The equilibrium relations in question were studied experim entally and the following results were obtained.
(1) When equilibrium temperatures were constant, C and Si contents in the pig iron respectively increased and decreased, as the basicity of the slag became higher.
(2) When the basicity of the slag was constant, the Si content in the pig iron increased as temperature rises and the C content in the pig iron was almost independent of temperature.
The equilibrium relation between the C and the Si in the pig iron was also determined.

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The specific electrical conductivity (κ) of the systems FeO-SiO₂ and FeO-MnO-SiO₂ was measured over the temperature range 100°-1420°C. In the conductivity-temperature curves gerenally appeared two kinds of anomalous points, of which the one was faint and the other more appreciable. The former corresponded to the temperature of the precipitating primary phases and the latter to that of solidifying.
The conduction was ionic over the measured range of concentrations in molten state, but in the solidified state electrons also took part in the conduction.
The conductivity decreased with increasing SiO₂mol%. In the system FeO-SiO₂ logκ changed linearly with SiO₂mol% in molten state. The same relation was obeyed by some of the other binary systems.
The curve logκ-1/T (T: absolute temperature) consisted of the two straight lines, and the energy of activation at higher temperatures was 1.5-2 times as large as that of at lower temperatures.
This is due to the fact that at lower temperatures the conduction was mainly cationic, but with increase of temperatures anionic conduction also occurred increasingly.
For the binary systems the specific electrical conductivity increased in the order of CaO-SiO₂ MnO-SiO₂, FeO-SiO₂ and the viscosity in the reverse. This order corresponded to that of cation radii (by G orldschmidt)-Ca₊₊(1.06A)>Mn₊₊(0.91A)>Fe₊₊(0.83A). When the ionic radius was small, the ion produced a strong field in its vicinity and will affect the structure of the SiO₄-tetrahedron. Accordingly it decreased the stability of the bonds Si-O, and so reduced the viscosity, which made it possible for the eations to pass throngh the interstices of the melt more easily, resulting in the increase of the conductivity. The ionic radii of cations controlled largely the structure of molten slags.
In the system FeO-MnO-SiO₂ generally the conductivity decreased with increase of SiO₂mol% When MnO was substituted for FeO, the conductivity decreased slightly, except for high SiO₂ contents, where that decrease was somewhat larger.

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The following studies were made to ascertain the effects of calcium silicide on the microstructure and chemical properties of nickel cast iron (Ni 5-50%, G 3.57%, Si 1.15%, Mn trace, P 0.035%, S 0.013%) and hypereutectic cast iron. Through the result of these studies, the following facts were found:
1) In the case of nickel cast iron containing more than 25% of Ni, the spheroidal graphite was made by adding 3% of calcium silicide.
But those with more than 10 per cent of Ni change into the spheroidal graphite by adding 5% of calcium silicide.
2) In the case of hypereutectic cast iron with no Ni, the spheroidal graphite cast iron was formed by addition of 5 to 10% of calcium silicide. The spheroidal graphite cast iron having the following chemical composition and mechanical properties was made when 9% of calcium silicide was added to the Swedish charcoal pig iron of Table 4.
C 4.14% Si 3.73% P 0.05% Mn 0.4% S 0.01% T.S. 62kg/mm Elg. 14% Rockwel-B 78.6
3) The inner shrinkage cavity of the spheroidal graphite cast iron made by calcium silicide addition was smaller than in the case of Mg addition and the running property of this iron was extremety good.
4) There often appeared snow-flake graphite in this cast iron.

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By the actual use of the Stiefel-Mannesmann Piercer, the authors studied.the effects of inclined angle upon the state of piercing phenomena from various points of view. The variations of angle were from 5° to 9°, with the other factors kept constant. The results obtained by us were enumerated as follows:
In case the inclined angle was increased,
(1) The K.W. increased linearly, but the K.W.H. decreased, resulting in the increase of rolling efficiency.
(2) The deformation in the course of piercing process remained unchanged, but the angle of torsion during the piercing process increased.
(3) The axial moving speed of tubes increased linearly.
(4) The revolving speed of tubes decreased.
(5)The reduction in the piercing process increased, but the reduction speed remained almost constant.
(6) The cracks that appeared on the inner and outer surfaces of tubes. increased when the round billets were not good in quality, but no difference would presumably appear when the billets were in excellent quality.

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In the first report, the age-hardening phenomena of Timken 16-25-6, the heat-resisting alloy for gas turbine material was studied. The solution-treatment was determined at 1150°C for 1 hour.
In this report, the influence of solution-treatment temperature (1100°C-1250°C) and time (30 minutes, 10 hours) on hardness, grain-size, and high-temperature age-hardening phenomena was studied.
In general, the higher the solution-treatment temperature and the longer the heat-time was the lower became the degee of hardness, the larger the grain-size, and the more serious the distribution of mixed grain. After the age-hardening at 800°C for 50 hours, the result wes nearly the same in every case, althongh there were differences in the condition of grain-size and mixed grain.
Hence, the temperature and time of solution-treatment should not be discussed from the viewpoint of hardness after aging, but from the view-point of the grain, size and mixed grain conditions. In this report, the solution-treatment seemed effective at 1100°C and 1150°C for 30 minutes to 1 hour, or at 1200°C for 30 minutes approximately.

