Showing papers in "Isij International in 1996"
TL;DR: In this paper, the philosophy of the development and the resulting properties of a new austenitic stainless steel was presented, which contains 15-18% chromium, 3-6% molybdenum, 10-12% manganese, and 0.9% nitrogen.
Abstract: The paper presents the philosophy of the development and the resulting properties of a new austenitic stainless steel. The steel contains 15-18% chromium, 3-6% molybdenum, 10-12% manganese, and about 0.9% nitrogen. The most important feature of this steel is the complete absence of nickel as alloying element. The austenitic microstructure is obtained exclusively by adding nitrogen. Besides being nickel free, the steel is further characterized by an excellent corrosion resistance, the absence of ferromagnetism, and outstanding mechanical properties. The unique combination of these properties makes this steel most interesting for its use in items which are in direct contact with the human body. By using these new steels, nickel allergy can be prevented.
231 citations
TL;DR: In this article, the relations among the compositions of inclusion, steel and top slag were thermodynamically studied at 1823 K in tire cord, valve spring, ultra low carbon sheet, bearing and sulfur free-machining steels.
Abstract: The relations among the compositions of inclusion, steel and top slag were thermodynamically studied at 1823 K in tire cord, valve spring, ultra low carbon sheet, bearing and sulfur free-machining steels. In case of a tire cord and valve spring steels, the equilibrium among inclusion, steel and top slag was found to be established in practice with respect to Si and Mn. The contents of Si, O and Ca in an ultra low carbon sheet steel were determined as a functin of top slag composition, and the higher oxygen contents observed in practice were explained by the effect of FetO in slag. Themodynamic discussion was made for the formation of spinel inclusions in a bearing steel and the precipitation of CaS in a sulfur free-machining steel.
215 citations
TL;DR: New nickel-free CrMnMo austenites with up to 1% nitrogen developed by VSG exhibit properties which correspond particularly well to medical engineering requirements as mentioned in this paper, such as strength, toughness, corrosion resistance, wear resistance and cost efficiency.
Abstract: New nickel-free CrMnMo austenites with up to 1% nitrogen developed by VSG exhibit properties which correspond particularly well to medical engineering requirements. The combination of strength, toughness, corrosion resistance, wear resistance and cost-efficiency which these alloys display is not attained by any other material.
169 citations
TL;DR: In this paper, the effect of B on microstructure and toughness at the heat affected zone after welding thermal cycle simulations has been investigated in steels containing titanium oxide particles, which contribute to preferential nucleation of MnS and TiN precipitates on Ti2O3.
Abstract: The effect of B on microstructure and toughness at the heat affected zone after welding thermal cycle simulations has been investigated in steels containing titanium oxide particles. The titanium oxide is identified as Ti2O3 with cation vacancies, which contribute to preferential nucleation of MnS and TiN precipitates on Ti2O3. The Mn-depleted zone is formed around Ti2O3 after the precipitation of MnS. The Ti2O3, particles with TiN and Mn-depleted zone act as preferential nulceation sites for intra-granular ferrite. The segregation of B at austenite grain boundaries suppresses effectively the nucleation of grain boundary ferrite. Ferrite nucleation at the interface between Ti2O3 and austenite matrix is not affected by B addition because of B-depleted zone arisen from the diffusion of segregated B into Ti2O3 via cation vacancies. Consequently the B addition to steels with Ti2O3 promotes the formation of fine intra-granular ferrite grains so that the toughness in heat affected zone is improved even after large heat input welding.
157 citations
TL;DR: In this article, a combined model is used to analyze the residence time distribution of fluid in a tundish, where the fluid volume is considered to be consisting of the plug flow, well-mixed flow, and dead volumes.
Abstract: Melt flow in continuous casting tundishes is normally characterized by a combined model. The model is used to analyze the residence time distribution of fluid in a tundish. In this model, the fluid volume in tundish is considered to be consisting of the plug flow, well-mixed flow, and dead volumes. Although this model was proposed over 20 years ago, most researchers have either used it incorrectly or made an assumption in analyzing melt flow in tundishes. Both approaches may lead to incorrect and misleading calculations of the dead volume. In this paper, the combined model has been discussed and its correct application to tundish melt flow has been outlined.
152 citations
TL;DR: In this article, the possible role of N in the steps of pitting, initiation, growth and possible repassivation are discussed, and most important appears the favorable effect on passivation and repagnivation, which is effective also for Fe-N alloys.
