JOURNAL OF THE JAPAN WELDING SOCIETY
Online ISSN : 1883-7204
Print ISSN : 0021-4787
ISSN-L : 0021-4787
Volume 51 , Issue 2
Showing 1-19 articles out of 19 articles from the selected issue
  • Kunihiko Satoh, Masao Toyoda, Shigetomo Matsui, Eisuke Mori, Shigeki S ...
    1982 Volume 51 Issue 2 Pages 98-105
    Published: February 05, 1982
    Released: August 05, 2011
    JOURNALS FREE ACCESS
    The creep tests for welded joints with higher creep rate and lower strength weld metal and with lower creep rate and higher strength weld metal respectively which are subjected to transverse and longitudinal loads respectively have been carried out.
    In case of the joints subjected to transverse load, the creep strain is influenced not only by the magnitude of a gage length but also by the ratio of the weld metal width to the diameter of a specimen. The rupture strength is dominated fundamentally by the ratio of the weld metal strength to base metal strength, though there is an effect of the ratio of the weld metal width to the diameter of a specimen on the rupture strength of a welded joint with higher creep rate and lower strength weld metal.
    In case of the joints subjected to longitudinal load, the secondary creep rates are affected by the ratio of the weld metal width to the specimen width. The rupture strength is dominated not only by the rupture strength ratio of the weld metal to the base metal but also by the creep rate ratio of the weld metal to the base metal.
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  • Kunihiko Satoh, Masao Toyoda, Kazuhiro Nohara, Risto A.J.Karppi
    1982 Volume 51 Issue 2 Pages 105-111
    Published: February 05, 1982
    Released: August 05, 2011
    JOURNALS FREE ACCESS
    Stress field parameter FI. which controls the stress level in the vicinity of the root of first-pass weld and the notch of the Implant specimen has been proposed by the authors as a controlling parameter for weld hydrogen cracking. The previous papers reveal that the correlation between Implant test results and RRC/TRC test results of 80 kg/mm2 high strength steel (HT80) can be explained with fair accuracy by using the stress field parameter FI.
    In the present paper, adresses applicability of the stress field parameter FI to cover not only HT80 steel but also 50 kg/mm2 high strength steel (HT50). Moreover, it proposes the applicability of the parameter FI for the another H type crack test.
    The FI parameter newly proposed in the present paper proved applicable for considering the correlation between the deep notch Implant test and the RRC/TRC test for not only HT80 steel but also HT50 steel under the same conditions in the testing of both the remaining hydrogen content HR100 and the HAZ microstructure.
    The FI-parameter is affected by the various geometrical factors of the root weld. The FI-value calculated by using the average geometrical parameter can be applied to consider the correlation anong the various cracking tests.
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  • Yoshinori Ito, Mutuo Nakanishi, Yu-ichi Komizo
    1982 Volume 51 Issue 2 Pages 111-118
    Published: February 05, 1982
    Released: August 05, 2011
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    The morphology and the crystallographic aspects of low carbon low ahoy weld metals have been investigated by mean of both optical and transmission electron microscopy.
    The ferrite morphology of the weld metal was characterized by the Grain Boundary Ferrite, Widmanstatten Ferrite Side Plates, Acicular Ferrite and the Upper Bainite, and the transformation temperatures of these microstructures were examined. The Grain Boundary Ferrite and Ferrite Side Plates were transformed by the diffusion. It is confirmed that the Acicular Ferrite consisted of the bainitic ferrite transformed at many transformation sites, i.e., non-metallic inclusions.
    The WM-CCT diagram was proposed to represent the transformation characteristic of the weld metal.
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  • Itaru Watanabe, Motoaki Suzuki, Yoshitaka Yamazaki, Takanobu Tokunaga
    1982 Volume 51 Issue 2 Pages 118-126
    Published: February 05, 1982
    Released: August 05, 2011
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    An investigation was carried out to improve the toughness of weldments made by high-heat-input welding of the Al-killed steel for LPG tankers and LPG storage tanks. In the present investigation sole and mutual effects of nitrogen, aluminium and titanium on the notch toughness of the weld HAZ were determined, and it was demonstrated that, when reducing nitrogen into 40 ppm or less and adding alumi-nium in excess of 0.04 %, the detrimental effects of free nitrogen could be suppressed, resulting into a remarkable improvement of HAZ toughness. Further it was also demonstrated in the present investiga-tion that the addition of micro-titanium below 0.01 % was useful for the improvement HAZ toughness. As a result, the high Al-low N-micro Ti type steel was determined to be suitable for high-heat-input welding. The present investigation was undertaken with a view to providing evidence to indicate the superior HAZ toughness of the newly developed Al-killed steel, performing various welding tests, intended for construction of LPG tanker and storage tank.
