We observed the different phenomenon of "Earing" at deep drawing test of commercial 2 S sheets which produced from chill-cast slab and semi-continuously cast slab. We studied this phenomenon as follows; measuring of the orientation of slab and sheet, after hot roll and after finish annealing. And we investigated which stage is most effective to this problem. We tested several properties; mechanical test, earing test, macro or micro structure and X-Ray test, on chill cast slab and semi-continuously cast slab as same method and positions. And we compared these results usually between chill-cast slab and semi-continuously cast slab.
1. Chill-cast slab.
From X-ray transmission test the patterns were approximately same at any point of slab. The patterns of X-ray test on sheets, after hot roll and after finish annealing, was isotropic.
And "Earing" at deep drawng test was very small.
2. Semi-continuously cast slab. From X-ray transmission test the patterns were different at the position of slab. The most different pattern appeared at the poured point of slab. The other positions were approximately same as chill-cast slab. On the hot rolled sheets the patterns of X-ray test were different at the positions. The most different patterns appeared at the poured point as same as the case of slab test. After finish annealing the pattern of X-ray test on sheets were different at position.
The effect of poured point was residue also after finish annealing,
The "Earing" at deep drawing test was occured at 45° to rolling direction. From this point we consider as follows; The casting texture appeares strongly at semi-continuously cast slab and this texture directed preferencely the orientation of sheets in after stage. The poured point of semi-continuously cast slab shows abnormal macro-structure. And at this point the casting structre, rolling direction [100] axis, appeares more remarkably than any other positions.
We found peculiarity in this poured position after hot rolling. And it makes further at 380°C annealing (001)-[100] recrystallization texture, which has also prefered orientation comparing with other positions. This part has remakable elongation to 45° angle direction at mechamical test and also makes higher ear than the other direction.

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A methed for the judgement of workability of aluminium sheets was studied. By a bending tester which was made by authors, workability at the deep drawing or bending of aluminium sheets was very simply measured.

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The influence of the heating velocity on the recrystallized grain size and recrystallizing temperature of 3 S alloy and the effect of recovery on the grain size have been studied. The results obtained are as follows;
(1) It has been ascetainerd that the grain size was smaller, the faster the heating velocity, whose effective one was the heating velocity passing through the recrystallizing temperature. A relative curve between a grain size (D) and a heating velocity (log v) is formed of 3 stages. There exisits a linear relation, that is D=A-klog v, at the middle stage, in which the grain size is refined severely by the effective heating velocity. But in the both end stages the refining effect slows down.
(2) It has been considered with the application of an assumed relation between N/G and heating velocity that the refining effect of heating velocity on the grain size was affected by the combination of the both influences of heating velocity in the recovery period and in the recrystallizing period.
(3) Any grain size of the preheated sample is smaller than that of the non-preheated specimen with the same heating velocity. Concerning this phenomena, it would be explained better by the change of matrix followed by N/G variation rather than the dispersoid precipitated owing to the lowering of Mn content in solid solution during the preheating.
(4) The increasing of the heating velocity follows the lowering of the recrystallizing temperature, and its cause has been explained through the relation between the working degree and the recrystallizing temperature.
(5) The longer the recovering time, the grain size becomes coarser at the constant heating velocity. This phenomena can be explained well by the nucleus point theory of Collins and Mathewson.

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As part of a systematic investigation of alloys hardened by magnesium silicide precipitation and being good corrosion-resistant, the combined effects of 0.1-1.0%Fe, 0-0.4%Cu, 0.3-0.7%Mn and 0.25%Cr have been assessed in three kinds of base alloy A (1.1%Mg, 0.65%Si, Bal Al), B (0.75%Mg, 1.3%Si, Bal Al) and C (1.3%Mg, 1.3%Si, Bal Al), which were considered most typical in Al-Mg-Si ternary system.
All alloys were hot and cold rolled to sheet of 1mm thick; through the subsequent heattreatment O (450°C, 2hrs), T4 (520°C, 2hrs, water quenched and room-temperature aged for 10 days) and T6 (520°C, 2hrs, water quenchend and tempered at 175°C, 10hrs) temper were prepared.
The corrosion tests were carried out for one and three months immersed in solution containing 5.85%NaCl and 0.3%H₂O₂.
The effects of three adding elements were as follows; copper increases the strength of each alloy, while it has detrimental effect on corrosion resistance. Iron is always detrimental to mechanical properties and corrosion resistance. Addition of manganese or chromium increases slightly strength and suppresses deterioration of tensile properties by iron, as well as hardening by artificial ageing.
Chromium indicates good effects to suppress the deterioration of corrosion resitance by copper and iren, while manganese similar effect only to iron.

