The open-hearth plant, the plant of which is shown in Fig. 1, consists of four tilting furnaces of 100tons capacity and one active mixer of 300 tons capacity. These are in one line, the mixer being placed between two pairs of furnaces.
The building, the cross-section of which is shown in Fig. 2, consists of four bays, namely, stockyard bay, charging bay, tapping bay and casting bay. The stockyard, which is not completely covered in, has two 15ton overhead box lifting and magnet cranes and two 20ton larry cars running along the bunkers full-filled with iron ores, manganese ores, calcined lime and others carried to by a locomotive. The charging boxes are handled in special containers, each holding 3 boxes. The boxes, having been filled on the ground floor, are lifted on to the extention of the furnace platform projecting into the stockyard.
The furnaces and the mixer, designed suitable to use the mixed gas, are served by two 5ton revolving type open-hearth charging cranes, each having 10ton auxiliary hoist.
The hot metal is charged into the furnaces or the mixer in the tapping bay, the pre-refined metal from the mixer provided to them by two 60ton hot metal cranes on the upper rails and three 100ton ladle-cranes on the lower rails. in the same bay.
From the inception of the plant, it was decided to exploit the use of mixed gas of the coke-oven gas and the blast-furnace gas, in order to a minimum the purchase of external fuel. To secure the most efficient use of the gases, the plant is well supplied with instruments. The gases are metered separately at each point of use for the purposes of holding at a good mixing rate as economically possible. The amounts used are continuously recorded for each individual part.
The slag is taken from the furnaces on the charging side the slag-ladle being run into position from the stock-yard bay side under and at right angles to the furnaces, there being a track to each furnace and two tracks to the mixer.
The finished steel in the furnace is tapped into two 60ton ladles which are transfered to the teeming cranes moved in the casting bay.
Then the ingots are cast in moulds arranged in the casting-pits, and carried off by a locomotive to the blooming mills, after baving been sat on the cars by three 12ton stripping cranes running over the casting bay.

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A number of alloy steels were melted in a 500kg. acid-lined high frequency electric furnace. The excellent diminution of iuclusions a ere attained by the followine operation.
The Fe-Mn (0·2-0·4%) and acidic slag (1-2%) were added before melt-down of the furnace charge. The FeO-enriched slag was removed twicely and replaced by glass or CaO-SiO₂ mixture during the refining time. Then, the electric circuit was broken for 20-30 minutes after the last deoxidizer was added and made again for few minutes before tapping.

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The author investigated the difference between the properties of charcoal pig irons and coke pig irons, and found that the superiority of charcoal pig irons is to be chiefly attributed to the less content of nitrogen. The author intende I to know more exactly the effect of nitrogen on the graphitization, measured the eutectic change of cast irons which melted in various conditions, and obtained the following results;
1) in the cast irons, whose nitrogen content is below 0·0015%, the eutectic always appears at constant temperature and obtained very fine uniformly distributed graphite.
2) in the cast irons, whose the nitrogen content is above 0·0020%, the cutectic does not appear at constant temperature and obtained flaky graphite colonies surrounded by the fine graphite and free cementite.
3) to obtain the eutectic graphite or pearlite cast iron, it is necessary to cast the materials whose nitrogen content is very small and the eutectic change appears at constant temperature.

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Since the internal stress was found to be distributed in the interior of specimen which was given twisted defomation, the releasing condition of the stress due to annealing at various temperatures was studied. It was found that a large portion of the stress disappeared in the range of temperatures 300-500° in the case of iron and carbon steel, 100-400°C in the case of copper, and 50-200°C in the case of magnesium.
The change of microstructure due to variation in annealing temperature at a fixed position in Armco iron which was given a twisting deformation by the amount to 0·2π/cm, was studied. The surface hardness of some metals were also measured by a Vicker's hardness tester. The results were found to agree satisfactorily with each other.

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