Stoichiometric chemical equations have been used to show the equilibrium relation between gas phases and liquid or solid phases in the field of chemical metallurgy, or of especially the physico-chemical studies of fundamental reactions concerning steel-making. But in those procedures the equations means are physically ambiguous, so that the equilibrium constants, namely, the relations between partial pressures of gas phases and concentrations of solute molecules in molten or solid phses, founded on such equations are only satisfied approximately in the case of very low concentration or in the case of energies of mutual interaction between solute atoms being very small as compared with kT. Therefore, we must avoid the use of the stoichiometric chemical equations in treating these problems. Free energies of gas phases and condensed phases dissolving the gas atoms were calculated on the basis of statistical mechanics, and theoretical formulas were obtained to show the relations between the partial pressures of gas phases, concentrations of dissolved atoms and temperature from the general principle that the chemical equilibrium between gas phases and condensed phases are satisfied when the total sum of their free energies has a minimun value.
In this paper, as an example, the following problems were treated accorbing to the method described above, [i)] chemical equilibrium between the molten iron and gas-mixtures of H₂ and H₂O [ii)] equilibrium relations between the molten iron and gas-mixtures of CO₂ and CO.

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It was pointed out that the chemical equation such as 3Fe+2CO\ ightleftarrowsFe₃C+CO₂ does not represent the essential features of this equilibrium.
We treated this problem on the basis of statistical thermodynamics apart from the above equation and determined the numerical values of the constants ΨFe_c, \varphi_cc and θ_c in the theoretical formula by comparing with the observation carried out recently by Smith, which represent the interaction energy between Fe ane C, the energy-contribution of C-C pair and the vibrational characteristic temperature of carbon respectively in the γ iron. Results obtained by this procedures are as follows. & Ψ_Fec=-135.98 Kcal
& \varphi_cc=8.35 Kcal  (at 1000°)
& θ^c/j_c=473°
It was shown, then, that the equilibrium properties of this system could be derived over the whole range of temperature and of gas compositions when these fundamental physical constants concerning the Fe-C interstitial solid solution were used.

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The statistical thermodynamic method for the basic reactions concerning steel-making, which was given by Takeuchi in the 1st report, was discussed from the expermental data of the equilibrium relation between the molten iron and H₂O-H₂ gas mixture. It was shown that oxygen in molten iron was not dissolved in the form of diatomic FeO but atomic type, moreover, the mutual Interaction energies between gas atoms dissolved in the molten iron were negligible small compared with kT, and the temperature dependency of the equilibrium constants was approximately proportional to 1⁄T only in small range of temperatures.
The potential energies between atom pairs Fe-O, Fe-H and the characteristic temperatures of vibration θ_O, θ_H of these atoms in molten iron were determined in comparison with the experiment.
The temperature dependency of P_H2O⁄[O][H]², which was calculated by using the data above mentioned is good agreement with the observation.

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Theoretical formulae showing the relations between partial pressure ratio \dfracP_CO²P_CO2 or \dfracP_CO2P_CO of the gas phase, concentration of carbon and oxygen atoms in molteniron and temperature, which is obtained on the basis of statistical thermodynamics without using the stoichiometric chemical equations between molten iron CO and CO₂ gases in the 1st report, were compared with the observed data. For comparing with the experimental data values of some constants ψ_c, \varphi_cc and θ_c in the theoretical formulae, which correspond to the interaction energies of Fe-C and C-C pairs and the vibrational characteristic temperature of carbon atoms occupying inter lattice points in the molten iron, must be determined numerically. They were determined from an equilibrium condition μ_C^L=μ_G on the solubility-line of the graphite in molten iron, where μ_C^L is the chemical potential of a carbon atoms dissolved in the molten iron and μ_G free energy of a graphite atom.
These values were substituted into the theoretical equations and the equilibrium constants at 1560° were calculated numerically, these are in good agreement with the observed values of Matobas Varcher and Hamilton’s results when the concentrations of oxygen and carbon atoms are very small as compared with 1. Calculated temperature dependency of the equilibrium constants was in reasonable agreement with the Matoba’s and Chipman’s formula.
It was shown theoretically that the equilibrium constant logK₂ depends upon the concentration of carbon atoms on account of the interaction energy \varphi_CC when it approaches the saturation value.

