A modified closed chamber method has been applied to determine the effect of the alloying element on the activity coefficient of manganese in liquid iron alloy. The results obtained are summarised as follows: (1) Interaction parameter eMn(X) in liquid iron alloy at 1570°C: The value of eMn(C) is in fairly good agreement with those of previous investigators obtained by a different method. (2) Enthalpy coefficient hMn(X) and entropy coefficient sMn(X) defined by Chipman et al. are obtained for X=C and Si as follows: (3) In consideration of the large discrepancy in eMn(SI)'s of the present authors and previous investigators, it is shown that H2-H2O method has a possibility of making considerable errors by the effects of hydrogen, oxygen, and SiO in determination of eO(O), eSI(SI), and eO(SI), which were used to obtain eSI(Mn) by the previous investigators. (4) A regular periodic relation is found between the interaction parameter εMn(X) and atomic number of the alloying element X. (5) The interaction parameter εeMn(X) shows a tendency to decrease with increasing the effective number of free electron nx, eff of the alloying element X.
The deoxidation process of Al-Si alloys, which was consisted of 5 stages, was obtained through the experimental results in stirring and quasistatic liquid iron. The behavior of Si at the addition period of deoxidizer, formation period of Al2O3 inclusion, and reoxidation period was especially important. So these complex deoxidation effects were investigated by further experiments. The experimental results are summarized as follows. (1) At the addition period of deoxidizer, the dispersion and transfer of Al-Si alloy into molten iron is better than that of Al or Si deoxidizer. This is due to the effect of Si in the deoxidizer and its first stage behavior is the same as that of Ca-Si alloy. (2) The formation of Al2O3 cluster is retarded considerably when Si is remained in molten iron as soluble Si. This behavior is discussed through the measurement of the interfacial energy between molten iron and Al2O3 inclusion. (3) On the reoxidation period, the total oxygen content is kept low for a long time while soluble Si is remained in molten iron.
Studies have been made on the formation of bubbles in mercury and in liquid silver by using the single nozzle facing upward. Nozzles used in the experiments are of the sizes 0.22-0.82cm in O. D. and 0.10-0.30cm in I. D. The gas chamber volume Vc and the gas flow rate Vg are varied from 0.15 to 200cc and from 0.0167 to 70cc/ sec, respectively. The size of bubbles is determined from the frequency of bubble formation and the gas flow rate. A table is presented to show the effects of Vc and Vg on the size of bubbles. The size of bubbles found experimentally is compared with that calculated from theoretical or experimental equations obtained for wetted nozzles. The experimental values of bubble size do not agree with the values calculated using the inner diameter of the nozzle. On the other hand, when the non-wettability of the nozzles in liquid metals is taken into account and the outer diameters are adopted as the nozzle diameters in the equations, a close agreement between the experimental and the calculated results is obtained. Thus, it is shown that the quantitative estimation of the size of bubbles from a single nozzle in liquid metals is possible.
The present paper deals with a kinetic study of decarburization of liquid iron in Ar-CO-CO2atmospheres at 1600°C. The study has been especially devoted to determining therate-controlling step at low carbon contents of the melt. At concentrations of carbon highr than 0.02-0.05 %, the rate of decarburization is controlled primarily by gaseous mass transfer. At concentrations of carbon lower than 0.02-0.05 %, the rate of decarburization no longer depends on the gas flow rate, if it is higher than 1300cc/min. The rate-co, ntrolling step of decarburization under this condition varies according to the composition of Ar-CO-CO2. Chemical reaction becomes important in rate-controlling mechanism as the partial pressure of Ar or CO in the gas mixture increases, while mass transfer of carbon becomes important as the partial pressure of CO2 increases. In the range of chemical reaction control, the experimental reasults are explained reasonably by the model based on the simultaneous reactions: CO2+C←/→2CO, CO2←/→CO+O, C+O←/→CO. In the range of mass transfer control, the value of mass transfer coefficient of carbon is the same as that for the decarburization by CO-CO2 and Ar-CO2.It is concluded that the mechanism of decarburization by CO-CO2 and Ar-CO2, previously studied, can be explained on the basis of the present study.
Electron microscopy were made to examine the structural features of the tempered martensite and the isothermally transformed bainite produced in 5%Ni-0.5%Mo steels with the following varibles; austenite grain size (fine and coarse) and carbon content (0.15 and 0.30%). The tempered martensite and the lower bainite were found to be composed of the lath packet of single orientation the lath packet of mixed orientation and the large martensite or bainite. Lowering of carbon content or coarsening of austenite grain size was found to cause the increase of lath width in the martensites. While the characteristic side-by-side growth of bainite lath was found to be dominant mode in the lower and upper bainite transformed from the fine-grained austenite of 0.15%C steel, the lower bainite from the fine-grained austenite of 0.3%C steel was composed of lath bundles randomly nucleated and the upper bainite were granular. The lower and upper bainites from coarse-grained austenites were considerably different from those from fine-grained austenites; the initial austenite grains were partitioned by the networks of straight lath packets which enclosed several massive bainite. The transition from lower bainite to upper bainite, which occurred at 350°C for those of 0.3%C steel and 400°C for those of 0.15%C steel, caused a drastic increase in both lath width and carbides size.
Structures and magnetic properties of Fe-Fe2Ti eutectic alloys containing 11, 16 and 18 wt%Ti respectively and those of unidirectionally solidified Fe-16 wt%Ti alloy have been investigated. As the result of magnetic analysis, Fe-Fe2Ti eutectic alloys consists of two ferromagnetic α-Fe andFe2+xTi1-x phases (λ>0). The Curie temperature of the former is 780°C and that of the latter is around 100-135°C, depending on Ti content in alloys and heat treatment condition. It seems that the Ti content of Fe2+xTi1-x; in Fe-Fe2+xTi1-x eutectic alloys, annealed at 1 000°C for 1 hour, is around 29 at% by magnetic measurement. The structure of unidirectionally solidified Fe-16 wt%Ti alloy has the lamellar or rod-like Fe2+xTi1-x phase in matrix of α-Fe phase. The results of metallography, X-ray diffraction and powder patterns indicate that a great part of ‹0001› of Fe2+x, Ti1-x phase and ‹100› of α-Fe phase are parallel to the crystal growth direction on the crystallographic orientations of both phases. Similarly, the magnetic properties of unidirectionally solidified alloy show anisotropy depending on solidification rates. The magnetic anisotropy for this unidirectionally solidified eutectic alloy may be mainly caused by crystal anisotropy of Fe2+xTi1-x phase and shape anisotropy of α-Fe phase by magnetic torque measurement up to 285°C.
A report is given the method for preparing the sample with stainless steel chips from lath (Kieseling) machine for spectrochemical analysis of stainless bloom. Each stainless steel chip was needed to be embedded some material to remove oil and scale from the surface with belt grinder. Lead and tin were most suitable materials for embedding the chips because no interfering elements for the analysis of stainless steel were contained in them. Procedure of the preparation of the sample was as follows; Aluminum ring (diameter 25mm) was put into die of briquetting press and was filled with granule lead or tin. The stainless steel chip was cut into 24mm×20mm and was put on the lead or tin and then was pressed with 20 tons. The briquetting sample could be grinded and was suitable for spectrochemical analysis. After the analysis, the stainless steel chip was easily removed from briquetting lead or tin by wrench both side of the sample with a pair of pinchers or pliers. By this procedure, the analytical results were obtained within 6 minutes and good accuracy and reproducibility were obtained.