Abstract: The beneficial effect of nitrogen in steels in resistance against localized corrosion, pitting and crevice corrosion is well proven, but not yet fully understood. The results on dissolution of nitrogen steels in acids are controversial, but the dissolution of Fe-N alloys is enhanced compared to pure iron. Many surface analytical studies have been conducted in the recent years to find out about the state of nitrogen, and mainly the presence of Nδ– in the metal surface and NH3 or NH4+ in the passive layer are well established, and moreover, NH4+ is the species transferred into the electrolyte in a wide range of potentials. Formation of NH4+ will somewhat buffer the acidification in pits. The possible role of N in the steps of pitting, initiation, growth and possible repassivation are discussed, and most important appears the favourable effect on passivation and repassivation, which is effective also for Fe-N alloys. Many authors assume formation of stable Cr- and Mo-nitrides in the steel surface upon dissolution, and retardation of pit growth by these nitrides, however, this mechanism would not apply for Fe-M alloys. Desorption of the aggressive anions induced by the segregated Nδ– just after the local failure of the passive layer is proposed to be the mechanism by which nitrogen favours the rapid repassivation of pits.
142 citations
TL;DR: In this article, the role of Mn depletion at the interface of MnS and ferrite matrix was investigated to elucidate the mechanism of intra-granular ferrite transformation in the Heat Affected Zone (HAZ) of welded joints.
Abstract: Intra-Granular Ferrite (IGF) transformation in the Heat Affected Zone (HAZ) of welded joints has been practically applied in structural steels, but the mechanism of IGF nucleation has not been elucidated yet. Then, the role of Mn depletion was investigated to elucidate the mechanism of IGF nucleation. It was first demonstrated to prove the direct evidence of Mn depletion at the interface of MnS/ferrite matrix by the nano-probe analysis of Field-Emission Transmission Electron Microscope equipped with Energy Dispersive X-ray Spectroscopy (FE-TEM-EDS). The presence of Mn depletion is also believed to promote IGF nucleation at the interface of MnS newly precipitated on (Mn, Si) oxide, which is considered to have no coherency with ferrite matrix.
127 citations
119 citations
TL;DR: In this paper, a new model, which was considered from the viewpoint of the accommodation mechanism by an accommodatin helper such as a liquid or glassy phase, was proposed in which superplasticity was critically controlled by the accommodation helper both to relax the stress concentration resulting from sliding at grain boundaries and/or interfaces and to limit the build up of internal cavitation and subsequent failure.
Abstract: High-strain-rate superplasticity (i.e., superplastic behavior at strain rates over 10-2s-1) has been observed in many meterials such as aluminum alloys and their matrix composites and it is associated with an ultra-fine grained stucture of less than about 3 μm. Its deformation mechanism appears to be different from that in conventional superplastic materials. Experimental investigations showed that a maximum elongation was attained at a temperature close to the partial melting temperature in many superplastic materials exhibiting high-strain-rate superplasticity. Recently, a new model, which was considered from the viewpoint of the accommodation mechanism by an accommodatin helper such as a liquid or glassy phase, was proposed in which superplasticity was critically controlled by the accommodation helper both to relax the stress concentration resulting from the sliding at grain boundaries and/or interfaces and to limit the build up of internal cavitation and subsequent failure. The critical conditions of the quantity and distribution of a liquid phase for optimizing superplastic deformation was discussed and then applied to consider the possibility of attaining high-strain-rate superplasticity in ceramic materials.
114 citations
TL;DR: A short review of beneficial effects of nitrogen in steel is given including mechanical and corrosion properties, and the data of interatomic interactions and distribution of solute atoms in solid solutions are discussed with the aim of explanation of the physical nature of nitrogen steels as mentioned in this paper.
Abstract: A short review of beneficial effects of nitrogen in steel is given including mechanical and corrosion properties, and the data of interatomic interactions and distribution of solute atoms in solid solutions are discussed with the aim of explanation of the physical nature of nitrogen steels. The concept is presented according to which aloying by nitrogen enhances the metallic component of interatomic bonds and provides more homogeneous distribution of substitutional solutes through short range ordering of nitrogen atoms and strong chemical interaction between nitrogen and alloying elements, which results in the high thermodynamical stability of nitrogen austenitic steels. The opposite tendency to clustering and concentration inhomogeneity of austenitic steels due to carbon is shown. Inheritance of the atomic distribution by martensite is discussed in terms of short range atomic order and data on crystal structure of precipitations during tempering of nitrogen martensite are presented as compared to carbon and carbon+nitrogen martensites.
