We have introduced a new theory of plasticity standing on the basis of crystallog_??_aphic correlation between plastic gliding and lattice transformation which occurs in a supercooled or overheated state of alloys.
In this paper c_??_i_??_ical shear stresses of binary all_??_ys were calculated from the above theory. They can be determined by two parameters X=^RT/_Qa-Qb and Y=^Φ₁/_Qa-Qb where Q_a and Q_b are the heat content-difference between the crystal states when the metal a and b have the face centered cubic lattice and body centered cubic lattice respectively, -Φ₁ is the so-called “Ordering energy” of the alloy. Curves of critical shear stress vs. concentration of alloys, are unsymmetrical in the case of small value of X and are symmetrical in large X. The central part of the above curves become flat when an absolute value of Y is large. These theoretical results where compared with observed values of the alloys. Au-Ag, Cu-Xi. and Cu-Zn, which have a wide range of solid solution. The observed curves of the former two alloys are symmetrical to their concentration and the latter alloys have a curve with approximately a flat part in, the range over 20% Zn. When we put X_??_4, Y-5 in the case f Au-Ag, X_??_1.74, Y-2.0 in the case of Ni-Cu and X_??_1.3, Y-12 in the caze of Cu-Zn the calculated curves in every case showed good agreement with the observed values. The heat content-difference Q mentioned above means a heat evoluted when a part of crystal lattice in tire narrow region arround the dislocation centre changes its lat_??_ies type al_??_ne accompanied with no change of its electronic structure.

View full abstract

When steel, especially chrom-steel. is super-carburized, its case becomes so brittle that it often suffers danger of flaking or cracking in heat treatment or mechanical working. There are a few methods to prevent super-carbarization. The most effective one is mild carbarization by the use of any suppressor by adding to the carburizer consistsing of charcoal and such a promotor as BaCO₃ or Na₂CO₃ There is also anothr mild carburization method which is to use a carburizer containing a weak promotor or decayed carbuized by repeated using. In view of reactions between suppressors and promotors, we classified the former into three systems; Silica-. Alumina-, and Phosphate-. In the first the mechanism of mild carburization in Silica- system was investigated, and it was found that silica reacts with promotor BaCO₃ or Na₂CO₃ forming BaO•SiO₂ at carburizing temperature, and since such a product has little effect for carburizing, the strong promotive power of BaCO₃ or Na₂CO₃ decreases in using it together with silica. Si on Fe-Si as suppressors suffers oxidation in carburizing atmosghare, and then the produced oxide, SiO₂ reacts with the promotor as above.

View full abstract

Electrolytic brightening or “polishing” of metals was carried out by means of an alternating current, and it was revealed to be available for the specimens of nickel, iron, steel, aluminium, tungsten, zinc, tin, copper, brass and molybdenum. In this case, the mechanism of polishing is almost equivalent to the so-called “rapid method of electro-polishing” which is adopted in the ordinary direct current method, with a proviso that the current density required is fairly higher compared with the case experimented by a direct current.

View full abstract

The acid Cu-plating solution is unsuitable for this purpose, but alkaline Cu-plating solution is very good and its best composition is;
CuCN 33g, NaCN 38g, Na₂CO₃ 14g, Na₂S₂O₃ 0.3g, H₂O 1L.
It is unnecessary to use the excess of Na₂CO₃ or Na₂S₂O₃. The current efficiency is increased according to the elevation of the temperature, but the solution becomes turbidity above 65°. The current efficiency is increased according to the concentration of the solution, but the preventive capacity of the carburization reaches the maximum when its composition is CuCN 33g, NaCN 38g.
The thickness of the alkaline Cu-plating which prevents certainly is min. 0.008mm and it needs same constant thickness, whether or not carburizing time is long or short. The preventive capacity of the acid Cu-plating is very poor, thus protection by the alkaline Cu-plating is necessary.

View full abstract

It was stated in the 1 st and 2 nd reports that in the dry wear chromium plating bad great wear resistance when its thickness was 8 μ against the grinding atone and 3 μ against carbon steel.
In this paper I have studied on the chromium plated shuttle body (sewing machine part). When the chromium thickness was 2_??_3 μ, the wear resistance was not sufficient, but a thickness of more than 5 μ had sufficient wear resistance. The causes of these results and the mechanism of wear are discussed.

View full abstract

The dry slip wear test of the chromium plated steel pieces were made by the anther using the Amsler wear testing machine. under various electrolytic condition. As the result of this test, it was found, that the hard chromium plating (50° 50 A/dm²) and gray chromium plating (40° 100 A/dm2) had high wear resistance, and the former which ai nealed in the neighbourhood of 600° had the lowest resistance to wear. This annealed hard chromium plating steel was much superior to the hardened carbon steel and the hardened high carbon chromimu steel in reference to wear resistance.
From the above tests it is clear that the resistance to wear is greatly due to the proper hardness of chromium.

View full abstract

Cast irons having 2.5%_??_4.7% C were decarburised at temperatures of 850_??_750° with hydrogen, and the structures obtained were microscopically observed.

