A study of simultaneous effects of the major processing variables on the extent of reduction of a column of iron ore fines surrounded by coal fines in an externally heated shaft reactor is reported. The variables studied are ore particle size, coal particle size, coal/ore ratio, time, and temperature. Statistically planned series of isothermal experiments have been carried out to quantitatively assess the effects of each of these variables and of their interaction on the extent of reduction. Within the range of the variables studied, use o f computational methods to find the values of each of the variables to obtain the maximum extent of reduction have also been discussed.

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The geometry of a raceway zone can be described by its volume, depth, height and width. This paper investigates these factors theoretically based on a simplified raceway shape model.
The results obtained are as follows;
(1) The raceway volume, V_R is closely described by the product of depth, D_R, height, H_R and width, W_R.
V_R=0.53D_RH_RW_R
(2) The power law is applicable to the relation between the penetration factor (depth divided by tuyere diameter, D_T) and the raceway factor, RF.
D_R/D_T=0.315RF^0.587
(3) The dimensionless width is related to the penetration factor.
W_R/D_T=2.631(D_R/D_T)^0.331
(4) The height is obtainable from the depth, the width and the tuyere diameter.
(4H²_R+D²_R)W_R/(H_RD²_T)=23.1(D_R/D_T) ^1.052
The trends of the derived results are compared with data reported by various researchers with reasonable agreement.

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In this work, the equilibrium distribution coefficients of phosphorus k^P₀ in Fe-P binary and Fe-C-P ternary systems were obtained experimentally and the carbon content dependence of the equilibrium distribution of P was discussed using Distribution Interaction Coefficient. Temperature dependence of k^{P, α}₀ for α phase is given by
k^{P, α}₀=N^s_P/N^l_P=0.715-3.2O×10^-4T.
From the above equation, k^{P, α}₀ at infinite dilution of P, that is to say, at the melting point of iron, is 0.136, k^{P, γ}₀ for γ phase at high carbon concentration is about 0.09. k^{P, γ}₀ increases with the concentration of carbon and k^{P, γ}₀ at infinite dilution is 0.06. Also, the relation between k^X₀ of various elements for α phase and that for γ one was derived thermodynamically.

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As one of the fundamental researches on the refining of molten iron by soda ash (Na₂CO₃), the experiments were made of dephosphorization of liquid iron by the sodium silicatetux containing Fe₂O₃ or Na₂CO₃, with various ratios of Na₂O and SiO₂ at the temperatures of 1550, 1600, and 1650°C.
The results o f these experiments indicated clearly the effects of the addition of Fe₂O₃, the slag basicity, the temperature, and the initial phosphorus content in liquid iron on dephosphorization by the slag of Na₂O-SiO₂ system, and the investigation also showed the refining actions of Na₂CO₃ in the flux.
Furthermore, a discussion was made on the equilibrium relationship of the dephosphorization reaction by Na₂O-SiO₂ Fe_tO slaps, and the following expression was obtained.
2P+5(Fe_tO)=(P₂O₅)+5Fe
logk_P=log {(%P₂O₅)/([%P]²•(%Fe_tO)⁵)}=8.67log(%Na₂O)-14.55 (1600°C)
From the comparison of the value of k_P obtained in this work with that for the CaO-based slag reported previously, it became clear that the Na₂O-based slag is more effective on dephosphorization than the CaO-based slag.

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The solubility of nitrogen in liquid chromium and chromium-iron alloys has been studied by a sampling method at the temperatures of 1550-1780°C and under 0.04-1.0atm of nitrogen.
The equilibrium constant of the solution reaction and the activity of nitrogen in liquid chromium and chromium-iron alloys were determined by applying the interstitial model to the experimental results.
The results obtained are summarized as follows:
(1) Nitrogen dissolved in liquid chromium and chromium-iron alloys up to 50% Fe does not obey the Sieverts' law, and the solubility of nitrogen in liquid chromium is given by the following equation.
log K(Z)=5515/T-3.19₃,
K(Z)=a_N/√<P_N2>=ψ_NZ_N√<P_N2>
(2) The activity coefficients of nitrogen based on pure liquid chromium are expressed as follows:
log ψ^N_N(Cr)=(4235/T-1.51₃)•Y_N Y_N<0.21
log ψ^Fe_N(Cr)=1.80•Y_Fe Y_Fe<0.7
(3) The activity coefficients of nitrogen in liquid iron-chromium alloys based on pure liquid iron are shown by the following equations:
log γ^Cr_N(Fe)=(-13765/T+3.10)•X_Cr X_Cr<0.16
log f^Cr_N(Fe)=(-148/T×0.033)•[%Cr] [%Cr]<15
where, Y_N Z_N: the mole ratio and the lattice ratio of nitrogen in the liquid metal, respectively.

