In the steel making practice, it is very important to know the temperature of molten steel.
Generally the optical pyrometer is used, but the temperature measured is not accurate as the personal error is apt to become large, and also as the oxidized film or gases issued covers the surface of the molten metal.
To gain more accuracy, the author studied the contact pyrometer in using W-C thermo-couple.
With the special devises, he found that this thermo-couple is applicable in practice, especially in the case of the casting temperature measurement.
By this method the personal error occurs rarely, and also the error of the temperature measured becomes very small in comparison with the optical method as we can dip the tip of the thermocouple in the steel bath itself.
The value of E.M.F. obtained from this thermo-couple is in the same order as in the case of Pt-PtRd couple, and so we can use the ordinary millivolt-meter to measure the temperature.

View full abstract

In meiner Arbeit über die Oberflächenspannung der Eisenlegierungen, deren Ergebnisse schon vorher veröffentlicht wurden, waren die Dichtemessungen auch notwendig. Damals wurden die Messungen nach einem dilatometrischen Verfahren ausgeführt. Also wurden die Dichte durch die Ermittlung des Volumens der Legierungen von bekanntem Gewicht in geschmolzenem Zustande festgstellt. Damit sehr interessiert, dass zur Bestimmung der Dichte man auch den Auftriebsverfahren oft braucht, hat Verfasser auch eine Versuche ausgeführt, die Dichte dieselber Eisenlegierungen die vorher zur Messungen nach dilatometrischen Methode gebraucht wurden, zu bestimmen und mit der schon festgestellten Werte zu vergleichen. Der Grundgedanke meines diesmaligen Messverfahrens ist es nur so, durch einen Senkkörper das Auftrieb der flüssigen Legierungen zu bestimmen und daraus natürlich ganz theoretisch die Dichte zu berechnen.

View full abstract

In the ease, when steel is pickled in the solution of hydrochloric or sulphuric acid to remove the scale, the mechanical properties of steel are changed at the same time. This fact is known as "Acid Brittleness", and is recognized to be caused by the diffusion of nascent hydrogen, which -is generated during the pickling, into the interior of steel.
The author observed the change of tensile strength and elongation of low carbon steel tubes, small in diameter. which were pickled in acid solutions different in concentration and temperature, The ascertained results of the experiments are as follows:-
1) Steels which are pickled in acid solution show increased tensile strength and decreased elongation.
2) To prevent the acid brittleness of pickled steel, the use of some inhibitor is much effective.
3) Acid brittleness is recovered by means of heating the pickled steel at low temperature or Setting at room temperature for several days.

View full abstract

The elongation and reduction of area of the tensile specimen newly taken from a considerably large alloy steel forging may increase strikingly according as the specimen is tested after few days, with no change in the tensile strength but a remarkable alteration of the fracture. The author studied on this special aging phenomenon and obtained the following results:
(1) This aging phenomenon appears clearly in tension test and less in impact test. (2) Heating the specimen, even at 100°C., remarkable effect is produced. (3) With the increasing cross-section of specimen, it is found necessary to apply a longer time, proportional to crossectional area, to eliminate the aging phenomenon perfectly. (4) The elongation and reduction of area of the steel in cast condition are raised and almost attained the values for the forged condition provided that the time and temperature of heating are sufficient. (5) This aging phenomenon appears conspicuously in the steel forging with flakes. (6) Before and after aging of the specimen, there is considerable difference in hydrogen content. (7) By heating the aged specimen in hydrogen gas for 1 hour at 500°C., the mechanical properties, the hydrogen content and the apperance of the fracture of specimen are returned to their original states.

View full abstract