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  • Hirohito Hira, Sotaro Yamada, Takao Uemura, Atsushi Shiomi, Kazuo Aman ...
    1982 Volume 51 Issue 2 Pages 126-134
    Published: February 05, 1982
    Released: August 05, 2011
    JOURNALS FREE ACCESS
    There are two types of friction welding machine, one is brake type and another is inertia type. Main difference between them may be the deceleration condition of rotation. Rotation is stopped abruptly in the brake type welding process, however, it is stopped gradually in the inertia type welding process.
    In this study, effect of the decelerating condition of rotation on the burn-off behaviour and macrostructure of joint was studied by controlling the brake ability of rebuilt brake type welding equipment in order to clarify the characteristics of each type machine. Used material was heat resisting steel FV 607. In addition, combined effect both of the axial pressure change and of the time-lag between pressure change and start of deceleration on them were also examined.
    Obtained results are as follows;
    1) Burn-off rate increases with the deceleration of rotation. And additional burn-off during deceleration is in proportion to deceleration time.
    2) When axial pressure is not changed, shape of heat affected zone becomes narrower and concave shape with increase both of axial pressure and of deceleration time.
    3) When axial pressure is changed and deceleration time is sufficiently long, effect of prior axial pressure, friction time and time-lag on the shape of HAZ becomes insignificant.
    4) Added burn-off at final stage by deceleration of rotation shows different effect on the shape of HAZ from that by upset pressure.
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  • Kozo Okita, Masatoshi Aritoshi, Hirohito Hira
    1982 Volume 51 Issue 2 Pages 134-141
    Published: February 05, 1982
    Released: August 05, 2011
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    The authors have been studying the friction welding phenomena of same diameter bars and of different diameter bars of SUS304 austenitic stainless steel by brake type friction welding equipment. In any case, friction torque, burn-off rate and temperature of friction surface are close to the constant value, while constant axial pressure and friction speed are maintained. This may mean that equsai steady state arises at the friction surface. And, these three constant values might signify the thermal balance.
    In this study, following relationship of thermal balance were assumed.
    Q1=Q3+Q4+ΔQ
    Q1 means the friction heat, that is a function of friction torque. Q3 is the removed heat by thermal conduction, so it is in proportion to temperature gradient. Q4 means the heat removed with upset collar, this factor depends on burn-off rate and temperature at friction surface. And, dQ includes generated heat by defomation and relesed heat to the airs.
    Relation between Q1 and Q4 was examined by studying the mutual relationship among three constant values of steady state in the same diameter bar friction welding of 1020 mm. And Q3 was examined by the extrapolation of Q1 and Q4 relation. This value of Q3 was nearly the same value of Q3 from the calculation of thermal conduction.
    Assumed relationship was sufficiently adapted for experimental data.
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  • Kunihiko Satoh, Masao Toyoda, Kazuhiro Nohara, Yoshikazu Suita, Masabu ...
    1982 Volume 51 Issue 2 Pages 142-148
    Published: February 05, 1982
    Released: August 05, 2011
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    Stresses and deformations arised from the uniform inherent strain existing in a rectangular region on the surface of a thin-walled pipe are obtained by applying the Green function, introduced by Shirakawa, for a non-stationary thermoelastic problem in a thin circular cylindrical shell. The results are developed to an analytical model for calculating residual stresses and deformations due to axial and/or circumferential welds of a pipe, and the parameters determining the residual stresses and deformations such as radial deformations, change in curvature are derived analytically for both axial and circumferential welds. In case of axial weld, the parameters are βx=√a/h⋅a/l and θ0/π, where a, h and l are the mean radius, thickness and length of the pipe respectively, and θ0 is the half angle of the region of the inherent strain in circumferential direction. In case of circumferential weld, the parameters are βθ=l/√ah and 2l0βθ/l, where lo is the half width of the region of the inherent strain in axial direction.
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  • Kazuyoshi Matsuoka, Tamotsu Naoi
    1982 Volume 51 Issue 2 Pages 148-155
    Published: February 05, 1982
    Released: August 05, 2011
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    The residual stress distribution brought about by a circumferential weld between two pipes (cylindrical shells) is quite different from that by a butt weld between two flat plates. Many researches are brought out, and the reasons for the difference are pointed out and shown.
