint of the mold. The deformation leads to short mold life because of thermal fatigue cracking of the mold. The computed locations and time to failure of the mold in fatigue agree very well with observations of the appearance of mold surface cracks in an operating caster. The models are also used to develop an improved mold design.

Thermodynamics of boron in a silicon melt

Abstract: The activity coefficient of B in a Si melt and the interaction parameters of boron and nitrogen in molten silicon were determined by equilibrating solid BN and liquid Si in a nitrogen atmosphere from 1723 to 1923 K. The standard Gibbs free energy change of the nitrogen dissolution into silicon is also obtained. The activities of BO1.5 in the CaO-CaF2-SiO2 and CaO-MgO-SiO2 systems are estimated in relation to the removal of boron from silicon by these fluxes.

Calculation of thermophysical properties of carbon and low alloyed steels for modeling of solidification processes

Abstract: Algorithms and a computer software package for calculating thermophysical material properties of carbon and low-alloyed steels, associated with the simulation of solidification processes, have been developed. The earlier studies on kinetic phase transformation modeling are applied and are the base of the present work. The calculation algorithms are based on thermodynamic theory connected to thermodynamic assessment data, as well as on regression formulas of experimental data, and they take into account the temperature, the cooling rate, and the steel composition. The calculation algorithms and some results of calculations are presented in this article.

Study of nonisothermal reduction of iron ore-coal/char composite pellet

Abstract: Cold-bonded composite pellets, consisting of iron ore fines and fines of noncoking coal or char, were prepared by steam curing at high pressure in an autoclave employing inorganic binders. Dry compressive strength ranged from 200 to 1000 N for different pellets. The pellets were heated from room temperature to 1273 K under flowing argon at two heating rates. Rates of evolution of product gases were determined from gas Chromatographie analysis, and the temperature of the sample was monitored by thermocouple as a function of time during heating. Degree of reduction, volume change, and compressive strength of the pellets upon reduction were measured subsequently. Degree of reduction ranged from 46 to 99 pct. Nonisothermal devolatilization of coal by this procedure also was carried out for comparison. It has been shown that a significant quantity (10 to 20 pct of the pellet weight) of extraneous H2O and CO2 was retained by dried pellets. This accounted for the generation of additional quantities of H2 and CO during heating. Carbon was the major reductant, but reduction by H2 also was significant. Ore-coal and ore-char composites exhibited a comparable degree of reduction. However, the former showed superior postreduction strength due to a smaller amount of swelling upon reduction.

Large-scale measurements of the physical characteristics of round vertical bubble plumes in liquids

Abstract: The hydrodynamics of air/water plumes in a large-scale model of a metallurgical ladle were investigated. The dimensions of the cylindrical vessel were 1600-mm ID and 2250-mm total height. The air was injected through a centered nozzle. Axial and radial profiles of gas concentration, bubble frequency, and liquid and gas velocities were measured using electrical resistivity probes and a propeller flowmeter. It was found that the bubble plume is not at a fixed position but wanders away from the vertical vessel axis. This causes difficulties in the measurements, and special methods have to be designed to define and deduce reproducible values for the characteristic plume quantities. In the analysis of the data, the various physical characteristics were related toz 0, the distance from the nozzle where the axial gas concentration is 50 Pct. The maximum values of the radial profiles are presented in nondimensional correlations.

Calcium deoxidation equilibrium in liquid iron

Abstract: Calcium-oxygen equilibrium was studied at 1873 K under normal pressure by the method of immersing a pure iron capsule containing calcium metal into liquid iron, which was equilibrated with CaO-Al2O3 slags in Al2O3 and CaO crucibles. On the basis of these and previous results obtained in the equilibrium experiments between liquid iron and CaO-containing slags, the equilibrium constant,K Ca, for the reaction, CaO (s) =Ca +O, and the first-order interaction parameter,e 0 Ca , were estimated. The measured value forK Ca reported in previous experiments, which was found to be significantly different from that calculated from the reliable thermodynamic data, was discussed. Nitrogen distribution ratios between CaO-Al2O3 slags and liquid iron were also measured.

