For easy determination of caking property of various kinds of coal, not a few simple methods on a laboratory basis, requiring only a small amount of coal sample and no special apparatus, have been proposed. In the present treatise the drawbacks of those methods are pointed out and a new simple method for the purpose, devised from a fresh angle, is suggested. This method has been applied to thirty-nine different kinds of coal and also to charge coal, with the result that their characteristics as material for making metallurgical coke could be determined with a compara-tively greater ease and accuracy.

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The reverberatory furnaces for roll-making in Yahata Iron and Steel Works were equipped with the Kubota's chain grate-stoker.
The following factors were studied to save the fuel costs and cut down the melting period:
1. Use the fuel oil by the auxiliary in this furnace.
2. The relation to the latent heat of ash and the factors of combustion.
3. The relation to the draft in melting room and leakage.
We decided the standard work from the preceeding studies and could increase the thermal efficiency by these methods.

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In order to study the hehaviour of the individual metallic oxide in molten slags, the electrical conductivity of the systems sodium-silicate-metallic oxide was measured. The concentration of the fundamental sodium-silicate was Na₂O 32.45mol%, SiO₂ 67.55mol%, and the content of additional metallic oxides SiO₂, Al₂O₃, CaO, MgO, MnO, FeO and NiO were 10mol% and 20mol%. Samples wree melted in an alundum-crucible Elema-furnace being used. Measurement was done by the conventional alternating-current-bridge method.
Generally when additinal oxides are acidic, the electrical conductivity was smaller than that of the fundamental system; and when basic, it was larger (except for CaO). This was explained to be owing to the modern acid-base definition.
When acid oxides were added, the number of mobile Na₊ decreased, lowering the conductivity, while by addition of basic oxides, the number of mobile cations increased, enhancing the conductivity.
In case the basic oxides were added, the specific electrical conductivity decreased in the order of NiO, FeO, MgO, MnO, CaO. This order corresponded to the increase of radii of cations of the added oxides (except for Mg⁺⁺), and to the decrease of εM (thermal energy per g-mol evolved when a solid oxide was formed from 1g-atom metallic ion and O^-- of the corresponding number both in the gas state) obtained by Huggins and Sum εM was by definition the strength of the bond between metallic ion and oxygen ion-that was the basicity of a metallic oxide.
Accordingly the weaker was the strength of the basic oxides added, the larger became the electrical conductivity.
The number of the mobile ions being same, only the mobility of ions was the controlling factor.
The smaller were the radii of cations, the more easily they moved; and the larger was εM, the more appreciably decreased the stability of bonds Si-O, and so again the more easily cations could move.
When CaO was added, the electrical conductivity decreased, being due to the fact that the mobility of Ca⁺⁺ was small.
The radius of cation and εM determined the form of the SiO₄-tetrahedron, and controllled the strength of bonds between cations and SiO₄-tetrahedron. This related to the activity of constituents.
In fact the order of activities of SiO₂ in several binary silicate melts corresponded to that of εM and so of the electrical conductivity.

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On the view point of the manufacture and the practical use of the stainless clad plate, the authors studied the effect of heating on the various properties of clad plate. The results of experiments and considerations, were stated as follows:-
When the stainless clad plate was heated, various alloy elements in the contact face of both metals were diffuεed, and their diffusion increased as the temperature rises and the holding time increased.
In case the clad plate was heated at temperature above 800°C, the alloy layer was made at the contact face by diffusion of elements. Once the alloy layer was presented, the binding strength of both metals was decreased. Therefore, the heating at high temperature must be avoided.
Moreover, by travelling of the carbon in the mild steel to the stainless steel by diffusion, the corrosion resistant property of the stainless clad was presumed to be inferrior. Then, the heating at high temperature must be avoided and the lower carbon content in the base metal was found of advantage.
The deflection produced in the clad plate by heating increases as the temperature rose and as the clad thickness increased. Specially, the deflection increased suddenly at about 800°C, because of the transformation contraction in the mild steel.
When the clad plate was utilized at parts where the deflection by temperature change was remar-kable such three layer clad plate must be selected which had same clad thickness at surface and bottom.

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On the purpose of protecting high temperature oxidation of iron and steel, the spraying of heat resisting alloys as Nichrome alloy or iron-chrome-aluminium alloys, was tested. The life of sprayed specimens was shown in Fig. 1-6, and it was found that the desirable thickness of the sprayed coating was more than 0.3mm. The soundness of sprayed coating of heat resisting alloys was more important factor compared with the case of aluminium spraying.

