Demand for the improved qualities of refractories has become more and more intense with extraordinary development of high temperature industries in recent years. Answering this demand, various kinds of new high-grade refractories have appeared. However, refractories of the MgO-base is most favorably studied as refractories for steel manufacture. Above all, refractories of the magnesia-chromite type are studied on their all sides and there have been published a number of excellent informations. Magnesite, chromite etc., which have been used heretofore as the best refractory materials are produced in limited destricts, causing some difficulty in transportation. Besides, each of them has become an important naw material for metal.
Therefore, refractories of the silica-magnesia type called " Forsterite" have become to be noted, which are of domestic produets and more ample than the aforementioned raw materials. In the present report, properties of refractories of such type were shortly described with special reference to "Magnite" refractories which have begun to be produced in industrial scale Since Showa-10(1935). Actual results of the use in various high temperature furnaces and some new applications were also informed.

View full abstract

The author made some consideration of a blast furnace which is acting in basic operation, at Yawata Iron Work of Japan Iron Mfg Co, Ltd (Nippon Seitetu K.K. Yawata Seitetuzyo) with regard to various furnace conditions of the blast furnace core and experimented on the moderate diameter of the core has intimate relation the oxidizing zone of the furnace The clearance of furnace wall and core is 2·5m maximum, depending on hearth temperatures. Considerations on the blast temperature, the blast pressure, the blast amount, the coke and the cause of hanging etc. were described in general. The moderate tuyere diameter is 0·097 of the Length of the hearth circumference.

View full abstract

The present study was made for obtaining a process manufacturing excellent steels following the fundamental investigation of the basic electric furnace operation. The 500-ton electric furnace of Heroult type was used in melting. Changes of compositions of the steel melt, slag, aid furnaces atmosphere were determined in the melting process according to different kinds of the operation.

View full abstract

For producing anchor chains the use of wrought iron has been exclusively adopted and no other material has been introduced in this field.
However, the existing situation, so far as the material supply is concerned, has made the wrought iron gradually scarce and this proved worse in the case of Hingley Bars, which had been considered the most suitable for this purpose and recently become quite unobtainaole.
Under the circumstances the necessity for looking into another suitable substitute material is keenly felt and has became a matter of great importance. Furthermore, in manufacturing anchor chains many processes have been taken into practice, among which the "welding" by hand hammering is most widely addopted at present.
Therefore the material for this purpose should accord with the aforementioned process. The author manufactured three kinds of steel, assimilated-wrought-iron, non-killed steel, and killed steel, by basic open-hearth furnace and rolled them down to 75-25mmφ round bars. After the careful testing, we was led to a conclusion that the following low-carbon killed steel is the most suitable for the purpose;
C 0·08-0·12%, Si 0·10-0·20%, Mn 0·35-0·45%, P 0·05% maximum, and S 0·05% maximum.

View full abstract

Cr-W-Mn non-shrinkiug steels (C1%, Mn0·6-1·0%. Cr0·9-1·0%, W0·8-1·5%) are generally used for gauge steels. We studied the heat-treatment of such steels using the Rockwell tester and the Skoda-Sawin wear testing machine and obtained the following result:
(1) The suitable oil quenching temperature for both hardness and wear resistance is about 840°-860°C and the tempering temperature is about 100-150°C.
(2) Even when water (NaCl 10%) heated up to 80°C or oil up to 180°C are used for quenching media, the same hardness. with that gained in the normal manner may be obtained. Moreover, when the temperature of the quenching medium exceeds 75°C, the expansion of the specimen diameter shows less change than when quenched in the oil of lower temperature. Such results may be appicable to the austempering process.
(3) When tempered at 100°C, the hardness rises a little during the first minutes and since then shows little change.
(4) The expansion of specimen by quenching in oil shows abbut 0·20mm/100mm in length and about 0·01mm/8mm in diameter. The maximum expansion is gained by oil quenching at 840-870°C and by water quenching at 780°C.
(5) Age hardening of this steel is so remarkable that two days are required to reach the maximum hardness. Aging at 100°C for only five hours is nearly enough to develop the stability of steel.

View full abstract

It is necessary to know the effect by different conditions in order to consider the purpose of applications of a material and to estimate the properties required thereof. As an example, the authors made the static tensile test, the torsional fatigue test, and the repeated as well as the simple impact test, the results of which were compared with each other and considered with reference to the effect on the resistance to slip and to decomposition. It has been made clear that the mechanical properties are different according with forms and manners of loading, and that, in the phenomenon of temper-brittleness, the slip resistance has been increased by tempering and also the slip resistance enhanced with the increase of the silp velocity (due to the increase of stress velocity), and that both factors have come to check the slip deformation even at the stress velocity below that of the Charpy impact test. According to the idea of the transition velocity in relation to the impact, it is possible to consiedr that this transition velocity has been removed to the low-speed side by embrittlement. However, the effect on the static and fatigue test was very slight even in specimens which were presumed to have been embrittled considerably by the Charpy impact test.

View full abstract

The effect of the gas containing hydrogen sulphide against metallic materials has become more and more important recently in various synthetic chemical industries. There are some reports concerning the corrosion test against the gas containing hydrogen sulphide, but each of them concerns steels alloyed with a single element, high-chromium steels with more than 20%, Cr, or chromiumnickel steels. Therefore, the author limited the chromium content to 3% with regard to the corrosion of the gaseous mixture of hydrogen sulphide and steam under ordinary pressure, and experimented with such kinds of low-alloy chromium steels which had been added with suitable quantities of Al, Si, Mn, W and Mo. The temperatures of the experiment were 300°C and 600°C. The au hor also experimented with an aluminium-base alloy at 300°C. Moreover, basing on the result of experiment at 600°C the author tested on the effect of temperature and time factors and also the mechanical properties.

View full abstract