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Discussion has been given on the equilibrium state of Wustite with gas phase by using the stoichiometric chemical equations and their equilibrium constants.It is known that the lattice imperfections which give excess oxygen of Wustite over the stoichiometric composition FeO are the vacant lattic points on the rion lattice of FeO. Consequently, it is improper to treat the phase of Wustite as the molecular solid solution of FeO and Fe₃O₄, so we adopted the atoms as the constituents. Assuming that the vacant lattice points are found on the iron lattice, and that the accompanying electron deficits are distributed in the form of Fe⁺⁺⁺ ion statistically, we calculated the thermodynamic probability of such a state, and by minimizing the total sum of the free energy we obtained the theoretical formulas which show the relation between the gas phase and the corresponding Wustite. These results show very good agreement with the experimental data, especially with the detailed and precise one. Our results are applicable to all gas mixtures, which are concerned only in oxydation and reduction. So, when the partition functions for those gases are known, we can calculate the composition of gas phase which is in equilibrium with Wustite of given oxygen concentration. By calculation we traced the behaviour of Wustite to the gas mixtures of H₂ and H₂O from the data of Wustite to the gas mixtures of CO and CO₂.

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The experiments on the absorption of nitrogen by molten iron were performed between 1530 and 1750°, with the following results.
The saturation value of absorption and the velocity of absorption are affected considerably by the existence of a small amount of other elements or impurities. (as shown in Figs. 2, 3, 4,). The saturation value of purest iron hitherto measured in my laboratory is 0.039₁ wt.%N₂ at 1600°; The temperature coefficient is about 1.4×10⁻⁵ wt.%N₂/°C, though the temperature function of absorption is not linear to the temperature as shown by equation (18). The velocity of absorption increases with the addition of a small amount of C, Si, Mn, Cr, but decreases with addition of Ni. (Figs. 2,4)
The problem on the absorption of nitrogen by liquid and solid iron were studied by means of statistical thermodynamics. The fundamental conceptions of the theory are as follows: The liquid state of metal is quasicrystalline, and the gas atoms absorbed situate interstitially in the vacant position of the lattice. Thus, the equations (18) or (19), (20,), (21) were obtained for the saturation values at any temperature. The experimental results were explained satisfactorily by the above equations.

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In the previous paper⁽¹⁾ it was concluded that the so-called “Rueckbildung” phenomenon occurring in Al-Cu alloys is not a return to the original solid solution, but it is an incomplete dissolution of pre-precipitation clusters until a certain state is reached. This is because of the following two conditions : —(1) the solubility of the cluster is increased considerably at the temperature of Rückbildung, and (2) in the aged state, the copper concentration in the super-cooled solid solution is not uniform, i. e., in the neighborhood of the cluster it is decreased down to the solubility, while in the distant region it is not yet so much decreased, as is shown in Fig. 1 in the text.
But the first condition, which had been put as an assumption before, was thereafter experimentally verified and numerically given by Borelius, Anderson and Gullberg. On account of this, in the present paper, calculation has been revised by using their data. The result has yielded a reasonable value for the activation energy of diffusion of copper atoms in super-saturated solution, and thus the conclusion previously obtained has been confirmed.

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The hardness of cold-worked alpha-brass increases, if it is annealed at the temperatures below recrystallization temperature. This hardening phenomenon is a sort of strain age-hardening. The hardening curves at constant temperatures are hyperbolic in type. This age-hardening, therefore, must be the one which should be called the pseudo-precipitation type(it was called the non-precipitation type, in the preceding paper, this journal, Vol. 12, No. 7-12, p. 16, 1948), or which is caused by the formation of Guinier-Preston aggregates. Concerning the reason of this idea, the readers are refered to the preceding paper (loc. cit.). The activation energy of the strain age-hardening process of alpha-brass is 20000 cal/mol, which is very much smaller than the activation energy of diffusion of zinc atoms in alpha-brass.