108 citations
TL;DR: In this article, an analysis of the pass-by-pass evoution of austenite grain size during the rod rolling of plain carbon steel was conducted by organizing previously developed equations relating grain size and hot working parameters into a commercial computer spreadsheet program.
Abstract: An analysis was conducted of the pass-by-pass evoution of austenite grain size during the rod rolling of plain carbon steel. This was achieved by organizing previously-developed equations relating grain size and hot working parameters into a commercial computer spreadsheet program. By considering the substantial "redundant" strains developed during rod rolling, the analysis reveals that metadynamic recrystallization (MRX) is the dominant microstructural process, and this is confirmed by the mill grain size measurements reported previously. The spreadsheet was also employed to examine the effects of modifications to rod rolling practice aimed at refining the austenite grain size. Little benefit is obtained by increasing the strain rate or by reducing the distance from the final rolling pass to the laying head. On the other hand, increasing the cooling rate on the forced-air cooling deck should lead to measurable grain refinement. Lowering the temperature during rolling can lead to even more refinement, and various strategies to achieve this are discussed.
TL;DR: In this paper, the effect of S content n the MnS precipitation with various kinds of oxide nuclei was investigated. And the average diameter of MnS, calculated by using a mathematical model considering the oxide nucleis with changing the precipitation ratio according to S content and to the kind of oxides, agrees well with the experimental data.
Abstract: Manganese sulphide formation experiments were carried out by deoxidizing with various elements and by changing S content to clarify the effect of S content n the MnS precipitation with various kinds of oxide nuclei. The behabvior of MnS precipitation on oxide particles in the steel with 1 mass% of Mn was characterized according to S content. When S content was below 100 ppm, a lot of MnS precipitated only on some kinds of oxide. It is effective to use an oxide having high sulphide capacity and low melting temperature for uniform dispersion of fine MnS. On the other hand, when S was above 100 ppm, almost all the oxides worked as the precipitation sites of MnS. In that case, for the MnS dispersion, it is better to select the oxide which tends to disperse finely itself in steel. The average diameter of MnS, calculated by using a mathematical model considering the oxide nuclei with changing the precipitation ratio according to S content and to the kind of oxides, agrees well with the experimental data.
TL;DR: The number of ferrite particles per unit area of bonded interfaces was measured using Schwartz-Saltykov method and was compared with the number of particles formed at grain boundaries as discussed by the authors.
Abstract: Pure polycrystal ceramics (TiC, TiN, TiO, VN, AIN and Al2O3) were heat-pressure-bonded to an Fe-0.1 mass%C-2 mass%Mn alloy and were isothermally reacted below the Ae3 temperature for the proeutectoid ferrite reaction to occur. The number of ferrite particles per unit area of bonded interfaces was measured using Schwartz-Saltykov method and was compared with the number of particles formed at grain boundaries. VN was most effective in stimulating ferrite nucleation whereas TiO was least effective. All other ceramics showed more or less similar potencies for ferrite formation. VN is capable of forming lower energy interfaces with ferrite than other ceramics, through the possibility of V diffusion into the alloy during and after bonding may not be ruled out in this experiment. On the other hand, the least effectiveness of TiO in stimulating ferrite nucleation is possibly due to the proximity of thermal expansion coefficient to iron.
TL;DR: In this paper, the logs for plan C-Mn grades form four different hot strip mills were analyzed in order to calculate the mean flow stress developed at each stand, taking work roll flattening, redundant strain, and the forward slip ratio account.
Abstract: The logs for plan C-Mn grades form four different hot strip mills were analyzed in order to calculate the mean flow stress developed at each stand. The calculation, based on Sim's equations, takes work roll flattening, redundant strain, and the forward slip ratio account. The stresses are compared with the predictions of a model based on an improved Misaka mean flow stress equation in which strain accumulation as well as the kinetics of static and dynamic recrystallization are fully accounted for. A good fit is observed between the model predictions and the mill data, with agreement generally falling within the interval ±15%.
