It is very hard in practice to get a sound sheet ingot without gases and cavities in the casting of pure aluminium. The gas content of aluminium has been hereto examined by many investigators and its contentt was recently brought to clear to be as small as less than 1c.c/100grs.
The authers studied the comparative value of gas content and the porosity of 60kg's sheet ingot with 99.9%, 99.5% and 99.2% purities which were cast in book mould and direct-chill mould, and the following results have been obtained.
(1) The higher the purity of aluminium, the lower the value of gas content.
(2) The gas content increases towards the surface layer from its centre layer of sheet ingot.
(3) The percentage of hydrogen in total gas is 64-71%.
(4) The gas content of sheet ingot by C. C. P. is smaller by 50% than that of book mould process.
(5) The percentage of porosity in the sheet ingot by C. C. P of 99.5% purity is lesst han 1%, on the other hand that of book mould is generally more than 3%.
(6) There is no direct relation between the blister on sheet and the gas content of sheet ingot, but no blister occurs on the sheet rolled from C. C. P sheet ingot.

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This investigation was carried out in order to ascertain the effect of chlorination upon the purification of metal.
(1) The course of purification by chlorination in a large scale furnace was similar to one in a small scale furnace, but the consumption of chlorin decreased with the increase of surface.
(2) The purification by chlorination was carried out by physical and chemical action, above all it is due to the latter to achieve the purpose of purification in shorter hours.
(3) The change of the specific gravity or α in the course of chlorination was different according as the gas content of the metal.
(4) It is always required to stand the metal for some hours after chlorination and the relation between this time, the temperature, the size of the gas particles dissolved in the molten metal and the depth of metal was introduced theoretically.

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It is said that the blister of Al-sheets are caused by gass involved in slabs which expands when annealed and appears as blisters, and it has been beleived that this gas is contained in molton aluminium at melting, which consists almost of H₂-gass. It is however, cleared by investigating the shapes, the sizes and the time of their appearance that they are caused not so simply and their constituents is rather complicated. Cutting out the blister and examining it by electron difraction. I recognized the rays of graphite, Al₂O₃, Al, respectively according the kinds of blisters, and that graphite, oil, air, and H₂-gass can also be considered as the causes of blisters.
Further, I tried statistic control analysis based on the data of practical operation in order to investigate the factors of causes of blisters, and noted that pre-heating of slabs before hot-rolling has great influence on blisters. It is also studied that, when annealing sheets, if the temperature is below about 420°C it has no influence on number of blisters or size of blisters, indefferently to the time and degree of temperature of annealing. And when it is above 425°C. blisters increase by great degree.
By analysing blisters it is noted that blister contains more volume of Si than the other parts do.
There are two steps in a process of blister's appearance, at first they appears at low temperature and secondly at the temperature more than about 425°C.

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Blister of Aluminum and its alloy has hitherto been considered to be caused by the influence of H→H₂.
After experiments in various respects on Blister, however, I wish to insist that it is influenced by Si→H
(Silicon hidride), namely metallic silicon. I report hereunder about my experiments.
(a) Surplus silicon in Aluminum and its alloy does not combine with Aluminum but exist as metallic silicon.
(b) More metallic silicon is found in a part with blister than the other part that is free from blister.
(c) The yields of blister is in proportion to the quantity of metallic silicon and those have a little silicon in them are of good yields.
(e) When annealing the sheets which have been cold-rolled, it is only metallic silicon that moves within a molecule, and it is believed that this metallic silicon is conbined with hydrogen gas, that is silicon hydride and causes blisters.

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Many reports have been published on the unusual growth of recrystallized grain of Al-Mn alloys. We found, however, the remarkable differences between the conclusion of these reports, even if they carried on the same problems. These differences were resulted from the antecedents of samples and the experimental errors in annealing treatments. In this report, we studied into the origines of these differences and derived the following experimental cautions.
(1) Specimens rolled from the slab which was cast in book mold are locally not homogeneous as for the grain size and the starting period of recrystallization. Then we should cast the uniformly chilled slab, otherwise take the adjoining specimens in the same experiment.
(2) As the temperature of bath is not always equal to that of specimen, the temperature of each specimen should be measured respectively in any annealing experiment.
(3) Mass-effect should be considered because the mass of specimen remarkablly affects on heating rate.
(4) Idea of "Time" should be introduced into any annealing experiment.