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At first the direction of crystallization of zinc was investigated by the interference-dilatometric method, and the following results were obtained, the length of the specimen being about 13 mms.
When the velocity of cooling is small, crystals become columnar and hexagonal, the base being nearly parallel to their axes. The curve I, Ia, IIa of Fig. 3, 4, and 5 show the distributions of expansion coefficients of a cast specimen. When the specimen is rolled the distribution changes as shown in the figures. The directions of hexagonal axes of a rapid cooled specimen, initially distributed evenly in the chill surface, becomes nearly parallel to the direction of rolling, the plane of rolling coinciding with the chill surface.
Then mechanical twins are formed and most of the hexagonal base become nearly parallel to three coordinate planes of the specimen, if the axes are taken as the direction of rolling, perpendicular to the plane of rolling and perpendicular to each of them. If the direction of rolling coincides to that of crystal growth, the deformation of the rapidly cooled ingot becomes extremely easy, cracks do not occur, accompanying mechnical twins and the larger part of the hexagonal bases become perpendicular to the direction of rolling.

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The formation of twin, slip line and crack are observed under the microscope by bendeing a chill cast specimen of Zn. The deformability is measured by the bending angle. The effects of Pb, Cd, Sn, Fe, and Al are discussed.

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This study concerns the mechanical properties of zinc sheets, mixed electrolytic and refined zinc in the ratio of 50:50, rolled under varions conditions. The experimental results obtained are as follows.
(1) The material can be rolled easier and elongation of cold rolled sheet increases with elevatiug rollig temperature. When materials are rolled at temperatures higher than 200°, they tend to crack.
(2) By intermediate annealing after hot rolling, subsequent cold rolling becomes easier and cold rolled sheets have better bending properties but erichsen values are smaller than those of cold rolled without intermediate annealing. If materials are cold rolled with intermediate annealing, there bending properties become better but erichsen value and tensile strength decrease with thinning of the thickness of hot rolled sheets.
(3) Bending properties become the best at about from 20 to 30 percnt cold rolling reduction after final annealing but tensile strength increases as cold rolling reduction is raised.
(4) Directional properties decrease and elongation and erichsen value increase by cross rolling at cold reduction, but on materials rolled with 40% or more in one direction after cross rolling these effects disappear.

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Experiments have been made on the heat-treatment and the stress-corrosion tests of 25 different alloys in the Al corner of the Al-Zn-Mg Alloy system, containing up to 30%Zn and 10%Mg. The most suitable temperature of the solution treatment for practical purposes is 440° and the most practically useful compositions are 4-10%Zn and less than 2%Mg, provided the total contents of Zn and Mg do not exceed 10%. These alloys have the highest tensile strength when aged at 150°, after quenching from 440° into hot or cold water. They cannot obtain superior mechanical properties than super-duralumin, when aged at room temperature. Alloys of the Al-Mg-Zn₂ line have the highest saturated hardness as shown in the former report by the authors ; and alloys containing mere Zn or alloys on the Al-T(Al₂Mg₃Zn₃) line have considerable hardening effects.The Al-MgZn₅ section diagram was investigated by thermal analysis and microscopic examinations peritecto-eutectic reaction at 323° was discovered to form MgZn₅.

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The individual influences of Fe, Si and Cu were examined, by adding 0.5, 1.0 and 2.0% to the Al-Zn-Mg alloys, containing Zn 7, Mg 1 (T-series), Zn 10, Mg 1(J-series) and Zn 1, Mg 5 (K-series), respectively. Age-hardening curves at room temperature and 150° for T & J-series and 200° for K-series were obtained (Rockwell B & H Hardness). The as-quench-hardness (H₀) of each alloy was obtained by keeping the quenched alloys in a freezing mixture and measuring their hardnesses in the room below 0°. The tensile tests of the hardened alloys (aged at room-temperature and at 150° for T & J-series, 200° for K) were also carried out. The results were as follows :
Addition of Cu, up to 1% is almost harmless but the drawability will be decreased when it exceeds 1%. Si decreases the hardenability (ΔH) and reduces the strength. Fe increases the saturated-hardness (H_s) but reduces the hardenability, because the Al-Fe-Zn ternary compound “Y” is composed at the expense of Zn. Stress-corrosion-resistance will also be reduced by the addition of Fe. These harmful effects of Si and Fe may be reduced by increasing the Zn content, but no remarkable effect can be expected within the composition allowed for the commercial alloy (Zn+Mg<10). The Y-compound was detected both by the microscope and X-ray photograph, but composition and crystal structure of it has not yet been defined because of some difficulties in experimental technique.