TL;DR: In this paper, the newly established technique of stress relaxation has been applied to measure the kinetics of static and metadynamic recrystallization of austenite in a low-carbon steel subsequent to compression executed at a strain rate of 0.1 or 0.01 s-1 at 900°C or 1000°C.
Abstract: The newly established technique of stress relaxation has been applied to measure the kinetics of static and metadynamic recrystallization of austenite in a low-carbon steel subsequent to compression executed at a strain rate of 0.1 or 0.01 s–1 at 900°C or 1000°C. The characteristics of static recrystallization were found to be consistent with those previously reported from double-stage deformation tests. Metadynamic recrystallization, contrary to static one, showed no dependence on strain and hardly any on temperature, but significant dependence on strain rate. The Avrami exponents were almost identical for the two processes, about 1.5-1.6 at 0.1 s–1 but decreased to 1.0-1.3 at 0.01 s–1. Metadynamic recrystallization resulted in complete softening except when relaxed after compression to a strain of 0.3 or beyond at a low strain rate of 0.01 s–1 The law of mixtures approach was found to be more accurate than the uniform softening model to describe recrystallization in partially recrystallized and subsequently deformed austenite. The results confirm the feasibility of the stress relaxation technique as an efficient method for investigating recrystallization kinetics in hot-deformed austenite.
TL;DR: In this paper, the use of thermodynamic data in describing calcium modification of aluminium oxide inclusions has been summarised and reviewed, using ThermoCalc, the activities of CaO and Al2O3 have been calculated and compared to the published data.
Abstract: The use of thermodynamic data in describing calcium modification of aluminium oxide inclusions has been summarised and reviewed. The majority of the published Al-S equilibrium diagrams, based on the following reaction:3CaO+3S+2Al=3CaS+Al2O3, vary significantly due to different sources for thermodynamic data, especially for the activity of CaO and Al2O3. Using ThermoCalc, the activities of CaO and Al2O3 have been calculated and compared to the published data. Calculations in the present work pertaining to the molten range of the system are in good agreement with the most recently published experimental data of Fujisawa et al.Based on the assessed thermodynamic data and observed phenomena during calcium modification of inclusions in steel melts of moderate sulphur content, a model for alumina modification by calcium treatment has been developed. According to the model, the reactions progress by the following sequence until the activity of Al2O3 becomes so low that precipitation of CaS occurs:Al2O3⇒CA6⇒CA2⇒CA⇒CAx(liquid)
TL;DR: The deformed structure of cold rolled IF steels consists of a large number of α fibre and γ fibre oriented grains and a small number of (110) oriented grains, each with a distinctive grain shape, subgrain structure, hardness and etching appearance.
Abstract: The deformed structure of cold rolled IF steels consists of a large number of α fibre and γ fibre oriented grains and a small number of (110) oriented grains, each with a distinctive grain shape, subgrain structure, hardness and etching appearance. Early nucleation occurs mainly in γ fibre grains and (110) grains. The texture of the early nuclei consists of a γ fibre with a spread towards (221) together with a weak // ND fibre. Numerous nuclei develop within a single deformed grain. α fibre grains are consumed only after 70% of the materials is recrystallised.
TL;DR: In this article, the fatigue crack growth rate of nickel base superalloys has been modelled using a neural network model within a Bayesian framework and a committee' model was also introduced to increase the accuracy of the predictions.
Abstract: The fatigue crack growth rate of nickel base superalloys has been modelled using a neural network model within a Bayesian framework. A committee' model was also introduced to increase the accuracy of the predictions. The rate was modelled as a function of some 51 variables, including stress intensity range ΔK, log ΔK, chemical composition, temperature, grain size, heat treatment, frequency, load waveform, atmosphere, R-ratio, the distinction between short crack growth and long crack growth, sample thickness and yield strength. The Bayesian method puts error bars on the predicted value of the rate and allows the significance of each individual factor to be estimated. In addition, it was possible to estimate the isolated effect of particular variables such as the grain size, which cannot in practice be varied independently. This demonstrates the ability of the method to investigate new phenomena in cases where the information cannot be accessed experimentally.
TL;DR: In this article, the effects of carbon and sulfur on the longitudinal surface cracks have been investigated by calculating the non-equilibrium pseudo binary Fe-C phase diagram and introducing the strain in brittle temperature range for continuous casting of steels.
