The oxydisability of the practical open hearth slag is so great that any means to retard this actions is not found except the controlling of viscosity of the slag. The controlling of acid slag viscosity is performed mainly with the amomt of solid SiO₂ in slag. As resultant effect of many factors, the reoxydation at the final period of scrap remelting process is barely obtained.

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The mean variation of nitrogen during the smelting in the basic open hearth furnace is represented approximately by the next equation
or
The formal equation is deduced from the relation between the real action of nitrogen and carbon graphically and the latter is deduced from the ratio of mean velocities by the least square.

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The ingot mould made of cast steel, instead of cast iron, were adopted by our Works to lessen the increased consumption caused by lack of pig iron and coke of good quality.
The results were satisfactory enough: the slab mould weighing 1, 200kg endured to the contineous use of average 142 times. The suitable carbon content was 0.4-0.5%. The special device was taken to avoid its strain by heat.
The author expects, under present condition of Japan, 3-5 times durability compared to that of cast iron mould, whereas the manufacturing cost of it falls 2-3 times of the latter.

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Steel used for the casting should have special properties compared with the structural steel. These properties are analysed by the following classification
1. Gas hole, shrinkage cavity
2. Hot tear
3. Weldability
4. Mechanical property
5. Fluidity
To satisfy these properties, at first, compositions of the steel are studied and we acquired following results:
1. To prevent the happening of gas holes, gasses in the steel must satisfy following conditions, O₂<0.01%, (Mn>0.65%, Si>0.35%) H₂<0.0004%, N₂<0.005%. Shrinkage cavities are lessened when degassing are sufficient.
2. To decrease the defect of the hot tear, the steel must have fowllowing compositions; S<0.01%, Mn>0.7%, and Al used for deoxidizer is apt to increase the hot tear, so that Al content is preferable under 0.05%.
3. Weldability of the cast steel is not so much inflnenced by compositions, but following compositions are preferrable for welding operation, less than 0.3% of C, and S must be as small as possible.
4. Mechanical properties of the cast steel are not so much influenced by the compositions, too, except C should be determined by the strength demanded.
5. Also, fluidity of the cast steel is not so much influenced by the normal compositions, To obtain good fluidity, the molten steel should have sufficient temperature. By the above mentioned results, necessary compositions of the medium carbon cast steel are summarized as follows. C<0.3%, Si>0.35%, Mn=0.7-0.9%, P<0.05%, S<0.05%, O₂<0.001%, H₂<0·0004 %, N₂<0.05%.

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The authers carried out the experiment of effect of vanadium on the tool steel for hot work by the same method as the first report. As the results of this investigation, it is ascertaind that the moderate quantity of vanadium are about 0·3-0·5% for tool steel for hot work contaning C 0·25%-0·35, Cr 2·5, W 9-11%.

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The development of heavy cold-rolling operations of the backed-up type has drawn attention to the rolls employed. The paper is a record of the pioneer's research and experience with the large working rolls in Japan. The process of manufacturing steel ingots with basic electric furnace and then forging, quenching, machining, grinding, and finally inspecting methods are discussed. The stress relationships occurred in quenching period are also discussed. Some suggestions are advanced for improving cold roll performance.

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The reduction equilibriums of fayalite by carbon monoxide and by hydrogen were investigated thermodynamically. The following results were obtained by calculating the free energy in the formation of fayalite and from the experimental data for the reduction equilibrium of ferrous oxide obtained by Eastman;
a) by CO ΔF°=7604+6.335TlnT-0.00317TT²+0.00000025T³-45.031T
b) by HH₂ ΔF°=18138+6.735TlnT-0.001378TT²-59.657T
Then, it was found that those reactions were endothermic, and the heats of reactions were also calculated between 600°C and 1000°C.

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