JOURNAL OF THE JAPAN WELDING SOCIETY
Online ISSN : 1883-7204
Print ISSN : 0021-4787
ISSN-L : 0021-4787
Volume 50 , Issue 3
Showing 1-17 articles out of 17 articles from the selected issue
  • Yoshikazu Kuriyama
    1981 Volume 50 Issue 3 Pages 227-229
    Published: March 05, 1981
    Released: August 05, 2011
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  • Yoshihiko Mukai, Masayoshi Uchida
    1981 Volume 50 Issue 3 Pages 230
    Published: March 05, 1981
    Released: August 05, 2011
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  • Yukishige Fukase, [in Japanese]
    1981 Volume 50 Issue 3 Pages 231-235
    Published: March 05, 1981
    Released: August 05, 2011
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  • Futoshi Fukui
    1981 Volume 50 Issue 3 Pages 235-240
    Published: March 05, 1981
    Released: August 05, 2011
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  • Tutomu Nishima
    1981 Volume 50 Issue 3 Pages 240-246
    Published: March 05, 1981
    Released: August 05, 2011
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  • Tadao Ogawa, Takashi Zaizen
    1981 Volume 50 Issue 3 Pages 246-250
    Published: March 05, 1981
    Released: August 05, 2011
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  • Kiichi Saito
    1981 Volume 50 Issue 3 Pages 251-257
    Published: March 05, 1981
    Released: August 05, 2011
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  • Ryoichi Yoshimura, Yoichi Hirose
    1981 Volume 50 Issue 3 Pages 257-261
    Published: March 05, 1981
    Released: August 05, 2011
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  • Yoshikuni Nakao
    1981 Volume 50 Issue 3 Pages 261-264
    Published: March 05, 1981
    Released: August 05, 2011
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  • Kunihiko Satoh, Masao Toyoda, Fumiyoshi Minami, Toshiaki Fujimori, Ter ...
    1981 Volume 50 Issue 3 Pages 265-270
    Published: March 05, 1981
    Released: August 05, 2011
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    In the present paper, consideration has been carried out of the relationship between the defect detectability of NDT and the repair rate of welds and the reliability of inspected welds.
    In order to get a certain high quality level of welds, critical level for repair Acr should be set smaller than the critical allowable defect size acr. That is, acr/Acr is the factor of safety to defect detectability of NDT.
    The more setting smaller of critical level for repair or deteriorating the accuracy of defect measuring by NDT, the more repair rate of welds γ increases. Increasing of γ does not always realize increasing of the reliability of welds R. In the case of deteriorating of accuracy of measuring the defect, k decreases even if γ increases.
    The reliability of welds increasess according to increasing repair rate in the case of increasing sampling ratio or in the case of inspecting with emphasis on higher defective joints even if sampling-ratio is equal to the case of random sampling.
    Based on the above consideration, the decision method is discussed of the rational inspection method for assuring a certain reliability of welds and also minimizing the total cost of inspection.
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  • Shozaburo Ohta, Shoichi Kudo
    1981 Volume 50 Issue 3 Pages 270-277
    Published: March 05, 1981
    Released: August 05, 2011
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    Various mechanical methods of improving the fatigue strength were investigated by testing the base plate and cruciform fillet welded joint specimens of 40 kg/mm2-80 kg/mm2 class steels. The results obtained are summarized as follows:
    1) If a peening condition is suitable to a material, the compressive residual stress induced by peening increases as a yield strength increases. As the ratio of applied cyclic stress range to absolute value of the compressive residual stress decreases, the waste of compressive residual stress by applied cyclic stress decreases and the effect of improving a fatigue life (strength) increases. Therefore, the peening effect can increase with incresaing the yield strength of material.
    2) It is possible to consider that a suitable condition of peening is to add the compressive residual stress as large as a yield strength of the material used, and that ari over peening ravages a surface, and may rather result in a reverse effect.
    3) As a result of increasing the yield strength of a weld toe and inducing. the compressive residual stress to a weld toe, by peening., a root failure occurs sometimes in the case of non-load-carrying type cruciform, fillet welded joint similarly in thee case of load-carrying type fillet welded double tee joint. Therefore, it is necessary to consider the critical leg length according to a treating condition of a weld toe, in a joint design.
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  • Masayoshi Kureishi
    1981 Volume 50 Issue 3 Pages 278-283
    Published: March 05, 1981
    Released: August 05, 2011
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    A mathematical solution, derived from heat flow, was proposed for determining pulsed TIG welding conditions for various thin plates. The justification of it was confirmed through experiments of welding with mild steel, stainless steel (18Cr-8Ni), Invar (35-36%Ni) and pure copper.
    Welding conditions of various thin plates can be determined by some calculations and a few experiments if the thermal properties are given.
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  • Isao Masumoto, Hirohito Hira
    1981 Volume 50 Issue 3 Pages 284-290
    Published: March 05, 1981
    Released: August 05, 2011
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    Fine grained microstructure enhances grain boundary diffusion, so diffusion weldability of fine grained material may be better than that of coarse grained material.
    Three types of diffusion welding specimens were prepared. Each abutting surface had coarse grained microstructure, fine grained microstructure, which was prepared from friction weld interface, and cold-worked microstructure. Third one was expected to change into small recrystal at diffusion welding temperature. These were welded by various diffusion welding conditions. And, tesnile strength and microstructure of weld, and deformation of specimens were examined in order to estimate the effect of prior microstructures on diffusion weldability.
