The changes in mosaic blocks of aluminum subjected to deformation by hot working are studied by means of electron microscope. The said hot working is carried out the following four types (show in Fig. 1). The growth and rotation in mosaic blocks are marktedly influenced by working temperatures compared with reduction. In the secondary annealing process, a block worked at 350° has a larger length than that of a block worked at 450°, as it is shown in the table.
Working temperature 350° 450°
As hot rolled 17μ 17μ
Annealed at 300° 33μ 21μ

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When Al is rolled in cold, the hardness H increase as the production of rolling R increases. The relation between H and R is known as a smooth parabolic curve. But in the case of some Al α solid solution alloys, such as Al-Cu, Al-Mg, Al-Zn, Al-Ag abnormal hardening occurs at some degree of reduction.
The same results were obtained in Cu α solid solutions. Other α solid solutions may also be the same in result. Why? that is the very interesting problem, and the reason can easily be assumed. In the next stage, many phsycal properties of such cold rolled solid solutions must be determined, and then the internal movement may be cleared up.

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The cracks caused by working of Aluminum slab often originate in the casting cracks, so the experiment was carried out to find how these cracks could be prevented under different casting conditions. About 1kg of Aluminum was cast in an iron mould, the inner dimension of which was 200 × 120 × 16mm. The mould was fixed with the melting crucible and they were rotated together by a driving motor to get a difinite pouring speed. The metal was a poured at different casting temperature, pouring speed and temperature of mould, and after the solidification, the ingots was examined with eyes or under microscope.
The results were as follows:
a) The faster the pouring speed was, the greater was the cracking of ingot at the upper parts.
b) The higher the temperature of the mould, the less the cracking was.
c) With pure Al, the ingot was crack for its large grains.
d) The lining of the mould could present the casting crack.

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As an attempt to enhance the strength of age-hardenable Aluminum alloys, the effect of the addition of small amount of Beryllium was investigated whether Be can increase the age-harden- ability of any Al alloy to a considerable extent or can prevent stress-corrosion to make Al-Zn- Mg alloy of more Zn content become practically useful.
Firstly, small amount of Be was added to each one of the commercial Al alloys. The effect of the addition of Be was proved to be remarkable in Al-Cu system; where 0.3%Be could increase the strength of 4%Cu alloy up to the level of super Duralmin. However, the effect was found to be less in Al-Cu-Mg system. These results were discussed in relation to the changes occurred in Al-Cu or Al-S (Al₅ Cu₂ Mg₂) diagram when be was added respectively. The corrosion resistance of Al-Cu, Al-Cu-Mg and Al-Zn-Mg alloys could be improved only slightly by the addition of Be and the stress-corrosion characteristic of Al-Zn-Mg alloy was not so much improved as well as its strength when Be was added. The Vickers hardness of Al-Zn-Cu-Mg-Be alloy, containing 8%Zn, 2%Cu, 2%Mg, and 0.2%Be will exceed 150 when aged at room temperature. But more study seems to be necessary to find suitable composition range for industrial use as the workability and stress-corrosion resistance of this system are not yet satisfiable.
Secondly, nine binary Al alloys were studied, choosing Zn, Ag, Mg, Sn, Si, Mn, Ni, Sb and Cd as the second element, when 0.5%Be and 0.5%Mg were added respectively. No alloy system. however, was found to have more hardness than 100 in Vickers when fully aged, except Al-Zn-Mg-Be system already considered above. Al-Ag-Mg-Be and Al-Mg-Be system followed, but they are not satisfiable as high-strength Al alloys from the economic point of view.
Other Al alloys; Al-Mg-Si, Al-Zn-Cu, Al-Cu-Mn and Al-Mg-Fe, containing 0.2%Be respectively were considered. The second and third system were found to reach the strength of super Duralmin by room-temperature ageing. Therefore, these two systems may be used commercially, if Be will become much less expensive to be got in Japan.
In conclusion, several aluminum alloy sy stsms, such as Al-Cu-Be, Al-Cu-Mg-Be, Al-Zn-Cu-Be, Al-Cu-Mn-Be and Al-Zn-Cu-Mg-Be, the last one being the strongest, were found to have enough strength as super Duralumin. It will be an economic problem whether any of these systems can be used in industry. However, it seems to he extremely difficult to enhance the strength of Al alloy by the addition of Beryllium in such an epoch-making wise as in Cu-Be alloy.

