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Volume 38, Issue 7
Displaying 1-11 of 11 articles from this issue
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[in Japanese]1969 Volume 38 Issue 7 Pages 675-690
Published: July 25, 1969
Released on J-STAGE: August 05, 2011
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Tadayoshi Sasaki1969 Volume 38 Issue 7 Pages 691-701
Published: July 25, 1969
Released on J-STAGE: August 05, 2011
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Haruyoshi Suzuki, Junjiro Okamoto1969 Volume 38 Issue 7 Pages 702-713
Published: July 25, 1969
Released on J-STAGE: August 05, 2011
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Kiyoshi Terai1969 Volume 38 Issue 7 Pages 713-718
Published: July 25, 1969
Released on J-STAGE: August 05, 2011
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Kiyoshi Terai1969 Volume 38 Issue 7 Pages 718-729
Published: July 25, 1969
Released on J-STAGE: August 05, 2011
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Tomio Senda, Fukuhisa Matsuda, Mitsuaki Kato1969 Volume 38 Issue 7 Pages 730-738
Published: July 25, 1969
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSFatigue tests were undertaken on the base metals and welded joints of commercially pure aluminum. During the tests, X-ray differaction patterns were obtained for these specimens. Then the ratio of half-value breadth was examined for each specimen and also the diffraction patterns were Fourier-analysed to get the lattice strain and the apparent grain size. Conclusions obtained are as follows:
1. The change in the ratio of half-value breadth during the fatigue process was qualitatively the same as the change in the lattice strain obtained by Fourier-analysis of the diffraction patterns.
2. In the case of annealed specimen, the lattice strain increased initially and took a minimum value at about 0.25 of the ratio of cyclic number. Afterthat, it again increased linearly and the specimen fractured. This change in the lattice strain seems to be explained qualitatively by the change of microstructure obatined with electron microscope.
3. In the case of tensile strained and welded specimens, the lattice strain decreased while the apparent grain size increased. This means that the phenomenon of recovery occurred. Moreover, the lattice strains of all specimens have approximately shown the same value in fracture, though the initial conditions of the specimens were different.
4. It was confirmed that it would be possible to estimate the fatigue life by examining' the change in the ratio of half-value breadth.View full abstractDownload PDF (4716K) -
Thermal Characteristics of the Tungsten Arc in Argon AtmosphereToshio Yamamoto, Wataru Shimada1969 Volume 38 Issue 7 Pages 739-743
Published: July 25, 1969
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSThe thermal characteristics of an arc with straight polarity formed between a tungsten electrode and a water-cooled copper plate in argon atmosphere of 18 to 760 mm Hg are examined in relation to the electrical characteristics mentioned in the previous report. The experiment is made under the following conditions. Pressure of atmosphere P : 18 to 760 mm Hg
Arc current I : 250, 450 A
Distance between electrodes L : 1 to 25 mm
The facts elucidated are as follows.
1. The ratio of anode power to arc power is 93-95% at L≅0 mm and decreases linearly with increasing L. At the pressure above 320 mm Hg and below 50 mm Hg athe decreasing tendency of the ratio is particularly remarkable.
2. At the pressure below 50 mm Hg, anode power decreases continuously with L. This tendency should be explained as follows: the power carried away from the cathode lone increases remarkably with increasing Lbecause the power is larger at lower pressure condition, resulting in the decrease in the transfer rate of the power to the anode, on the other hand the power of arc column increases little with increasing L.
3. The variation of cathode power with gas pressure is small and the ratio of cathode power to arc power is about 5-7%. Joule's beat of the tungsten electrode is as large as or larger than the cathode power, hence within the pressure range used in the experiment, the power generated at the cathode is made negative by the cooling action of thermally emitted electrons just as under the atmospheric pressure.View full abstractDownload PDF (391K) -
Influence of Each Operation of Hot Galvanizing Process on the Fatigue Strength of Steel Welned JointIsao Masumoto, Mitsumasa Iwata1969 Volume 38 Issue 7 Pages 744-751
Published: July 25, 1969
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSIt was shown in previous report that the fatigue strength of welded joint with reinforcement is remarkably improved by hot galvanizing treatment in comparison with that of non-treated joint. However, the reason why the fatigue strength of joint is improved by the treatment has not yet been made clear. Therefore, each step in hot galvanizing process is analysed and the effects of steps on the fatigue strength of welded joint are experimentaly investigated in this report.