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The shuttle body is the most important and complicate part in the sewing machine.It is made from low C steel, carburized, heated in salt bath, water quenched and grinded. As it is much deformed by heat treatments, the removed amounts by grinding are much and its hardness is not uniform as a result. I have tested the induction hardening and obtained the following results ;
(1) The deformation by induction hardening was smaller than that by salt bath heating and as much as that by salt bath surface heating.
(2) The heating condition of shuttle body by induction heating. Inlet power-80∼90 KW, heating time-1.4∼1.5 sec, cycle 50000∼100000. cooling method-water jet.
(3) The wear resistance of shuttle body which was induction hardened heatnig was as good as that by carburizing salt bath heating and water quenching. But the hardness by induction heating or salt bath surface heating was smaller than that by carburizing, salt bath heating and quenching.
(4) The direction of deformations by induction hardening were unifom, but these by salt bath heating or salt bath surface heating was not unifom.
(5) The C content of steel of the shuttle body for induction hardening which gave the best results in heat treatment and machining was than 0.35∼0.40%.

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The new method of heat-treatment of the age-hardening alloys is to quench the alloy not into cold water but into the bath kept at a higher temperature where the alloy will be kept for some time and quenched again into cold water from this temperature. By this treatment, An alloy aged at higher temperature will be aged again at room temperature.
Experiments have been made on Al-Zn-Mg alloys, commercial duralumin and commercial super-duralumin. The intermediate temperatures used in these experiments were 100°, 150°, 210°, 221° and 280° and the keeping time at the respective temperatures were 2, 10, 30, 60 and 120 minutes; for instance, a Al-Zn-Mg alloy was quenched from 440° into boiling water and kept there for 30 min. and then again quenched into cold water and aged at room temperature. If precipitation does not occur during ageing at intermediate temperatures, the hardness of alloys treated in two stages will attain the same hardness as the saturated hardness of the normal room-temperature hardening. This was observed both in the cases of Al-Zn-Mg alloys and duralumin.
This new treatment will reduce the quenching-stress of the alloy and will avoid the deformation and stress-corrosion and ageing effects will be obtained in a shorter time than usual the quenching method.

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The author carried out a series of experiments with three different high speed steels, and studied the effect of heating temperature and cooling velocity on the transformation point and hardness, and then also the effect of cooling velocity from quenching temperature on the tempering hardness and transformation.
The results obtained are as follows : Ar₁ point is generally lowered as the heating temperature become higher and cooling velocity increases and Ar″ point is also lowered as well as, and then both transformation point become higher as the cobalt content increases. Retained austenite due to quenching increases as the cooling velocity from 1300° increases, and temper hardening become larger.
When the cooling velocity from quenching temperature of 1300° increases more than 5°/min, some austenite are retained.

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Effective riser for casting is investigated for aluminium casted from 750° in a sand mould.Cooling and solidification of riser and casting is measured by thermal or differential thermal analysis. As the result, the central part of the riser solidifies tardily by the surrounding hot air raising up in a clearance between metal and moulding sand, and this induces feeding of metal to the casting.

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In this report, the orientation changes during recrystallization and “Sammelkristallisation” were considered from a crystallographic point of view. Growth rotation twins occur during annealing, and the texture becomes (110), [001]. We have observed clearly by the etching figure method that the axes of rotation are [110] and [112]. We have conisdereid from these experiments the mechanism of orientation changes during cold-rolling and annealing, and from these fundamental considerations, we have been able to obtain silicon-steel sheets that have good magnetic anisotropic property by a skin pass (reduction 2∼6%) followed by low temperature annealing.

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The art and protecting coloring of copper, zinc and brass by using selenious acid only wihout adding chroric acid was investigated.

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The determination of sulphur in iron and steel by the titration of barium chloride solution using sodium rhodizonate as an indicator after combustion was studied.Sulphur dioxide and sulphur trioxide which was formed by combustion of iron and steel were absorbed with sodium peroxide solution and neutralized, and after the addition of an equal volume of alcohol and sodium rhodizonate indicator solution, the titration with barium chloride solution was carried out.

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