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There are two methods of manufacturing the various tempers of 2S-aluminum sheet, one of which is the strain hardening method and the other is the annealing method. The former is the normal method and has used in America and the latter is abnormal, but frequently used in our country.
In the present paper, the difference of the characteristics of 2S-aluminum sheets tempered by above both methods are investigated.
The results obtained are as follows:
1) In the case of tempering by the strain hardening method, the higher final annealing temperature hastens the hardening and lowers the elongation, and also erichsen value.
2) When the soft materials are strain hardened, the general elongation are rapidly reduced and the almost elongation concentrated to the broken point. Therefore, the local elongation become comparably high.
3) Tne recrystallization textures of cross rolling are quite different from that of normal rolling, so that the softening curves and earing behavior of both case are quite dissimilar.
4) The directionality of sheet tempered by strain hardening method is less fhan that by annealing method at the same temper. In the case of strain hardening, the lower final annealing temperature is favourable for directionality.
5) The drawnability of sheet by the annealing mefhod is superior to that by strain hardening method.

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Generally the surfaces of Al and Al alloys are covered with the films of Al oxide. So that, the chemical and physical properties on the surface of Al are subject to the states of the films of Al oxide. For that reason, the exact determination of the electrochemical and chemical properties of Al is very difficult, Usually the examination of the state of Al with the film of oxide, is more important than that of the properties of Al without the film of the oxide. It is very difficult to exactly measure the standard electrode-potentials of Al. The data of the potentials of Al which were measured by many people, are as follows:
Neumann measured in some electrolytes be overved the next datas.
-1.13 volt in Al sulfate solution
-1.29 volt in Al chloride solution
-1.05 volt in Al nitrate solution
Latimer and Green felder calculated fromthe elec trode potential of Al and obtained
-1.69±0.01 volt at 25°C
Similary Kistialscrosky -1.32 volt
Prossbacle -1.33 volt
Wilsmore -0.9 volt
Heyrovsky -1.33 volt
Miller and Hulzl used many solution abd measured the electrode-potentials of Al which scraped the Film of oxide off the surface of Al.
Allender measured the potential between Al and Pt electrode in the NaCl solution. He examined the properties of samples which carried out mechanical treatments, or the influences of heat rreatments. Sato measured the electrode-potential of Al film (positive electrode) which used in electrolysis as accumulator Igarashi and Kodama measured electrolytic solutionaltension of 99.99%Al in hyrogen atomosphere. The results are give in in their paper that the potentials of improving. sampales risen as soon as it is steeped in the solutions and approached to the constant value, but the potentials of annealing sample continued to rise, repeating descent and rise, and gradually approached to the constant value. R. Ergang measured potential of Al in the NaCl solution, i. e. the late of potential are following;-
99.95% Al -0.85 volt
99% Al -0.83 volt
Experimental
We measured the potential of Al with vaccum tube potention meter which is newly originated. The character of the apparatus is the use of vaccum tube 6c6. When two tubes is connected In the circuit of bridge and put unknown electrode milli the solution, the equilibrium state to brolsen off. The differluce of potential is measured by milli voltmeter, connecting circuit, milli-voltmeter is used 45 m. v. pyrometer and sensibility of the millivoltmeter is regulrated by resistance box, connecting paralel in circuit. In the adjustment of potentiometer, we used the Westarn Standard cell and measured the milli-volt, kupping constant electric pressure
When the electrode is dipped in the electrolyte, the equilibrium state is distructed, We measured it by milli-voltmzter. The measurement of potential were used by the conbined cell, i. e. Single electrode cell (Al were dipped in 3%NaCl+0.1H₂O₂, 0.1%HCL, 0.5%H₂SO₄) is combined with the standard calomel electrode cell, (Sat. Hg CL cells), by liquid.
In this way a complete cell were constructed by measuring metal electrode and standard electrode. The potential between two electrodes, were measured by newly originated vaccum tube potentiometer.
Results
1. The potential is similar inclined to electro-positive.
2. The potential is chanted by the purity of Al. The more purity is high, the more potential is high.
3. The potential is changed by the degree of improvement of samples.
4. The potential is changed by the heat treatment of sample.

