The object of this series of studies is to find the mechanism and the characteristics of internal friction of metals due to plastic strains, and in this report, the method of experiments and the characteristics of internal friction vs. stress curves are described. Low speed torsional damping vibration was used for the measurement of internal friction, as it is believed to be better for minimizing the effect of thermo-elastic internal friction than any other methods and accordingly the most effective for observing the effect only of the internal friction due to plasticity.
According to the results of the measurements of various metals, the plastic internal friction is closely related to the plasticity obtained statically; in other words, both of them have structure sensitivity and show changes corresponding to each other by heat treating, cold working, etc. The causality of them is confirmed by considerable coincidence between experimental values of internal friction and calculated ones induced from plastic strains which were measured statically.In all metals used for the measurements. except aluminium, existence of shoulders on the internal friction vs. stress function curves and specially distinct ones for gray cast iron were recognized. This is considered to be due to existence of exceedingly plastic components (such as free carbons), and these shoulders can be made to reappear by combining models of two specimens having remarkably different plastic strengths. As the plastic internal friction, varies with stress amplitudes, it is desirable that the friction should not be dealt with as having a single numerical value, as to any materials, but attention should be paid to the function curve of stress, because it is useful for ascertaining the internal state of materials.

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It is well known that the internal friction of metals increases with cold working. But this phenomenon conflicts with work hardening which is seen from the measurement of hardness, and accordingly it is difficult to explain clearly the relations between them. This study was intended to solve this seeming contradiction by observing variations of internal friction, hardness, creep etc. of metals appearing immediately after cold working. The method of experiments was reported in the previous paper. The specimens were mild steel,brass, aluminium and aluminium crystal. The results were as follows:
(1) The internal friction varied with cold working, and the condition of variations was different with the amplitude of vibration; in other words, the internal friction increased for a range of small amplitudes, but decreased for that of large amplitudes. The relations between the internal friction and the hardness of metals after cold working can be explained satisfactorily, because the latter is measured for a wide stress range.
(2) It was found that the plasticity and the creep of metals have the same structural sensibility for cold working as the internal friction, and the variation of them is highly dependent upon each other.

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Having examined the effect of annealing upon the magnetic properties of the plastically deformed mild steels, we obtained the following results. The permeability of perfectly annealed mild steel was decreased by plastic deformation, and restored to the original values when the specimen was annealed at the temperature above 450° after deformation. On the other hand the strain sensitivity was increased by plastic deformation, and it vanished or turned into negative when the specimen was annealed at the temperatures 450∼700°. The reason may be as follows : If the specimen is annealed at the temperatures. 450∼700° after deformation, the residual stress caused by plastic deformation disapears perfectly, and as cementite precipitates, the lattice structure of ferrite becomes almost as perfect as that of pure iron. As the size of the ferrite grains are rather small, the interior of the crystal grain will have little defects and dislocations except for their boundaries. Insignificant strain sensitivity will be a property of these perfect crystals.
When the annealing temperature is above 820°, the strain sensitivity appears again, and it seems that the internal structure of specimen restores its original state which contains the considerably many microscopic internal stresses caused by resolution of carbon. And when the annealing temperature is about 100° and 300°, the magnetic properties show abnormal changes. These two changes will be closely connected to the aging and blue-shortness respectively.
From the manner of changes of magnetization curve and strain sensitivity, it is inferred that the internal domain structures of specimen are not always identical,although the magnetization curves are quite the same.
The result mentioned above will be explained successfully by our idea “Uuit Region”. However, this idea we advocate now, is not synonymous with the so-called region advocated by Koudorski (J. Phys. USSR. 1941,93).

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Using aluminium-copper alloys containing 5.5% copper, Cu-K absorption spectra have been taken by an X-ray spectrometer of Johann type. Their rocking curves are given in Fig. 2. These results affirm the conclusions that have hitherto been obtained by X-ray crystal analysis concerning the formation of θ″, θ′ and θ (CuAl₂) during the aging or tempering of this alloy.

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In order to make clear the mutual effect of Magnesium and Lead on the “Zamak”, the equilibrium diagram of the ternary system Zn-Mg-Pb has been studied.The diagram obtained is shown in Fig. 1, and its several sections are shown in Fig. 2.