    Obtained results were as follows;
    (A) Very fine grained microstructure, in which grain diameter was about 7 μm, was hardly to change into coarse grain even keeping at 1000°C.
    This specimen could be joined at lower diffusion welding temperature than coarse grained specimen, in which grain diameter was about 100 μm.
    (B) Cold-worked specimen started joining with onset of recrystallization into small grain.
    Diffusion weldability of this one was between that of fine grained one and that of coarse grained one.
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  • Takashi Yatake, Nobutaka Yurioka, Ryuichi Kataoka, Eeiichi Tsunetomi
    1981 Volume 50 Issue 3 Pages 291-296
    Published: March 05, 1981
    Released: August 05, 2011
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    In the previous reports, the authors studied the effects of various factors on the occurence of cold cracks including root cracks, toe cracks and under-bead cracks in the heat-affected zones of base metals. They proposed the preheating temperatures necessary for the prevention of these cold cracks as a function of the chemical composition of steel, the groove shape, the restraint and the hydrogen content in weld metal.
    There have arised cases where not only base metal cracking but also weld metal cracking must be considered in the selection of the preheating temperature, especially for the welding of steels with lower carbon contents. A number of cold cracking tests have thus been conducted in order to find the necessary preheating and inter-pass temperature, θpr*, for preventing cold cracking in multi-run weld metals.
    The θph* is given by the following empirical equation as:
    θph*(°C)=120+120 log (HJIS/3.5)+5(hω-20)+8(σB-83)
    where, HJIS is the diffusible hydrogen content in weld metal by the JIS method (0.1 to 40 ml/100gr), hw the weld metal thickness (15 to 40 mm) and σB the tensile strength of weld metal (60 to 90 kgf/mm2).
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  • Hisanao Kita, Tatsuji Wada, Takamitsu Nakazaki, Yoji Akutsu, Yoshiaki ...
    1981 Volume 50 Issue 3 Pages 296-302
    Published: March 05, 1981
    Released: August 05, 2011
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    Heliotron E, which is a large-scaled device of Heliotron series, is in operation in Kyoto University. Target plasma parameters of this machine are as follows; plasma density 1×1020m-3, electron temperature 1 keV, ion temperature 0.8 keV and nτ 1018-1019 sec/m3. Plasma confining magnetic fields are produced by the helical coil current. To assure the accuracy of the helical coils, the high level of accuracy was required to the profile of the vacuum chamber. The vacuum chamber twists around the torus by 9.5 times and its poloidal cross section shows a race-track shape in any toroidal position. Major radius is 2200 mm and minor radius is 215.5 mm. The material is the high-strength non-magnetic steel which has low permeability (μ<1.4), high yield strength (≥40kgf/mm2) and special chemical composition (25Cr-12Ni-0.3N). The thickness of the wall is from 20 to 33 mm.
    To make the vacuum chamber, 190 pieces were joined together by EB welding after the hot press forming.
    A giant apparatus (6.5 m×6.5 m×3.5 m) was prepared and applied and a special re-focusing coil was used for the long beam welding.
    The profile accuracy of the vacuum chamber has been controlled as follows; major radius ±3 mm, minor radius ±4.5-1.5 mm, where minus means the inner side.
    X-ray and dye-penetrant quality of all welds was acceptable for ASME pressure vessel code and JIS. The laekage was less than 1.3×10-8 Torr 1/sec. The final pressure is 2×10-8 Torr.
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  • Tsutomu Omae, Hiroshi Miyake, Yuzo Kozono, Koichi Koyama, Takeshi Aray ...
    1981 Volume 50 Issue 3 Pages 303-308
    Published: March 05, 1981
    Released: August 05, 2011
    JOURNALS FREE ACCESS
    In a nuclear power plant, a large number of pipes must be set in very complex and narrow places. A remote control pipe welding equipment is developed, in order to solve difficulty of welding in such a narrow place. Characteristics of this equipment are summarized as follows.
    (1) All welding sequences are controlled by a mini-computer.
    (2) From the information displayed on the screen of control panel, which inculdes a TV monitor, the operator can evaluate results of welding, torch positioning and the groove shape.
    (3) The operating panel includes a keyboard which is used for parameter input and for communication with the welding equipment to make necessary adjustment.
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  • Sadao Fukushima, Takeshi Fukushima, Junichi Kinugawa
    1981 Volume 50 Issue 3 Pages 308-314
    Published: March 05, 1981
    Released: August 05, 2011
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    The possibility of improving the ductility and notch toughness of underwater wet plasma welds was investigated by controlling the chemical composition of them using filler metals.
    The welding environment was selected in fresh water under the pressurized condition of 10 kgf/cm2 [gauge].
    Results of this experiment are summarized as follows.
    (1) Two kinds of filler metals, one of them had the basic composition of 0.013 wt% carbon, 0.081 wt% silicon, 1.05 wt% manganese and iron as the balance-base filler metal-and the other was added 0.59 wt% titanium to the above-mentioned base filler metal, were shown the possibility of improving the ductility of single pass double Vee butt joint.
    (2) Addition of niobium alone or molybdenum with boron to the base filler metal had less contribution to the improvement of weld metal ductility.
    (3) It is necessary to reconsider the chemical composition of filler metal for filled pass in multi-pass welding, because the dilution of the deposited metal with the base metal in filled pass differs from that of the root pass.
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