Chemical equilibria between silicon and slag melts

Abstract: The equilibria between silicon and slags of the systems CaO-SiO2, Na2O-SiO2, and CaO-SiO2-Y with Y being A12O3, MgO, TiOx, B2O3, and Na2O have been investigated in silica crucibles. The calcium content under silica-saturated CaO-SiO2 slag is 262 parts per million (ppm) at 1500 °C. The aluminum and magnesium contents increase with increasing alumina or magnesium oxide contents, respectively, reaching about 1800 ppm Al at silica/mullite or about 390 ppm Mg at silica/protoenstatite saturation. Boron has a distribution ratio [B]/(B2O3) of 0.18. The sodium content under silica-saturated Na2O-SiO2 slag is 25 ppm at 1500 °C. In contrast, the titanium content of the silicon, if Y is TiOx, and (Ti) is in the percent range, is highand varies with the titanium content of the slag according to [wt Pct Ti] = 2.7 √(wt pctTi). In other experiments, it is shown that metallurgical grade (MG) silicon can be purified from aluminum, magnesium, and calcium by treatment with suitable silicate slags.

Modeling of the incorporation of ceramic participates in metallic droplets during spray atomization and coinjection

Abstract: In the present investigation, a theoretical model was developed to study the penetration behavior of ceramic particulates into metallic droplets during spray atomization and coinjection. In formulating the penetration problem, a force balance approach was adopted that considers the variations of both surface-tension resistance and fluid drag during the penetration processes. Using this model, the factors that affect the penetration behavior of ceramic particulates into Al droplets were systematically discussed. These include size, morphology, and density of ceramic paniculate; wetting angle between ceramic and liquid Al; and fraction of solid contained in the semiliquid droplets. It was found that the critical velocity required for penetration increased with increasing wetting angle and fraction of solid but decreased with increasing particulate density. The penetration ability of various ceramic particulates was compared. It was found that the penetration ability of ceramic particulates that are normally encountered in Albased metal matrix composites (MMCs) decreases in the following sequence: TiB2, Al2O3, SiC, and graphite.

Modeling of metallurgical emulsions

Abstract: Emulsification behavior caused by gas bubbles rising through a slag/metal interface has been studied in both a thin-slice model and a three-dimensional model using low-temperature oil/aqueous and oil/mercury analogues. A generalized model characterizing the transitional volume of droplets entrained in the upper phase in the emulsification process was developed. The transient volume of “metal” entrained,V d(t), following the start of bubbling followed the relationV d(t) =V ∞(1 −e (t/Τ)). This model is also of general significance to other metallurgical emulsification processes, such as those induced by iron ore reduction and top blowing, regardless of the mechanisms of droplet generation. Based on this model, the birth rate and mean residence time of droplets dispersed by rising bubbles can be quantified. Dimensional analysis was used to express the volume of lower liquid carried up into the emulsionper bubble, thereby allowing better estimates of the droplet birth rate in a practical emulsification process induced by bottom blowing. Emulsification behaviors in industrial in-bath smelting processes were interpreted with the present modeling results.

The effect of steel chemistry on the formation of Fe-Zn intermetallic compounds of galvanneal-coated steel sheets

Abstract: The effects of steel chemistry on the formation of Fe-Zn intermetallic compounds in the galvanneal coatings have been investigated by examining the microstructure of galvanneal coat-ings on extra-low-carbon (ELC) steel, interstitial-free (IF) steel, and interstitial-free rephos-phorized (IFP) steel. The layer structure of the coatings was revealed by chemical etching. Phases present in each layer were then identified using electron diffraction in transmission elec-tron microscopy (TEM). A two-layer structure, one consisting of the δ phase with a small fraction of the ζ, phase dispersed on the surface and Γ phases and another consisting of the δ and Γ1 phases, was observed in the ELC sample and the IFP sample, respectively. A three-layer structure consisting of the δ, Γ1 + δ, and Γ phases was observed in the IF sample. The presence of C in the steel substrate retarded the alloying between Fe and Zn; while P in the steel favored the formation of the Γ1, phase over the Γ phase by its surface segregation in the steel substrate. The orientation relationship between coating and substrate was also studied by electron diffraction. Three α-Fe/Γ orientation relationships were frequently observed.

