Many studies have already been made on the reactivity of coke, but test samples of coke used in those experiments were mostly under 6mm in size and so by far the smaller as compared with the coke in use for blast furnaces, hence, of little value as samples to be used for actual operation.
Cracks which generally occur in coke are supposed to have a great influence on its reactivity, therefore the authors performed experiments in connection with this nature about several kinds of coke, using test samples of as large as 55mm angle. In consideration of their cracks, the authors tried to clarify the influence of grain size, the reaction temperature, and the crushing strength of coke upon its reactivity and especially the ultimate relation between the reactivity of coke and the operating condition of blast furnace. The conclusion was that as for the coke manufactured in Yawata Iron and Steel Works, the higher the crushing strength became, and the lower the reactivity was, the more desirable was the coke for the operation of blast furnaces.

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By the actual use of the Stiefel-Mannesmann Piercing Mill, the authors studied the effects of both the gorge distance and the diameter of plug upon the state of piercing phenomenon from various points of view, The variations of the gorge distance and the diameter of plug were from 69mm to 79mm and 65mm to 75mm respectively, the diameter of billets being 90mm. The results obtained were summarized as follows:
In case the gorge distance was decreased and the diameter of plug (i.e. the degree of deformation) increased,
(1) The outside diameter of tube remained almost constant, but the thickness of tube increased linearly.
(2) The twist of tube surface increased.
(3) The power required increased: especially in case of higher degree of deformation, extraordinary power consumption was observed.
(4) The axial moving speed of tubes during piercing dereased, but it increased at the latter stage of piercing owing to the elongation of tubes, and at the outlet of the mill it increased together with the degree of deformation.
(5) The revolving speed of tubes during piercing decreased.
(6) The reduction rate and speed in the piercing process increased.
(7) The cracks that appeared on the inner surfaces of tubes increased when the round billets were good in quality. But no difference was appeared when the billets were of excellent quality.

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Refer to the Report (I) (Nov. 1952 issue of Tetsu-to-Hagane)

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Following the 3rd. report; die steel corresponding to No. 3 was studied as a specimen for the spring material at high temperature. In this study. the tests of microstructure, hardness and tensile strength were carried out on the one which treated by normal quenching-tempering method (martemper) and also by austemper method and the same tests were done on Si-Mn steel in comparison with above materials.
The results obtained were as follows:
1. Die steel was superior generally in spring properties than Si-Mn steel.
2. Austemper method was superior generally than martemper method in die steel.
3. In martemper method, about 1, 100°C quench and 550°-600°C temper was effective and in austemper method about 1, 100°C quench and 600°C hot bath treat was effective.
4. Die steel was excellent in toughness property than Si-Mn steel.

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In order to utilize stainless-clad steel, specially 18% Cr; 8% Ni stainless clad plate, the authors already reported on manufacturing method and general properties of the clad plate. In this report, the authors studied on welding characteristics, oxygen-acetylene gas cutting properties and corrosion resistance of stainless clad plate. Results of these tests were summalized as follows:-
1. In welding process of clad plate, particular cautions should be taken, because of transformations caused by rising of welding temperature and because of decreases of corrosion resistance resulted by diffusion of alloy elements. Therefore, the following methods must be taken:-
a) In welding of the stainless-clad side, it was necessary to use direct current and the strength of current should be as lower as possible.
b) It was recessary to use stainlees welding rod which contained higher alloy element than clad stainless steel.
c) It was necessary to contemplate further, considering to put the welding methods in good order.
d) If any transtormation could not be permitted, both side stainless clad might be used.
2. In gas cutting process of clad plate, the authors cut easily by using larger size cutting torch and higher oxygen pressure than in the case of plain carbon steel plate which had same thickness, and inclining torch about 15 degree forward. When the clad thickness increased over about 30% in total plate thickness, gas cutting of these plate became very difficult.
3. From the result of corrosion test on 18-8 stainless steel, it was supposed that non-metallic inclusion in stainless steel remarKably affects on corrosion resistant property.
4. At the design of stainless-clad steel construction, attension to avoid sharp bend of clad plate must be taken, in order to detain stress corrosion of 18-8 stainless as little as possible.

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Recently, some methods have become popular to connect chip to shank on account of saving an expensive high speed steel.
They were used without much defects for ordinary light cuttings, but it happened to occur the chip part separated from shank in the case of heavy cuttings in using a strong vibratory machine.
From this reason, a new method of connecting chip to shank was devised by the author (Patent No. 151927) and after studies were made on its material property in practice, an extreme superior one was found than the former method, with good experimental results.

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A rapid analytical method for hydrogen in steel was described. The method involved vacuum fusion of the steel sample and subsequent measurement of the thermoconductivity of the extracted gas. By this method, hydrogen and oxygen in molten steel could be analyzed within 17-191/2min including sampling time. Sampling method, amount of hydrogen that escaped from the sample, and comparative study to the standard 800°C vacuum extraction method are described. Applications of the apparatus in practice were also given.

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Sulphides in steel were presumed to exist as iron sulphide and manganese sulphide, and the former had an influence on the brittleness of steel at high temperatures. In practice, desulphurization was carried out and the remaining sulphur was converted into manganese sulphide by addition of manganese.
Several methods which had been heretofore published for determination of these two sulphides were considered to be unreliable, In this investigation the electrolytic method was adopted, and from its residue, iron sulphide and manganese sulphide could be determined respectively.
In the analysis of some low carbon steels containing several amounts of manganese and sulphur, generally satisfactory results were obtained.

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No. 10 blast furnace of Kamaishi Works was completed after its reconstruction during about 2 months and commenced its operation on 28th, August, 1952. This report represents the outline of the process of works and the main improved parts of the furnace.

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This article dealt with a new method of surface treatment of metals called shot peening. The wonderful effcets of shot peening, the development of it and the methods of shot blasting were descrihed. Various factors that affect the effects of shot peening, as size and hardness of shot, velocity of impact and the time of blasting were inspected. The influences of coverage and arc height upon the fatigue strength are also discussed.

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