We measured the bath temperature of the aluminium electrolytic cell at our factory, and obtained the following conclusions.
(1) Electrolytic bath showed a gradient of the temperature from 950°C at the slag of the side wall, which corresponded to the melting point of the bath to 1000°C-1020°C at the middle of the bottom of the anode, although it was stirred by the evolution of the anodic gas and the heat convection.
(2) After the feeding of alumina, the bath temperature dropped by 16°C at the feeding side, by 9°C at the opposite side. We presumed that feeded alumina completely divcrsed in the bath, after about 30 minutes. After 80-90 minutes, the bath temperature of the feeding side was so high as that of the opposite side. Then, temperatures of both sides began to rise slowly.
(3) After the tapping of metal, the bath temperature rose by about 10°C, and after one hour, the bath temperature of the tapping side rose to same temperature as that of the opposite side.
(4) Since one hour before the outbreak of the anode effect, the bath temperature had been rising beyond 980°C, after this outbreak, it rose at 1010°C, then dropped to about 965°C, with the feeding of alumina and the eliminate of the anode effect.
(5) When bath temperature rose over 990°C, and dropped under 950°C, the electrolytic cell became abnormal.

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In this report, the effect of B and Ti in Al is described
Studying the casting structure and recrystallization on macro-structure, X ray Laue spot and micro-hardness, the result obtained are as follows;
(1) In the use of flux, the maximum content of B in pure Al is 0.15% The best flux for grain refining is KFBF₃, but Borax is able to use in high temperature treatment.
(2) In the case of grain refining, Al containing B have fine equiaxial grain at 0.05% B and Al containing Ti have fine equiaxial grain at about 0.2% Ti…Peritectic point….
(3) The recrystallization temperature of Al-0.1% B alloy is the same to pure Al but the more B content increase, the higher recrystallization temperature rises. The recrystallization temperature of Al-0.04% Ti is the same to pure Al. The more Ti content alloy have more or less high recrystallization temperature.

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The various rates accompanying with the recrystallization of high purity Al-Mn alloys, up to 1.2%Mn, given the cold reduction of 5% by elongation and of commercial 3S alloy given a 10% cold reduction have been studied. All specimens were treated by the suitable salt bath heating to equalize their initial grain size prior to the final annealing. The results obtained are as follows;
(1) For a unique specimen, recrysllization rate, growth rate, and nucleation rate are larger the higher the annealing temperature.
(2) These rates decrease as Mn concentration in solid solution increases.
(3) So then, activation energies Q_N, Q_G and Q_R get larger with increasing the Mn concentration.
(4) As-recrystallized grain size is finer the higher the annealing temperature for a single specimen, but is larger the higher the Mn content.
(5) N/G value gets larger as the annealing temperature increases in a specimen, but becomes smaller with the increase of Mn concentration.
(6) It seems that there is a quantitative relation between N/G value and as-recrystallized grain size.

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This report consists of two experiments.
First, factors which effects the grain size of duralumin type alloy sheets was studied and the conclusions, different from that of Chadwick's⁸⁾, are made.
(1) Fine grain is gained by high temperature intermediate annealing than low temperature one.
(2) Cooling rate after heating also effects the grain size. Slow cooling and rapid cooling are equivalent to high and low temperature intermediate annealing.
(3) The grains once fully recrystallizaed duralumin sheet seldom grow, even thouth the sheet is heated for a long time at higher temperature.
(4) In some specimen, results the coarser grain by heavier reduction. Specimens which are annealed intermediately at low temperature produce such coarse grain.
Second, experiments were made to find which element of duralumin alloy is responsible for these characteristics. Also efforts were made to find the effects of some elements on grain size of aluminium sheet, especially about the correlation between reduction effect (4) and elements, by adding some element to high pure aluminium. And the results are as follows;
a) Alloys which contain Mn display phenomena (1), (2), (3). Fe is also the cause of (1), (3).
b) Phenomenan (4) is considered to arise when the alloy contains Fe, Mn or Cr.