On the formation of pipes and centerline segregates in continuously cast billets

Abstract: Centerline macrosegregation in continuously cast steel billets, blooms, and slabs is a significant problem. Thermal contraction of the solidified shell at the final end of the liquid pool causes a separation in the central portion of the strand and formation of a pore. When this pore fills with liquid, centerline macrosegregation results. Segregation formation is influenced by the cooling and casting conditions. The effects of those parameters are discussed in this article. Thermal contraction also causes formation of a large pipe in the very last portion of the strand. The casting parameters that control the centerline macrosegregation also control the size of the pipe.

An electrochemical study on the dissolution of gold and copper from gold/copper alloys

Abstract: The dissolution behavior of gold and copper from their elemental states and from gold/copper alloys in cyanide solutions has been investigated using a rotating-disc electrode. The anodic and cathodic reactions were studied separately, and the resulting polarization curves were combined to examine the overall dissolution reactions. The dissolution rate of pure gold in the aerated cyanide solutions was inhibited by the anodic passivation on the gold surface, whereas the dissolution rate of pure copper was found to be mass-transfer controlled. On the other hand, the dissolution of gold and copper from the alloys was partially controlled by electrochemical reaction and largely by mass transfer.

Thermodynamics and phase relations of the Fe-O-S-Si2(sat) system at 1200 °C and the effect of copper

Abstract: A laboratory investigation was carried out in which iron was reacted in silica crucibles with an atmosphere of controlled oxygen and sulfur partial pressures The equilibrium compositions of the melts were determined over the range 10−12 to 10−9 atm oxygen and 10−275 to 10−1 atm sulfur and it was found that the Fe-O-S-SiO2 system can exist as either a slag or oxysulfide The oxysulfide contained appreciable quantities of dissolved oxygen and silica, although the levels decreased as the sulfur content was increased Sulfur also had the effect of reducing the solubility of silica in the slag When copper was added to the system, the solubility of oxygen and silica in the oxysulfide phase decreased dramatically The results are examined in terms of the thermodynamics of the relevant reactions, and the predominance area diagram for the copper-free system was established by combining the present results with those of earlier investigations

Kinetics of the reaction of H2O gas with liquid iron

Abstract: The rate of the decarburization of carbon-saturated liquid iron by H20 gas between 1673 and 1873 K has been studied under conditions in which the effect of mass transfer is negligible, or a reasonable correction for its effect can be made. The rate was measured for water vapor pressures in the range 0.002 to 0.3 atm and sulfur contents in the metal from 0.005 to 0.5 mass of H20 on the surface. Sulfur was found to significantly decrease the rate, and the residual rate phenomenon was observed at high sulfur content. The rate constant for the dissociation of H20 on liquid iron is given by $$k = \frac{{k^\circ }}{{1 + K_s a_s }} + k_r $$

Vanadium distribution in melts intermediate to ferroalloy production from vanadiferous slag

Abstract: Processing of vanadiferous slags through the pyrometallurgical process route appears to offer advantages both in terms of ferroalloy production and in the potential for efficient vanadium recovery from hot metal. In order to investigate the effect of slag composition on the phase distribution of vanadium, a series of laboratory smelting experiments was carried out. The effect of basicity adjustments on the slag/metal distribution of iron, vanadium, and manganese was investigated using carbon and FeSi as a reductant. A simulation of the final stage of slag reduction was also carried out to determine the efficiency of vanadium recovery during metallothermic smelting using aluminum and FeSi.