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Research on Lead-alkali-alkaliearth bearing alloys was performed in past years in Europe and America,but very little in Japan.
Dr.Shinba researched the cable sheath alloy Pb-Ca, particularly with regard to its properties for age-hardening and as an extension material.
I have researching on the age-hardening properities of Pb-Ca-Ba bearing alloys. I found difference between these bearing metals (containing about 1%Ca) and the cable sheath alloys (containing about 0.04%Ca). The usual age-hardening properties are more remarkable in worked alloys than in cast ones. The age-hardening properties of cast Pb-Ca bearing metals, however, are particularly good. When this material is quenched the hardness increases gradually. After the hardening, a sudden softening occurs at thelower temperature. There are many interesting problems about the mechanism of the age-hardening properities of Pb-Ca-Ba alloys.

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The author found the metallographic similarities between the ternary alloys Sn-Sb-Ag and Sn-Sb-Cu,especially with tin-rich compositions.
The test was to compare the qualities of the two metals. Under heavy load of more than 60 kgs per cm² Sn-Sb-Cu was shown to be superior to Sn-Sb-Ag, and under light load of less than 60 kgs per cm³ the Sn-Sb-Ag was the better.

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The removing method of H₂O vapour contained in various atmospheres used for bright heating with calcium carbide was investigated fundamentally. The rates of the reaction CaC₂+2H₂O(g)→Ca(OH)₂+C₂H₂, under various conditions were measured with the dynamic method passing wet air into the layer of particles of carbide packed in a reaction tube. The following results were obtained :
(1) The relation between reciprocal of flow velocity of wet air and logarithms of partial pressure of H₂O vapour was linear. (2) The reaction rates were proportional to the quantity of carbide packed in the reaction tube, and inversely proportional to the size of the particles. (3) Although the reaction rate was rapid at room temperature, it became slow exponential with rising temperature.

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The martensitic structure of steel of chromium less than about 16%Cr; carbon less than about 0.1∼0.2% is (A) group, which may contain small percentages of nikel, silicon, molybdenum. The corrosion resistance is very satisfactory in high chromium ranges for resisting weather,water,steam and many organic and inorganic corrodents.
The ferritic and martensitic structure of steel of chromium more than about 16% is(B) group; carbon quite low can increase as chromium goes up and corrosion passes resisting properties superior to (A) group and is especially good for nitric and other oxidizing acids.
The austenitic structure of steel of chromium and nickel is (C) group,which contain enough to make steel for austenitic and non-magnetic structure, and usually contain twice as much chromium as nickel or viceversa; total alloy contain at least 26%, carbon quite low and the steel may contain small percentages of copper, silicon, molybdenum.
Corrosion resistance depends largely upon total alloy content.
This (C) group wall resist nearly all corrodents measurably better than group (A) and (B) and the steel is especially good for organic acids.
The research on these stainless steels for several industries such as the paper manufacture, textile, pulp and dye used for the woven goods and bleaching adjustment will be used by means of heated or cold dilute sulphuric acid, and such as shose hot treated acetic acid, concentrated formic, oxalic or tartaric acids and other organic acids at some temperatures.

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Wires of german silver, eureka, copper and iron, from 0.12 mm to 0.20 mm thick, were immersed in sea water at 25°C; and the manner of their corrosion was investigated, by means of tensile tests, carried out before and after moderate time elapses of immersion. In all cases, the corrosion took place in one mode;in the beginning very slowly, but,in course of time,with monotonous acceleration to the end. This mode of progress do not permit to assume that the reaction zone would propagate with a constant velocity through the substance. The cause of this phenomenon is discussed, and as a conclusion, it is attributed to the heterogeneity of distribution of the “chemically singular points”, caused by the heterogeneous plastic flow which occurred in the interior of the wires when drawn.

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The influences of foreign metallic ions such as Al, Mg, Cu, Zn, Cd, Sn,Pb,Bi, and Sb, upon the method of the determination of Mn, using a reaction of induced oxidation for the analysis of nonferrous metals and alloys,as well as the safety amount of HClO4 to be used were investgated.
(1) The results obtained were summerized as follows:
(1) The results are effected by nothing less than the presence of 1.53 g. of Al,Cu,Mg, Zn and Cd ions.
(2) With the addition of sufficient amount of acid to the solution, no disturbances are given by the presence of a large amount of Sn, Bi, and Pb.
(3) The good results were obtained, by the HF-H₃PO₄ method, from the solution containing a large amount of Sn.
(4) The cloudy precipitate was formed in the presence of Sb over 0.3 g.in the solution, even in the addition of 15 ml. of H₂SO₄ (conc. ), and the results found were less satisfactory.
The evolution of Sb as SbCl₃ by the addition of KCl at the H₂SO₄- fuming treatment, was the most satisfactory separation of it by this method.
(5) The safety amount of HClO₄ (60%) to be added was determined, with which it was possible to yield the good results.
(6) From the results, of these studies some experimental procedures were proposed for the determination of Mn in non-ferrous metals and alloys, and several results obtained were also tabulated.