    The paper presents the analytical model and the computer method. The first part deals with the state of stress and the residual stress distribution in a thin-walled cylinder, under the distribution of "inherent stress" due to weld shrinkage. Then the formula is presented for estimating the "inherent stress"; that depends upon the welding parameters and the material property (yield stress). In the final part of the paper, the analytical results are compared with experimental results. The analytical results show good agreement with the experimental results.
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  • Teruyuki Nakatsuji, Mitsugu Kuramochi, Toshiaki Fujimori, Masao Toyoda ...
    1982 Volume 51 Issue 2 Pages 155-161
    Published: February 05, 1982
    Released: August 05, 2011
    JOURNALS FREE ACCESS
    In the case of performing NDT for quality assurance of welds, sampling inspection is applied generally. Considering from a viewpoint of ensuring the quality of welds, it is rational to employ the sampling inspection method where the sampling rate varies according to the percent defective of welds.
    From above consideration, the new sampling inspection method named "Sampling Inspection for Continuous Production with Adjustment" is proposed in this report, that is applicable to filed welding of the steel framed structure where the process is severe. The characteristic of that sampling method is. to adjust the sampling rate of the fraction inspection in "Sampling Inspection for Continuous Production", according to the quality of welds.
    Furthermore, the decision method is disussed of the rational sampling factors of the proposed sampling method taking the properties of weld defect occuring into account.
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  • Masaki Nakajima, Akira Nohtomi, Toyoaki Kusano
    1982 Volume 51 Issue 2 Pages 162-168
    Published: February 05, 1982
    Released: August 05, 2011
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    Effects of particle size and mixing rate of transition metal carbide NbC powder with austenitic stainless steel SUS 304L powder on the weld crack sensitivity in plasma arc overlay welding process have been studied.
    The following results were obtained.
    1) Some part of NbC powder which is fed to molten pool is dissolved in matrix and solidifies as primary or eutectic carbide. Microscopic analysis shows that the volume of these crystallized NbC decreases as mixing rate of NbC increases, and that in the case of high mixing rate of small particle, the matrix contains less crystallized NbC than in the case of same mixing rate of large one.
    2) The weld crack sensitivity overlay weld metal depends not only on mixing rate of NbC, but on its particle size. In the case of low mixing rate, overlay weld metal with small particle of NbC shows higher weld crack sensitivity than that of large one, while it shows lower weld crack sensitivity in the case of high mixing rate, which can be understood from the ductility of matrix depending on the volume of dissolved NbC.
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  • Toshi Enjo, Toshio Kuroda
    1982 Volume 51 Issue 2 Pages 168-174
    Published: February 05, 1982
    Released: August 05, 2011
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    An investigation has been made into the microstructure of weld heat affected zone (HAZ) in commerciai Al-Mg-Si system 6063-T5 alloy.
    The precipitation amounts of G.P.Zones, β' precipitates, β phase and relatively insoluble compounds respectively in the HAZ can be evaluated quantitatively by means of electrical resistivity measurement of an isochronal annealing technique.
    The partial or all dissolution of G.P. Zones and β' precipitates occurs in a narrow band of the HAZ where the temperature has reached above 240°C during welding.
    The softening zone remains in these parts of HAZ in spite of natural aging after welding.
    The softening zone can be considerably improved by means of artifical aging treatment at 180°C for 8 hrs after welding.
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  • Kenji Ohshima, Minoru Abe, Takefumi Kubota
    1982 Volume 51 Issue 2 Pages 175-181
    Published: February 05, 1982
    Released: August 05, 2011
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    A nonlinear characteristic of power source is proposed for improving the stability and self-regulation of the pulsed current transfer in a constant feeding speed system. The pulsed current transfer is achieved by pulsing the current between the globular and spray transfer current ranges. Droplets are ejected one by one from the electrode tip at a regular frequency synchronizing with the frequency of current supplied from a power source with periodically varying nonlinear characteristic.
    The behavior of the arc is described by nonlinear differential equations. The phase plane analysis is applied to the study of the solution. The current and voltage of the arc constitute the coordinates of a representative point in the phase plane. Our object is to improve the stability and self-regulation of the pulsed current transfer. For this purpose, it is useful to investigate the trajectory of the solution in the transient state.
