The author investigated the change of the sturcture on the rolling and annealing process and the appearance and growth of secondarily recrystallized grain by light figure, etch pit and X-ray method using 99.6%Al polycrystal. The following results were obtained : (1) The rolling texture seemed to change gradually from random orientation to (123)[112] with the progress of rolling reduction. (2) The author recognized few differences in the rolling texture between the specimen straight-rolled and cross-rolled. (3) The texture of the 30%-rolled specimen became random in orientation by annealing for 5 min above 400° but the 50%- and 80%-rolled specimens both had still a fiber texture even by annealing for 5 min, at 500° and the primary textures of these later specimens were very fine-grained as compared with the former. (4) Although a few secondarily recrystallized grains appeared in the 50%- and 80%-rolled specimens by 5∼10 min annealing at 600°. The coarsening of the grain was observed only in the 50% -rolled specimen and not in the 80%- rolled specimen. On the other hand, no secondarily recrystallized grain appeared in the 30%- rolled specimen. Considering the above results, the author infers that in polycrystal Al the grain boundary energy plays the chief role in the coarsening phenomenon.

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The effect of various inoculants on Mg-treated iron was investigated by measuring the rate of spherulitic graphitization of irons, and the following results were obtained: (1) When 0.1∼0.2% of inoculants are added to iron treated with 0.5%Mg in the form of 80%Ni 20%Mg alloy, the effect of inoculants on such iron was shown to be Si-Al-Ti>Si-Al>Ti>Al>Si. In the process of the reaction on molten iron, small addition of Al or Al plus Ti causes more shift of the eutectic composition in Fe-C alloy towards lower C content than in the case of the addition of Si only, which results in significant effect of small addition of Si alloys containing Al or Al plus Ti. (2) The order of the effect of inoculants on iron treated with 2%Mg₃N₂ was found to be Si-Al-Ti>Si>Si-Al>P>SiC in the case of 0.5% addition. Al or Ti in the form of Si-Al or Si-Al-Ti alloys must be added in the amount less than 0.1% to Mg-treated iron, the reason being that the increase in such elements promotes the disintegration of the spherulitic form of graphite.

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The effects of degree of reduction by cold-drawing and annealing temperature on the fatigue strength of red brass,cartridge brass and Albrac at 10,000,000 cycles were studied on rotating-beam fatigue tester. The following results were obtained ; (1) Cold-drawing increases the fatigue strength of the alloys but excessive working reduces the fatigue strength. The relations between the fatigue strength and degree of reduction up to 50 per cent are shown in Fig. 5. (2) Low-temperature annealing treatment after cold-drawing is more effective for heightening the fatigue strength. (3) The fatigue strength increased by cold working is not effected or only slightly increased with annealing treatment up to recrystallzation temperature and decreases with annealing treatment over recrystallzation temperature. The fatigue strength reduced by excessive cold working increases with annealing teratment up to recrystallzation temperature and then decreases with annealing treatment over recrystallzation temperature. Those results are shown in Fig. 9.

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Making annealing temperature-tensile strength and elongation curves of aluminum foils by a small tension tester and comparing with those of sheets of the same composition, we obtained the following results : (1) The increase of elongation after recrystallization of foils was lowered very much as compared with those of sheets. (2) The decrease of tensile strength of foils began from the early stage on annealing but the increase of elongation occurred only due to recrystallization. (3) There was no appreciable coarsening of crystals by annealing in foils thinner than 0.4 mm. As to their microstructure, the thinner the foils, the smaller the grain-size after recrystallization, but the diameter of the grain grew up to several times as large as the thickness. In thicker foils, deformation occurred uniformly over their all crystals, but as they become thinner, the numbers of deformed crystals decreased and even micro-cracks were observed. In the recrystallization texture of foils, by X-ray observation, there was no difference from the results of previous studies on aluminum rollings.

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Of the effect of chemical composition on the graphitization of white cast iron, in this paper, the effect of copper was investigated by varying the copper content to 0.32, 0.82 and 1.15% in the case of 2.35% of carbon and 1.75% of silicon content. The behavior of graphitization of white cast iron was studied in the same method as described in the previous paper. The results obtained were as follows : (1) The time required for the completion of the first stage of graphitization was shortened with increasing amounts of copper. (2) The time required for the completion of second stage of graphitization by means of the direct transformation was prolonged (and by means of the indirect transformation was shortened) with increasing amounts of copper. (3) The temperature range, in which the graphitization was completed by only the direct transformation, was enlarged up to the lower temperature below the metastable eutectoid temperature with increasing amounts of copper. (4) The temperature range, in which the direct transformation made the time required for the completion of graphitization shorter than the indirect was found in the case of all the iron samples tested in this work.

