It is an important problem on industrial view that metallic impurities in commercial pure aluminium Fe, Si, Cu, Mg, Mn, Zn and Cr have various influences on its properties of sheets. Up to this time many researches which was studied partially about this thema had already been reported.
But there is no summarization because which contents is so wide. Among these metallic impurities, Cu, Mg, Zn and Cr are mixed from return scraps and secondary ingot, and Fe and Si are from virgin ingot.
Recently with the elevation of purity in Aluminium virgin ingot, commercial composition has come into question. In Alcoa specification of impurities in 2S, sum of Fe and Si are less than 1%. In B. S. Standard Fe must be less than 0.7% and Si less than 0.5%. But practical chart of operation is reported as follows: In Alcoa, Si is 0.15%, Fe0.55% and in British Aluminium Co. Si is 0.18-0.20% and Fe more than 0.4%.
From its impurities, commercial pure Aluminium must be cosidered as Al-Fe-Si ternary alloy metallurgically.
In Al-Fe-Si ternary system, eutectic point of Al-Fe exists in Al-side nearer than Al-Si, and then Fe is attached greater importance to various properties than Si.
In rolling pure Aluminium sheets, from metallurgical view, various properties of Aluminium sheets production are classified as follows:
1) Casting crack (Hot shortness). 2) Blister and surface scratching.
3) Pattern appearing on anodized aluminium sheets. 4) Corrosion.
5) Mechanical properties and grain-size. 6) Orientation in deep drawing.
7) Others.
In this paper, we studied technically the only influence of Fe and Si in commercial pure Aluminium, that is 2S, based in light metall industry and summarized above problem.
Concluson:
1) Si effectively promotes its casting crack and Fe has no influence, but combination of Fe and Si have a great effect to it.
2) In blister phenomenom, Aluminium purity is proportion to its appearance, but effect of Fe and Si cannot be recognized. And blister is considered to depend on gas contents of cast slab. The cause of surface fractures is not of metallic but non-metallic impurities.
3) About the pattern appearing on anodized sheets, various pattern which is presumed to derive from metallic compound appearing with combination of Fe and Si.
4) Corrosion property is not influenced with Fe and Si, but Al-purity.
5) In these Al-purity, elongation and Erichsen value show no change with Fe and Si, but tensile strength and grain size show a great change.
6) The more Fe/Si, grain size remarkably becomes the finer.

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Aluminium sheets of industrial purity were cold-rolled from hot-rolled stocks without intermediate annealling. It was found that the anisotropy of cold-rolled or annealed sheets was in-fluenced by the duration of preheating before hot-rolling. The anisotropy before recrystallization decreases with an increase of the preheating duration, moreover by changing the cold-rolled direction across the hot-rolled. When the duration was too short, 45° ear was found after recry-stallization.

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It has been actually experienced that the commercial pure aluminium sheet made from continuously cast slab shows the distinct orientation in deep drawing, although it solves the blister problem. The orientation of the sheet made from the poured part of slab which has columner structure is more remarkable than that from the other parts.
As these anisotropy cause the growth of "ear", the advantage of diminishing blister seems to be certainly offset.
It has been also reported that there exist the difference between the patterns revealed on the anodized surface of sheets made from these slabs.
In this report, we examined that there was some change in the anisotropy and the pattern of anodized surface by the reduction and the annealing temperature of the sheets made from these slabs.
1. The anisotropy is strongest in the sheet made from the columner parts of continuously cast slab and weakest in the sheet made from book mould cast slab, through all reductions and annealing temperatures.
2. Earing value is lowest in the sheet which has about 87% cold reduction. 3. The annealing temperature has lttile effect on the earing value in the range of usual annealing temperatures. (300-400°C).
4. The more the maximium difference of the elongations at the directions of 0°, 45° and 90° to rolling direction, the stronger the anistropy
5. The pattern revealed on the anodized surfacc of the sheet made from continuously cast slab is a little conspicuous than that from the book mould slab.