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Fundamental studies on the age hardening in hydronalium alloys 52S and 56S has been carried out to obtain some basic informations to consider the problem of intercrystalline corrosion. The ageing process at 40°C and 200°C has been observed by measuring the changes in Vickers hardness and the results thus obtained has been compared with that of binary Al-Mg alloys and 3S alloy. A small peak found in the ageing curves; at about ten minutes from the beginning of ageing at 200°C has been discussed and an explanations has been proposed that the slight hardening is caused by the homogenization of strain which has been heterogenously distributed after quenching.
Precipitation occurs locally first, followed by general precipitation and after all over-ageing can be observed when excess coalescence of the precipitates occurs. Hardening occurs in 52S if quenched from 500°C, but the hardening was found to occur chiefly at the grain boundary region. This seem to have an intimate relation with the intercrystalline corrosion problem whether the hardening is caused by local precipitation at the grain boundaries or by the enrichment of Mg atoms at the boundary region.
The slight hardening called "first peak" as mentioned above has been discussed, paying attention to the analogy to the first peak in the low-temperature anneal hardening in brass which has been studied by the author and others in details. This hardening, however, seems to have no practical importance since it is completed within a month at room temperature after the cold working.

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Study on the mechanical properties, electrolyic potential, and corrosion resistance of aluminium riveting materials has been carried out.
The results obtained were summarized as following table;
Considering the mechanical properties and corrosion resistance, we recommend NR 5 as the rivet material for ANP plate.

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本研究は昭和9年広海軍工廠航空機部に於て現場に於ける資料を得るため実験したものであるが、今日迄未発表であるので〓にこの実験結果を整理し、その要旨を報告するのである。

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Effect of Ca, Ti, P, S and C, which will possiblly be alloyed in Silumin from the raw material; Silicon, on Silumin has already been reported. In this report effects of other 20 adding elements (Ag, B, Ba, Be, Bi, Cd, Co, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Pb, Sb, Sn, V, W and Zn) on the hardness, microstructure and casting surface of Silumin has been studied. Relations between the content of additional elements and the Rockwell hardness (B scale) of Silumin are shown in Table 2 and Fig. 1a-d. Microstructures of slowly cooled or chillcast specimens are shown in Photo. 1-92, and the casting surfaces are also shown in Photo. 96-115. The results of observations may be summarized as follows;
(1) The most effective element to increare the hardness of Silumin is found to be Mg followed by Cu, although the addition of Co, Cr, Ni and Mn are found also to be very effective, and the effect of Ba, Bi, Ag, Fe and Mo is not so conspicuous. Zn, Cd and Pb have little or no effect.
(2) Ba, Sb, Bi and Mg modify the structure of Silumin especially as chilled but their modifying power is not so strong as Na. The microstrcture of Silumin modified by these elements are not so fine as modified by Na especially as slow cooled.
(3) Ba, Sb, Bi and Mg make the casting surface of Silumin like toad's skin which is disliked by founder. This phenomenon is a result of feeble modification in which Al dendrites grow rectangular to the casting surface.

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The effects of content variations of Magnesium, Silicon and Manganese in the specified range of JIS H5201 FAlACl (approximately corresponds to Alcoa 214) are investigated in view of mechanical properties, casting behaviours and corrosion resistance.
The result obtained are as follows;
Silicon has remarkable effect on tensile properties of this alloy, especially reducing its ductility, whilst little influence upon its corrosion resistant properties.
Magnesium increases the tensile strength and 0.2% proof strength proportionally with its content, but decrease elongation contrariwise, and alloys with higher Magnesium content have more troubleness in melting and casting.
Manganese has little effect on mechanical properties, but improves the sensitiveness to overheating and deterioration of corrosion resistance by Iron content.

