JOURNAL OF THE JAPAN WELDING SOCIETY
Online ISSN : 1883-7204
Print ISSN : 0021-4787
ISSN-L : 0021-4787
Volume 50, Issue 10
Displaying 1-12 of 12 articles from this issue
  • Experimental Results and Travelling Mechanism
    Kunio Fukakusa, Tsugihiko Satoh
    1981 Volume 50 Issue 10 Pages 953-958
    Published: October 05, 1981
    Released on J-STAGE: August 05, 2011
    JOURNAL FREE ACCESS
    In general, the rotational plane (the friction plane) and the metal boundary plane (the press-welded plane) during friction welding have been considered to be identical. Anthers have found the travelling phenomena of the rotational plane that the rotational plane and the metal boundary plane are not identical in some combinations of dissimilar material specimens and in some combinations of similar material specimens with different diameters welded under the friction welding conditions which include conventional welding conditions, moreover the distance between the rotational plane and the metal boundary plane increases as the heating time increases, and reaches a saturated value.
    In this report, some examples of the travelling phenomena of the rotational plane are shown, then effects of welding conditions and of variations in specimen diameters on the travelling distance of the rotational plane are investigated. The travelling phenomena and saturation mechanisms are also discussed.
    Main results obtained are as follows:
    1) The rotational plane generally differs from the metal boundary plane during friction welding under the friction welding conditions which include conventional welding conditions.
    2) The travelling and saturation mechanisms can be qulitatively explained by the plastic deformation resistance of specimens and the temperature distribution in the neighborhood of the rotational plane.
    3) The travelling direction of the rotational plane is determined by the quality of specimens and the difference between specimen diameters welded.
    4) The travelling distance increases as the heating time and the difference between specimen diameters increase, and decreases as the heating pressure and the rotational speed increase.
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  • Study on Hardfacing Process Using Extremely Hard Material (2nd Report)
    Masaki Nakajima, Masato Ueda, Akira Nohtomi
    1981 Volume 50 Issue 10 Pages 959-964
    Published: October 05, 1981
    Released on J-STAGE: August 05, 2011
    JOURNAL FREE ACCESS
    In the previous report, the test results of the newly developed hardfacing process with transition metal carbide powder by the conventional DCSP plasma torch were described. In this study, bead-on-plate and multilayer overlay welding tests by the trial manufactured DCRP plasma torch have been carried out of improve weldability of this process.
    The results obtained are summarized as follows:
    1) It is necessary to add a small amount of oxidizing gas (CO2 or O2) into the carrier gas in order, to stabilize the arc. By the addition of oxidizing gas, the weldability is improved due to increase of the wettability of overlay weld metal, though the penetration of overlay weld is increased.
    2) The deposition efficiency is also improved, because the powder feeding rate can be increased exceedingly even at the lower heat input level than the case of DCSP welding.
    3) In the case of high carbide content, the cathode flame is apt to occur due to fixing cathode spot of oxidizing gas is not added. Once the cathode flame occur, it will become impossible to'carry out favorable overlay welding, because the shielding is disturbed and the cleaning action is gone out.
    4) The occurrence of the cathode flame can be prevented by an addition of 0.20.4% CO2 or O2 in the one-layer overlay welding, but this preventing effect. is not. observed at the second and upper layers in the multilayer overlay welding. Therefore, in the multilayer overlay welding of carbide content above 80%, it is hardly to obtain the sound overlay weld without any welding defects such as blowhole and lack of fusion.
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  • Kenji Ohshima, Minoru Abe, Takefumi Kubota, Toshiyuki Okada
    1981 Volume 50 Issue 10 Pages 965-971
    Published: October 05, 1981
    Released on J-STAGE: August 05, 2011
    JOURNAL FREE ACCESS
    A power source characteristic is proposed for improving the stability and self-regulation of the wleding arc in a constant feeding speed system. The welding system is described by nonlinear differential equations. The phase-plane analysis is used for the present investigation. The current and voltage of the arc constitute the coordinates of a representative point in the phase-plane. The steady solutions which are correlated with singular points in the phase-plane are first sought for various characteristics of the power source. The stability of steady solutions is discussed by considering the behavior of, variations from the steady solutions. Our object is to improve the stability and self-regulation of the welding arc. These problems are investigated by studying the solution in the transient state, which, with the lapse of time, ultimately yields the steady solution. For this purpose, it is particularly useful to investigate the trajectory of the solution in the phase-plane and the time response of the solution in the transient state.
    When the power source has a constant voltage characteristic, the time response of the welding arc may usually be quick. However, a slight deviation of the arc voltage from the singular point may produce such a large value of variation of the arc current that the spray arc cannot be sustained. When the power source has a drooping characteristic or a constant current characteristic, it may usually, but not necessarily, take a long time for the representative point to reach the vicinity of the singular point. From the analytical results, it will be deduced that a nonlinear characteristic of power source is useful for improving the stability and self-regulation of the arc.
    We have developed a nonlinear characteristic power source consisting of transistors and function generators, and performed the experiments by making use of the power source. The arc phenomena are observed by means of the high speed motion pictures. The validity of the theoretical results is confirmed by the experimental investigations.