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The results to be found in the method of sulfur determination in cast or pig iron by the combustion way, are always somewhat low. In this research, the sources of errors to be introduced, are classified as follows: (1) The formation of aerosol from the combustion products, (2) The incomplete combustion of the sample, (3) The loss of gasses produced.
In order to consider these matters, several experiments were carried out, and the followings are recognized as the best conditions for the actual analysis. (1) Air instead of O₂, should be used for combustion,(2) Clean clay boat should be used after washing to remove a clay dust, and pre-heating at 1260∼1280°C, (3) About 0.1∼0.2 g of B₂O₃ should be added as a flux, (4) The amount of sample taken should be 0.1∼0.2 g and the its size should be about 12∼32 mesh, (5) The dimension of the boat should be about 110×8 mm, (6) Combustion temperature should be above 1250°C, time required for combustion should be 20∼40 min, and the rate of air flow should be controlled, thus 100 ml per min at the beginning of combustion, then increase the rate of flow to 100 ml per min for each 5∼10 min, and then to 400∼500 ml per min at the finish. (7) Air should be introduced for combustion by using water-aspirator from the rear point of the train.
Applying these matters pointed out above, one of the experimental procedure was proposed, and the several results thus found were also tabulated.

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The abnormal colour change of starch-indicator, as blue→purple→purple red→colourless, at the end point of the iodometric titration of copper, is apt to cause the excessive titration over the equivalence point and therefore,higher results than the truth. This error is comparatively large when starch is added at the beginning of titration. This led the authors to the present study on the method for diminishing this error and following methods were found to be recommendable: (1) Add the indicator when the colour of the solution has changed to faint yellow and you are just before the end point. (2) If starch is added at the commencement of titration, add it after diluting the solution with water to a volume four or five times as large as the initial, or add it with about 2 g. of KCNS. (3) When the colour of the solution turned purple, stopper the flask with a rubber-stopper after each addition of one drop of Na₂S₂O₃ solution and shake vigorously.(4) Add an excess of Na₂S₂O₃ solution, and titrate back it with the I₂-standard solution, using starch as indicator. In this case it is also necessary to shake the solution well near the end point.
The use of the diluted solution (0.004%) of methyleneblue as indicator instead of starch also gives a comparatively sharp colour change, green to blue, at the end point.

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The content of Fe₃O₄ in scales is usually estimated by calculation from the value of Fe₂O₃ under the assumption that in scales all of Fe₂O₃ are present in the form of Fe₃O₄. But this is clearly not correct,because existence of Fe₂O₃ besides Fe₃O₄ in scales is already proved by microscopic and X-ray investigations. The present authors studied a new method of separating Fe₃O₄ as completely as possible by a magnetic method, and found that it can be separated almost completely from other iron oxides when its magnetic separation is done in the medium of absolute ethyl alcohol.Thus the authors succeeded in obtaining most highly reliable values of not only Fe₃O₄, but also other iron oxides in scales which are : FeO ca. 58%,Fe₃O₄ ca.34%,Fe₂O₃ ca.7%;while the usual method gives the following result: FeO ca.38%, Fe₃O₄ ca.45%,Fe₂O₃ 0%.
Moreover, some thick scales were separated into compact outside and coarse inside layers and oxide contents of each layer were determined by the authors’ method as follows: Outside layer; FeO 37-40%, Fe₃O₄52-57%, Fe₂O₃ 5%; inside layer (the metal-side layer): FeO 60-70%, Fe₃O₄ 12-20%, Fe₂O₃ 16%.

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The present authors published previously a new rapid method for determining lime in basic iron slags which consists of adding NH₄OH and ammonium oxalate to the solution of sample, filtering off the precipitates of calcium oxalate, Fe(OH)₃, Al(OH)₃, etc., and titrating the excess of oxalic acid in the filtrate with permanganate solution. In the present work the authors studied the effect of manganese on this method and obtained the following conclusions:
(1) When only the solution of MnCl₂ was treated, no formation of precipitation was noticed.
(2) When MnCl₂ is added to the solution of slag or lime, results higher than the truth were obtained. The cause of this error was inferred, by analyzing both the precipitate and the filtrate for manganese and oxalic acid, to be a part of manganese precipiatting as oxalate
(3) When manganese is present as a component of slag, the result obtained is quite contrary to the case (2) and satisfactory results are obtained, even if its amount is considerably high. What causes such difference between case (2) and case (3) with the action of manganese remains to be investigated.

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