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It is very difficult to determine microamounts impurities in ferro-tungsten. Antimony, tin and arsenic has been determined by volumetric or gravimetric method in JIS and A.S.T.M., so the determination of microquantities of these elements is difficult. It would be suitable to determine microamounts of these elements by photometric method. The spectrophotometric determinations of antimony, tin and arsenic in ferro-tungsten which is used as a routine method applying photometry developed in our laboratory are described here. Namely, after these elements were separated as sulfide from main elements such as iron, tungsten and others, the precipitates obtained were dissolved and definite volume of this solution were used in the following procedure. Arsenic with one portion of it was determined with molybdenum blue method directly, and antimony and tin with other portion of it were separated from copper and others by the coprecipitation with manganese dioxide and then determined respective by with methyl violet-amyl acetate extraction method and cacotherine method.

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It took nearly 3 months from September 1954 to build and set-up the furnace and then about a year to accomplish its test operations and remodeling. The actual carburizing of work parts was commenced in January 1956 and on the whole satisfactory results were obtained. A brand of refined domestic propane gas was used, which did generally well enough but we found a generator of high performance was needed. An imported generator was used and continuously operated for nearly 11 months, giving good results without causing troubles. The deviation of carbon content in the pieces worked with this furnace was found very low as compared with that of pieces treated by the pack carburizing method in general use in Japan so far. Consequently we can predict a low deviation in the micro-structure, the effective case, the hardness and the deformation of the parts processed in this furnace.

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Discussing the applicability of various methods for determination of oxygen content in metals which have high vapor pressures in the molten state, it was concluded that vacuum fusion method can not be applied and the following method was proposed : Metal samples were melted in a graphite crucible in nitrogen atmosphere. CO and CO₂, produced by reduction of the metal oxide, were trapped by liq. air and then expanded in constant volume. By measuring the pressures, the oxygen contents were determined. Applying the method to the determination of oxygen content in Bi, Pb, Sb and Cu, good results were obtained.

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The relations between the fatigue strength and the average grain size of annealed red brass, cartridge brass, Albrac and Admiralty brass were studied. The results of rotating-beam fatigue test from 100,000 cycles to 20,000,000 cycles are shown in Fig. 3∼6. The following results were obtained : (1) The fatigue strength depends upon the average grain size, and the specimen of larger grain size shows lower fatigue strength. (2) The experimental equation on the relations between the fatigue strength and the grain size for each cycle is as follows : σ_w=K/α^nσ_w: Fatigue strength, kg/mm² ; α: Average grain size, mm ; K and n: Constants (which depend upon the material and the repeated test cycles).

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The maximum transformation temperature in eutectoid reaction for 5.37%Cu-Si alloy cold-worked after quenching from 750°C (at which temperature it had been kept for 10 hours) was determined by measuring the electric resistance at constant heating velocity. Its activation energy and frequency factor were calculated by the formula of first order transformation and k₁ the velocity constant of transformation, was determined from Arrenius’ formula with these calculated data. The following results were obtained : (a) The transformation temperature for heating velocity above 10°C/min was transferred to the side of higher temperature in the case of working ratio less than 7% and was very sensitive to the heating velocity in the case of working ratio higher than 7%. (b) The activation energy was decreased according to the increase of working ratio. (c) The difference of inclination of the-logk curve for working ratio below 7% was much more perceptible than in that for a ratio above 7%.

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The process of the peritectic reaction depending on the relative position, ‾LS⁄‾SP, of the three phases on the non-variant system was studied for the ‾LS<‾SP peritectic system by the same method as in the 1st Report. From the result, it has been confirmed that the process of its reaction was decided by its ‾LS⁄‾SP value.

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In the previous studies on the secondary recrystallization of high-purity Al single crystal, it was found that the coarsening phenomenon occured only in the specimen which had received a large internal strain energy by cold rolling and had a fine grained structure with an intense primary preferred orientation. In the present study, the author investigated the effects of various impurities (Fe, Sn, Mn Cu and Mg) on the coarsening of high-purity Al single crystal. The following results were obtained : (1) All impurities induced the coarsening at reduction between 50 and 75%. This range in reduction is slightly lower than that in high-purity Al single crystal. (2) In the present specimens which induced the coarsening also, the primary texture was a fine grained structure with a comperatively intense primary preferred orientation. (3) The orientation of the secondarily recrystallized grain was almost the same as that in high-purity Al and spreads from (113) to (156), irrespective of the kind of alloying element. (4) The coarsening range of rolling reduction and of orientation was not different by the kind of alloying elements of 0.2% in amount.

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The oxidation processes in atmospheric air of Ti, Ti-Al (3∼10%Al) and Ti-Si (0.3∼1.5%Si) were studied through the weight-increase, and the surface films formed on them were examined by electron diffraction. The weight-increase versus the oxidation time curves obtained at 700∼800° showed that the law which controlled the oxidation was not simply parabolic, but more complicated, being in accord with many previous works, and that the oxidation was slightly suppressed by addition of a small quantity of Al or Si to Ti, especially at lower temperatures. The surface oxidized at 400∼700° gave diffuse diffraction rings due to TiO₂ of rutile-type and occasionally a few rings due to TiO₂ of anatase-type, too, while the patterns consisted of rutile only at 800∼1000°. Two kinds of selective orientation of rutile crystals to the substrate were found at 700∼900°. Throughout the present study, neither titanium oxides other than TiO₂ nor oxides of the additional elements have been observed.