    When the power source has a constant voltage characteristic, the time responsee of the arc may usually be quick. However, a slight deviation from the steady value of the arc voltage may produce such a large value of variation of the arc current that it may cause the transfer by globular mode to go out of synchronism. When the power source has a drooping characteristic or a constant current characteristic, it may usually take a long time for the representative point to reach the vicinity of the trajectory in the steady state. From the analytical results it will be deduced that a nonlinear characteristic of the power source is useful for improving the stability and self-regulation of the pulsed current transfer.
    We have developed a special power source with the nonlinear characteristic consisting of transistors and integrated circuits, and performed the experiments by making use of the power source. The pulsed current transfer phenomena are observed by using the synchroscope. By noting the metal transfer sequence, it is possible to determine the power source parameters in which the transfer by globular mode may synchronize with the pulsating current. Hence, the pulsed current transfer is reasonably stable with a sufficiently short arc. The validity of the theoretical results is also confirmed by the experimental investigations.
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  • Hiroshi Maruo, Isamu Miyamoto, Yoshihiko Inoue, Yoshiaki Arata
    1982 Volume 51 Issue 2 Pages 182-189
    Published: February 05, 1982
    Released: August 05, 2011
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    A C02 laser was applied for welding A12O3-SiO2 sintered ceramics with 48-99.5 wt% alumna contents. The effects of welding parameters and preheating temperature on the bead shape, penetration depth and weld defects including underfill of the bead, porosity and cracking were discussed. The results obtained are summarized as follows:
    (1) Paralled-sided and deeply penetrated beads were obtained in mullite ceramics and the penetration depth, which is inversely proportional to the welding speed, was deeper than that of laser welding of SUS304. In high alumina ceramics, a wine-cup bead was resulted from the laser-produced plasma. The differences in welding characteristics between ceramics and metals were discussed on the basis of the welding mechanism.
    (2) Underfill due to material vaporization is remarkable when the depth-to-width ratio of the bead is one, resulting in around 75 % of heat loss, whereas the underfill is sufficiently small when the focal position is on the workpiece surface.
    (3) Porosities were formed along the fusion boundary in low alumina mullite and in the nail head of the bead in high alumina ceramics.
    (4) When the preheating temperature is not high enough, there appeared two types of weld-cracks; a transverse crack, which 'propagates perpendicularly to the bead and a longitudinal crack; which propagates parallelly to the.bead from-the bottom surface.
    (5) At high welding speeds, the transeverse crack is prevented at the preheating pemperature Tt, where the materials have plasticity; Tt is 1000°C in mullite; 1200°C in 95wt%A12O3; 1400°C in 99.5wt% A12O3. At low welding speeds, transverse crack can be prevented by widening the heat affected zone at preheating temperatures down to 600°C in low alumina mullite.The longitudinal crack occurs around critical speeds for full-penetration welding, and can be prevented at preheating temperatures 200°C higher than Tt.
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  • Kunihiko Satoh, Mitsuru Tamura, Taka-hi Ohmae, Yukio Manabe, Kozaburo ...
    1982 Volume 51 Issue 2 Pages 189-195
    Published: February 05, 1982
    Released: August 05, 2011
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    The authors have carried out the evaluation and improvement of the mechanical properties of the "Locally Drying Underwater Welding" joint. The results arc summarized as follows:
    1. The effect of welding conditions on the cooling characteristic of the welded joints is basically equal to that of the head welds. The joint by low current-low speed welding condition has a hardness distribution close to that of the air weld, and has good mechanical properties with respect to elongation, reduction of area, charpy absorbed energy, etc.
    2. The range of temperature which the slow crack preceded the brittle fracture occurred in the underwater welds in the three-points bend COD test is -85°C to -75°C. Therefore, with underwater environment taken into account, there is little possibility of brittle fracture in these welds. 3. To improve the mechanical property of underwater weld joint, the possibility of induction heating in water has been studied, and it has been shown that the weld can be heated up to 650°C by this heat treatment, and the mechanical properties of the weld have improved nearly up to that of the air weld.
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  • 1982 Volume 51 Issue 2 Pages 196-209
    Published: February 05, 1982
    Released: August 05, 2011
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  • 1982 Volume 51 Issue 2 Pages 198
    Published: 1982
    Released: August 05, 2011
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  • 1982 Volume 51 Issue 2 Pages 199
    Published: 1982
    Released: August 05, 2011
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  • 1982 Volume 51 Issue 2 Pages 200
    Published: 1982
    Released: August 05, 2011
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  • 1982 Volume 51 Issue 2 Pages 211-251
    Published: February 05, 1982
    Released: August 05, 2011
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