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The strength of 61S-T which tempered immediately after quenching is stronger than that tempered after natural aging. This phenomenon is an example of the "SplitAging" named by H. K. Hardy. Effect of "heat-treating factors" (such as quenching temp., tempering temp., and temp of quenching water etc.) on this phenomenon were studied.
Results obtained are as follows,
(1) The difference of mechanical properties caused by "Split Aging Effect" are: Tensile strength 2-4kg/mm² Proof strength 2-4kg/mm² Elongation nearly zero. Hardness (V. H. N.) 10
(2) The strength of T6 state decreases with lengthening natural aging period before tempering. This decrease is most remarkable within imtial 24Hrs of natural aging and, after 2-4, days becomes negligibly small.
(3) The effect of natural aging on the strength of T6 state becomes larger as the quenching temp. increases up to 540°C, and above this temp. the effect is nearly constant.
(4) Suitable tempering temperature is 170-180°C, regardless of aging period before tempering.
(5) Hardness of specimen tempered immediately after quenching changes with tempering period more rapidly than that tempered after natural aging.
(6) Effect of temp. of quenching medium on the spilit aging is negligibly small.
(7) Preliminary tempering of short period at 175°C, or long period at 100°C, immediately after quenching counteracts the natural aging effect.
(8) Streching of quenched sheet has no effect on split aging.
(9) Corrosion resistivity of T6 condition is independent on the natural aging period befor tempering.

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Two-steps ageing treatment, as the author calls it, is a heat-treatment to change ageing temperature during its process. As the number and the stable size of the precipitate or pseudo-precipitate differs with the temperature of ageing the distribution of the precipitate or pseudo-precipitate can be changed by such treatment within a wide range, and thus the properties of the alloy at its final state can be changed; in some cases they may be inferior to the corresponding properties of the same alloy when normal ageing saturates, whereas in other cases when the condition is adequate, superior properties may be obtained. It is of tremendous interest from the industrial stand point to try to improve the properties of high strength aluminium alloys by means of such treatment, to say nothing of its theoretical interests in the study of ageing.
Various kind of treatment belonging to this type, which have been hitherto carried out by the author and other workers, can be classified into two main groups, 1) two-stage treatment, where the alloy is quenched into the temperature within the upper range of its ageing temperature, kept there for a suitable period, then cooled to the room temperature without completing ageing and will be aged once more at the room temperature, and 2) split ageing or two-steps ageing treatment in a narrow sense of the word, where the alloy is once quenched and brought to the room temperature and then aged primary at a temperature followd by the secondary ageing at another temperature.
A brief survey of the former report by late Dr. Imai and the author concerning the 1) treatment (1949) has been made with some further discussions. Then 2) treatment has been considered based on the experimental results obtained by the author this time and that of other workers. The most interesting results of the author's experiment, from the indstustrial stand point has been shown when Al-Mg₂Si alloy was once aged at the higher temperatures above its normal ageing temperature (to avoid the effect of partial reversion at the initial stage of secondary ageing) for a short period, followed by room temperature ageing and then aged at the normal temperature; 20min, at 190°C gave the best results and the properties thus finally obtained was found to be superior to the properties when the alloy is normally quenched and aged. This will also serve as an aid to solve the problem of preventing the deterioration of strength when room temperature ageing might be included between quenching and tempering, which is often the case in industrial practices.

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Some of the fundamental problemes on the contact corrosion of aluminium and its alloys (99.99%Al, 99.8%Al, 99.5%Al, 99.0%Al, 3S, 52S) with dissimilar metals (Pb, Cu, Ni, Brass, Fe, Cd, Mg, Zn, 18-8 stainless steel, 13 Cr stainlees steel) in the aqueous solution containing 5.85% sodium chloride and 0.3% hydrogen peroxide were studied. The results are summarized as follows.
(1) Although the higher purity aluminium has the superior corrosion resistance to the lower purity one in the corrosion test by itself (as shown in Fig. 2, Photo. 1), the lower purity aluminium is superior to the higher purity one in the contact corrosion test with copper. (See, Fig. 3, Photo. 3)
(2) Zinc protects aluminium cathodicallly from corrosion, but magnesium does not protect aluminium cathodically although it makes itself the anode.
Ragarding to the relation beween the penetrations of aluminium and the relative potentials and the solutional currents, nickel, 18-8 stainless steel and 13 Cr stainless steel have the special features. Iron has not only the poor corrosion resistance to this solution by itself, bus gives considerably severe contact-corrosion attack on aluminium.
13 Cr stainless steel gives severer attack to alminium than iron, while 18-8 stainless steel attacks weaker than iron. (See, Fig. 4, Photo. 4)
(3) When aluminium is corroded by this solution contacting with copper, the surface-area of copper defines the quantity of dissolved aluminium. (See Fig. 7, 8, 9)
If the distance between aluminium and copper varies from zero as frequently encountered in the actual application, the corrosion pits are concentrated around the copper. (See, Photo. 7, 8.)
(4) The values of solutional current and relative potential are not always constant throughout the whole testing period, but they vary with the submerging time. (See, Fig. 7.)
(5) One of main factors dominating the contact corrosion is not the surface area of aluminium but that of dissimilar metals.

