The Kukioka No. 1 coke oven (Nittetsu compound type having 75 retorts) was first put to operation on August 5, 1991. It was compelled to suspend its function and to cool down since the airraid of August 8, 1945 through the subsequent postwar confusions.
Damages worth special mention about the oven condition at that time were that in some places the chamber wall was bent in one direction (at the worst spot expanding outward by no less than 105mm.) and that more than 15 retorts were not working normally.
Maintenance during the time of suspension was not satisfactory. Having passed three winters before resuming the operation on July 23, 1949, the bricks of the oven body had considerably got wet through.
A survey of the bricks showed that, although they had deteriorated to a certain degree, they were not unfit for continued use.
For the resumption of the oven operation, no renovation at all was made on the cracks in the oven body or the brick bonding; in other words no pointing up with mortar was done at all. No repair work was conducted inside the regenerator either.
As regards the combustion chambers whose walls had been bent, 6 of them (12 chambers) were thoroughly repaired and dried before starting the oven operation again.
The result is quite satisfactory in the general tone of operation, including the oven condition after drying, the spread of oven temperature when the blast furnace gas is used for heating, throughout its pig-steel processes.

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Determined the equilibrium constant K₁=PH₂O/PH₂S of the reaction
at 1000-1100°C and obtained the following equation
Hence, from the above result, obtained the equation
for the reaction

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Sand mould expands or contracts when dried by heat. And a part of the expansion or contraction does not retire, but it is retained after cooling. We must have in mind the expansion or contraction to produce accurate castings. The author studied these volume change of sand mould and concluded that the moisture per cent in the sand mould have the important effect.

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We have some proofs, even if indirect, that there are many minute cavities in steel. Modified the hydrogen theory of white spot studied by German investigators, Prof. K. Honda advanced the cavity theory (Containing also the thermal and transformation stress theory). The author tried to consider more extensively about the effect of cavity on the behaviours of hydrogen in steel.
The discussion covers the hydrogen pressure in cavity and the effect of cavity on the diffusion of hydrogen in steel. In the ideal case when the hydrogen equilibrium between metal and cavities is always realized without any hydrogen loss from metal body, the hydrogen pressure attains to its maximum at nearly about 150°C, and the maximum value increases with hydrogen content and with reciprocal of cavity's volume.
The hydrogen pressure becomes very high at the segregated zone even in the case of normal hydrogen content, soon after the most segregated part transforms prom γ to α phase, and this may be one of reason why flakes are apt to appear in the segregated zone, while it does never flake in austenitic condition according to the higher solubility of hydrogen in austenite. Actually, it takes time to attain to the hydrogen equilibrium in the case of variation of physical condition, and the lower the temperature is, the longer the time. On the other hand, the greater part of hydrogen in steel precipitates into cavities at lower temperature, and yet, if the total volume of cavities is considerably large, the quantity of hydrogen in cavities can not be neglected up to higher temperature, espceially in the case of a phase. In this case, the diffusion of hydrogen in steel and the escape of hydrogen from steel body are retarded to a great extent.

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Experiments performed after the publication of the 1st report reveal the fact that the Mn titer of one and the same As₂O₃ solution varies according to Mn content in the standard steels used for standardization. It signifies that standard steels containing approximately the same amount of Mn as actual samples must be chosen-as accurately as possible on principle-in order to prevent errors. The above-mentioned method, however, is too inconvenient to be adopted as routine analysis in plants where many sample pieces are dealt with. The experiments, carried out with a view to eliminating such a defect, point to the conclusion that satisfactory and concordant results are always obtainable by adding a chloride such as KCl or NaCl before the titration.

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The effects of quenching and tempering refrigerant, (rape-seed oil, coco-oil, machine oil, lead bath, salt bath and air) on the hardness, microscopie, (ordinary etching and electrolytic etching method) and cutting tests of the various high speed steels were investigated.

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The author, whose speciality is chemical industry, has an intention of giving a few impressions of the iron and steel industry of Japan after his tour of inspection of the same industry of America. He learned that the following points are particularly needed:
(1). Increase of the kinds of products in addition to the quantity of them. (2). Changing our point of view for the things in order to put the idea above mentioned into effect. (3). Attaching importance to technical research.

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Since the end of the War, spring steel has become one of the most important special steels in Japan.
In 1948, the production of spring steel amount to 29, 714 tons in the total amount of special steel production of 87, 136 tons. Meanwhile the level of quality of spring in Japan, may be lower than that of in America and in Europian countries. Therefore, for general reference, the auther collected here the various recent data of spring steel, such as the history, chemical composition, mechanical property, heat treatment, mass effect, cold working etc, which will be thought to be useful for manufacturing spring and spring-steel.

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