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In the previous investigation it was found that the dielectric properties of plain high-purity aluminium foil (99.99%) were improved by the addition of small amount of Mg or Zn.
In this time, the effect of these elements on the electrostatic capacity of etched foil, which is one of the most important properties for electrolytic condenser, was investigated.
Then it was found that Mg is very effective to improve it and Zn has little effect.
In general, {110} orientation appears dominently in 99.99%Al foil with a heavy reduction.
By this investigation, it was brought to be clear that in the case of addition of Mg {100} orientation increases and {110} orientation decreases and it is hardly to find out any changes of these orientations in the case of addition of Zn.
Consequently the cause of the increase of electrostatic capacity of etched foil by addition of Mg seems to be due to the decrease of {110} orientation and to the increase of {100} orientation

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We reported previously in this journal¹⁾ on the effect of Al ion in aluminium anodic oxidation by 15% sulphuric acid.
That report discussed the effects of dissolved aluminium ion on specific electric conductivity of electrolyte, current density and properties of anodic film.
In this report, we studied the effects of Al ion dissolved in electrolyte on properties of oxide film of Al anodized in oxalic acid at our production shop and our laboratory.
We studied the relation between the increase of dissolved Al ion and current quantity (A. H.) at our production shop, and the effects of Al ion on the specific electric conductivity, current density and properties of anodic oxide film, at our laboratory.
The results are as follows.
(1) The increase of dissolved Al ion is proportional to current quantity (A. H), and the dissolved Al ion increases at the rate of 0.0085gr/A. H.
(2) Concentration of oxalic acid is proportional to specific electric conductivity, and this relation is shown by following experimental formula.
K=0.0060+0.0120x x=concentration of H₂C₂O₄% 0.5<x<3.
Concentration of Al ion has little effect on specific electric conductiviy. As it has, however, the property which prevents the current in anodizing, the increase of dissolved Al ion lowers the current density.
(3) The effects of Al ion on the properties of anodic oxide film are summarized as follows.
When the electrolitic voltage is constant (AC 80V, AC 70V, + DC35V), current density decrease by the effect of Al ion. And then film thickness becomes thinner.
The corrosion resistance of anodic oxide film lowers til the dissolved Al ion increases up to 2g/l, but when the content of Al ion increases above 2g/l, it becomes rather better.
The abrasion resistance of anodic oxide film is rapidly lower as the dissolved Al ion increases. According to the results of the constant electric power anodizing keeping the oxide film at constant thickness, the effects of Al ion on corrosion resistance and abrasion resistance have the same tendency as above mentioned, although the effect of the film thickness has been eliminated.

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1) 2S程度の純度をもつ展伸材の硅素を分析する際酸分解によつて生じた沈澱には暗褐色と淡黄色～白色の2種類が認められる。前者の試料をJISのアルミニウム地金比色分析法により行うと、分析値のバラツキが大であるが、後者の場合はその結果がよく揃う。一般に前者の暗褐色沈澱を生ずる展伸材では質別が半硬のものに多く後者の場合は焼鈍材に多い。そこで分析方法としては前者は溶融法、後者はいずれの方法(酸法、溶融法、比色法)でも分析値がよく一致する。
2) ヂエチル•ヂチオカルバミン酸ソーダによる銅の比色定量はヂエチル銅を抽出して銅を比色定量しているため分液漏斗を使用して分別操作等繁雑となり、現場の分析法としては好ましくない。そこで銅標準液0.05～1.0mg(250cc中)を用いてアムモニア性液より発色させ光電比色計を用いて吸光度を測定し、そのヒストグラムや管理図等を作り検量線を求め、そのバラツキを推定した。またこの方法は同一試料で銅と同時に鉄もスルホ•サルチル酸比色法により分析できる。特に高純度アルミニウム地金の分析にも適し、分析の迅速化を要する現場の方法として実用性あるものと認めた。

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The study on the recrystallization of high purity magnesium obtained by distillation process was carried on by hardness test, optical microscopy and X-rays analysis.
The beginning and finishing temperature of the recrystallization, the influence of working temperature on the recrystallization and the effect of annealing time on it were investigated.
The results obtained are as follows:
a) The beginning of recrystallization is 100-125°C and the finishing is 225-250°C on specimens compressed at room temperature.
b) The beginning on spesimens compressed at 200°C is 150-175°C and the finishing is the same on specimens compressed at room temperature.
c) The recrystallization begins at working operation on specimens of compressing at 400°C.
d) The recrystallization begins after annealing for about 50min, at 125°C, about 10hrs at 100°C and about 75hrs at 75°C.

