JOURNAL OF THE JAPAN WELDING SOCIETY
Online ISSN : 1883-7204
Print ISSN : 0021-4787
ISSN-L : 0021-4787
Volume 46, Issue 4
Displaying 1-7 of 7 articles from this issue
  • Taiji Kataza
    1977 Volume 46 Issue 4 Pages 182-189
    Published: April 05, 1977
    Released on J-STAGE: August 05, 2011
    JOURNAL FREE ACCESS
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  • Jiro Tajima
    1977 Volume 46 Issue 4 Pages 189-196
    Published: April 05, 1977
    Released on J-STAGE: August 05, 2011
    JOURNAL FREE ACCESS
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  • Isamu Tsuji, Kazuya Ogawa
    1977 Volume 46 Issue 4 Pages 197-202
    Published: April 05, 1977
    Released on J-STAGE: August 05, 2011
    JOURNAL FREE ACCESS
    In the previous report, thermal stresses and deformation of a steel strip subjected to local heating were analysed by the finite element method, and useful knowledge on temperature, strain and stress distributions was obtained.
    In this continued report, the effects of latent heat, the breadth of the strips and external restraint on these distributions were investigated.
    The results obtained are as follows.
    1) The temperature distribution in the vicinity of melting zone can be evaluated more accurately by considering latent heat.
    2) The effects of latent heat on stress distributions as well as deformations of the strips are considerably small.
    3) The maximum tensile residual stress occurs near the boundary of heated region, and shows a tendency to increase as the breadth of the strips increases.
    4) The angular distortions of the strips can be evaluated simply by using the beam theory provided that an amount of inherent strain in the heated region is estimated properly.
    5) Removing end restraints after the completion of thermal cycle, it is possible that a large amount of deflection may occur compared with that in free condition.
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  • Toshihiko Okada, Yoshihiro Morimoto, Takeyuki Watanabe, Kazuyuki Ishim ...
    1977 Volume 46 Issue 4 Pages 202-207
    Published: April 05, 1977
    Released on J-STAGE: August 05, 2011
    JOURNAL FREE ACCESS
    Gas flame spot heating is usually used for an object to remove the distortion of welded thin plate structures. However, in such a way, heating easily causes buckling distortion, and then it is not so easy to control of heating temperature and heating area, and to restrain its distortion.
    Now, in spite of the existing of these technical problems, it is widely owed to manual work, and automatic performance system is not still developed.
    In this investigation, it is studied that restraint of buckling distortion is automatically performed by using pinched gas flame heating process.
    Especially this report discribes effect of pinched gas flame heating on restraint of buckling distortion and its application techniques on rolling stock passenger car body assembly.
    The recsults were obtained as follows;
    1. Pinched gas flame can be made by cylindlical air flow around of propane-oxygen gas flame.
    2. Restraint of buckling distortion can be effectively performed by new pinched gas flame without other restraint apparatus. And its quantity is calculated by theoritical analysis.
    3. New developed automatic multi-pinched gas flame heating machine is effective and economical for restraint of buckling distortion on roof sheet of passenger car body.
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  • Sadao Nobuhara, Takefumi Kubota, Isamu Ukita
    1977 Volume 46 Issue 4 Pages 208-213
    Published: April 05, 1977
    Released on J-STAGE: August 05, 2011
    JOURNAL FREE ACCESS
    When the AC TIG Arc Welding Processes are applied to base metals such as aluminum, copper, magnesium, etc, the higher frequencies which are superimposed to steady the arc give rarely rise to radio interferencies, the complete means, however, to solve the troubles have not yet been found.
    Therefore, in respect of this complicated problems, we have been studying the reignition phenomena on AC TIG arc. This study was carried out to make clear the reignition phenomena with a rectangular current pulse. When a rectangular voltage pulse was impressed to the gap at the zero current phase, the arc reignitions at every reverse polarity were caused by the pulsed arc discharge which followed an abnormal glow discharge having a duration of a few microseconds and a gap voltage of a few hundred volts. Then it will be supposed that the pulsed arc discharge is able to maintain the ionized region between the electrodes for appreciable periods after current zero.
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  • Shizuo Mukae, Mitsuaki Kato, Kazumasa Nishio, Yasumasa Nakayama
    1977 Volume 46 Issue 4 Pages 214-220
    Published: April 05, 1977
    Released on J-STAGE: August 05, 2011
    JOURNAL FREE ACCESS
    The effect of Zirconium on the austenite grain growth in a coarsend-grain region in the weld heat affected zone of a plane carbon steel was investigated using the constant temperature annealing method.
    Also, the welding experiment was carried to study the effect of Zirconium on the solidification mode and microstructure. The results obtained are as follows.
    (1) The austenite grain grows according to the equation, D=k0tn on the higher temperature than 1150°C. The temperature dependence of the time constant, n is weak and its values are less than 0.3. While, the temperature dependence of k0 can be expressed by Arrhenius type. The apparent activation energy for the austenite grain growth obtained from the experiments exhibits twice with 0.04% Zr as large as without Zr.
    (2) The suppression effect of Zr to the austenite grain growth is remarkable with Zr content over 0.04%. It will be depended on the existence of ZrC particles which are nearly as large as 1.0μ, in diameter and distributed in the austenite grains.
    (3) The influence of Zr upon the solidification mode and structure of weld metal can be negligible primarily because so little Zr is used, that is, the cellular substructure near fusion line and the cellular dendritic structure around bead centre, regardless of the presence or absence of Zr. The cell size, however, tends to fine away as Zr content is increased.
    (4) As increasing Zr content, the temperature range between Ar1 and Ar3 becomes narrow because Ar1 point rises, and the tendencies to decrease the needle-like ferrite and to increase the granular ferrite are recognized. The addition of Zr does not contribute to increase the hardenability of the specimens, but tends to low the maximum hardness in the welding heat affected zone.
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  • Hiroshi Kimura, Takuji Yamaguchi, Masakazu Tsubokawa, Kazuharu Tsujimu ...
    1977 Volume 46 Issue 4 Pages 221-228
    Published: April 05, 1977
    Released on J-STAGE: August 05, 2011
    JOURNAL FREE ACCESS
    This paper describes an experimental study on the characteristics at low temperature of welded polyamide (Nylon-6). The results of some measurements on the mechanical properties, fracture surfaces and X-ray diffraction pattern are reported and discussed.
    This study intends to clarify the low temperature characteristics of weld comparing with those of base material, and to discuss the change in mechanical properties from room temperature down to the neighborhood of -70°C and fracture in low temperature experiment from a microscopic viewpoint.
    Notch and load velocity effects on the brittle fracture tendency are also discussed. Testing materials were polyamide board of 2 mm in thickness, and tests were carried out at low temperature of methylalcohol and dry ice. A heat plate welding apparatus, with which specimens could be secured under fixed contact force, was made in order to carry out the experiment of welding.
    The following summary can be made of the experimental results.
    (1) Welded parts of polyamide must be used very carefully in low temperature atmosphere.
    (2) Low temperature characteristics of welded parts are different from those of parents in polyamide.
    (3) Effects of load velocity and notch are observed both on the basic and welded parts of polyamide in low temperature atmosphere, and brittleness becomes great.
    (4) Low temperature characteristics on welded parts of polyamide are considerably refined if welding is conducted under the condition below 2.0% water contents.
    (5) Correlations are observed between fractured surface and mechanical testing results, as well as between X-ray diffraction pattern and mechanical testing results.
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