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With the objective of optimizing the process parameters of the R. H. Degassing Unit of USIMINAS (Brazil), the circulation rates in a 1: 5.3 scale model were evaluated for various gas injection rates and dimensionless correlations were obtained at for three different experimental conditions of static water level in the upleg. In general, the circulation velocity increases with increasing the gas injection rate and it shows a maximum when the water level in the upleg reaches the barometric height. The circulation velocities calculated from energy balance were close to the experimentally observed values. Application of the results of cold model experiments to the industrial installation has been discussed.

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This paper deals with the behavior of liquid in the shaking ladle as revealed in model experimental study. A series of experiments have been made by the use of four size models with different liquids, by varying eccentricity, rotational speed and the amount of charge. Four critical states of liquid motion in the shaking ladle have been discovered; oscillatory motion, the 1st and 2nd monobreaker wave motions, multiple breaker motion and rotational paraboloid motion. The 2nd and the multiple breaker wave motions as well as the rotational paraboloid critical states are o f practical importance to metallurgical production. The stirring action strongly promotes the chemical reaction in the liquid bath. Some empirical formulas for calculating these critical rotational speeds have been established from experiments. The results obtained by the use of a 10-ton commercial shaking ladle with liquid iron at above 1200°C, are in good agreement with those of laboratory scale investigations. Consequently, optimal shaking parameters have been proposed for production operation.

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In order to investigate the effect of Al and N on workability at elevated temperatures attained by cold working, ductility of steels with varying Al/N ratios was examined by tensile test conducted at R. T.-250°C for low carbon steels (JIS S15C) and case hardening steels (JIS SCR420). In the low carbon steels, the ductility at those elevated temperatures was reduced markedly for lower Al/N ratios than 1.2, but did not decrease so much for higher Al/N ratios than 3.3. On the other hand, in the case hardening steels, the reduction of ductility at the same elevated temperature range was smaller and did not depend on Al/N ratio.
It appeared that the ductility of steels at those elevated temperatures is affected by the content of nitrogen in solution, which in turn depends on Al/N ratio, cooling rate from austenite, and content of other alloy elements.

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Effects of various factors on strength of both as-quenched and aged plates in Ti-6%Al-4%V alloy were systematically investigated. The solution treating temperature, chemical compositions and grain size of primary α phase were widely varied, while the aging condition was fixed at 538°C for 6hr. The equation of O_eq, for this alloy was formulated based on the multiple regression analysis between chemical compositions and strength. The α grain size dependence of strength was also evaluated. The volume fractions of primary α phase and α' martensite, their microhardness and grain size of primary α phase were quantitatively measured, and the variations in strength with various factors were analyzed by the law of mixture for strength in the two-phase microstructure consisting of the primary α phase and α' martensite.

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The hot deformation characteristics of Nb-bearing austenitic stainless steel have been studied by means of tensile test and transmission electron microscopy in reflection to the stacking fault precipitation of NbC. Tensile tests were carried out at temperature ranging from 823 to 1173K at an initial strain rate of 2.1×10^-4s^-1.
Although the yield strength of the solution-treated specimen was quite low, remarkable work hardening occurred at temperature ranging from 1023 to 1123K. In this temperature region, a deep ductility trough accompanied by intergranular ductile fracture was also observed. This can be explained in terms of the dynamic precipitation of NbC within the grains as well as on the grain boundaries.
In the aged specimen, on the other hand, the yield strength was much higher than that of solution treated, but the work hardening was less significant. Such a high yield strength is probably due to the refinement of the average effective grain size, i.e., an austenite grain being separated into several regions by the hard platelets of stacking faults with fine NbC particles. The ductility trough in this case was rather shallow because of the reduction of dynamic NbC precipitation.
At temperatures above 1123K, the ductility of the solution-treated specimen increased with increasing deformation temperature, but that of the aged specimen was lamely reduced. This ductility loss could arise from local dynamic recrystallization in the vicinity of grain boundaries.

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