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The kinds of annealing twins and their growth processes in aluminium polycrystals were examined by etching pits method and by optical microscopy.
They were obtained from the samples which are rolled to about 10 percent or tensioned to about 50 percent at room temperature respectively, and annealed from 5 minutes to 10 hours at more than 500°C.
These results suggest that there are three kinds in annealing twin and their growth proceeds chiefly by the growth of non-coherent twin boundary along (111) coherent twine boundary in the same way as mechanical twinning in body centered cubic crystals.
But their rates of growth are generally smaller than the normal grain boundary migration, since their growth are accompanied with the formation of coherent twin boundaries.
The reaults mentioned above are discussed theoretically.

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I) Preface
II) Experimental study
1) Existence of metallic sillicon.
2) Total silicon in blistered and non-blistered part.
3) The influence of various elements except silicon
4) Metallic silicon in blistered and non-blist-ered parts.
5) The relation between heat-treatment of hot rolled plate and metallic silicon from semi-continuously cast slab.
6) Blister of annealed sheet in hot rolled plate from semi-continuously cast slab.
7) Blister of annealed sheet in hot rolled plate from chill cast slab.
8) The relation between heating temperature, time and metallic silicon.
9) Blister of annealed sheet in hot rolled plate.
10) The surface transition of metallic silicon in hot rolled plate by heat-treatment.
11) The reaction of metallic silicon and hydrogen gas at various temperature.
12) The existence of silicon hydride in blister gas.
III) Conclusion.
IV) Reference.
I) Preface
It is often found in general chemical analysis that brown or blackbrown coloured residue is formed when sample is dissolved in acid to determine silicon in aluminium and its alloys (except silumin). The residue which is insoluble in acid (but in nitric acid and fluoric acid it dissolves gradually) is called "Graphitic silicon" or "Metallic silicon". Generally, the states of silicon contained in aluminium and its alloy are classified as:
1) silicide combined with other elements, such as Fe, Cu, Mg, Cr, Mn, Go, etc,
2) partially solid solution by annealing treatment.
3) free or metallic silicon, if excess. It is clear that silicon doesn't combine with aluminium to form silicide and have various influences on the properties of aluminium and its alloys.
The author has become to think that blister of aluminium will be influenced by silicon content and through many experiments shown below, reached to the conclusion that metallic silicon is the cause of this blister phenomenon.

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Recrystallization of cold rolled Aluminium containing La, Ca or Ba individually was studied on the beginning temperature of recrystallization and recrystallization texture. The beginning temperature of recrystallization was determined by means of X-ray Laue method and hardness measurment.
Furthermore, casting structure and rolling texture of these alloys were investigated. The results obtained are as follows:
(1) La, Ca or Ba has no effect respecting to the grain refining of Al castings.
(2) Cold rolled plates of these alloys have fibre structure of which axes are [111] parallel to the direction of rolling.
(3) 0.83%Ca-Al alloy begins the recrystallization growth at 50°C and 0.71%Ca-Al alloy almost finishes it at 100°C.
(4) Excepting lower Ca content alloys, beginning temperature of recrystallization of Al-La, Al-Ca and Al-Ba alloys are about 200°C, 200°C and 250° respectively, and notwithstanding the concentration change of alloying element, these temperatures are not varied.
(5) The higher the content of these alloying elements, the more the recrystallization texture have the fibre structure whose common axes are same as the rolling texture.

