The world aluminium industry is briefly reviewed by countries and the future project is also reported.

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The gas cavity in aluminum has been able to determine by measuring its specific gravity. We conducted the following experiments using the standard samples prepared after the 57% cold working.
(1) The effect of the operation of electrolytic cell to the gas cavity in deposited aluminum.
(2) The variation of the amount of gas cavity in aluminum metal, from taping to casting.
We found that the amount of gas in the molten metal is increased by charging raw materials in the electrolytic cell, and is increased or decreased in proportion to the temperature.

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It was previously reported that the sheet rolled from preheated ingots can be completely annealed at 350°C even in an electric air furnace without any grain growth. On the other hand, one rolled from an un-preheated ingot could not be anealed at less than 450°C in an air furnace and its grain size became too large to use for deep drawing.
In the present investigation, the authors looked into the effect of preheating of ingots on the recrystallization temperature and the grain size by means of microscopic and X-ray analysis.
Then it was ascertained that the recrystallization temperature of 3S sheet is affected by the preheating of ingot, i. e. it was 270°C or 340°C in the case of preheating or not, respectively. These remarkable differences of recrystallization temperature may be due to the initial grain size of annealed sheet (2.5mm).
Furthermore, the effect of preheating on the grain size of sheet and the relations between grain size, heating temperature and heating time were systematically investigated in this research.

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We have frequently noticed that anodized pure aluminum sheets have skin patterns, such as honeycomb, pine-needles and fleecy patterns. Our investigations of such surface blemishes gave the following results.
(1) We have confirmed that these skin patterns can be perceived on a surface of a sheet which was directly rolled from virgin ingot, namely the origin of the patterns should be recongnized already in the virgin ingot.
(2) Chemical analysis of aluminum sheets having skin patterns on their surfaces shows that honey comb pattern can be seen mainly on the sheets of 99.5% or higher purity and pine-needle and fleecy patterns mainly on the sheets of less than 99.% purity.
(3) These patterns can be visible in case either iron or silicon of smoll amount is added to high purity aluminum (99.9%), particularly iron is more positave than silicon in producing distinctive skin patterns.
(4) Through microscopic observation it was found that these blemishes were actually the patterns of a group of fine metallic compounds of Al-Fe-Si, in other words they are the collective figure due to discontinuous distribution of metallic compounds.
(5) Fleecy pattern can be eliminated by heating to 500°C for 1hr., but honeylomb and pine-needle patterns can not easily be removed through a heat treatment.
(6) These patterns were formed to disappear by a severe working, because the fine compound group is dispersed in all direction or is aligned up into fibriform by severe hammering and rolling.

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As regards the mechanical properties of annealed aluminum sheets, the percentage of virgin ingots in charge is seemed to give extremely an important effect. The more it decreases, the mechanical properties decrease and in higher percentage of return scrap in charge its tendency becomes severe.
By the results of study that was made on from 99.6 to 99.8 percent purity of aluminum, the more percentage of return scrap increases, the more the tensile strength and elongation decrease together and in the percentage of return scrap until 30 percent those decrement is rapid and then after it becomes slow.
There results are seemed to show that aluminum oxide in its melt is most effective at all. As its proof, a recovery of mechanical properties has recognized. In melting process of the melt of return scrap only, holding-treatment at 800°C have recovered its mechanical properties to the nearly same value of charge of 10 percent of return scrap.

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The effects of Si, Cr, Cu, Fe and Mn on the tensile properties and corrosion resistance of Al-Mg-Si alloy were investigated. In the experiments Mg contents were varied as 1.0, 0.85, and 0.7% while Si content were varied from 0.4 to 1.0%. In the case when Cr, Cu, Fe and Mn were added, their amounts were 0.25, 0.25, 0.4 and 0.2% respectively, These alloys were annealed (0), quenched (500°C × 30min.) and natural-aged (T4), quenched and tempered (175°C × 9hrs) (T6), quenched and rolled by 6% (T36).
Corrosion test was conducted for 6 months by means of wet-and-dry method in 3% NaCl solution. Fig. 20-22 are the results of the accelerated test by which the specimens were immersed in 3% NaCl+0.3% H₂O₂ solution for a month. The relative resistivities of the alloys were evaluated by measuring the decreases in elongation and analysing them by "Analysing of variance".
The effects of each element are as follows,
1) Si: When Mg. content is constant, tensile strength increases linearly whth Si content, but if Si content becomes too excess, that is, the amount of Si is more than that which is necessary to make Mg₂Si, elongation of O and T6 decreases suddenly, and increasing rate of proof stress (0.2% permanent elongation) becomes large. Corrosion resistance decreases with increasing Si content and its decreasing rate is larger when free Si begins to be seperated.
2) Cu: The strength is increased by adding 0.25% Cu, while corrosion resistance is adversely effected.
3) Mn: If 0.2% Mn is contained, the elongation of O decreases and tensile strength increases, but in the case of other heat-treatment, it is not so influential. Corrosion resistance is not effected by Mn.
4) Fe: When Fe content is increased from 0.14% to 0.4%, the strength of O becomes a little higher, its effects on the tensile properties, generally, being small. Nevertheless corrosion resistance falls by increasing Fe content.
5) Cr: Addition of Cr makes the strength of O and T4 higher and the degree of temper hardening small. Therefore Cr is not favorable for the tensile properties of O and T6. But if Cr is presented with Cu, Cr prevents the fall of corrosion resistance which is caused by addition of Cu.
6) Heat-treatment: Corrosion resistance of T6 is generally inperior to other qualities irrespective of whether or not Cu is added