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At First, we made eight kinds of sample, i.e. Mg contents in Aluminum, 0.46%, 1.01%, 1.50%, 2.08%, 2.49%, 3.36%, and 3.43%; and then measured the corrosion in distilled water and city water.
And then, we produced the vaccum tube potentionmeter for the following experiment. The corresive agent was 3%NaCl 0.1%H₂O₂. The samples were Al alloy including 0.66%Fe, 0.49%Si and 3.36%Mg, and they were polished electrically and chemically. In these samples, the change of electrode potential was measured. The condition of electrolytic polishing was specific gravity 1.575…H₃PO₄, V=50 volt and A=75 amp.; and that of chemical polishing was
H₃PO₄ (s.g. 1.7) 520cc
HNO₃ (s.g. 1.37) 720cc
Water 21cc
Temp. 120°C
Time. 30Sec.
As tale results we can report as follows:
1) In the distilled water 1.5%Mg alloy was good.
2 In the city water 2% and 3%Mg alloy was good.
3) Results of using the new designed vaccum tube potentiometer was not so good, and we
could not measure the relation between corrosion volume and potential so distinctly.

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The improvement of pretreatment for painting on light metals is the subject of corrosion prevention for ship construction. The electrolytic-polishing, almite, M. B. V. or B. V. methods, are superior in anticorrosion to ordinary phosphate-alcohol method, but these methods can not easily applied on the large plate for ship construction in view of the capacity of electric source or the equipment of heating.
After the study of the corrosion test in salt solution, it has been developed to the new modified phosphate alcohol method. This can be applied by either brushing or immersion the concentration of phosphate being 25% for brushing and 15% for immersion, and both need not solution heating. In each process, water can be used instead of alcohol. and after this treatment, the metal surface can be immediately painted without water rinse.
Phosphate and chromate method or sodium phosphate and chromate method are also exert good influence on the light metals at room temperature and its corrosion resistance by these method is equal to the resistance by albond method.
These new method can be applied almost equally on 2S, 61S, 52S and 56S plate. Paint film by these treatment adhere to metal surface and can endure long time against the weathering test.

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The effects of electrolytical condition include those of anodizing voltage, time and kind of electric current.
If the temperature of bath is constant, the higher the voltage and concentration of sulphuric acid are, the poorer the lustre is, but the other hand, the stronger the adsorptive power is. (See Fig. 11-13)
If the temperature and the concentration are constant, the longer the anodizing time is, the poorer the lustre is, but the stronger the adsorptive power is. Fig. 14-16 are the results when direct current is used and Fig. 17-19 are the results when alternative current is used. Regarding to lustre, D. C. is superior to A. C., but as for adsorptive power, A. C. is better.
If the current is changed A. C. for D. C. or D. C. for A. C. in some period during anodizing, lustre varies as shown in Fig. 22. This figure illustrates that the A. C.→D. C. change gives good results for lustre and adsorptive power.

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The corrosion tests of various aluminum alloy casting specimens were carried out in atmosphere, tap water and sea water for one or two years. Resulto oftained were as follows.
1) The decrease of tensile strength of the secondary aluminum castings caused by corrosion in atmosphere and in tap water during two years was about 15-50% and 45-65% respectively.
2) Two types of the relation between corrosion rate and time were recognized, the one was liner and the other was parabolic.
3) The corrosion resistance of the secondary aluminum castings was for inferior to that of the pure aluminum one, but the formor was not so warse than the case of the Al-Cu-Si and Al-Cu-Mg alloy castings which was made vergin metals.
4) On the Al-Mg alloy castings, the reduction percentage of the tensile strength caused by on year corrosion, was about 10-15% at the both cases of tap water and sea water.
5) The effect of the heat treatment on the corrosion resistance of the Al-Mg alloy castings was recognized at the case of tap water, but it was not found on the corrosion in sea water.
6) the corrosion product which was produced on the surface of the Al-Mg alloy castings in sea water, contained Ca O and Mg O. The thick coating on the surface of them, was conposed mainly by Ca(OH)₂, Ca(ClO₂) 4HO and SiO.