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The influences of carbon content on the various properties of commercial pure titanium have been studied in our laboratory, and the report on the effects of carbon on the mechanical properties, fabricating properties and heat treatment properties was already published in the "Light Metals", No. 12 (Aug., 1954 issue).
This paper reports on the influence of carbon on the chemical coroosion resistance on the commercially pure titanium.
Titanium, which has excellent chemical corrosion resistance, is being utilized as a construction material in the field of chemical, petroleum and synthetic fibre industries in the place of the conventional corrosion resistant metals such as stainless steel, stellite and hastelloy. And reflecting the situation, various reports on the chemical corrosion properties of titanium have already appeared in domestic and foreign literatures.
We, also, conducted experiments on the property using the commercially pure titanium which was produced in our plant. Compared with previous papers on corrosion properties, our report is characterized in the following points:
(1) The influence of carbon on the corrosion properties was studied.
(2) The standard single electrode potential of titanium and other metal was calculated, and the corrosion resistance of titanium was examined from that view point.
(3) The hydrogen and oxygen contents in specimens were analysed by the N. R. C. vacuum fusion gas analysis apparatus before and after dipping test.
As the result we obtained the following conclusion:
(1) Kobe Steel Work's titanium has excellent corrosion resistance against almost all chemical reagents except the following cases: a. HCl 20°C, >90%; boil, >1% e. AlCl₃ boil, >25% b. HF f. Oxalic acid boil, >0.5% c. H₂SO₄ 20°C, >70%; boil; >1% g. Formic acid boil, >25% d. H₃PO₄ boil, >10% h. Trichlor acetic acid 100°C 100%
(2) Carbon content in the specimens has no influence on the corrosion propreties when in the range of 0.05-0.12%.
(3) As the result of theoretical calculation of the standard single electrode potential, it was clarified that the position of titanium in the ionization series was between aluminium and zinc.
(4) By means of gas analysis by the N. R. C. vacuum fusion gas analysis apparatus it was confirmed that-
a. When titanium was dipped in the nonoxidizing acid such as HCl or H₂SO₄, the hydrogen content in the specimens increased remarkably, while oxygen content after dipping was nearly equal as before dipping.
b. When titanium was dipped in the oxidizing acid such as HNO₃, both hydrogen and oxygen contents did not increase and kept the original value.

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Some experiments i. e. the preparation of ductile Th, work-hardening by rolling and texture of rolled Zr, Th and La plate, recrystallization of Zr foil have been examined. The results obtained are as follows;
(1) The block prepared from powder Th by powder-metallurgy can be rolled to thin foil, though cracks break out.
(2) The hardness of Th and La increase monotonously with the degree of reduction, but as for Zr it does not increase above 50% reduction.
(3) The rolled Th plates have fibre structure of which axis is_??_111_??_parallel to the direction of rolling and_??_1120_??_with respect to Zr and La.
(4) Rolled Zr plate begin recrystallization at 500°C when annealed 30min.

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Resistance of some of the aluminium alloy sheets to weathering under various conditions in Japan is examined for certain long periods by the Japan Light Metals Soc. associated with laboratories of several universities and manufacturers to contribute to architectural and other usages of alumimum.
The materials to be tested are eleven aluminium alloy sheets such as 1S, 2S, anodized 2S, 24S, alclad 24S, 43S, anodized 43S, 52S, 61S, 63S, and anodized 63S, as well as some aluminium sheets manufactured by Alcan, pure copper, brass and galvanized steel sheets for comparison with these aluminium alloy sheets.
They are exposed to weathering at sixteen locations under different atmospheric conditions in this country for six months, 1 year, 2, 4, 7, 10, 20, 30, 40 and 50 years.
Tensile test and measurement of mean and maximum depths of corrosion-pittings of the sheets are performed after each exposure period in order to determine the mean corrosion-rate of each allay in each location.
This examination will be commeced on December 1, 1955.

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