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The solvus surface at Al corner in Al-Mg-Si ternary diagram was determined by means of electrical resistivity meassurement. As a result of this experiment, it was decided that the most favourable alloys as high-tensile and corrosion-resistant alloy were A (1.1%Mg, 0.65%Si, Bal Al) and B (0.75%, Mg, 1.3%Si, Bal Al) alloy. The former corresponds with the principal composition of Alcoa 53S and the latter the one of Alcoa A51S and B. S. AW10.
After this, a study on the influences of Cu and Fe on the tensile properties and corrosion-resistance of A and B alloy were carried out. Copper increases the tensile strength of these alloys, while it decreases markedly the corrosion resistance. Iron decreases the age-hardenability and corrosion-resistance of these alloys. So in the case of service under the severe environments, for example marine use, the content of Cu and Fe in these alloys should be as low as possible.

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The orange peel surface taked place at the deep drawing practice of 2S sheet, recrystallized at comparatively lower temperature, was perfectly prevented by the proper arrangement of the process of hot rolling and the degree of reduction at cold rolling.

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In the 3rd reports, the authors had reported the results measured the flowing current of pure Al, which contains 99.9% purity. The results obtained in an investigation of flowing current of pure Al, which are 99.5% and 98.8% purities, in this paper and the electroytes used was 3% NaCl + 0.1% H₂O₂, 0.1% HCl, and 0.5% H₂SO₄, and measuring time was 0.5, 1, 1.5 and 2 minutes. Samples were heated at 100, 200, 300, 400 and 500°C with following air cooling and quenching in water from 400°C, 450°C and 500°C and after that treatment. Samples were prepared by buff polish or usual polish with flannel.
Conclusion:
1. Samples which used was the electrolyte 3% NaCl + 0.1% H₂O₂ and 0.1% HCl indicated immediately after dipping the increasing of the flowing current.
2. Samples which used was the electrolyte 0.5% H₂SO₄, indicated after dipping the decreasing of the flowing current.

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Several methods of protection of aluminium alloys to corrosion in contact with diss milar metals, that is inserting of zine plate, cadmium plate and calking paste, are compared about their effect combined to the painting.
Tests were carried out in respect to the change of appearance and the decrease of tensile properties of aluminium alloys after corrosion in 5.85%NaCl + 0.3%H₂O₂ solution for 1 month and 3 months. To the panel plate of 52S-O or ND-O one band of mild steel or brass was attached by means of mild steel r vets. Many combinations of vehicles and pigments as calkcng paste were compared on the effect of protection from contact corrosion, resulting that the paste of alkyd resin containing aluminium powder, zinc powder and zinc-chromate were proved to be the most effective. After this, when aluminium alloy plate is not painted, inserting of zinc plate is the most effective, while the consumption of zinc is comparatively large. When aluminium alloy plate is painted, inserting zinc plate unfavourably destroies the paintcoats. So the calking of paste between aluminum and dissimilar metal band before finish painting is the best.

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We have been studying the electrolytic capacitor these many years, and recently have completed that of 30, 000μF in capacitace. When this capacitor is employed to discharge, we can get easily an instantaneous current of as much as 120, 000A which enables the satisfactory welding of aluminum plates, several mm, in thickness. In this paper we have dealt with the discharge wave at the welding carried out in that way. The analysis gave the magnitude of both initial and final contact resistances between the electrodes and the aluminum sheets to be welded, leakage inductance, and resistance change of aluminum during welding. We may classify the welding prosess into three stages; namely (1) The beginning stage when the contact resistanc develop much heat, (2) the mid stage when aluminum melts and made weld, and (3) the final stage when welded material is forged under pressure. In our case, the first stage finished in 2/10, 000sec., and the second stage finished in 4/1, 000sec. These are considered to be for quicker than the sequence taken place in any other type of welder in the similar case.