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It seems necessary to examine if the cathode plate which is used today is the best one in respect to its strength, its corrosion-resistance and its efficiency. Therefore, we examined some problmes on the strength of one of the cathode plate used to-day.
1) The strength of aluminum reduces according to its purity and especially this inclination is more remarkable when the purity rises above 99.5%. In the view point of strength, therefore, it is better than 99.0-99.3% aluminum is used for the material of the cathode plate. But this reduces its electro-conductivity and its corrosion-resistance.
2) As for the relation between the rolling process and the electrc-conductivity, when the annealing temperature during the cold rolling is held at 275°C., the electro-conductivity is 2% better than annealing at usual temperature.
3) As for the shapes of bar, one having T-type section is the best in the view point of strength. But this type of section is not always available if theother bath-equipment is not fitted.
4) From the stress-strain curves of this material and the stress which is imposed on the bar of this cathode plate, it may be proved that the repeated stress as strong as about elastic limit are imposed on this bar. On the other hand, corrosion weakens the strength of this bar. From two reasons mentioned above, it may be surmised that such bar as examined in this experiment willbe deformed during the repeated using.In designing such bar, therefore, the utmost care must be given to its shape and the protection of corrosion.

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In case a light metal is used as material for the construction of ships, the employment of the method of electric welding for the building of their hulls with that material is advantageous as in the case of the use of steel material for the same purpose. Accordingly, the writer has conducted researches in the electric welding of light metals along the undermentioned lines.
The researches in question concern the trial manufacture of a welding rod for use for light metals and comparison of that rod with the one made by The Alcor and Lincoln Cos. in respect of weld-ability and the physical properties of welded part.
Welding rod:
The welding rod made by way of trial, composed of pure aluminum and 5% silicon, was tested, and a flux was made from the chlorides and fluorides of alkaline and alkaline earth metals. To be precise, the flux was prepared by adding some lithium chloride, sodium fluoride and aluminum fluoride to a mixture of cryolite, salt and kalium chloride.
How electric welding was carried out:
A direct current was used for the welder and the parts to be welded had previously been heated to 170°C-200°C.
Result of experiment:
A rod composed of aluminum and 5% silicon showed better results than the one of pure aluminum. The tensile strength of the welded part was, in the case of 52S material, 14.3kg./mm²-a value fully meeting the requirements of the A. W. S. specification.
Conclusion:
As compared with the rods made by The Alcor and the Lincoln Cos., the rod containing 5% silicon above referred to indicated no marked difference in respect of strength, but the writer is inclined to think that there is room for further study in chemical composition of the rod and the ratio of the mixture and use of the flux.

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Using the Shinko Metal-arc welding rod test on the metal-arc welding of thick aluminum plate and liquid-tightness of welded tank carried out.
The results obtained are summariesed as follows:
1) Metal-arc Welding of Aluminum is suitable for welding of thick plate.
2) Liquid-tightness of Aluminum tank of 4m/m thick welded by metal-arc is good.
3) Tank weld in vertical position is easy and good.
4) Preheat work is not difficult.
5) Strain due to metal-arc welding is less than that of gas welding.

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This report is on the standard specification of aluminum roofing and siding, consisting on general remarks, cutting and drilling, bending, rivetting, jointing, locking, nailing, clipping etc., discussed on the committee of architecture in the Light Metal Society of Japan.

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We studied as to the sealing of anodized aluminum treated with 3% aqueous solution of oxalic acid under the similar purpose to the Ist Report which includes the case of sulphuric acid aqueous solution was used as electrolyte and obtained following results.
(1) In the case which the sealing time is constant at 20 minutes and steam pressure for sealing is variable, the corrosion resistance of anodic oxide film increases at the ratio of 10.6sec*1/1b/in² in proportion to the increment of steam qressure, while its abrasion resistance decreases a little.
(2) In the case which the steam pressure is constant at 751b/in² and the time for sealing is variable, the corrosion resistance of anodic oxide film increases at the ratio of 10sec*2/min. in proportion to the increment of sealing time, but its abrasion resistance decreases slightly.
Remarks *1, *2, ; The time (shown with second) showing corrosion resistance (in the case of *1, *2) is according to the units illustrated in JIS H 8601 (1952).

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Insulation test of aluminum foil has been carried out by the horizontal wall method in which the distance between lower steel plate and upper aluminum one was 80mm according to the actuat wall of carriage. Various insulation methods were tried in that air space of 80mm and the heat transfer coefficients were calculated in the heatings of steel plate at 100°C and 200°C.
Then, it was found that the three layers of aluminum plain foil and the crumpled method of nine foils are the most effective at 100°C and 200°C respectively. And some practical application on the electric annealing furnace was discussed in detail.