Thermodynamic simulation model of the isasmelt process for copper matte

Abstract: A computer model has been constructed to simulate thermodynamically the behavior of the minor elements Zn, Pb, As, Sb, and Bi as well as the major elements Cu, Fe, Si, O, and S in the Isasmelt process, producing copper matte. The model is based on the new concept that there are two independent reaction sites in a slag bath: one for fast oxidation and the other for slow reduction. The oxidizing reaction at the first site produces matte, magnetite-rich slag and gas from chalcopyritic concentrate and siliceous flux. The slag is then partially reduced with lump coal at a site removed from the first site. The oxidizing and reducing reactions are assumed to proceed under a separate set of equilibrium conditions. The process heat balance and thermodynamic distribution of the minor elements are united and expressed as functions of varying weights and compositions of concentrate, flux (silica, limestone), coal, oil, and oxygen-enriched air. The process chemistry was analyzed in terms of Fe3O4, FeO, and FeS activities, as well as SO2 partial pressure. The thermodynamic model explains well the minor element distributions observed in the 15 tons per hour pilot furnace, and it is used to project the optimal smelting conditions for the full-scale 100 tons per hour Isasmelt furnace.

Processing, microstructure, and properties of laser-clad Ni alloy FP-5 on Al alloy AA333

Abstract: This article describes the results of laser cladding Ni alloy FP-5 on Al alloy AA333, microstructure and crystal structure characterization, and properties of the clad evaluated by Vickers hardness measurement and wear testing. Direct cladding of Ni alloy on Al alloy creates brittle Ni x Al y compounds in the interface, which make the interface very brittle, and result in cracking at the interface. The compound formation is avoided by introducing an intermediate layer of Cu or bronze. The cracking tendency of the clad is prevented by preheating the substrate to 673 K. The microstructure and crystal structure of the clad and interface are investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Five phases in the clad layer (including three new phases) and two phases in the interface are identified by convergent beam electron diffraction (CBED) and selected area diffraction (SAD) studies. The mechanical properties of the laser-clad Ni alloy are evaluated by Vickers hardness measurements and wear testing, which show superior results over Cu- and Fe-based alloys.

Investigation of the Kinetics of Reduction of Nickel Tungstate by Hydrogen

Abstract: In the present work, the kinetics of reduction of nickel tungstate, NiWO4, by hydrogen was investigated by a thermogravimetric method in the temperature range 891 to 1141 K. The experiments were conducted under both isothermal and nonisothermal conditions. The products were examined by X-ray diffraction analysis. The results indicate that the reduction reaction proceeds in two steps; first, reduction of NiWO4 to nickel as well as WO2 and then WO2 to tungsten. From the isothermal experiments, the activation energies of the two reaction steps were calculated to be 95.3 ± 4.9 and 80.8 ± 6.4 kJ · mol−1, respectively. The activation energy value obtained from nonisothermal experiments for the first step is in agreement with the isothermal experiments. The values are compared with the activation energies reported in other literature for the individual oxides.

laser cladding of Ni-Al bronze on Al alloy AA333

Abstract: The present study investigates the effects of laser-processing parameters, such as laser power, traverse speed, powder-feed rate, and flow rate and species of assisting gas, and material prop-erties, such as substrate surface condition, on laser cladding of Ni-Al bronze on Al alloy AA333. The proper processing parameters were determined experimentally and are discussed in terms of their effects on laser-clad quality and microstructure as observed using optical and scanning electron microscopes. Despite a large difference in melting points between the cladding material, Ni-AI bronze (MP = 1063 °C), and the substrate, Al-alloy AA333 (MP = 577 °C), clads of thickness from 1.2 to 2.5 mm that are crack-free and had good fusion were achieved. The substrate surface condition and the flow rate and species of assisting gas were found to be important for clad formation. A sandpaper-polished substrate absorbs less energy at the molten pool front and facilities reducing dilution. A large flow rate of assisting gas, such as helium, also has an effect on reducing dilution. A laser-generated molten-pool model was developed to explain the preceding experimental results.

Standard enthalpies of formation of some praseodymium alloys by high-temperature direct synthesis calorimetry

Abstract: The standard enthalpies of formation of eight Pr alloys were determined by direct synthesis calorimetry at 1473 ± 2 K. The following values of ΔHskƒ/°(kJ/g atom) are reported: PrNi5, −(25.6 ± 1.0); PrRu2, −(16.9 ± 1.5); PrRh2, −(60.4 ± 1.7); PrPd, −(78.8 ± 2.5); PrPd2, −(82.7 ± 3.1); PrIr2, −(70.7 ± 2.8); PrPt, −(103.4 ± 2.7); and PrPt2, − (93.5 ± 2.4). The results are compared with data from available literature for some of the Pr alloys and with predicted values from the model of Miedemaet al.