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Primary recrytallization phenomena with or without preheating for high purity Al-Mn binary alloys containing up to 2%Mn and for ternary or quarternary alloys containing 1.2%Mn and up to 1%Fe or Si have been studied. For all specimens given 92% cold reduction, the annealing treatment were carried out in the air bath keeping the temperature below 600° followed with 1 hour holding and in the range of heating rates 25-400°C/hr. The results are as follows:
(1) Mn in all the binary Al-Mn alloys is retained in solid solution and the temperature of complete recrystallization is raised with increasing the Mn content, that is 280°, 440° and 550° for Al, 1.1%Mn and 1.92%Mn respectively. Fe contained in this alloys results in the formation of primary Al-Mn-Fe compounda nd in lowering the recrystallization temperature, but Si remains in solid solution and causes raising of the recrystallization temperature. Preheating for all the alloys is accompanied with a considerable drop in the recrystallization temperature corresponding to the structural change.
(2) Concerning the primary recrystallized grain size, the general effect of Mn in solid solution is to increase the grain size which is coarser the higher the Mn content and is finer the higher the heating rate. Fe or Si addition to the alloy refines the grain size without preheating. On the other hand, preheating causes the precipitation of dispersoids resulting in the refinement of the recrystallized grain size except of alloys containing Si in which a peculiar phenomena appears that the recrystallized grain size gets coarser with the proceeding of preheating. But, in the Al-Mn-Fe alloy and Al-Mn binary alloy, the grain size becomes finer the stronger the preheating proceeds and the higher the heating rate.

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Recently, the phenomena of age hardening is studied with dislocation theory by Cottrell.
According to his paper, solute atoms will cluster around dislocations forming "atmosphere", and stringlet cluster may be formed,
However, the formation of platelet cluster and nucleus will be almost impossible from his theory. These difficulties caused by considering a single dislocation only.
The auther proposed in this paper that if we regard a vacancy disk or a extra plane disk, forming from dislocation pair and intersection of screw dislocations, instead of single dislocation, these difficulties can be considered as more probable processes in aging.
At first, the formation and the stability of vacancy disk or extra plane disks were proved with the relation between interaction force of unlike dislocation in dislocation pair, Fy, and the force of vacancy which pull away a dislocation from the slip plane, Fv.
Secondly, that solute atoms will cluster into the disks with the interaction energy of dislocation pair and solute atoms in the same way as Cottrell's mechanism.
Consequently, it is concluded that the forming nucleus are characterized by the following properties.
(1) Nucleus is established on slip planes or lattice planes perpendicular to slip plane in the matrix.
(2) Nucleus is continuity to and most fitable in the lattice structure of matrix. So, they have the structure resembled to the lattice structure of matrix.
(3) The shape is a disk or a flat rotatory ellipsoid which have several angstrom thick and about several hundred angstrom diameter.
The applications of the theory proposed here show good agreement with experimental results qualitatively.

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It has been reported that in molten Al and Al Alloys fluidity-temperature curves and thermal analysis curves had change points at 765°C and 855°C. We researched that the maximum heating temperature about the change points affect on casting structure.
On pure Al the higher the temperature, the larger the eqiaxal grain between the two change points. But at higher than 855°C the grain size decreased with temperature.

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In studying the method of detecting hair cracks in wire bars before rolling, the specific gravity of its surface and central parts was measured.
The specific gravity of the surface was lighter than the central part in defective bars, and the specific gravity of the surface was heavier than the central part in non-defective bars.
The results of this study confirm the findings already ascertained by rolling mill operations.
It is concluded, therefore, that one method of detection defects in wire bars is by the measuring of specific gravity of the surface and central parts.

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The endurance tests were carried out with Ono's rotary bending machine. The results of these tests were indicated on each figure and studied the relation between fatigue strength at 10, 000, 000 cycles and tensile properties.

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Study on the corrosion-fatigue propertice of several corrosion-resistant aluminium alloys has been carried out under 3%NaCl aq. solution with Ono's rotary bending machine. The following results were obtained;
(1) Endurance strength of those alloys was much reduced under the liquid and results were summaried in Fig. 9.
(2) Endurance strength at 10, 000, 000 cycles under the liquid was not so affected by the T4 or T6 heat treatments or drawing reduction, but influenced by the chemical compositions.
(3) Resistance to the corrosion-fatigue in the cace of Al-Mg alloy was increased with Mg content and in the case of Al-Mg₂Si alloy was increased with Mg₂Si content, and author discussed the slope and type of S-N curves under the liquid.

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The corrosion resistance of galvanized aluminium and its alloys by various methods is determined systematically. The results obtained are summarized as follows;
1. The copper electric plating on the surface of aluminium and its alloys for preliminary treatment must be avoided because of their corrosion resistance.
2. In general, galvanized aluminium and its alloys have a low resistance corrosion in various solutions.
3. The corrosion phenomena of aluminium and its alloys are divided into two parts; one is a contact potential difffrence, the other is an imcomplete galvanization. The former defect is protected by means of the author's method.

