巻号一覧
19 巻, 2 号
選択された号の論文の5件中1～5を表示しています
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大根田 昇, 志村 宗昭, 竹内 庸1969 年 19 巻 2 号 p. 41-46
発行日: 1969/02/28
公開日: 2008/11/05
ジャーナル フリーThe effect of pre-ageing on artificial age-hardening of an Al-1.32%Mg2Si alloy at 170°C was investigated. Hardness was measured and it was found that there was some correlation between the hardness and microstructure revealed by transmission electron microscopy. The following results were obtained.
(1) When the pre-ageing was made at below the room temperature, the maximum hardness after ageing at 170°C was about 10% lower than that of no pre-ageing. On the contrary, when the pre-ageing was made at above 50°C, the maximum hardness after ageing was about 10% higher than that of no pre-ageing. However, in the latter case, the maximum hardness was lower when the pre-ageing was made for a very short time.
(2) The critical temperature for pre-ageing, at which the two-stepped ageing effect changed from positive to negative, was about 36°C.
(3) The observation of the structure by electron microscopy showed that coarse acicular precipitates were disperssed after the pre-treatment at 0°C for 7 days; while, fine acicular precipitates were very homogeneously distributed after the pretreatment at 100°C for 24 hrs.
(4) As the results of hardness reversion experiments, it was suggested that the thermal stability of G. P. zones formed by the pre-treatment was higher in the aging of at 100°C for 24 hrs. than that of at 0°C for 7 days.
Most of the above results of experiments can be interpreted by Pashley's kinetic model.抄録全体を表示PDF形式でダウンロード (1028K) -
萩原 理樹, 福井 利安, 杉山 禎彦, 寺井 士郎1969 年 19 巻 2 号 p. 47-54
発行日: 1969/02/28
公開日: 2008/07/23
ジャーナル フリーThe corrosion tests of TIG-welds in 1080, 5052, 5083-O, H plates, 6061 and AlZnMg-T4, T6 plates were made for a period of one year in industrial and marine atmospheres and in industrial and sea waters.
The results obtained were summarized as follows:
(1) Many small pits were produced on the whole surface of all specimens corroded in industrial and marine atmospheres. There were no differences to be observed among the all kinds of materials.
(2) In industrial and sea waters, 1080, 5052 and 5083 alloy welds had high corrosion resistivity, while 6061 and AlZnMg alloy welds were severely corroded in their heat-affected zones.
(3) The decreases in tensile properties of welds by corrosion were negligibly small, except the AlZnMg alloys corroded in industrial water.
(4) In industrial water, the solid solution zone of welded joints in AlZnMg-T6 specimens and all parts of T 4 specimens, except for weld metal, were severely corroded.
(5) Intergranular corrosion was found in the fusion zone and solid solution zone of welds in heat-treating alloys such as 6061 and AlZnMg.抄録全体を表示PDF形式でダウンロード (1705K) -
田中 孝一, 斎藤 寿雄1969 年 19 巻 2 号 p. 55-59
発行日: 1969/02/28
公開日: 2008/07/23
ジャーナル フリーInvestigation was made to examine the effects of heat treatments on the stress corrosion cracking of ternary Al-Zn-Mg alloys such as Al-4.5wt.%Zn-3wt.%Mg, Al-4.5wt.%Zn-2wt.%Mg, and Al-4.5wt.%Zn-1wt.%Mg. The results obtained were as follows.
(1) The stress corrosion cracking was the most liable for the alloys aged to have the approximate maximum strength.
(2) The cracking was more liable when the temperature of solution treatment was higher and the rate of quenching was higher.
(3) The cracking was more liable with the increase in zinc and magnesium contents.
As shown by the transmission electron microphotograph, the above results were summarized as follows : The stress corrosion cracking of alloys was more liable when the range of precipitate-free zone was narrower in the grain boundary and the precipitates was finer.抄録全体を表示PDF形式でダウンロード (1081K) -
志村 宗昭, 大日方 一司1969 年 19 巻 2 号 p. 60-71
発行日: 1969/02/28
公開日: 2008/07/23
ジャーナル フリーFatigue crack propagation in aluminum alloys was studied in thin plate under plane bending the microscopic observation of the surface of specimen and electron fractography.
There were two types of fatigue crack propagation according to the conditions of ageing. One was a continuous growth type; for instance, in Al-1.5%Mg2Si alloy after natural ageing, the fatigue crack was generated at the central hole of the specimen and was developed to grow up until final failure. The other was a discontinuous propagation type; for instance, the fatigue crack of the above alloy, fully age-hardened, predominantly propagated by the linking of many isolated cracks.
The results of analysis for the growth of fatigue crack by Master curve method showed that there were two stages of the growth and only the 1st stage depended on ageing conditions. The rate of growth in the 2nd stage would be a function of the product of grass strain amplitude, εG and a square root of half crack length, √l. The transition from the 1st to the 2nd stage also depended on the ageing conditions.
The examination of the fatigue fracture by electron fractography showed that characteristic feature of the fracture suface depended on the stage of crack growth and the ageing conditions. The 1st stage was the shear mode of crack growth and the surface was often characterized by parallel lamellae along the direction of the growth of the crack. The 2nd stage was the tensile mode of crack growth and the surface was characterized by the striations normal to the local direction of the crack growth. Each striation represented the position of the front oftranscrystalline crack at each load cycle. There were observed two types of striations; ductile and brittle. However, the latter was observed only in aluminum alloys fully age-hardened.抄録全体を表示PDF形式でダウンロード (2349K) -
本間 梅夫1969 年 19 巻 2 号 p. 72-78
発行日: 1969/02/28
公開日: 2008/07/23
ジャーナル フリーPDF形式でダウンロード (1199K)
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