This is to report on the study of the effect of the boron treatment on the mechanical properties and electrical conductivity of Al-Mg-Si ternary alloy.
The fiindings are as follows:
(1) The addition of boron restored the decrement of electrical conductivity by titanium impurity contained in Al-Mg-Si alloy. In this case, same amount of boron to restore the electrical conductivity as titanium was added and that exceeded the amount of boron repuired at the reaction of Ti+2B_??_TiB₂.
It might be due to the formation of more boron rich compound than TiB₂ or of AlB₂ compound from a part of boron.
(2) Boron itself did not improved the electrical conductivity of aluminium and its alloy free from titanium.
(3) Regarding the effect of boron on the aging characteristics of Al-Mg-Si alloy, it was found that the retrogressive temperature (Rückbildungs-temperatur) was raised about 10°C by the addition of boron. Therefore it could concluded that, aging at the temperature of 180°to 190°C, the electrical conductivity of Al-Mg-Si alloy treated with boron decreased more than that of boron free alloy.
(4) Sprit aging treatment had more undesirable effect on the mechanical properties and electrical conductivity of Al-Mg-Si alloy with or without boron than that of the material aged immediately after solution heat treatment.

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The influence of the soaking temperature on the occurrence of ear in deep drawing of one-way-and crossway-rolled sheets (both are not intermediate-annealed) is examined. The soaking temperature of the continuouscast 2S slab is changed to 360°C and 490°C, the cold reduction (one-way rolling and cross-way rolling) is changed in the range of 78.5-95.7% and the annealing temperature is changed in 290°C-450°C. The directionality of sheet is examined as follows:
(1) The directionality is detected mainly by measuring the Knoop ratio and the decrement of Harbert pendulum. It is found out from the experiment that the directionality is superior in 45°-direction to the rolling direction in the case that the high soaking temperature and the hard reduction are given and it is superior in 0°, 90°-direction in the case that low soaking temperature and the small reduction are given.
(2) The directionality of the one-way rolled sheet is superior in 45°-direction than that of the cross-wayrolled sheet under the same reduction and heat treatment.
(3) The directionality expressed by the proportion of Knoop ratio "m" and the proportion of Harbert decrement "p" makes the above mentioned facts clear. And the ratio "m" and "p" are in the closed connection with the occurence of ear in deep drawing as mentioned in previous report, so that the earing may be forecast even without the deep drawing test.
(4) The results obtained from the experiment to detect the directionality by the predominant orientation of grain are completely agreed with the results in the ratio "m" and "p". The directionality detected by means of tension test also matches the above mentioned results.

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The excellent heat resistance properties of the "Hot-dipp" aluminized steel is by dint of the presence of the iron-aluminium layer. This layer is, however, rather brittle and hard in its nature, restricting the workability of the "Hot-dipp" aluminized steel.
For the better workability, the coating must be stronger enough for the deformation of a certain degree. The coating thickness and structure of the "Hot-dipp" aluminized steel are thus quite important factors for determining its resistance against deformation.
This is to report on the study about the relationship between the thickness and structure of the coating and the cracking susceptibility and peeling properties of the material, where the effect of the thickness and structure of the coatings on failure of the iron-aluminium layer is determined by tensile and bend tests.
The results of the tests are as follows:
1) In case the thickness of aluminium layer is same, the rupture stress works more to the thinner ironaluminium layer than to the thicker one.
2) Most of cracks appear at the boundary between aluminium layer and iron-aluminium layer and then grow toward the base steel.
3) Cracks which reach the relatively hard and brittle layer of iron-aluminium pass through the mountainpeaks and go into the base steel. There are few cracks pass the valleys.
4) In bending test, cracks take place in early stage at tension side. However, the coatings have the better adherence than in the case that it is deformed under compression.
5) When stressed in tension, the cracks at iron-aluminium layer develop vertically but not in the form of peelings.

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A titanium plate of 6mm thickness was ammealed for 30 minutes at 800°C and cold-rolled by maximum 63.6% and then edge-prepared. This plate was then welded by invert gas are tungusten (Argon gas T. G.), and was investigated on the phenomena occurred by welding heat, at the part of welding joints as well as in the base metal.
The results of the exqeriment are summed up as follows:
(1) When the cold-rolled titanium plate is welded, the structure of the deqosited metal, zone of grain growth, recrystallized zone, zone of recovery, and the base metal as rolled can be seen from the side of deqosited metal.
(2) Banded and dendritic structure made by rapid cooling at the temperature of β→α transformation, 883°C, are seen in the zone of grain growth and deposited metal.
(3) From the distribution of hardness at the welding joint, it is found that the deqosited metal and zone of grain growth are little harder than the recrystallized zone, and that the deviation of hardness is very remarkable, showing the unstability of the structure.
(4) Results of tensile tests with specimens which is taken by cutting out verticully against the welding bead show that the tensile strength as welded state is about 42-43kg/mm². The specimens are broken down at the recrystallized zone. This means that the tensile strength has nothing to do with the degree of working which is given to the base metal before welded.
The tensile strength of the welding joint after annealing at 600°C for one hour is about 38-40kg/mm² and specimens break down in the zone of grain growth or deposited metal.
(5) The average size of recrystallized grains in the zone recrystallized by the welding heat depends upon the working degree which is given to the base metal before welded, and coarser grains are seen in the case of about five percent of cold working being given.

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Titanium is a light and corrosion-resistant material. But the thermal conductivity is very low. To make a good use of the merits and to make up the defect mentioned above, titanium-clad steel sheet has been developed. This material has high corrosion resistance of titanium and high strength of steel. In addition, its thermal conductivity is well improved by the tight adherence of titanium and steel.
The writer has, for several years, studied to produce titanium clad steel with the co-operation of K. K. Nihon Seikosho and has got the successful fruit.
This will make good service as the material for the equipments of chemical industries, particularly for the reaction equipment, lining of distillation tower and heat-exchanger.
This is to report on the outline of the production process, mechanical properties, and welding procedure of this material.

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