The ΔE-effect, i.e. the change of Young's modulus of elasticity with magnetization, in the annealed state of electrolytic iron, decarburized 0.1 per cent. carbon steel, electrolytic nickel and electrolytic cobalt has been measured in detail, in the magnetic field up to 900 Oe, by the method of magnetostrictive oscillation and measuring apparatus, which were described in a previously published paper. In every metal the course of change of Young's modulus by magnetization has been found to be not so simple as was hitherto known; the moduli of iron and nickel display both a secondary increase in the field range preceding the saturation, and that of cobalt shows a maximum and a minimum in the weak field or the low magnetization range. The ΔE-effect is positive for all of the metals examined. The saturation values of the change of Young's modulus relative to that in the non-magnetized state, (ΔE/E)∞ are 0.2822, 0.4851 and 12.60 per cent. for electrolytic iron, decarburized mild steel and electrolytic nickel, respectively, and for electrolytic cobalt the value of the relative change of the modulus at the highest magnetic field applied, (ΔE/E)_max is 0.2208 per cent., the value of (ΔE/E)∞ obtained by the extrapolation being 0.464 per cent. The saturation value of ΔE-effect in decarburized 0.1 per cent. carbon steel coincides perfectly with the value expected from the experimental results on the ΔE-effect in carbon steels of varions carbon contents, described in the previous report, and this fact contributes to the further establishment of the proposition that the amount of ΔE-effect in carbon steels disminishes continuously with the increase of carbon content. The comparison of the experimental results of the ΔE-effect of both iron and nickel with the theories proposed by Akulov and Kondorsky, Brown, Takagi, and Becker and Döring indicates that, every theory agrees well with the experiment for the ΔE-effect of iron, while for that of nickel only two theories by Takagi and Becker-Döring give the calculated values coinciding with those measured. A theoretical consideration also shows that the difference between measured values of (ΔE/E)∞ of iron of to kinds is primarily due to that of their susceptibilities.

抄録全体を表示

The magnetization of single crystals of iron, as well as nickel and iron-nickel alloys, in very weak fields, has not yet been measured. So the present writers prepared single crystals of iron having a large dimension ratio, such as 100, and used an astatic magnetometer of large sensibility for measuring the intensity of magnetization. At first, the magnetization of single crystals of iron in very weak fields was measured by a usual method of demagnetization by alternating fields. According to the result of measurement, the field-range of reversible initial susceptibility is very low, and the initial susceptibilities of iron single crystals in three principal directions are as follows:- κ₀[100]=26.6, κ₀[110]=18.7 and κ₀[111]=13.9, their ratio being 1:¹/_1.42:¹/_1.90 The effect of weak stress and that of dimension ratio on the initial susceptibility were also measured, and found that the stress affects to diminish κ₀[100] and to increase κ₀[110] and κ₀[111] and so the anisotropy diminishes as a whole, and that as the dimension ratio decreases, the anisotropy of κ₀ also diminishes at first slowly and then rapidly, v_??_nishing in a dimension ratio of about 10.
Next, the magnetization was measured by means of demagnetization by heating and found that the initial susceptibilities are three to four times greater than those obtained by the demagnetization by reversals, as shown below; κ₀[100]=85.4, κ₀[110]=46.8, κ₀[111]=69.2 and κ₀[100]:κ₀[110]:κ₀[111]=1:¹/_1.82:¹/_2.24. This large difference in initial susceptibilities obtained by these two methods of demagnetization was found to be due to the diminution of number of unstable elementary magnets present in the boundaries of magnetic domains by gradually decreasing alternate fields, or briefly by agitating effect of magnetostriction due to the alternate fields. The change in the initial susceptibility caused by the alternate fields also differs in the directions of three principal, axes of iron. It is large in a low temperature and diminishes as the temperature is raised, and vanishes at the critical temperature.
The temperature-dependency of the anisotropy of initial susceptibility of iron crystals mentioned above was found to diminish with the rise of temperature, and also with the latter the ratio of initial susceptibilities in three principal directions decreases, tending to 1 just below the critical temperature.
In the case of iron-nickel alloys containing 18.5% Fe, the magnetostriction of which is zero, the initial susceptibility is almost independent of temperature, and also the effect of alternate fields on the initial susceptibility is zero. The above complicated phenomena were successfully explained on the basis of Honda-Okubo's theory of magnetization.

抄録全体を表示

This is the second report for the “Impact Torsion Test of Quenched and Tempered Tool Steels”.⁽¹⁾ The Impact torsion values of heat-treated 10 kind tool steels were measured by changing tempering temperatures; the results are shown in Table 1 and Figs. 1 to 11. The impact values show some max. points between 150° and 200° in the tempering temperature, indicating that β-marteusite is more tough than _??_. The amount of this toughness is generally small, except Cr-W steel as shown in Fig. 5. The max. values as reported by Luerssen and Green in America on carbon tool steels were not obtained for carbon steels, but Cr-W steel is found to be comparable with their résult. The impact torsion test is a suitable method for measuring toughness of hard and brittle materials, the relation between Charpy Impact values being shown in Fig. 12.

抄録全体を表示

In order to find the influence of extruding condition on the nature of fractures in α+β brass rods, the foIloving experiments have been carried out, vig.:
(1) Study of effects of extruding temperature, speed and rate of extrusion, angle and shape of dies and pressing discs, pressure of extrusion and some other extruding factors on the mechanical properties, appearance of fractured surface, and micro-structures of the extruded products.
(2) Examination of the flow of metals at successive stages of direct and indirect extrusion using composite billets.
It was found that, in all respects, the indirect method is superior to the direct method. By adopting the indirect method, not only can be obtained a rod having quite uniform structures for full length, but also the core-structure on the fractured surface will be eliminated entirely. Even by the indirect method, however, the coarse crystalline appearance of the fracture can be avoided with difficulty, in some degrees.
It would appear probable that these coarse crystalline surface of fractures in the extruded rods of α+β brass is consisted of extremely stretched fiber structure caused by peculiar actions of extruding operation, hence the extruded products of the coarse crystalline fractures are not always show unsatisfactory qualities.

抄録全体を表示

As we all know, the X-ray radiography has been adopted successfly for various non-destructive tests. It is customarily in practical radiography to construct the charts for guiding the operator in choosing the proper conditions. These charts consist of a series of curves in which the exposure necessary to produce a definite film density is plotted against the thickness of the sample. But the such chart must be prepared by a very definite condition. For this reason we usualy meet in practice, a difficulty and in some conditions we cannot use the chart.
In the following pages, we described a method of X-ray radiography that directly use the X-ray quantity which penetrate the marteial and reach the film. By this method, we could eliminate many troublesome matters and put in operation a perfect X-ray radiography.

抄録全体を表示