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Commercial Silicon always contains Fe, Al, Ca, Ti, P, S and C as impurities, which tend to segregate as shown in Table. 1. Test bars of Silumin made from same Aluminium ingot and socalled same charge Silicon have often different values in their properties. Some proportion of impurities in Silicon is assumed to be alloyed in Silumin, but their influences on Silicon have not yet been studied. In this report influences of Ca, Ti, P, S and C on Silumin are investigated using standard Silumin and mother alloys shown in Table. 2. P and S were added in Silumin by melting the mixture of Silumin borings and P or S in hot graphite crucible, and also by charging in molten Silumin by phosphorizer, C was added in Silumin by violently starring the mixture of molten Silumin and graphite while cooling and heating again at 1000°C about one hour. Influences of Ca or Ti on mechanical properties of Silumin are shown in Table. 3, Fig. 1 and Fig. 3, Chemical compositions in Table. 4, and their microstructure and casting surface in Photo. 1-11. The results obtained are as follows:
(1) Ca has modification effect on Silumin, but it is not so remarkable as that by Na. Tensile strength of Silumin containning 0.05% of Ca is equal as Silumin modified by Na, but elongation is lower. Ca over than 0.05% injures both tensile strength and elongation of Silumin, because of the appearance of CaSi₂. Ca also makes casting surface of Silumin so-called "toad skin" disliked by founder. This phenomenon is a sort of modification in which primary Al dendrites crystalize in the normal direction to casting surface.
(2) Ti less than 0.05% has little influence upon mechanical properties and microstructure.
(3) P acts as nucleus of Si crystal as phosphide. C also acts as nucleus, but effect of S as nucleus is feeble.
(4) Oxide that might be included, and observed in fact, above treatments, has little nucleation effect.

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本研究は昭和9年広海軍工廠航空機部において実験したものであるが、今日まで未発表であるので〓にその実験成績を整理しその要旨を報告するものである。

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本研究は昭和9年広海軍廠航空機部に於て実験したものであるが、今日迄未発表であるので〓に其の実験成績を整理し其の要旨を報告するものである

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Relations between oxidation time and weight increase were measured and the oxidation products were determined by X-ray and electron diffraction methods. The prevention of oxidation by spinel coating composed of MgO, ZnO or BeO were examined. The results obtained were as follows:
(1) The curve of weight increase with time was straight at initial and parabola at final stage, and the activation energy of oxidation was calculated as 39, 000cal/mol and 51, 000cal/mol, respectively for each stage.
(2) The oxidation products were determined as TiO (NaCl type) and TiO₂ (Rutile) at initial and TiO₂ (Rutile) at final stage.
(3) Using H₃PO₄ as a mineraliser, the forming of spinel compound of MgO, ZnO or BeO on Ti plate was examined and the former two were successful for spinel formation and the prevention of oxidation, but not in the case of BeO. The lattice constant of 2MgO•TiO₂ and 2ZnO•TiO₂ were obtained as 8.45Å and 8.44Å respectively.

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We have previously reported¹⁾ the weldability of Al-Mg alloys. In this experiment, we studied the weldability of ANP plate, using Sigma, Heliarc and oxyacetylene welding.
The results obtained are summarized as follows:
(1) Porosity-free welds are obtained using cleaned filler wire and mother plate.
(2) In Sigma welding, low arc voltage and current produce porosity weld.
(3) Argon arc welding (Sigma and Heliarc welding) are recommended for ANP plate, for mechanical properties welded by these processes are the best. The tensile efficiencies are over 90%.
(4) Oxyacetylene welding is not recommended for thick ANP. plate. Mechanical properties of this weld are extremely inferior to that of argon arc welding.
(5) The electro-chemical potential of weld zone is nobler than that of mother plate, and weld zone is anticorrosive in sea water.

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