Generally, hot galvanizing process contains five steps, that is, pickling, rinsing, flux coating, dipping in zinc bath and cooling. At first hydrogen absorption in steel during pickling, rinsing and cooling in water are investigated. Hydrogen in steel during galvanizing process is released with time, but galvanized zinc layer retards the releasing rate of hydrogen. The fatigue strength of hot-galvanized steel decreases owing to the hydrogen, but it recovers if the hydrogen is released. Dipping of the joint for long time in rinse bath containing a little acid has no good effect on the fatigue strength. The higher is the temperature of zinc bath, the more effective is hot galvanizing for improving the fatigue strength of steel welded joint. The iron-zinc alloying phase formed at higher than 495°C is a ductile δ1 phase. When the joint is cooled in water bath immediately after dipping in zinc bath, the fatigue strength of it increases, but decreases by air cooling. The alloying layer formed during air cooling is harmful for the fatigue strength of welded joint. The iron-zinc alloying layer by hot galvanizing has hardly any influence on the fatigue strength of steel welded joint.View full abstractDownload PDF (4243K) -
Ichiro Kawakatsu, Tadashi Ariga1969 Volume 38 Issue 7 Pages 752-759
Published: July 25, 1969
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSThere have been a few reports on the relation to impact strength of copper brazed butt joint with BCuP types brazing materials. However, these results of investigation do not show any definite tendency.
Indifiniteness.of tendency in these experiments was considered to be due to differences in brazing temperature and in joint structure. So, it was tried to obtain a definite impact value under definite brazing temperature.
The results are summarized as follows:
1. With BCuP 2, BCuP 5 brazing materials and brazing temperature at 750°C, 850°C and 950°C, there is a relationship between joint thickness and charpy impact value in a range of temperatures. Charpy impact strength of a definite tendency can be gained with an increasing joint thickness. In a torch brazing where the temperature control is difficult, the relation between joint thickness and impact value differs depending on the joint structure.
2. The relation detwecn brazing temperature and impact value. At brazing temperature of 950°C, impact value was high. It seems that copper base metal was dissolved in molten brazing materials and this was because of an increasing ductile copper phase in the matrix.
For small brazing thickness high impact strength was obtained but when brazing temperature was high and brazing thickness was large, high impact strengh could be gained.
3. Effect of cooling velocity on impact strength at brazing temperature of 850°C degree, structure became acicular dendritic after quenching and in this case, impact strength decreased by about 0.2 Kg.m/cm2 at brazing temperature, of 750°C and 950°C, there was not so much difference in the joint structure after quenching.View full abstractDownload PDF (5546K) -
On Effect Chemical Compositions on Weld CrachingYoshikazu Moriwaki, Masayuki Fujino1969 Volume 38 Issue 7 Pages 760-767
Published: July 25, 1969
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSThe relation between the intensity of restraint (K), the reaction stress ((σw)t=∞) and ((σw)t=∞) and weld cracking at testing bead was clarified quantitatively on the X section model specimen built-up with a kind of steel in Report 2.
These experiments were carried out to explain the effect of the chemical compositions (mainly carbon content) varied artificially in various steels on weld cracking by the same testing method as that of the previous paper.
The results obtained are summarized as follows:
1) The intensity of restraint (K) has not influenced on the chemical compositions.
2) The critical intensity of restraint (Kcr) and the critical reaction stress ((σw)cr) for cracking are in the linear range of the (σw)t=∞-K diagram, but they are considerably affected by the angle, steel size and chemical compositions.View full abstractDownload PDF (505K) -
1969 Volume 38 Issue 7 Pages 768-788
Published: July 25, 1969
Released on J-STAGE: August 05, 2011
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