Abstract: Effects of carbon and sulfur on the longitudinal surface cracks have been investigated by calculating the non-equilibrium pseudo binary Fe-C phase diagram and introducing the strain in brittle temperature range for continuous casting of steels. The cracking tendency as a function of carbon content was well described by the strain in brittle temperature range. The strain in brittle temperature range was influenced by the other solute elements as well as carbon. The carbon content at which longitudinal surface cracking is maximized decreased with increasing sulfur content. At a given carbon content, the possibility of surface cracking increased with increasing sulfur content.
TL;DR: The introduction of nitrogen by alloying, pressure metallurgy, powder metallomics and solid state diffusion is briefly reviewed in this paper, where examples of martensitic, austenitic, duplex and dual phase HNS are given and applicaions already realized or tentative ones are presented.
Abstract: The introduction of nitrogen by alloying, pressure metallurgy, powder metallurgy and solid state diffusion is briefly reviewed. Examples of martensitic, austenitic, duplex and dual phase HNS are given and applicaions already realized or tentative ones are presented.
TL;DR: In this paper, a mathematical model has been developed to determine the optimum bubble size for the removal of inclusions from molten metals by flotation, where the probability of collision between a bubble and an inclusion, PC, and probability of adhesion of an inclusion to a bubble by sliding, PA, are defined to describe the efficiency of inclusion attachment.
Abstract: A mathematical model has been developed to determine the optimum bubble size for the removal of inclusions from molten metals by flotation. The probability of collision between a bubble and an inclusion, PC, and the probability of adhesion of an inclusion to a bubble by sliding, PA, are defined to describe the efficiency of inclusion attachment to a bubble. The results show that small bubbles have a high PC, while small inclusions have a high PA and low PC. By considering the overall probability, P (=PC×PA), and the floating time of the bubble, the model suggests that the optimum bubble sizes for the removal from steel of alumina inclusions less than 50 μm in size are in the range of 0.5 to 2 mm in diameter.
TL;DR: In this paper, a three-phase model of a gas-stirred steel bath covered with a slag layer has been developed, and the predicted steel surface velocities have been shown to be in at least five times greater agreement with the predicted velo-graphs.
Abstract: A three-phase model of a gas-stirred steel bath covered with a slag layer has been developed. Predicted steel surface velocities have been shown to be in at least five times greater agreement with ...
TL;DR: In this paper, the effect of varying the initial grain size from 12 to 83 μm on the static recrystallization kinetics of a 0.08%C-0.055%Nb steel was investigated at 950°C by means of interrupted hot compression tests; the results obtained in this way were analyzed using three different methods for assessing the fractional softening.
Abstract: The static recrystallization kinetics of a 0.08%C-0.055%Nb steel were investigated at 950°C by means of interrupted hot compression tests; the results obtained in this way were analyzed using three different methods for assessing the fractional softening. In particular, the effect was studied of varying the initial grain size from 12 to 83 μm. The exponent relating initial grain size to the time for 50% recrystallization was found to be about 1.7. This is somewhat less than the exponent of 2.0 conventionally employed for plain C-Mn steels, and which is often quoted in the literature as applicable to Nb grades. In addition, by means of comparison with previous work on grades with lower levels of Nb and Mn, it is shown that higher levels of Mn make significant contributions to the retardation of static recrystallization in Nb steels.
TL;DR: In this paper, a procedure and appropriate criteria for water modeling of flow and inclusion flotation and removal are outlined, and the choice of model inclusion to water density and the model inclusion size needed for proper simulation of a given inclusion size in molten steel are discussed.
Abstract: Water modeling of tundish melt flows offers useful insight into the underlying flow phenomena occurring in the tundish. Most of the water modeling studies have been carried out under isothermal conditions with water at room temperature, and have employed full as well as reduced scale models. In water modeling, a reduced scale model can not simultaneously satisfy the Reynolds as well as Froude similarity criteria. Many industrial modeling studies have employed full scale models while many university researchers have used small scale models based on the Froude similarity criterion. This paper discusses the importance and validity of these criteria. For simulation of inclusion flotation in water models, gravitational force becomes important. The choice of model inclusion to water density and the model inclusion size needed for proper simulation of a given inclusion size in molten steel are discussed. A criterion for quantitative determination of inclusion agglomeration in the water model is also suggested. Thus, a procedure and appropriate criteria for water modeling of flow and inclusion flotation and removal are outlined.