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In this paper, we report.
(1) Specific Gravity of oxide film is 2.75, and it will be 3 when sealed by high pressure steam, according to the weight of film weighed by dissoling it into hot CrO₃-H₃PO₄ solution and to thickness measuued by microscope.
(2) We observed the change of appearance and the amount of growth of oxide film affected by heat treatmeut of Al-plate at various temperature. The shade of oxide film treated at low temperature is darker, and at high temperature, paler. The growth of oxide film increases at higher temperature of heat treatment,
(3) We observed the change of appearance and the amount of growth of oxide film affected in various steps of tension working. The appearance and the amount of growth of oxide film are independent of tension working.

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The chemical polishing of non-ferrous alloys has been successfully performed since 1948; however, it seems that of steel is still in the research stage, and almost no systematic literatures on the polishing of steel have been published. The principle of chemical polishing is unknown.
The mechanism of chemical polishing, deduced from experimental results, is proposed by the authors in this report.

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Al-7Cu-2Si type alloy is widely used for crankcases, oil pans, differential carriers, transmission cases, camshaft housings, cylinder heads for water cooled automobile engines in U. S. A and Europe, because of its excellent machinability and its high tensile and hardness value without any thermal treatment. This type alloy is not, however, well known in Japan. It has not yet been standardized in Japan as Al casting alloys. Recently technical coalition with German diesel engine has advanced, and this alloy is being used more in our foundry. Accordingly the study of this type alloy has become necessary, and effect of impurities upon hardness, tensile strength and elongaion of this type alloy have been studied. Especially effect of impurities upon hardness has been studied minutely, a hardness of non-heattreated sand casting of this type alloy must be over 90 in Brinell Hardness number and tensile strength or elongation is not so strictly necessary in Japan. The upper limit of each impurity varies according to DIN, SAE, Alcan standards as shown in Table 1 and effect of each impurity (Fe, Mg, Mn, Zn, Ti, Cr, Pb, Sn) upon hardness, tensile strength and elongation, using the sample containing 6.5% of Cu and 2.5% of Si, has examined as shown in Fig. 3-10. Microstructure is also examined for purpose of explaining the action of Mn which improves elongation in high Fe content. From results of this testing, the following points have been explained;
(1) Mg is most effective to increasing hardness and tensile strength of this type alloy, but decreases its elongation. And Fe is the next. Mn, Zn, Ni, Cr, Ti, Pb and Sn have little effect within the upper limits of the standards.
(2) For the using purpose in Japan with over 90 Brinell Hardness number as sand cast non-heattreated condition, Mg must be added unavoidably within 0.5%, but Fe must be kept low to maintain its ductileness.
(3) In the case of containing high Fe content, Mn is effective to improve its elongation because it makes round the needle-like compound containing Fe.

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The origination of residual stress and deformation in casting is discussed in connection with ununiform cooling. According to a assumption that casting materials are ideally plastic at higher temperature and below a critical temperature they are perfectly elastic, difference of contraction between two adjacent parts of equal length in a casting may be neutralized by plastic deformation in both side. But when slowly cooled side is plastic and the other turus into elastic, plastic deformation is occured only in the former and the casting takes a newer deformed length, this is the casting deformation. When this part is cooled to the elastic region, difference between the amount of contraction in both side caused by cooling to room temperature is resided as stress in them; this is the casting residual stress.
This critical temperature can be determined by measuring Young's modulus of specimens at high temperature calculated from determination of vibrating cycles in their natural frequency by electro-static force method, And the coefficient of contraction is also determined by dilatomation. Theoretical calculation of residual stress in pipe casting is attempted applying these measures.
Actual residual stress in pipe castings of Alcan 356 alloy and castiron were measured by Sach's method using wire strain guage.
Deformations in a parabora antenna casting were measured in whole portion, and it is found that there is a close relation between cooling velocity and deformation in each portion.

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Aging phenomena in magnesium rich binary manganese-mangnesium alloys, containing respectively 0.7% and 3.21% manganese, were studied. The results are as follows:
(1) When specimens, quenched at 650°C, were agcd at room temperature and 200-350°C., age hardening induced by precipitation of supersaturated solute was not so remarkable as those of magnesium rich zinc-magnesium or aluminium-magnesium alloys.
(2) On tempering either at constant temperatures or as cending temperature, precipitation of manganese or intermetallic compound Mg₉Mn from supersaturated solid solution, took place at higher temperatures as compared with magnesium rich zinc-magnesium or aluminium-magnesium alloys, that is, over 250°C on costant temperature tempring and at 300-380°C on ascénding.
(3) By tempering precipitation took place more in 3.21% Mn-Mg alloy than in 0.72% Mn-Mg alloy, nevertherless, magnitude of hardening was almost equal.
(4) When the magnitude of internal strain induced by precipitation at a temperature, e. g. 200°C, in manganese-, zinc-and aluminium-magnesium alloys with maximum supersaturated degree, is compared, it is least in manganese-magnesium alloy. Of these three alloy systems, in manganese-mangnisium alloy the highest temperature is required for precipitation starting in a time. These facts cause to reduce the degree of hardening in manganese-magnesium alloys received.

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