A new apparatus for measuring stress distribution and dynamic friction coefficient in cold rolling of aluminium plates was made by the authors. It consists of a small tungsten pin which is set along the radius direction of the under roll, and a wire strain gauge which changes with deformation of the small pin. The wire strain gauge is sufficiently sensitive even to a small load, as the bobbin of gauge is made of cloth-bakelite.
With the apparatus a series of experiments was carried out to clarify rolling stress distribution, stick-slip and dynamic friction coefficient in cold rolling of aluminium plates.
The results are as follows: Many slips exist in cold rolling of aluminium plates; generally, curves between rolling stress and angle of contact part are of bell-type, and the maximum rolling stress increases proportionally to an increase of rolling reduction ratio; and dynamic friction coefficients are calculated at the neutral point, and the coefficient increases with an increase of rolling reduction ratio, too.

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The detection of directionality is usually achieved by means of measuring the tensile strength and the elongation in the tension test, or by means of X-ray, but these methods are complicated in operation and are industrially inconvenient. So, instead of the special preparation of the test piece, we propose a new method using the Knoop indentator or the Harbert pendulum on aluminium and its alloys, which method determines the directionality simply and distinctly.
Using the Knoop indentator, we are able to know the directionality by observing the differences of the major diagonal length L of the Knoop depression corresponding to the angle θ against the direction of working, and as the minor diagonal length l or the depression is affected. by the heaving-up of elliptic depression of the depression, we can detect the texture by means of the ratio (L/l). Using the Harbert pendulum, we know the directionality by measuring the logarithmic decrement of the oscillation of the pendulum or by comparing the amplitude after a certain damped oscillation with a constant amplitude of an incipient oscillation, and the directionality can also be obtained by comparing the ratio (a/b), the major axis of the elliptic depression of the footmark of the pendulum, a to the minor axis, b.
Still more, these methods can be applied to specimens of any shape or manufacture without large depression. Especially, in the workshop, they are easily applicable to industrial use without special preparation of the specimen.

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Precipitation behavior of the precipitates formed during the preheating of Al-Mn(-1.9%), Al-Mn(1.1%)-Fe(-1%), Al-Mn(1.1%)-Si(-0.6%) and Al-Mn(1.1%)-Fe(-1%)-Si(-0.7%) alloys has been investigated by means of measurements of the electrical resistance and micro-hardness, X-ray analysis and microscopical examination.
Results obtained are as follows:
(1) The precipitates in Al-Mn and Al-Mn-Fe alloys are MnAl₆ accompained by G phase (MnAl₁₂), and in the Al-Mn-Si alloy, are α (MnSi) at the first stage and MnAl₆ at the second stage. MnAl₆ is needle-like and has a property of coarsening the grain by heating, but α (MnSi) is of much finer particles than MnAl₆ and has no tendency of grain growth.
(2) Addition of Si in the Al-Mn alloy acceralates the velocity of precipitation which takes place more quickly than in the case of Fe in the alloy.
(3) The recrystallized grain in the Al-Mn and Al-Mn-Fe alloys becomes finer after heating, but in the Al-Mn-Si alloy, the recrystallized grain is coarser after heating.
This peculiar phenomenon may be explained as follows: Al-Mn-Si alloy has an uniform distribution of a great number of fine precipitates which results in an uniform distribution of working strain followed by a slow nucleation rate. The precipitates in the Al-Mn and Al-Mn-Fe alloys, however, are of large grains and have an irregular distribution of particles which result in a non-uniformity of strain distribution followed by a high nucleation rate.

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Researches on aging during one hundred years of Duralumin were projected by Prof. Masaji GOTO and cooperators in Metallugical division of the Aeronautical Research Institute, Tokyo Imperial University.
Test pieces were prepared in 1927 and has been preserved by Prof. Shiro ISida and subse-quently by Prof. Hiroshi ASADA.
Preparation of the test pieces was as follows:
Aluminium wire bar made in Aluminium Co. of England, magnesium ingot, electrolytic copper and Cu-Mn mother alloy were melted in graphite crucible. Standard composition: Grop I-Cu4%, Mg₂Si0.75%, Mn0.5%, Al the balance. Group II-Cu4%, Mg₂Si0.75%, Si1%, Al the balance. Maximum temperature for melting was 750°C. Ingot was 30×100×120mm of size and was hot-rolled at 450°C to 6mm of thickness and annealed at 350°C for 30 minuts and cold-rolled to 5mm of thickness. Tensile test pieces were quenched in water from 520°C after keeping in salt bath for two hours.
The test pieces had been preserved in a storage room of basement for some periods until 1934 without any protection, since when they have been preserved in a steel-locker in ordinary room.
It seems that, after 28 years, tensile strength has become more or less lower and elongation more or less higher.