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It is hardly necessary to expatiate upon the importance of the press-die in fabricating light metal sheets.
The press-dies made of metal or non-metal material hitherto in use incur a high fabricating cost and their trial manufacture or experiments is attended with much waste, even though their mechanical properties are excellent. In particular, in the aircraft and automobile industries, such waste cannot easily be overlooked when the ceaseless change in the typs of their products is taken into consideration. The "Ryusenzai" (sulpho-fibrous material) explained below is intended for breaking this bottleneck. It is an admixture of sulphur and fibrous material, its mechanical properties proven by various teste being as follows:
Tensile strength: 10kgs./mm² in compression test
Modulus of elasticity of: 1, 500kgs./mm² in compression test
Surface stress: 2, 155kgs./mm² _??_
Modulus of elasticity: 1, 517kgs.mm² _??_
B. N. N. hardness: 56.9 (10/500/30) _??_
V. H. N. hardness: 38.9 (wt.=20kgs.) _??_
Being a casting made by means of low temperature melting, this material has a meritorious feature in that its shrinkage is 4/1, 000-2/1, 000 and, as its surface is very smooth, it dispenses with finishing with a scraping machine, file or the like, after it is cast. The material need ed for This casting can be used over and over again by melting it and, moreover, its strength increases as such smelting process is repeated, a special characteristic never witnessed in any other material.
The material under notice was designed for the first time in 1944 and put to actual use in 1948, /being principally used by the automobile industry largely for press-dies for deep drawing of light metal sheets and for their trial manufacture and small-scale production (500-3, 000 pieces) and partly for small-scale production of soft steel sheets, with the result that their full usability has been ascertained. At present, experiments are being carried on to see whether this material admits of use as press-dies for the ceramic industry.

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The pressure of gas get out from core sand and the running velosity of molten Al alloy at the falling method, were investigated Results obtained are as follows: the running velosity increases with the area of holes at mould suporter. The pressure of gas is decreased immediately at the inside of sand, does not change beyond several milimeters upart from surface of core sand and it increases with casting temperature, moreover it is minimum at 5-7% moisture in sand the more the area of holes at mould surporter, the more the volume of gas escaped through mound becomes, so the fewer it escaped through core sand becomes.

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61S, which is a heat treatable high strength alloy, has the highest proof strength among Al-Mg₂Si group. It is a peculiar alloy containing Cu. as its main element, the percentage ranging 0.15-0.40, in spite of its high corrosion resisting property. Being unable to find any literature on the behavior of its Cu. element, I have made some tracings, the results of which were reported herein and can be summarised as follows:-
(1) Enumerated various wrought aluminum alloys of Al-Mg₂Si group. which are now being used in actual practice. Particularly I have measured the mechanical properties of sheets in 61S various temper conditions, namely F, O, T4 and T6, and tried to make sure what are the most adequate conditions for its heat treatment.
(2) To the composition of standard 61S, excepting Cu, Cu was added in various percentages. ranging from to 0.8. The material was rolled into 1mm. sheets. The variation in mechanical properties in accordance with the change in Cu content was measured under various temper conditions; namely as-rolled (F); annealed (O); solution treated and then quenched (W); naturally aged for 10 days after W treatment (T4); and tempered and artificially aged after W treatment (T6).
(3) As the result, it was cleared that tensile strength increased with the increase in Cu content for every temper.
(4) Proof strength for 0, T4 and T6 increases with the increment in Cu within the range of 0.08 to 0.17%, however the same does practically not increase even when Cu is added beyond the said limit.
(5) Elongation decreases suddenly with a minor increase in Cu content, but the rate of decrease is somewhat smaller beyond the limit of 0.1-0.2%, while the said rate has such a tendency to increase again rapidly above 0.6% of Cu content.
(6) The effect of artificial aging can be precieved in the increase of proof as well as tensile strength with the increase of Cu; especially within the range of 0.2 to 0.5% Cu the rate of hardening attains its highest value. Elongation remains almost constant.
(7) Summarizing the above results, I can easily understand that the lower limit of Cu for 61S was determined as of 0.15. However, I thought it rather overhasty to determine the upper limit of Cu content simply from the facts that the rate of herdening in terms of tensile and proof strength does decrease and also elongation decreases beyond the limit of 0.6% of Cu content. Only after having made through corrosion tests, I will come back to this matter again.

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