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In succession to the Part 1 and the Part 2 of this report, we examined the effects of bath-temperature and voltage on oxid film in sulphuric acid process. In this experiments, the type of current is D. C. only and the factors not examined are held in constant, i, e., concentration is 20% and time is 40 minutes. The inspection process for the properties of oxid film is the method specified in JIS P10431, 1951, which was used in the preceding experiments.
The results of experiments are as follows.
(1) The relation between thickness of film and bath-temperature and voltage is shown by following experimental formula. (See Fig. 2, Fig, 3, Fig. 4, and Table 1.)
T=(0.06+0.06h)e^bv _??_T=Thickness(μ)h=Bath-Temperature(°C) V=Voltage(V) b=0.1602(20%H₂SO₄) 10<h<30 10<V<20_??_
(2) From the results of the preceding experiments and the above introduced formula, the relation between thickness of film, voltage, concentration, time and bath-temperature is shown by following experimental formula.
T=(1.52C^-1.326-0.00325C+0.143)t/1.52^tC^-1.326+0.0053t+5.6-0.13C(0.06+0.06h)e^{(0.0176C0.657+0.0311)V}
_??_C=Concentration(%) 10<V<20 20<t<60 t=Time(min.) 10<C<30 10<h<30_??_
(3) The relation between thickness of film and electric power is shown by the same formula as in the Part 1. (See Fig. 5)
T=3.2+0.45W _??_Time=40mins. W=A/dm²×V_??_
(4) The relation between corrosion resistance and bath-temperature and voltage is shown by following experimental formula. (See Fig. 6, Fig. 7, Fig. 8 and Table 2, )
S=(0.44h-0.4)e^bV _??_b=0.169(20%H₂SO₄) 10<h<30 10<V<20_??_
(5) From the results of the preceding experiments and the above introduced formula, the relation between corrosion resistance, voltage, concentration, time and bath-temperature is shown by following experimental formura.
S=t/40(0.44h-0.4)e^{(0.0818C0.325-0.0666)V}
_??_10<V<20 20<t<60 10<C<30 10<h<30_??_
(6) The relation between thickness of film and corrosion resistance is generally shown by the same formula as introduced in the Part 1 of this report.
S=180T^0.253-239
But specific corrosion resistance (S/T) is somewhat reduced by the effect of bath-temperature when it rised up to 25-30°C.
(7) Abrasion resistance is considerably affected by bath-temperature. Regarding to the electric power (A/dm²×V) which is required in order to gain the same abrasion resistance, it is most economical to anodize at the bath-temperature of 15°C. (See Fig. 12)
(8) "Specific abrasion resistance" (abrasion resistance for unit thickness of film) of the film anodized at any voltage has its maximum value at about 15-20°C.of bath-temperature. Then, the most abrasion-resistant film is produced in this region of bath-temperature. (See Fig. 11)

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It is well known that the anodic oxide film produced on the aluminum or its alloys has good insulating property for electricity.
The experiments were done about the 39 kinds of specimens including the aluminum pure and alloys added each of Cu, Mg, Ni, Cr, Mn, Fe, Si, Sn, Zn, or Ca to 99.69% pure aluminum and 17S, 24S, Hydronalium and Y alloy.
The anodizing process used was the most common method in Japan known as Alumite process whose electrolyte was oxalic acid and electricity used were A. C. and D. C. superposed.
The produced film was sealed by steaming process. Measuring of puncture voltage of film was done by using Alternating Current.
Quotation of effects about specimens of anodizing time of 120 minutes are shown in the following.
(1) The group having higher puncture voltage (more than 500V) Hydronalium (containing 7.0%Mg and 0.5%Mn)…1, 000 Volts Zn 0.2%…830 Volts alloys containing slightly Si or Cu
(2) The group having lower puncture voltage 17S, 24S and alloy containing slightly Sn
(3) Alloys except above show about 350 Volts

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The procced paper describles the Shrinkage Coefficent for die castings and gravity castings.
But that castings have a core so that it can not shrink when casting is over.
Then we measured shrinkage of solid castings which have no core.
Shrinkage coefficent are measured 7.5 × 10^-3-6.0 × 10^-3 at aluminum alloys.
But shrinkage coefficent variete 9.5 × 10^-3 to 5.0 × 10^-3.
And we know that shrinkage cofficent regard to cooling ratio C_A and mean thickness of castings.
C_A=surface of castings/weight of castings
Namely, if we put that shrinkage Coefficent is ΔL and mean thickness is θ.
C_A1>C_A2 ΔL₁<ΔL₂
θ1>θ2 ΔL₁ΔL₂
And from report 2.
ΔL=α(t_s-20)-α_f(t_f-20)
But on this case.
t_s=T_s=k=Constant at some alloy
then α(t_s-20)=K
ΔL=K-α_f(t_f-20)
α_f, t_f=expansion coefficent and temperature of dies.
t_s=temperature of the castings begin to shrink.
α=expansion coefficent of the castings.
We know that shrinkage coefficent regard to die temperature.

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The anti-corrosive aluminum alloies are being used for the light construction of streamlined high speed trains in the U. S. A. and Europe.
At the present stage of car manufacturing in Japan, the anti-corrosive aluminum alloies are being used only for inside linings, ceilings and inside fixtures. But the all aluminum alloy cars are expected to be manufactured in very near future in Japan. In this paper some important points are discussed on the design of all aluminum alloy car construction.

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