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In the previous paper (Light Metals, No. 11, 1954, May), the auther reported the relation between aging and hydrogen evolution of Duralmin (17S).
I researched the relation between the aging and the Vicker's-hardness and potential in this paper.
Samples were water quenched froan 505°C. and then tempered at 130°, 165°, 190°, 220°, 240°, 260°, 280° and 300°C. After these heat-treatment, specimens are dipped in the electrolyte of 3% NaCl and then measured the electrode potential by the Valve-voltmeter.
Conclusion:
I recognized the intimate relation between the aging and hardness, potential and then the hydrogen evolution.

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The relation between the stress corrosion and microstructure of aluminum alloys of 4-7% magnesium with and without manganes and chromium were investigated and found that stress corrosion of these alloys have a very intimate relation to the precipitation of β.
(1) High magnesium-aluminum alloy reheated at low temperature precipitates β along the grain boundary continuously, which causes to crack by stress corrosion in a very short time.
(2) Low magnesium-aluminum alloy (Mg being under 5%) shows no crack by stress corrosion ever after reheated at low temperature, becouse β precipitates in a isolated particles.
(3) On the cold worked material, reheated at low temperature, precipitation of β occurs not only along the grain boundaries but also the slip band.
(4) Tendency of intercrystalline corrosion of these alloys decreases with the slow cooling fromt the high temperature.
(5) Addition of small amount of manganese and chromium to aluminum-magnesium alloy decrease the strees corrosion tendency because of variation of the precipitation of β.
(6) For practical use we now recommend aluminum-4% magnesium alloy with small amount of manganese and chromium, which is free from stress corrosion, from the view point of workability and high mechanical strength.

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The authers made the preliminary research with commercial aluminum (1S and 2S) to comply with the recent requirment for protective and transparent anodized films.
Chemically rolished 1S aluminum was anodized in various concentration of oxalic, sulfuric, sulfamic, phosphoric, chromic acid and sodium bisulfate, sodium carbonate, by applying D. C. 1.0A/dm², for 5min, at 25°C. The variations of reflectivity of polished surfaces and anodized surfaces were measured. Abrasion and corrosion resistance was measured according to specification of JIS.
Next the effect of current density were studied with the two typical baths, 10vol% sulfuric acid 5wt% oxalic acid. Further, decrease of reflectivity with anodizing time was measured by both D. C. and A. C. using 1S and 2S which were polished chemically or electrically.

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This is the stenographic report of above entitled two lectures, held on July, 1954, in the Hall of Mining Society, by the present writer.
In the first lecture, the cause of occurence of "hard spot" in the aluminium alloy die-castings as well as the compositions of the hard spot itself have been explained discussed in details, quoting the metallographic observations carried out by the preset writer. Even if there are no contaminations in the melt of aluminium alloys, the "hard spot" may be generated as the primary crystals of hard intermetallic compounds in the melting-pot, if the temperature of the melt is lowered. As to the sorts of the intermetallic compounds which may be found as the hard spot in the die-eastings, the ternary compounds; (Al Fe Si) α and (Al Mn Si) α respectively, as well as the quaternary compound; (Al Fe Si Mn) have been pointed out.
In the latter lecture, the difference in the structure of the aluminium alloy die-castings temperatures has been shown: When the casting temperature is fairly high; that is the complete melt is poured into the die, the structure of the castings is of course fairly homogeneous. On the contrally, if the half-melt is poured or pressed into the die, the primary aluminium-crystals, which are already generated in the melting-pot, may be detected to be gathered in some part of the die-casting, thus resulting the structure to be heterogeneous.

