Single crystals of iron and aluminium were prepared by the method of recrystallization and etched for different timeintervals with aqueous solutions of various concentrations of acids and salts. Light figures produced when light was allowed to fall on their three principal crystal planes (100), (110), and (111) were observed and photographed and the suitability of the observed figures for determining the orientation of the said metal crystals with the “method of light figures” was examined.
As found in the previous investigation of light figures in single crystals of nickel and copper, the symmetry characteristics of the light figure are naturally invariable, but their geometrical form changes variously with etching conditions, namely, the etching reagent and the timee and temperature of etching.
Clear light figures were observed on (100) planes by a short-time etching of several minutes, namely, the light figures siitable for the determination of the crystal orientation were obtained, in cases of iron single crystals etched with concentrated nitric acid and hydrochloric acid, dilute (10 and 20 percent) solutions of ammonium persulphate, and 70 percent solution of ferric chloride, and also in cases of aluminium crystals etched with concentrated aqua regia and hydrochloric acid, and 10 percent solution. of ferric chloride. When iron crystals were etched with 50 percent (in relative concentration) nitric acid, 50 and 5 percent (in relative concentration) aqua regia, 10 percent solution of iron ammonium alum, and 5 percent solution of cupric ammonium chloride, and aluminium crystals were etched with dilute (2 and 5 percent) hydrofluoric acid, clear light figures could he observed only after a long-time etching. In the other cases of etching, indistinct light figures were obtained or the characteristic light figures could not be observed at all, even by a long-time etching.

抄録全体を表示

(1). Heat contents of some iron scales ranging from
27.53 to 55.37% Ferrous oxide
68.32 to 39.88% Ferrous ferrite
0.19 to 0.55% Metallic iron
and 3.22 to 4.36% Impurities
ate measured by the method of mixture at different high temperatures, and the heat content-temperature relations of Ferrous oxide FeO and Ferrous ferrite Fe₃O₄ have been obtained by calculation therefrom. The apparent and true specific gravities of these scales were 5.275 and 5.303. respectively as the mean values. As the softening temperature of one scale 1356° was obtained.
(2) The mean specific heat of iron scale at high temperatures increases with the heating time, and temperature.
(3) The heat conductivity of iron scale is small in the range of low temperature but increases gradually with the rise of temperature.
(4) As the Curie point of Ferrous ferrite Fe₃O₄ 590° was obtained from the heat content temperature curve of iron scale.
(5) The magnetic transformation in Ferrous ferrite takes place in a range 190-200° or so, and the heat of transformation is about 15.34 calories per unit mass. This heat is about 4.33 times greater than that of A₂ transformation in pure iron.
(6) By the method of calculation, the heat contents and specific heats of Ferrous oxide FeO and Ferrous ferrite Fe₃O₄ in the temperature range 100-1100° were obtained from the heat content-temperature relation of iron scale.
(7) The mean specific heat of Ferrous oxide FeO is always greater than that of Ferrous ferrite in the temperature range 100-1100°, but in the true specific heat in the range of magnetic transformation is opposite. Both of these true specific heats, except that in the range of magnetic transformation of Ferrous ferrite, are represented aproximately by the following equations.
FeO C_p=0.218+3×10^-5t
Fe₃O₄ C_p=0.128+1.1×10^-4t
(8) From the change of weight of the scales before and after the experiments, we see that the rate of transformation from Ferrous oxide FeO to Ferrous ferrite Fe₃O₄ is proportional to the heating time and its temperature, and the effect of heating time is less than that of the rise of temperature.

抄録全体を表示

In order to obtain the quenching diagram using the bra un tube, the author has devised a new apparatus which electrically amplifies the elongation of a test piece and its temperature at the quenching. In the previous apparatus for the purpose of taking the quenching diagram, as Sato's method, the coordinate axis of the diagram was obtained as follows: i.e. the elongation of the test piece was magnified mechanically, but on the abscissa, the elongation of the neutral piece was used as the temperature scale. However, we can not obtain the true temperature by such a method, as the neutral piece does not absorb or generate any heat of transformation.
The other apparatus was improved by P. Dickens and G. Thanheisen, using no neutral piece. By their apparatus, the electrical changes caused by both the elongation and the thermo electricity of the test piece, were led to two coils which were equipped to rotate around each axis in a magnetic field. The axes of those coils were arranged to perpendicular to each other and the light beam reflected by two mirrors which were attached on the axes of these coils, describes quenching or cooling diagrams on a plate glass. By this apparatus, the period of natural frequency of mechanical part is 0.1 sec, , and it is not suitable to observe so rapid change as the water quenching.
Author magnified these electrical changes caused by the elongation and the temperature changes by means of the the amplifier, and then brought them on the vertical and horizontal deflection plates of the braun tube respectively. By these method, the unsuitable inertia effects were completely eliminated.
The dimension of the test piece was 5mm in diameter and 70mm in length. On the ordinate, the elongation of the test piece was mechanically magnified in 40 times and the electric resistance was changed by it, and the change of the voltage caused by this resistance change was amplified by the 2 stage direct-couple amplifier. While on the abscissa the thermo-electricity generated by a fine Pt Pt-Rh couple, which was inserted in the small hole at the central part of the test piece, was amplified by the 3 stage amplifier of the same type. Also temperature-time and the elongation-time curves were simultaneously obtained by the electromagnetic oscillograph. By this apparatus we obtained the quenching diagrams of the various carbon steels quenched into several media as air, oil and water.

抄録全体を表示

In the previous paper the author reported the change of hardness, microstructure and durability for cutting power due to the quenching temperature, holding time, and tempering temperature, etc.. In this experiment, using the same sample of five typical high speed steels as previous report, the following problems are investigated; (1) Effect of repeated temperings on the hardness and durability for cutting power. (2) Change of the durability due to the rise of repeated tempering temperature. (3) Effect of tempering time. (4) Comparison on the changes of durability of each high speed steel due to tempering temperature.
The results of this experiment are as follows: (1) The effect of repeated temperings on the hardness are more and more marked when they are done at lower temperature with larger cobalt, and when the quenching temperature is higher. (2) The max durability for cutting power is obtained by repeated temperings for twice or three times when the moderate quenching and tempering temperature are adopted. (3) At the tempering temperature above 500°, the maximum hardness obtainable by quick tempering at higher temperature is lower than that reached by slow tempering at a lower temperature. (4) As the cobalt content increases, the decomposition of the martensite becomes. slower in the tempering with the result that the material can stand against the softning effect of tempering. (5) As the cobalt content increases, the durability becomes higher, and tempering temperature giving the max durability shifts somewhat to the higher side.

抄録全体を表示

In view of the recent tendency toward wide application of the electrical metal spraying process-to ptand against heat, abrasion or corrosion-the author measured the physical, mechanical and chemical properties of the following metals and alloys, Al, Zn, Pb, Carbon Steel, 18-8, Stainless Steel, Nichrome, Pb-Cu Alloy, and the most suitable conditions for them in the spraying have been studied.

抄録全体を表示