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For the purpose of determining comparatively small contents of Zn in nodular cast iron treated with Zn-alloy, the authors studied on the separation of Zn from cast iron by applying the oxine volumetric method. The procedure obtained was as follows: -
1. Sample was dissolved in HCl+HNO₃, baked, and then dissolved again by adding HCl Si, graphite, etc., were separated by filtration.
2. The greater part of iron were removed by applying the ether extraction method.
3. The Cu was separated from the extractive acid layer solution by introducing H₂S gas into it and the remaining Fe and Mn were precipitated by adding NH₄Cl+NH₄OH and (NH₄)₂S₂O₈ reagent, and they were removed by filtration.
4. If Ni was contained in sample, it was precipitated by dimethyl-glyoxime reagent, and was removed by filtration.
5. The filtrate was prepared so as to be of slightly acetic acid solution, and Zn was precipitated by addition of oxine reagent, and dissolved wih HCl, and were titrated by N/25 KBrO₃ sol. and N/25 Na₂S₂O₃ sol.
By this method, reproducible results were obtained.

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Après quelques recherches sur la manière de prise d'essai et de décomposition du résidu pour augmenter la precision de la methode de Gakushin ou Kjeldhal pour le dosage de l'azote dans les aciers, fers et fontes brutes, les auteurs ont obtenu les resultats suivants: 1. L'additiond'aluminium pour calmer la prise d'essai de métal liquide n'est pas necessaire, parce que la teneur en azote de l'éprouvette calmée et de celle non calmée n'est pas differente.
2. Le dosage de l'azote dans le résidu est touiours necessaire, si l'on veut obtenir les resultats exacts.
3. En cas des aciers ordinaires ou speciaux, excepté les aciers rapides riches en tungsténe, la quantité d'azote dans le residu diminue à moins de 10% de la teneur totale d'azote par la trempe, mais elle croît beaucoup par l'addition d'aluminium.
4. Comme agent d'attaque du résidu un mélange de H₂SO₄, K₂SO₄ et Cu SO₄ est mieux que celui de HOlO₄ et H₂SO₄, car HOlO₄ Oxyde l'ammonium aipsi cause la perte en azote.
5. Au lieu de l'asbeste on peut employer le papier filtre Toyo No. 5A, qui donne la petite et reproductible valeur de l'essai á blanc, si l'on aspire les vapeurs dans la fiole d'attaque au moyen d'un aspirateur pendant env. 10 minutes après décomposition.

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The authors observed often huge carbides which could not be considered to appear in simple alloy steel such as the ball-bearing steel (C≅1.0, Cr≅1.5%), refering to the equilibrium diagram, generally at the cores of the steel billets. These carbides appeared at the phoshorus-rich parts in the segregation strip bands in the longitudinal section of the billets. Their appearances were almost same as the elongated slags of the manganese-sulphide series and in many cases they coexisted with these slags too. By many microscopic examinations of the production billets, they were closely connected with the segregating degree of the impurities which were apt to segregate, such as carbon or phosphorus, and the solidifying conditions of the molten steel in the ingot-cases had the decisive influences. After the solidification, it was difficult to eliminate them by the ordinary hot-workings or heat-treatments. By refering the results of microscopic examinations of the longitudinal sections of the many test-ingots which contained various amounts of carbon and phosphorus respectively and the results of examinations of the structures just after solidification of these samples, to the equilibrium diagrams of Fe-C-P and Fe-C-Cr series, it seemed that these huge carbides separated out as the eutectics at the places where the grain boundary segregations of carbon, phosphorus, etc. increased over the definite degree, or that they were the coagulations of the carbide θ which separated out by the solubility limit while cooling after solidification at the segregation parts, such as above described. Now these huge carbides dissolved at about 1060°C which was much higher than the solubility temperature in the equilibrium diagram, and in many cases the colonies of the fine particles rest undissolved at the places where the huge carbides were situated. These particles seemed to be the phosphide series, and, at about 1160°C, all of them dissolved too.
Next the authors measured the hardness differences by the micro-hardness tester, not only at the huge carbides, but also at the segregation parts after heat-treatment. For example, the huge carbides had the hardness about 1300kg/mm². Then the authors studied the influences of the added elements; when carbon increased near to the upper limit, though in the specification range, and when phosphorus to about 0.04-0.05%, the huge carbides became to appear very much. Sulphur accelerated their appearances considerably, aluminium and titanium, added as the deoxidizing materials, suppressed a little, vanadium suppressed also a little, but tungsten and molybdenum accelerated on the contrary. Based on these results the authors considered the device to decrease appearance of the huge carbides.

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Refering to the watch-spring, it may be classified in two, according to its size, for watches and for clocks. In general the former containing about 0.95-1.2 per cent carbon has the mixed structure of the sorbite and the spheroidal cementite, and the other containing about 0.7-0.85 per cent carbon has the sorbite structure having a few spheroidal cementite. On this second report the authors made research on what effect the size of the spheroidal cementite will give to the mechanical properties of the watch-spring.
The results were as follows:
(1) At the B heat-treatment, when the cementite size was below 2.8μ the fatigue breaking number, the torque test value, the proportiona limit and the Young's modulus were at the maximum value while the permanent strain and the damping capacity were at the minimum value.
(2) At the D heat-treatment, namely-below about 4.1μ of the cementite size the mechanical properties became worse abruptly and above this size they became the worst.
(3) At the A heat-treatment, namely the spheroidal cementite being absorbed in the austenite, the mechanical properties were inferior to the B heat-treatment. (Refer to Fig. 1 according to the means of the marks A, B, C, D, E, F, heat-treatment.)

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The synopsis of this study was already given in that of preceding report in the Journal of May 1952

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