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  • Masanobu Hamasaki, Yoji Ogawa, Munehide Katsumura, Yoshiro Matsukawa, ...
    1981 Volume 50 Issue 10 Pages 972-975
    Published: October 05, 1981
    Released on J-STAGE: August 05, 2011
    JOURNAL FREE ACCESS
    The authors have developed underwater automatic oxy-arc cutting method of tubes and this method was put into application to cutting of tubes of I m diam. and 16 mm thick used for construction of bridge pier at water depth of about 10 m. As a successful result was obtained, for the purpose of underwater cutting of beat-in-tube which is employed for preventing overturn of offshore platform, an experiment of underwater cutting using high pressure chamber was at this time carried out. Tubes used were 1 m diam. and 35 and 45 mm thick. Cutting at deep water depth was obtained the same result that at shallow water depth, however cutting oxygen pressure must be added 5-8 kg/cm2 to water pressure corresponding water depth.
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  • Toshio Enjo, Kenji Ikeuchi, Naofumi Akikawa
    1981 Volume 50 Issue 10 Pages 977-982
    Published: October 05, 1981
    Released on J-STAGE: August 05, 2011
    JOURNAL FREE ACCESS
    The measurement of electric resistance has been applied to an investigation on the decrease in the joint efficiency of diffusion-welded joint between titanium and aluminum which occurs in a process of holding the joint at a high temperature. A large increase in the electric resistance of the bond which is accompanied by a remarkable decrease in the joint strength has been observed in the process of holding the joint at temperatures from 873 to 913K in a vacuum of 10-3Pa. The activation energy for the increase in the electric resistance of the bond has been estimated to be 230 kJ/mol, which is nearly equal to that of interdiffusion in the binary system of titanium and oxygen. The electric resistance of the bond has increased more rapidly with the rise of the oxygen content of titanium base metal.
    The increase in the electric resistance of the bond and decrease in the joint strength are accounted for by the formation of aluminum oxide at the interface between the aluminum base metal and intermetallic compound layer. Oxygen atoms to form the aluminum oxide are supplied from solution oxygen in titanium base metal by diffusion.
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  • In Case of Moving Point Heat Source
    Yoshiki Muramatsu, Akira Okada
    1981 Volume 50 Issue 10 Pages 982-988
    Published: October 05, 1981
    Released on J-STAGE: August 05, 2011
    JOURNAL FREE ACCESS
    For calculating thermal cycle of bond in weld joint analytically, the equation is very complex by the term of plate thickness. In case of weld joints with.various shapes of groove it cannot be calculated. Then, F.D.M. or F.E.M. by computer are used for these cases, but. these methods are not convenient. The authors proposed the approximate equations for estimating thermal cycle of butt weld joint considering the change of dimension of heat flow and law of similitude in geometrically similar specimens. These approximate equations have terms of plate thickness, angle of groove and heat input. Datas for making equations were calculated by F.D.M. Values estimated from approximate equations nearly corresponded to the experimental values obtained from arc welding with coated electrode.
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  • Welding Procedure by Remote Control TIG Welding Equipment
    Satoshi Kokura, Hiroshi Miyake, Yuzo Kozono, Masayasu Nihei, Genji Tak ...
    1981 Volume 50 Issue 10 Pages 988-993
    Published: October 05, 1981
    Released on J-STAGE: August 05, 2011
    JOURNAL FREE ACCESS
    In a nuclear power plant, a large number of pieps are set in very complex and narrow places. A remote control pipe welding equipment, in which all welding sequences are controlled by a mini-com-puter, has been developed, in order to solve the difficulty in such narrow place welding. The welding conditions were determined by an experimentally developed algorithm. During the first pass, a torch does not weave, but makes a straight trace along the center line of a groove. It is important to melt an insert ring, but not so much that a concave bead may be formed on the reverse side of the pipe. During the following passes, it is important to make the surface of a bead flat, and neither convex nor undercut at all positions of the pipe. In order to control by a computer, the welding conditions during the first pass and subsequent multi-passes were decided by the welding algorithm. Welding parameters were com-firmed experimentally to give suitable penetration and bead shape.
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  • Hisao Matsushita, Hirosato Indow, Koji Kishimoto
    1981 Volume 50 Issue 10 Pages 993-1000
    Published: October 05, 1981
    Released on J-STAGE: August 05, 2011
    JOURNAL FREE ACCESS
    The role of crack-like weld flaws has been studied on fracture toughness of welded structures. Tensile tests were conducted at low temperature with small size specimens taken from MIG welded joints of KAS steel including lack of penetration, surface flaw, embedded flaw or through thickness flaw.
    The main results are summarized as follows:
    (1) Critical J-values Jc obtained through Rice's equation depended on the flaw shape and flaw size for σnc>σY and sensitively increased with increase of temperature when ρc>b
    (2) The relationships between Jc and critical elongation ec were analytically led out and have been experimentally confirmed;
    σnc<σY Jc/eyσY =πa( e*c/eY )2 σnc>σY Jc/eYσY =lo( e*c/eY -0.5)
    e=h/l0 a<<;B, W
    where σnc: fracture net stress, σY: yield strength, ρc: critical length of plastic zone, b: ligament width, h: displacement, io: gauge length, 2α: crack length, ep: yield strain, B: specimen thickness and W: specimen width.