TL;DR: Using torsion tests and applying the back extrapolation method, a study has been made of the influence on static recrystallization kinetics of the most common elements (C, Si, Mn, Mo) in low alloy steels as mentioned in this paper.
Abstract: Using torsion tests and applying the back extrapolation method, a study has been made of the influence on static recrystallization kinetics of the most common elements (C, Si, Mn, Mo) in low alloy steels and the most common elements (Ti, V, Nb) in microalloyed steels. In the latter case, this influence is studied only at the temperatures at which these elements are in solution, except for Titanium which was partially precipitated in the form of nitrides. Activation energy is the parameter most sensitive to variations in the chemical composition and an expression has been determined to predict its value as a function of the content of each alloying element. Of the different non precipitate-forming alloys sillicon is shown to be the element which most delays recrystallization. Carbon and vanadium in solution have no influence on recrystallization kinetics. It is demonstrated that Nb is the microalloying element which most delays recrystallization.
TL;DR: In this article, continuous cooling transformation diagrams are determined for microalloyed steels containing Ti, Nb, Mn and Mo in undeformed as well as in thermomechanically processed conditions using dilatometry.
Abstract: Continuous cooling transformation diagrams are determined for microalloyed steels containing Ti, Nb, Mn and Mo in undeformed as well as in thermomechanically processed conditions using dilatometry. Effects of thermomechanical processing, cooling rate and Nb content on γ/α transformation kinetics are presented. Thermomechanical processing is found to accelerate the onset of γ/α transformation (γ transformation start temperature, Ar3, is raised). However, the progress of γ/α transformation is retarded considerably in deformed samples. Increase in cooling rate lowers Ar3 significantly and accelerates the progress of transformation. Nb lowers Ar3 undeformed austenite but raises Ar3 of thermomechanically processed austenite.
TL;DR: The equilibrium experiments between CaO-Al2O3-MgO-MnO-0.5 to 2.3%S (mass content in %) slag and liquid iron were carried out at 1823 and 1873 K in order to assess the activities of Al 2O3 and MgO along the spinel saturation line as discussed by the authors.
Abstract: The equilibrium experiments between CaO-Al2O3-MgO-0.06 to 0.85%MnO-0.5 to 2.1%FetO-0.07 to 0.3%S (mass content in %) slag and liquid iron were carried out at 1823 and 1873 K in order to assess the activities of Al2O3 and MgO along the spinel (MgO·Al2O3) saturation line. The activities of CaO in an entire liquid region were first determined at 1823 and 1873 K from the reported values for sulfide capacity, coupled with the activity coefficients of CaS which were estimated from those in the CaO-Al2O3 slags. On the basis of these iso-activity lines for CaO, the activities of Al2O3 and MgO were calculated by using he method of Schuhmann, in which the assessed activities of Al2O3 and MgO on the spinel saturation line were taken as the starting points. The activity coefficients of FetO and MnO along the spinel saturation line were determined and the deoxidation equilibria of Al, Mg, and Ca were discussed.
TL;DR: In this paper, a mathematical model of the kinetics considering the evaporation of calcium and the reaction between inclusions and melt was developed to thoroughly examine these phenomena in calcium treatment.
Abstract: A major objective of calcium treatment in steelmaking is to improve product performance through inclusion modification. To establish inclusion modification, shape and composition of inclusions were monitored using SEM during and after addition of calcium wire into 2 kg heats of steel under various conditions of Ca consumption and Ca addition pattern. A mathematical model of the kinetics considering the evaporation of calcium and the reaction between inclusions and melt was developed to thoroughly examine these phenomena in calcium treatment. The calculated results were compared with the observed ones which were obtained in experiments.(1) Shape and composition of inclusions changed from a spherical SiO2-MnO system to almost lumpy Al2O3 with the addition of aluminum, and to spherical CaO-Al2O3 including CaS after addition of CaSi.(2) The process and consumption of calcium were found to affect the change of CaO and CaS contents of inclusions.(3) A mathematical model was developed assuming that vaporization rate of calcium from the melt and rate of reaction between melt and inclusions can be described by equations of the first order reaction, and that the size and number of inclusions remain constant during treatment.(4) The calculated [Ca] and CaO, CaS contents of inclusions showed good agreement with observed ones regardless of the conditions of CaSi addition.