The effect of grain size upon work-hardening, workability and the earing in the commercially pure aluminium sheets were investigated. Results obtained are as follows:
(1) The sheets cold rolled from the fine grain stock poccesses have superior mechanical properties than those rolled from the coarse grain one, but the degree of hardening of the former is smaller than that of the latter.
(2) The grain size of aluminium sheets affects remarkably upon the workability, however, it has nothing to do with the earing.

View full abstract

It is an important problem to bring to light the corrosion resistance in aqueous solution at high temperature and high pressure of the materials of nuclear reactor and chemical apparatus.
Therefore, the investigation on corrosion resistance of aluminium sheets with 99.2-99.998% and several aluminium alloys in the aqueous solution at 250°, 150°, 100°C were carried out and following results were confirmed:
1. What differs from the test under the ordinary pressure below 100° is the fact that super pure aluminium is most inferior and 2S is superior in the corrosion resistance.
2. Among the alloys such as 3S, 43S, M63S, reflectal alloys and 2S-1.2%Si, 3S is the most superior and reflectal alloys the most inferior.
3. Addition of Fe or Si to 99.99% aluminium improves corrosion resistancc and Fe is more effective than Si. Addition of both Fe and S is far more effective.
4. Corrosion proceeds clearly along the grain boundary and the reaction product (Al₂O₃•H₂O) of super pure aluminium falls off in layer. Furthermore, the corrosion which, in ordinary condition, occurs usually around the compounds and Si, is not observed.
5. Ni ion is effective as an inhibiter for the corrosion, but the blister corrosion tends to occur on the super pure aluminium. Fe ion delays the corrosion rate at first, but induces the pitting corrosion.

View full abstract

The authors investigated the effects of heating conditions of enamelling process on tensile properties of the fine aluminium wires, of which the enamel-coated lead wire was to be made. The structure of the wire was also observed by microphotography and X-ray diffraction.
Fine wires of 99.9% aluminium, 0.14 to 0.23mm in diameter, were annealed at 200 to 450°C for 1sec., 3hrs., or 10hrs. respectively, and their tensile strength was measured. The results were as follows.
Their recrystallization begins within 400-800sec. at 250°C, 6-8sec. at 310°C, and less than 1sec. at over 350°C. The tensile strength in this case is reduced to about 10kg/mm².
Prolonged annealing, such as for 2-10hrs. at 250°C, 30-100sec. at 310°C, or 1-10sec. at 350°C decreases the tensile strength to 7kg/mm² or less. Annealing in less than 1-10sec. results in coarsening the grain structure.
It may be concluded that enamelling of aluminium fine wire is better to be carried out at lower temperature than 300°C and as quickly as possible.

View full abstract

For the analyses of oxide in aluminium, several methods have been proposed, most of which have turned out to be still unsatisfactory having respective merits and demerits. The M. T. method, reported 1949 by M. Tournaire, however, was a good method, standing on the metallurgical view point, to nalise the nonmetallic impurities, especially the total insoluble oxide.
The authors, therefore, made a test analysis of alumina as a preliminary experiment by the M. T. method, and, as a result, found out that the insoluble oxide still remained almost unchanged, provided that the conditions, such as decomposition temperature, reaction time, etc, were appropeiate.
As the results of further experiments were also favorable, the authors made routine analyses by the M. T. method, of the total oxide of the same samples from each stage of rolling of aluminium sheet. The results were as follows:
1. Total oxide in original virgin ingot varies from 0.008% to 0.020%.
2. The total oxide gradually decreases during melt-treatment and shows a constant value in the final slab.
3. Distribution of oxide in the slab doesn't change by rolling.
4. Blister of the rolled sheet seems to have nothing to do with the oxide content, while the parts around scratch, crack, abnormal blow-hole, etc. contain more oxide than the normal and sound parts.
5. After all, it may be concluded that the oxide content of the normal parts of the rolled aluminium sheets show nearly constant value, about 0.010%.
Moreover, by means of the X-ray counter method, one of the physical methods other than the above, the authors observed α- and γ-Al₂O₃ in the vergin ingot, and α-, β-, and γ-Al₂O₃in the cast slab.

View full abstract

In case of quantitive spectro-analysis with solution type samples, many apparatus and process have ever been devised, becouse of its reveral advantages as compared with solid type samples.
In solution method, it is widely known that most the important factor which affects its accuracy of analysis is the quality, e. q. porosity, of carbon bar used for electrode.
When we use the solution method for routine analysis proper apparatus of electrode is prerequisite.
With several trial, we have designed new electrode which is not affected by its porosity and can be used in routine work.
Using this new electrode, we have confirmed ist utility value about both acidic and basic solution of boron.

View full abstract

This report deals with the further experiment on shrinkage coefficent of the casting in the dies without core.
In the previous experiment the calculated shrinkage coefficent differed from measured value. From the present experiment, however, we know that shrinkage coefficent varied according to the thickness of casting.
So that we must correct the conventional formula and set up a new shrinkage formula as follows:
ΔL=K-α_f(t_f-20)-a/t
ΔL: Shrinkage coefficent of casting.
K: Constant value according to the kind of material.
α_f, t_f: Expansion coefficent and temperature of die.
a: 2×(Surface roughness of die cavity surface).
t: Thickness of casting.
20: Room temperature (°C).
For the sperical case as boess or rib.
ΔL=α_e(T_c-T_s)+S+α(T-20)-α_f(t_f-20)-a/t
or ΔL=A+K+α_f(t_f-20)
or ΔL=K
α_e: Expansion coefficent of material in liquid state.
T_c: Temperature of casting when casting is over.
T_s: Temperature of casting when it bigins to solidify.
S: Solidification shrinkage of material.
T: Temperature of casting when solidification is over.
A: Constant value which is measured beforehand by experiment.
α: Expansion coefficent of casting material in solid state.

View full abstract

Some problems on the alloying zirconium with magnesium through ZrCl₄ were investigated.
The losses of thorium and rare earths in magnesium by adding ZrCl₄ were also studied. The result as follows:
(1) As for the properties of ZrCl₄ and ZrCl₄-KCl-NaCl fused salt, it is found that the latter is more stable against moisture and heat than the former, but their alloying efficiencies are the same.
(2) The impurities, such as aluminium, silicon and iron, inhibit the alloying of zirconium with magnesium. According to the experiment of alloying zirconium with magnesium various grades, it was recognized that the more amounts of impurities, the more loss of zirconium results in.
(3) Zirconium in the molten magnesium are segregate on the botton of crucible, in the forms of zirconium rich particles, free zirconium, etc. If the killing time is long, the dissolved zirconium in magnesium also tends to segregate.

View full abstract

With a growing demand for the extensive use of Magnesium alloy materials of good mechanical and thermal properties, studies on the effect of the addition of Zirconium to Magnesium alloys have heretofore been continued pretty laboriously. However, little investigation on of the addtion of Zirconium to wrought, especially rolled, Magnesium alloy materials has been reported yet.
So that we studied the characteristics of Magnesium rolled sheets containing Zirconium of various amount. The results obtained were as follows;
(1) The addition of Zirconium was much effective to refinement of the ingot structure which resulted in the better ingot working.
(2) As for mechanical properties, it improved the ductility of the alloy much better than that of Magnesium alone.
(3) It raised up the recrystallization temperature.
(4) It improved workalilities of Mg-Zr rolled sheet.
(5) As to the orientation, its strength decreares with an increase of Zirconium addition.

View full abstract