I bave measured the temperature of roasting kiln and the time when the iron ore pass through the kiln and have found out following proper conditions. (1) The suitable amount of coke breeze are 30-40kg/t of roasting ore and the proper roasting temperature is from 800°C to 900°C. (2) The rate of desulphurization is 50% (3) The proper size of iron ore is from 30 mm to 50mm and the fine ore damage the draft of kiln and make the roasting operation impossible.

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The author has investigated the effects of contained gases, especially hydrogen and nitrogen, on graphitization of cast iron. The results obtained are as follows:-
1) Sand acts to promote graphitization, while FeO, N₂ and H₂ hinders it.
2) The more FeO exists, the more H₂ and N₂ show a tendency to increase.
3) The less combined carbon is, the less N₂ are tend to decrease.
4) If the amount of FeO contained decreases belew 0.03%, strength decreases and toughness increases. Sand shows an opposite tendency to FeO.
5) The more N₂ and H₂ are contained, strength increases and toughness decreases.
6) The more Sand and H₂ are contained, the more flaky coarse graphite structure will increase.
The more FeO and N₂ are contained, the more fine or abnormal graphite structure will increase.

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By the various measurements, the scaling amounts of slab, billet and bloom are given by the following formula:
The scaling amounts of slab, etc.=Thickness of scale×Apparent specific gravity×Surface area of slab×0.7538×0.9
The components of scale and the oxidation heat are shown as follows:
M. Fe FeO Fe₃O₄ Fe₂O₃ Oxidation Heat
0.2% 58.4% 34.1% 7.0% 1, 006 kcal/kg. Scale or 1, 334 kcal/kg. Fe

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This experiment is also the continuation of former report (V, VI). The results are summerized as follows:
(1) If the heat-treated carbon steel with various C content be pickled, we can find the flakelike or fish-eye-like defects on the fracture of tensile test pieces as the variation of heat treatment.
(2) When high C steel is quenched in water, the flake-like defects are appeared during the pickling, and the appearance is just same as the defect of special steel. But when it is quenched in oil, no defects are appeared during the pickling.
(3) As the tempering temperature of quenched steel become higher, the appearance of defects vary from flake-like to fish-eye-like through cup-like appearance.

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The structure of the oxide coating of the Fe-Cr alloys which was produced high temperature oxidation was studied and the difference of the scale structure owing to chromium content was clarified. The thickness of the each layer of the scale produced by oxidation (1200°×2hrs) was shown in Fig 2, and the scale structure of the alloys was illustrated in Fig 3 and Fig 5. The layer I, II, III and IV is consisted of Fe₂O₃, Fe₃O₄, FeO and FeO·(Fe, Cr)₂O₃ respectively. The oxidation velocity is decreased by the glowing of the FeO·(Cr, Fe)₂O₃ layer, but the excellent oxidation resistance of the high chromium alloys is due to the Cr₂O₃ film.

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Some experiments of hardness curve of quenched steels (low carbon-for carburizing, medium carbon-for constructional and high carbon steels for tools) are described. It was found that
(1) there are two kinds of hardness curve, i.e. the flat type and the two step type and this two step type appears often in the steels containing much hardsoluble carbide, i.e. Cr-V-, Cr-Mo-, Gr-W steel and in the Si-Mn-Cr steel,
(2) Cr-V steel shows the agehardening on the room temperature,
(3) the quantity of residual austenite of Si-Mn-Cr steel is so much showing fair hardening by tempering.

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Hot concentrated phosphoric acid is thought to be most effective to dissolve rapidly certain kind of high carbon ferroalloys not easily decomposed by ordinary acid mixture. The authors used it in rapid analysis of ferro-chromium for chromium and ferro-vanadium for vanadium, and obtained satisfactory results in short time. The outline of the method adopted is as follows: In the case of ferro-chromium, transfer 0·1 gram of finely powdered sample to a 400cc beaker, cover it with a watch-glass, dissolve the sample in about 5cc of H₃PO₄ (sp. gr. 1.7) by heating carefully and keeping the state of slight fuming. Cool slowly on the asbestos to a little viscous but not yet syrupy state, add 20cc of H₂SO₄ (1:4) and a little HNO₃ (sp. gr. 1·42), and boil for 1 minute to expel oxides of nitrogen. Add about 150cc of hot water and determine chromium by the ordinary silver-persulphate method. This procedure occupies about 20-23 minutes. In the case of ferro-v nadium, dissolve 0.2 gram of finely powdered sample in 5cc of H₃PO₄ in the same way as the case of ferro-chromium, dilute to about 200cc with water and determine vanadium by the Gakushin method. The time required for the whole procedure is about 14 minutes.

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During the past two years, I have had the privilege of visiting the majority of both large and small iron and steel and ferroalloy plants in Japan. In my opinion, only one outstanding, but very important difference exists in ferrous industry organization in Japan as compared with that in the United States. In the Japanese metallurgical industry, there is no organization upon which management can rely to observe and detect, and to make a continuous study of the various daily phases of operations and procedures within their company on which to base improvement of operation. Some of the plants have a "so-called" thermal department (refer to chart No.1) which we in the United States refer to as a combustion department. This thermal department is also essential to good practice. But in comparing the function of thermal control with those of metallurgical control, the metallurgical control may be more important. Why? Because of the production economies involved, and because of its influence upon the high quality of the various products produced. I shall outline to you the general jurisdiction of the Metallurgical Control Department of the Bethlehem Steel Company.
(1) The Selection and checking of raw materials.
(2) Checking materials in process and the final production.
(3) Inspection of all products.
(4) Operation of chemical, physical, metallographic and other laboratories, as illustrated.
(5) Metallurgical observation of all hot metal operation.
(6) Experiments and development projects such as: (a) The use of pure oxygen in the various processes and methods. (b) Increase efficiency of ingot control.
(7) Specification.
(8) Metallurgical contacts or customer problems.
It should be emphasized that research in the industry must be at a high level of activity. Through the organization proposed in chart Number 2. a research organization entirely independent of operating and metallurgical departments, is maintained.

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