A comparison of three mathematical modeling procedures for simulating fluid flow phenomena in bubble-stirred ladles

Abstract: tribution between a FeS-Na2S flux and carbon-saturated liquid iron above 1200 ~ These researchers found that the distribution ratio increased with increasing FeS content in the matte and reached maximum at around FeS/ Na2S = 82/18. This trend is based on the fact that the activity of FeS in the matte increases significantly with increasing FeS content while the Ycu2s slightly increases. The temperature range of the present work is much lower than the preceding studies; however, the increase in equilibrium Cu2S content with increasing FeS content in the matte at a given temperature is similar to that of previous studies, lsl Reaction between copper and an FeS-NazS matte results in a high equilibrium Cu2S content which increases with temperature and starting FeS content. For a matte which has a starting composition of 82 wt pet FeS and 18 wt pet Na2S, the equilibrium concentration of CuzS is 52 wt pet at 1000 ~

Thermal separation of arsenic and antimony oxides

Abstract: Experiments were carried out to remove arsenic from antimony trioxide by two techniques: first, by selectively volatilizing the more volatile arsenic trioxide from a mixed oxide sample; and, second, by selectively condensing the less volatile antimony tetroxide at high temperatures, leaving arsenic trioxide to condense out at a lower temperature. Thermodynamic analysis of the As-Sb-O system indicated that if arsenic and antimony oxides behave like pure solid phases, then there is no limitation to producing pure antimony oxide by these proposed techniques. The selective volatilization experiments were carried out at 379 °C to 587 °C, using both nitrogen and air as carrier gases and an industrial antimony trioxide fume containing 13.8 wt pct As. The results showed it is difficult to achieve an arsenic content below 5.0 wt pct using either air or nitrogen, and formation of solid solutions between arsenic and antimony trioxides appears to be the main barrier to the removal of arsenic. Selective condensation experiments were carried out in which a mixed oxide vapor was progressively cooled through a series of condensers over a controlled temperature profile. Injection of oxygen into the vapor improved separation, and antimony tetroxide containing as low as 0.23 wt pct As was obtained. The recovery of antimony tetroxide in the experiments seems to have been limited by kinetic factors, and the results sug-gest that high conversions to antimony tetroxide are likely to be achieved only in antimony-rich vapors.

Activities of Fe t O in CaO-Al 2 O 3 -SiO 2 -Fe t O (<5 pct) slags saturated with liquid iron

Abstract: The activity coefficients of FetO in CaO-Al2O3 and CaO-Al2O3-SiO2 slags with 0.01 to 5 mass pct FetO were determined at 1873 K from the data obtained in the present and previous slag-metal experiments, using an alumina or lime crucible. It was found that the activity coefficients of FetO obeyed a dilute solution law and increased with increasing the content of SiO2. Based on the findings pertaining to the activity coefficient, the values for the activities of SiO2 and Al2O3 in CaO-Al2O3-SiO2 slags were assessed.

Thermodynamics of O, N, and S in liquid Fe equilibrated with CaO-AI2O3-MgO slags

Abstract: Nitrogen and S distribution ratios between CaO-Al2O3-MgO slags and liquid Fe were measured at 1873 K as a function of Al (or Mg, Ca) content in metal, using CaO, MgO, and A12O3 crucibles. Based on the results for the solubility product of MgO, the equilibrium constant,K Mg , for the reaction MgO =Mg +O and the first-order interaction parameter,e O Mg (e Mg O ), were estimated to be logK Mg = -7.8 ± 0.2 ande O Mg = -190 ± 60 (e Mg O = -290 ± 90), respectively. The activities of A12O3 at the slag compositions double-saturated with CaO/MgO, MgO/ MgO A12O3, and MgO Al2O3/CaO 2A12O3 components were obtained from the S distribution ratios between slag and metal, coupled with the reported values of sulfide capacities. Nitride capacities were also estimated from the N distribution ratios and the activities of A12O3.