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F. Sauerwald found that the grain refining occured with the addition of Zr to molten magnesium, and this grain refining effect of Zr was influenced by the alloying elements to Mg; those having unfavorable effect were the alloying elements such as Al, Si, Mn, Ni Sb etc.
In this paper the effect of zirconium on the grain refinning of cast high purity magnesium containing Al, Si and Mn as impurities and the influences of Al, Si and Mn as impurities on grain refinement of cast Mg-Zn-Zr alloy were reported.
Resualts obtained were as follows:
1. In the case of high purity magnesium without other elements as impurities, the grain refining effect was favored by the addition of 0.5% Zr.
2. The grain refinning effect was marked with the addition of Zr when small quantity of impuritiesexist.
3. When the quantity of Zr was 3.5%, the allowable limit of impurities for grain refinement was about 0.5%Al, 0.05%Si and 0.02%Mn.
4. Little prevcnting effect of impurities for grain refinement on Mg-Zn (3%)-Zr alloy was observed when the amount of Al, Si, and Mn was so small that they might be considered as impurities.

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Influences of impurities in magnesium on some mechanical properties and the corrosion resistivity were studied about supper high purity magnesium prepared by vacuum evapolation process, high purity magnesium containing several alloying impurities, and commercial purity magnesium.
The results obtained are as follows:
1. Fair deformability was obtained at super high purity magnesium.
2. The change on mechanical properties depending upon the change of kinds and quantity of impurities in magnesium was not remarkable, but Cu and Si slightly reduce deformability of magnesium.
3. Superior corrosion resistivity was obtained in the case of super high purity magnesium.
4. The corrosion resistivity of high purity magnesium fell off in order of Al, Si, Cu and Fe contained in magnesium.
5. In case of commercial purity magnesium, the corrosion resistivity was inferior, but better than magnesium containing some quantity of iron.

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The effects of Zr addition on some properties of wrought magnesium and its alloys were studied, and the results obtained were as follows:
(1) Zr refines the cast structure of magnesium, AZ31, Mg-4% R. E., Mg-4% R. E. -2% Zn alloy and also Mg-6% Zn alloy. The refined structure is stable and do not grow during hot working. Thus, the addition of Zr improves the hot workability of magnesium and its alloys.
(2) Zr raises the recrystallization temperature of magnesium about 100°C. The structure after recrystallization is also refined and the grain growth during high temperature heating is prevented remarkably by the Zr addition.
(3) Zr decreases the directionality of Mg sheet as rolled, especially after annealing it does more markedly.
(4) The strength of wrought Mg and its alloys is little affected by Zr addition.

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An investigation on the working and recrystallization of commercially pure titanium has been made chiefly by means of microscopic and X-ray method. The change of specific resistivity of titanium wires due to working and annealing was studied observing the coarse grain titanium specimens, in the course of heating with high ternperature microscope stage.
Metallic titanium is readily deformed by twinning, but not all the grains of which the specimens consist. According to Dube and Alexander three types of twinning occur by cold rolling of titanium sheets, and in our investigation, at a certain reduction by rolling at least two of them occur in the same specimen. At 23% reduction by rolling of coarse grain specimen, second order twinnings are observed and above 40% reduction by rolling twins become strikingly fine.
There seems no difference of hardness between twinned and not-twinned grains, however, sometimes the not-twinned grains show slightly higher hardness than the twinned.
Changes are observed when heated the cold rolled coarse grain titanium sheet with high temperature microscope stage. Many newly recrystallized grains nucleated from the deformed coarse grains of titanium are recognized moreover, when heated up the specimen through trans-formation range the newly recrystallized grains become finer again, that is, the grains are refined by transformation in the course of heating.
Contrary to our expectation, the recrystallization grains do not grow much even annealed at higher temperature.
Electric specific resistivity is recovered almost under 400°C, and there are its minimum values between 500°-550°C. But, when annealed above 650°C the resistivity increases again remarkably. And, when annealed the titanium wires in air the resistivity increased rapidly between 30min-60min and then it tends to be saturated.

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This report deals with a series of preliminary tests on zirconium and its alloys which has been carried out during the past 2 years in the authors' laboratory, preceeding the study on the applications of zirconium alloys to nuclear reactor that has recently been begun in the same laboratory. Work-hardening characteristics of pure zirconium and zircaloy-2 as well as some effects of heat-treatment on zircaloy-2 were investigated. Micrography of zirconium and its alloys by both optical and electron microscope was also studied by chemical etching method and the results obtained were satisfiable.

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