View full abstract

Investigations were made on the thermal expansion, hardness, corrosion, acbinability, abrasion and microscopic characteristies of the following materials for the purpose of use for high temperature and pressure values.
(1) Co-Cr-W series. (2) Cost iron of Si-Mn-Ni-Cr series. (3) 13% Cr steel etc.

View full abstract

It is generally known that cast iron melted by an electric furnace has more defects than a cupola furnace, that in the brittleness, shrinkage-hole, blow-bole and the fluidity. However there only a few reports on these points. Therfore the author investigated the metals melted by basic and acidic electric furnace.
The results obtained are summarised as follows:- (1) In mechanical properties, there is no difference between metals melted by an electric furnace and cupola, except in the case when coarse charging materials are used. (2) In fluidity, no difference was found by the common testing method. (3) Shrinkage-hole and blow-hole tend to appear in electric furnace melting. (4) In the case of basic process, the properties were not affected directly by the difference of slag as neutral or basic, but it is considerable when coarse charging materials are used. (5) When using coarse charging materials the properties of metals melted by an electric furnace is far less than by capola, however, whether or not these inferiorities are due to coarse materials or to melting process was not decided. (6) Metals melted by an electric furnace is affected sensibly by many operating conditions. (7) The figure of graphite appears different and is remarkably so in the case of abnormal operation. (8) The metal melted by an electric furnace is brittle, without any other inferior properties in general; thus, the brittleness of cast iron melted by an electric furnace is in need of further study. (9) The figure which appears on the surface of metal in liquid state, melted by an electric furnace, is slight and less so in basic process. The relation between the figures and other properties is vague.

View full abstract

This reports deals with chemical chompositions, physical properties and mechanical properties of chromium steel, chromium manganeese steel, chromium vanadium steel, chromium tungsten steel and chromium tungsten vanadium steel to find the substitute of the most valuable steels for proper steels for die bluck, such as, Nickel chromium molybdenum steel or chromium molybdenum steel.

View full abstract

Effects of small quantities of various addition elements on the tarnish-resisting properties of silver-bane alloys were researched by examining the degree of tarnishing produced when immersed in 0.1 N-Na₂S aq. solution. The invisible films formed by heating these alloys in air or in controlled atmospheres of low pressure were found to be highly protective against tarnishing. Good result wereobtained from binary silver alloys containing zinc, probably because of that the zinc in the alloy forms the type of oxide film in which cations are present in excass.

View full abstract

On the determination of manganese in iron and steels, the method based on the induced oxidizing reaction using K₂Cr₂O₇-NaAsO₂ investigated by Lang-Kurtz, were studied in order to extend its applicability to the field of actual metallurgical analysis.
Clarification of influences by various kinds of acid radicals in the sample solution and of a safty range of their concentration in which the reaction goes to completion is desirable.
In this paper, the results on the range of concentration of acid radicals introduced, adaptable for the complete: oxidation of Mn^II in the state of Mn^III, and about suitable quantitative relation between K₂Cr₂O₇ and NaAsO₂ in which the induced oxidation proceeds to completion, are given. The analytical procedure using HClO₄ was then proposed, especially for the sample containing chromium. The satisfactory results were obtained.

View full abstract

A rapid method for determination of Cu and Fe in the duralmin type-light alloys is the analytical procedures using liquid zinc amalgam.
The analytical mechanism adopted are as follows:
Dissolving the sample in H₂SO₄ and HClO₄, Cu and Fe are determined in the aliquot portion of the solution respectively. As for Cu, the solution is treated with an excessive amount of Ti⁺⁺⁺ solution prepared by the liquid Zn-Hg, the depositel Cu is removel by the addition of metallic Hg, and then, titrating the residual amount of Ti⁺⁺⁺ with KMnO₄ solution, Cu is calculated indirectly. And for Fe, the solution is reduced with liquid Zn-Hg in the usual way, where by Cu is dissolved in the liquid amalgam used and Fe is changed into Fe⁺⁺ state, the Fe⁺⁺ thus formel is titrated directly with KMnO₄ solution.
Extensive experience with this method in comparison with others has shown it to be unquestionably the more accurate and most speedy.

View full abstract

The influences given by the presence of a large quantity of deep colored metallic ions upon the so-called induced oxidation method for the determination of Mn and, the applicability of thelanalytieal method proposed by Lang-Kurtz were investigated.
The author found that in cases of a presence of Ni⁺⁺, Co⁺⁺ and Cr⁺⁺⁺ ions, the difficulty for recognizing the exact end point in the titration which was caused by the deep color of these ions can be considerably reduced by an addition of a little amount of NH₄VO₃ near the end point, Thus, one of the general analytical procedures for a minute amount of Mn not only in special steels and ferro-alloys, but also in metallic Ni, Co and Cr was proposed, with favourable results.
As for samples containing Mo, various troubles were recognized, so the, method is not suited unless the amt, unt of Mo is less than about 20mg.

View full abstract