The authors investigated the gaseous reducibility of several ores in order to estimate the maximum size of ore suitable for blast furnace charge.
About 1kg of each ore, which was crushed to various size (maximum of 3 in), was treated at 900°C using 20l/min/kg of H₂ gas as a reducing medium. The reduction degree was based on the total weight of oxygen which combined with the iron in ore, and measured by means of the loss-in-weight method.
It was found that the reduction velocity became higher in the sequence of magnetite→hematite→limonite, and that the higher the porocity of each kind of ores the higher the reduction velocity. Curves expressing the relation between the ore size and the time required for 90% reduction showed a trend to diverge in the case of magnetite and dense hematite, while in the case of porous hematite and limonite to converge.
Further, the authors assumed the maximum size (suitable for blast furnace charge) of hematite-ore of 24% porosity to be 2" (in dia.) and took the size of the other ore which reqiured the same time for 90% reduction as that of the above mentioned standard ore as its maximum size.
It was concluded from the results that the maximum size for magnetite was 25-30mm except those which had very low reducibility, about 40mm for dense hematite and about 50mm for porous hematite. With hematite and limonite of high porgsity or those which suffered cracks during heating, the size of org became no more a dominating factor upon reducibility.

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One of the important defects in the large carbon steel forging is the one relating, to the Λ segregated zone of the ingot from which the forging is forged. The reason why it has been very difficult from earlier time to control this defect, lies in the fact, that any definite theory on the mechanism of appearance of the Λ segregated zone in ingots has been unable to be established. Investigating into the Λ segregated zone of 20t ingot in order to get some clue of the problem relating to segregated zone, the author found several facts, which were regarded as valuable for a consideration about the appearance of segeregates, that is, the existence of a large number of segregated faces besides segregated lines in the Λ segregated zone, the relation between segregates and primary crystals, the characteristics of structure of segregates etc.

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Maintenance of certain percentage of perfectly round shots, while removing the broken shots and replacing those with new shots, is important in shot-peening treatment. With respect to this process, the life of shots will affect the necessary amount of supply, and stands as one of important factors which determine the economy of peening operation.
The authors investigated the life of several ferrous and non-ferrous shots by a specially designed testing machine. The results obtained were as follows:
Life of larger, harder and faster traveling shots was low, but could obtain higher peening intensity. Comparison of life of ferrous shots, under the same peening intensity, showed that the steel cut wire shot had the 1ongest life followed by that of cast steel and cast iron shots.

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This paper gave results of U-notch Charpy tests which were carried out at several temperatures ranging from -80° to 400°C for the purpose of determining the effect of arsenic, copper, tin and molybdenum on the transition temperature of dead soft steel and also determining the effect of carbon and arsenic on the transition temperature of carbon steels. The results obtained were as follows:
1) Carbon raised the fracture transition temperature of steel but in case of U-notch Charpy test it did not raise the ductility transition temperature such as that which was defined by 15 ft-lb energy.
2) Arsenic raised the transition temperature of steel, but arsenic less than 0.1% did not change the transition temperature of steel even when it was contained alone in steel or together with copper and tin.
3) Copper less than 0.35% does not change the transition temperature of dead soft steel when it is contained alone in steel or together with tin and arsenic.

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As one method of expressing rupture characteristics of steels, states of rupture can be used.
In this report, the author compared and studied the states of nominal stress-convertional strain-curve and elongation percentage etc. described in No. 2 report, thus obtaining characteristics of high-temperature high-speed deformation of various steels.
The γ-α-embrittlement, the 900°C-embrittlement recognized in the course of these experiments were also made clear.
By performing high-speed tension test at the super-high temp. of 1250°C up to the melting point, the author further discovered that deforming resistance uniformly continued to decrease until it reached the melting point.