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The effect of tension on the isothermal transformation of Si-Mn-Cr-Mo Steel was researched and discussed. The results were as follows:
1) The isothermal transformation was accelerated by the tension given at low temperature (400-700°C).
2) The isothermal transformation was retarded in a certain condition by the tension given at high temperature (870°C).

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Using Swedish carbon steels containing 0.5, 0.9, 1.3% C and Ti- and Cr-steels, spheroidizing of carbide was studied by means of the following four kinds of heat treatment, that is, quenchingand-tempering, slow cooling, repeated heating-and-cooling and isothermal transformation. From hardness of the spheroidized specimens obtained by thus four heat-treatments, the procedures of spheroidizing were compared, and the following facts were ascertained:
a). By the quench-and-temper method, the spheroidizing of carbide most slowly proceeded, but the sphericles were finely and uniformly distributed.
b). In hypo-eutectoid steels, the spheroidizing most rapidly proceeded by the repeated heating and cooling method. But after several repeat no more spheroidizing proceeded.
c). By slow cooling method, spheroidizing rapidly proceeded, but the pearlite structure came out easily unless the rigorous heating temperature was taken.
d). By the isothermal transformation method, the process of spheroidizing is comparatibly slow but the uniformly distributed structure was obtained.

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The high carbon-high chromium steel is today playing a very important role in the improvement of the efficiency of mechanical industries, particularly in the field of punching and cold drawing dies.
The authors carried out a series of experiments with four samples of high carbon-high chromium steel and studied changes in their hardness and deformation brought about by different heat treatments, and also tested their mechanical properties at room temperature and high temperatures.
As the results of these experiments, they found the most moderate composition and heat treatment of dies steel, concluding that 2% or more carbon content in the dies steel containing 14%Cr was the better for the punching and cold drawing dies.

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In this report, the effect of "hot-cold work" and "cold work" of Timken 16-25-6, the heat-resisting alloy for gas turbine material, was studied.
There are four different compositions in the specimens. Three of them were analysed in the author's first report. (Tetsu to Hagane 1952, Vol. 38, No. 5) Another one was Timken 16-25-6, but it contained 0.16% nitrogen.
After hot forged, these samples were solution-treated at 1150°C for 1 hour. The work was made at three states of temperature, 650°C, 900°C and 1000°C, by the Amsler's tensile test machine.
The ratio of work was computed as the ratio of reduction of area. After measuring of hardness and microstructure, these samples were tempered at 650°C or 800°C. Then changes of hardness were measured. From the view point of components, when Timken 16-25-6 alloy contained nitrogen, there was effect of "hot-cold work" or "cold work". Material worked at 650°C had the highest hardness, that worked at 900°C had next hardness, and that worked at 1000°C had hardly any effect of work.
From the view point of the temperature at which the material was to be used, work-strain (effect of work) did not remain at 800°C, but it remained at 650°C. It seemed that the "cold work" sample kept its high hardness by work-strain chiefly, with acceleration of precipitation-hardening.On the other hand, the "hot-cold work" sample kept its high hardness by the work-strain plus precipitation-hardening.

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In determing the sulphur in B.F. slags and O.H. slags by the combustion method, we break the combustion tube frequently, by heating at temperatures above the melting point of slag (1400°C).In order to remove this weak point from this method, the auther improved this method to be carried out at lower temperature (1200°C) by adding iron powder and B₂O₃ powder to the slags.

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Studies in the effect of boron on iron and steel have been made early in this century, but any practical application have been scarcely developed. During the recent war investigations of boron-treated steel were newly advanced, especially in the United States in industrial scale.
The purpose of this treatment was to improve hardenability of steel with small amount of less than 0.005% boron, and to save alloying elements, such as Ni, Cr and Mo. At the present, the tentative specification has already been determined, and put into practice in the United States, While much attention is paid in Europe and U.S.S.R. with interest.
In Japan, there have been basic investigations and a few practical data of some plants, and since a Boron Steel Research Committee has recently been installed, this boron-treated steel will be put in practice in some days.
In this article, the result of various studies in the influence of boron upon iron and steel to date is described, especially relating to the recent advancement of boron-treated steel.

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No. 3 blast furnace of Kawasaki Iron Works of Nippon Steel Tube Co. was completed in reconstruction and commenced its operations in December 1951. This report treats of an outline of the main improved parts of the furnace.

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