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  • Yoshimune Nakamura, Hideo Kobayashi
    1981 Volume 50 Issue 10 Pages 1001-1008
    Published: October 05, 1981
    Released on J-STAGE: August 05, 2011
    JOURNAL FREE ACCESS
    As to the austenitic stainless steel deposited metals by the covered arc welding and band arc welding, investigation has been made about influence of the arc voltage on ferrite content and distribution of ferrite in the bead. In case of the cavered arc welding, FN in the deposited metals has sharply dropped when the arc length is lengthened. This main cause is lowered Cr content in the deposited metals due to oxidization and remarkably increased N content on account of absorption of O and N in the air caused by the arc length increased. In case of the band arc welding, no change in N content has been found by the arc voltage increased.
    FN in the bead section produced by the covered arc welding has a distribution from, higher at the section center and lower at the bead surface and in the neighborhood of weld bond. FN of the bead section produced by the band arc welding has shown somewhat complicated distribution. As the results of analyzing these sections by means of EPMA, a density gradient of Cr corresponding to the change of FN has been noticed.
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  • Makoto Fujiwara, Toshiaki Tanaka, Shizuo Mukae
    1981 Volume 50 Issue 10 Pages 1008-1012
    Published: October 05, 1981
    Released on J-STAGE: August 05, 2011
    JOURNAL FREE ACCESS
    Fracture toughness, JIc in synthetic weld-heat affected zone of Al killed steel and its recovery by following reheating were investigated by three point bend test in low temperature range. Synthetic weld-heat affected zone was obtained by rapid heating at peak temperature 1250°C or 1350°C and by cooling for 10 sec or 80 sec from 800°C to 500°C. Following reheating was given by rapid heating at peak temperature from 700°C to 1000°C and by cooling for 10 sec or 80 sec from 800°C to 500°C. Main results obtained were as follows.
    (1) JIc, values in synthetic HAZ were inferior to those of as-received steel in every test temperature.
    (2) Remarkable recovery of JIc value was obtained in a synthetic HAZ heated at 1350°C and cooled for 10 sec from 800°C to 500°C, by following heating at 700°C and cooling for 53 sec from 700°C to 500°C, due to form tempered martensite and bainite structure mainly.
    (3) Maximum JIc, was obtained to Tc=20 sec, changing cooling time, Tc from 800°C to 500°C in a synthetic HAZ heated at peak temperature 1350°C.
    (4) Hall-Petch relation of JIc vs L-1/2 was recognized between JIc and facet size, L.
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  • Welding of Thin Copper Plate with Twin Electrode Switching TIG
    Satoshi Kokura, Masayasu Nihei, Yuzou Kozono, Eiji Ashida, Akira Onuma ...
    1981 Volume 50 Issue 10 Pages 1013-1017
    Published: October 05, 1981
    Released on J-STAGE: August 05, 2011
    JOURNAL FREE ACCESS
    Authors reported already that the twin electrode switching TIG welding method was effective to increase welding speed in welding of thin mild steel plate. This method is characterized by preventing the arc blow between closely spaced two electrodes. In the method, welding current is alternately switched to each electrode by the transistor circuits.
    In this report, it was applied to the welding of 0.8 mm thick thin copper plate and the following results were obtained.
    1) The critical welding speed at which acceptable beads are obtained is about 9 m/min. That speed is two times as fast as that of the one electrode DCSP TIG.
    2) The lead pool width becomes narrower than the trail pool width. However, the trail electrode sufficiently forms a large weld pool as same as the pool width of one electrode DCSP TIG by the preheating effect of the lead electrode.
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  • Hisao Aoki, Kenichi Nagai, Hideaki Kuwajima, Masaki Watanabe
    1981 Volume 50 Issue 10 Pages 1018-1023
    Published: October 05, 1981
    Released on J-STAGE: August 05, 2011
    JOURNAL FREE ACCESS
    The present study is attempt to establish estimation system for welding deformation of plate girder used in bridge. Welding deformations for actual plate girders (12 members) are measured, and approximate analyses are conducted by inherent strain and elastic beam, theory, forthermore, numerical estimation system is attempted using Fourier-series and analyzed results for welding deformations.
    The main results are follows.
    (1) Longitudinal shrinkage and longitudinal bending deformation caused by 4 fillet welds to make-up I-section plate girder are indicated by uniform shrinkage strain for neutral axis and curvature, and they are affected welding sequence, each fillet weld, and correlated respectively by approximate linear regressions with parameters Q/A, Qe/I (Q: welding heat input, A; area of section, e; moment arm, I; geometrical moment of inertia) for each fillet weld and welding sequence.
    (2) Distribution of deflection for a plate girder with varied sections along the longitudinal direction is estimated accurately by numerical analysis using above linear regressions and Fourier-series.
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