The overall change in the vital raw materials for iron manufacturing, inevitably caused by that time situation, came to the Wanishi Iron Works in July 1943. The faborite North China coal had to be replaced by the Hokkaido coal, so were the varied foreign ores by the domestic. The detailed progress and effects or the above change in raw materials, together with our countermeasures taken thereto, are the points in this report.

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By utilizing oxygen as an accelerating agent for the producer gas combustion in the open hearth furnace, the melting time can be shortened, and steel production rate increases. But the high cost of oxygen at present prevents the applicaion of oxygen into daily practice generally, therefore in place of oxygen compressed air was used and the comparison tests of both effects on shortening the melting time by the Venturi type acid open hearth furnace (Nominal capacity 40t) was performed. As the results, the melting time was shortened by 14% by use of oxygen and was shortened by 13% by use of compressed air. And the fuel comsumption during the melting period is saved about 10% by use of oxygen or compressed air.

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It was found that, with the addition of ferro-chromium in the last period of refining at the basic arc furnace melting the non-metallic inclusion in molten steel being decreased conspicuously, the chromium turned out to be one of the strong cleansers. The non-metallic inclusion was determined by the microscopic examination, which is the method established at the 19th Sectional Committee of the Japan Society for the Promotion of Scientific Research. The results obtained were as follows.
(1) In case of ferro-chromium aqdition to chromium-steel melting, about 30-80 per cent of oxide-inclusion was removed.
(2) The steel, in which chromium was added, has more clearity than the steel in which it was not.
(3) As the addition of chromium even the 0.1-0.2 per cent being effective in case of plain carbon steel, there is rather recommendable to apply the method to the melting steels capable to include about 0.15 per cent chromium.
(4) On behalf of the reduction of inclusion, the ferro-chromiun addition is prefered to be done after that of ferro-manganese.
(5) It was found that the inclusion decreasing ratio to be closely related with the basicity of slag. Namely, when the basicity (CaO/SiO₂) is proximately ahout 2.6-3.0, it shows the maximum of decreasing ratio of the inclusion, however, it is lowered as the basicity rises, and arrives to the lowest at the instance as it shows abont 4.2-4.5 of basicity. It must be noticed that when the basicity is below about 2.6, the decreasing ratio goes down either.
(6) Not only the decreasing ratio, but the inclusion containing ratio also keep close relation with the basicity of slag. Namely, when the basicity (CaO/SiO₂) is proximately about 3.2-3.5 before ferro-chromium addition, the inclusion containing ratio was the least. Accordingly we have to keep the basicity in about 2.6-3.0 in order to rise the decreasing ratio with ferro-chromium addition; but on the other hand, as such lower basicity runs the risk of increasing the inclusion containing ratio, it seems rather profitable to keep about 3.2-3.5 of basicity before the ferro-chromium addition for the reduction of inclusion.

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Using carbon steel and hyper-eutectoid special steels containing 1 and 2% of Si, Ni, Cr, Cu, Mn, Al, Mo, Co, V and W individually, effect of these special elementa on spheroidizing of carbides in these steels by tempering after quenching was studied.
Specimens quenched in water and in oil at complete austenite region were tempered at 600, 640, 680 and 720° for 20hrs, and the rate of spheroidizing of carbides was measured by means of Rockwell hardeness tester. In steels containing some elements which do not form special carbides spheroidizing of them easily proceeds, but in steels containing another elements which form them the rate of it is slow. Quenching condition of steels, such as in water or in oil, do not effect on the spheroidizing of carbides by tempering, and undissolved carbides in austenite at quenching temperature also do not effect.

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In succession to the previous egperiments, we have studied the residual stress of quenched high Ni-Fe alloys by G. Sachs' boring method. The results are as follows: (1) When the γ→α transformation is in the higher temperature range, the thermal contraction and the expansion caused by the transformation act on the residual quenched stress additively. (2) In the case of irreversible high Ni-Fe alloys, of which γ→α transformation lies in the lower temperature range, or in the elastic range, it seems that the effect of thermal stress has been erased and only the effect of transformation appears on the residual stress. (3) With regards to the high Ni-Fe alloys such as no transformation takes place above room temperature, we have obtained the distribution curve of pure tbermal stress type (outer-compression, inner-tension) about the usually quenched specimen. However, when the quenched specimen is still more cooled to the liquid oxygen temperature so as to pass the γ→α transformation range, it is recognized that the previous residual stress is relieved. (4) The effect of thermal stress on the residual stress of quenched specimen is more remarkable as the section becomes larger.
From the results of experiments above mentioned, we have tried to make aome theoretical explanation about the mechanism of origination of quenching stress when quenched from γ to α state of Ni-Fe alloys.

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Followlng the 8th report, the effects of Ti, Zr, U, Mo, Cr and Mn on the hardness microscopic and cutting tests of the standard tungsten carbide series tools made by the special deviced apparatus were investigated.
Moreover, the effects of the repeated tempering on the expansion, microscopic, cutting and hardness tests at room and high temperatures of the various high speed steels were investigated. In general, the results of investigations showed that the repeated tempering at short time of the high speed steels were superior to the continuous tempering at long time.

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The strain-age-hardening problem of the mild steel is as important in practice as in laboratory. The yield-point-jog appears in ordinary mild steel, its disappearance of after cold work and its reappearance on aging after cold work are the typical characters of this problem.
Therefore, a great deal has been investigated on this problem and recently interest has been increased by the confirmations that the both C-& N-atoms in the mild steel play a leading role in this phenomena and aging effects can be minimized by a drastic deoxidation.
In this paper, the author will try to introduce the representative three theories about the problem, that is, the skelton theory, the transformation theory and the dislocation theory.

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Since February 1949, recommendations have been constantly given by the many iron and steel experts visiting Japan to standardize the dimensions of oil fired open hearth furnaces in Japan. Since Jnly 1949, the Investigation Committee has taken up this subject for study and discussion and has recently arrived at a conclusion which it is hoped will serve as a yardstick for open hearth installations and renovations that may occur in the future.

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