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An X-ray pulse generator, capable of producing strong and short duration pulse of X-ray, has been constructed.
By this apparatus, we have observed several states of molten metal in moulds. Firstly, a thin sand mould and lead for the molten metal have been used (Exp. 1). In this experiment, three sorts of gates were used. Secondly, a simply formed shell mould and lead or Lautal have been used (Exp. 2). Thirdly, shell moulds, which were made for practical production, and Lautal have been used (Exp. 3).
From these experiments, we observed several interesting behaviours of molten metals, for example, these are illustrated in Fig. 6, 9, 16, etc.. And different figures of flows have been observed in different molten metals

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We studed the weldability and electrical conductivity of welded high purity aluminium bus-bar.
The welding methods were oxyacetylene, argon shielded arc, and metal arc process.
The electrical conductivity of welded aluminium bus-bar was guaranteed 63% IACS. on any welding method mentioned above.

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We are going to report herewith on the results of our various test regarding the adhesive "Araldite" produced by the "CIBA", Switzerland, which was introduced in Japan as an Adhesive of Aluminum and its alloys in 1951.
This paper shows the results as follow, obtained from the test pieces jointed by a simple lap with Araldite Type I, XV and 101 respectively, time and temperature of thier hot curing, time of cold setting, length of overlapping, effect by the thickness of Araldite, the influence of aging on strength both in and out room, and in water too, furthermore, the condition of adhesion of Gakko Bosatsu's Head our factory submitted this jointing works at Yakushiji Temple in Nara Prof., and also other references for this adhesive we have obtained.

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Results of research on coarsening of recrystallized grain in commercially pure Mg and Mg alloys which were severely deformed and annealed at higher temperature were previously reported.
Investigation on coarsening of recrystallized grain in high purity Mg which was manufactured by vacuum distillation process, and effect of slightly added elements as impurities to distilled Mg upon grain coarsening was carried on.
On distilled Mg which was compressed 30-70% at 250°C and annealed at various temperature, the range of compressing degree on grain coarsening, heating temperature for it, and heating period up to it were researched. Such impurities as Ag, Al, Bi, Cd, Cu, Mn, Pb, Sn and Zn were added to 0.01 and 0.05 atomic percentage and recrystallization was researched after the same treatment as the case of distilled Mg.
The range of compressing degree for grain coarsening on distilled Mg was wider than that of commercially pure Mg.
Orientation of coarsened grain was the same as that of commercially pure Mg or Mg alloys.
Added impurities lengthened incubation time up to the beginning of coarsening than distilled Mg and there was difference on incubation time by the kinds of impurities.

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Seven alloys, which have max. solid solubility and different equilibrium relations in solid, were examined on their age-hardening phenomena. They were quenched into cold water at different solution treatment temperatures, and aged from room temperature to 300°-350° at the heating velocity of 1°C per min.
The results are as follows:
(1) Alloys which contain more aluminium, show higher hardness at the quenched and aged states. But hardness increment of every alloy is almost efual (R_F20-25).
(2) Precipitation of δ from binary magnesium alloy containing aluminum, takes place at about 175° and that of Mg₂Sn from binary magnesium alloy containing tin at about 225°
(3) All alloys, having (Mg)→δ reaction as the first or second in solid at cooling, precipitate, at first, δ phase, that is, a precipitate to be deposited more easily, on their aging of super saturated solid solutions. Then, the reaction of (Mg)→δ + Mg₂Sn or (Mg)→(Mg₂Sn) takes place.
(4) Alloys, containing Mg₂Sn as a age-hardening constituent, increase, slightly, their hardness by formation of intermediate phase, at first, and then principally, harden by precipitation of equilibrium Mg₂Sn.
(5) The precipitation type of δ phase belongs to "discontinuous type", and that of Mg₂Sn to "continuous type".
(6) Softening by over-aging takes place at alloys, containing δ as a age-hardening constituent, more easily than at those contmining Mg₂Sn as a age-hardening constituent.

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Experimental results are in this paper which show the effects of carbon on the workability, mechanical properties, and structure of Kroll process Titanium. Ingots of about 30lb wt. of commercially pure and and low carbon alloys were double melted with consumable electrode arc furnace and high carbon alloys with induction furnace.

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