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The developments of strain markings produced in polycrystalline zinc by thermal cycles between room temperature and −196°C have been observed after each cycle. There is clear microscopic evidence that twins may be initiated by the high local stresses produced round the tip of cleavage crack. Some of the twins initiated by cleavage crack are seen to become lens-shaped twins separated from the cleavage crack after further cycles, but others spread or shrink along the cleavage crack with cycles. Some of the cleavage cracks being arrested at grain boundary initiate twins or kinks in the next grain. No twin initiates the cleavage crack. Many examples have been observed of cleavage cracks being arrested at a pre-existing twin boundary, but most of the cleavage cracks propagate across the twin after further cycles. Micro-kinks also may be produced at the tip of cleavage cracks, and many examples of micro-kinks along cleavage cracks were observed.

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In the present studies, X-ray analysis, electron diffraction and thermomagnetic analysis were carried out on carbides isolated from tempered plain carbon and low alloy steels, and the nature of carbides precipitating in tempering of steel were discussed. The electrolytic isolation of the carbides were performed with a hydrochloric acid cell containing 0.05% propargyl alcohol as inhibitor. In the first stage of tempering, hexagonal closepacked carbide, of which the unit cell dimensions are a=2.74 kX, c=4.34 kX, was precipitated. Reflections from the orthorhombic carbide precipitated in the third stage of tempering are very similar to those of the platelet cementite reported by K. H. Jack, and no positive evidence of the intermediate formation of iron percarbide has been obtained. These features of the tempering process are not influenced by alloying small amount of special elements in steel. However, the nucleation of orthorhombic carbide is retarded by alloying Si, Al and P, but hastened by S, Cr and V slightly hasten the nucleation, but retard the growth of orthorhombic carbide in tempering.

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The object of the present lecture is to give a general idea of the progress made in recent years in the process of sand moulding and thereby to call up the interest of the members of the Japan Institute of Metals for general founding of metals. From the nature of this plan the author has endeavored mainly to make clear the principle of various processes of making moulds.
In the first section the nature of molding sand is discussed, giving mineral analysis of natural sands and studying the thermal expansion of quartz and feldspar, the main ingredients of sands. They expand linearly 1.4 per cent on heating them to 1200°C. Various casting defects such as rat tails, buckling and seabbing are caused by this expansion, especially by the abnormal expansion due to the α—β transformation of silica sand at 575°C, and also by the acute temperature gradient from the hottest mold skin to the coldest buck sand.
In the second section the natures of clay and bentonite are discussed. The process of making sand mold is after all the process of binding of sand grains and the recent progress has been made by studying how to utilize organic and inorganic binders. As inorganic binders we use clay and bentonite which develope their binding action by electrochemical action of their colloidal particles. However minute their particles may be, they have no bonding action without the aid of OH ions in their crystal structure. They are merely non-bonding ashes if they are dehydrated at high temperatures. In the case of organic binders the binding action is caused by resin-aus polymers. The drying of core oils and the curing of shell mold resins are the examples of this type. We have another group of binders such as ethyl silicate and water glass. In this group the bonding of silica sands is made by the gelling action of Si(OH)₄ deposited from alcoholic or aquaus solution. In any case, organic or inorganic, the viscosity of binders, the setting time and the strength after setting are the main items in actual molding practice.
Standing on these viewpoints, the author describes the crystalline nature of clayey minerals, their thermal contraction, their dehydration and recrystallization, referring to many papers from various sources.
In the 3rd section he discusses the drying phenomena of core oils, the mechanism of which is not yet clarified but in final analysis, the binding action of baked core oil is nothing but the binding action of resinous polymers.
In the 4th section the author discusses the shell molding process. It has been generally known that many modern synthetic resins were used as binders for glass fibers, rock wools and compound plates. The Croning process is not an inconicevable method if we imagine the past utilisation of resins as binders.
In the 5th section he explains the lost wax process, which is an oldest art of oriental founding. In ancient time, molders engraved wax, enbedded it in loam mold, melted out the wax pattern by heating, and thereafter they poured bronze. We have many bronze articles which could not be produced except by this process. The modern investment castings are manufactured by sand mold-bound by ethylsilicate solution, the silicic acid Si(OH)₄ being the binder of this process.
In the 6th and the last section he describes the recent development of CO₂ process. The polymerised silicic acid, deposited by the decomposition of sodium silicate by the action of CO₂ gas, is again a gelatinous binder of silica sand.
In conclusion the author emphasises that there are so many processes introduced into practice under the cooperation of chemistry. Every process has its own field of application, the classical process using sand and clay having the widest and the investment casting using wax pattern and ethyl silicate having its special field of practical application. And if we suppose that the shell molding process, for example, is applic

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