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Both the low tempering temperature embrittlement and the transition characteristics of high strength steel are in close connection with the quality of steel, and the effect of Al, Ti and B addition upon them is thought to be very important from the industrial point of view, as it is related to the deoxidation, nitrogen-fixation and austenite grain size of steel.
The authors, therefore, have investigated the effect of Al, Ti and B addition on the low tempering temperature embrittlement of high strength Cr-Mo steel from the view point of impact transition characteristics.
Results obtained were summarized as follows:
(1) The Al, AI-Ti or AI-Ti-B treatment improved the impact values at the tempering temperature ranging from 100 to 450°C. Especially in the case of the Al-Ti-B treatment, the impact value in the range of embrittlement was markedly improved.
(2) The tempering embrittlement temperature was not changed by the Al treatment, and the embrittlement occurred at about 300°C. But the A1-Ti or A1-Ti B treatment raised its temperature to about 350°C.
(3) In each treatment, the transition temperature varied apparently with the tempering termperature: the tempering within the range of embrittlement at 300 to 350°C and at about 100°C causes a higher transition temperature, whereas the tempering at about 200°C(the impact value was maximum at this state) and at about 400-450°C resulted in a lower transition temperature.
(4) The Al, Al-Ti or-Al-Ti-B treatment lowered the transition temperature, especially the Al-Ti and Al-Ti-B treatments markedly lowered it in the range of embrittlement of tempering at 300 to 350°C.
Therefore, by the proper treatment with such elements, actual finished products were presumed to be given more security against the brittle failure.

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The steel products of Japan have contained more Cu than the mported products due to their raw materials, and after the War II that tendency has been especially remarkable. The authors studied the effects of Cu on the silicon-manganese spring steel, systematically, with the samples industrially produced. The results of the present paper concerning the hot properties were as follows:
1) Cu has scarcely affected on the growth of austenite grains.
2) On the eye-back work in the manufacturing of the springs, the temperature of generating the cracks lowered as the Cu content increased.
3) In the hot-tensile test, Cu increased slightly the tensile strength and the yield point of the steel but decreased very fairly the elongation and the reduction of area.
4) In the hot-impact test, the increase of Cu content promoted the brittleness of the steel at high temperatures.
5) The resistances to the deformation measured by the drop-weight method increased slightly with Cu.

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Characterized in light weight, strength, and excellent heat and corrosion-resistance, metallic titanium is coming into the limelight as a structural material. The properties of the element may be summarised as being intermediate between those of aluminum and stainless steel.
Although titanium alloys containing aluminum, manganese, chromium and molybdenum as alloying elements are still on the way to development at present, products of excellent quality are being produced out of industrially pure titanium.
Production of metallic titanium in Japan in 1954 was 610 tons, only next to the United States of America. Production plan for 1956 is aimed at 5, 000 tons.
Since titanium ore is iron sand abundantly produced on the sea-coast of the North-eastern region and other parts of Japan, she will not become short of the resources in the future.
A brief description of refining and processing techniques of metallic titanium is as follows: Researches in the refining process of iron sand to extract pig iron from iron sand had been made by Dr. Iwase and many other laboratory men in Japan. It was before 1942 when the electric furnace refining process was developed to yield 60% TiO₂ slag and pig iron on an industrial basis.
Therefore, slight improvements over the conventional know-how was all that was necessary to complete production technique for TiO₂, a material to be used in the industrial method of metallic titanium known production as the Kroll Process, which had been established by Dr. Kroll and Mr. F. S. Wartman.
The technique to chlorinate TiO₂ to produce titanium tetrachloride, then to reduce it with magnesium to produce sponge titanium was accomplished in 1952 with Dr. Kroll's close supervision. Further, the technique of melting was completed with Mr. Gilbert's direct assistance. The subsequent processing techniques as forging, rolling, drawing and extrusion, are on the way to completion by the utilization of techniqnes and equipments for processing special steel and aluminum.
As pointed out in the main text, however, part of these techniques needs basic improvements. In order to find a method to substitute the Kroll Process, researches have been made on the fusion electrolysis method, the refining method of lower chloride, and the sodium reduction method, each of which is already developed to a stage of yielding a material as good in quality as one obtained by the Kroll Process. But, since these productions have not reached an industrial scale yet, they are not discussed in the main text excepting several special examples.
Discussions contained in the main text are as summarized below. Introduction about various characteristics of titanium as a structural material will ensue in the next issue.
I. Flow sheet for titanium production in Japan.
II. Mineral deposits yielding titanium.

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