Online ISSN : 1883-7204
Print ISSN : 0021-4787
ISSN-L : 0021-4787
Volume 43 , Issue 2
Showing 1-13 articles out of 13 articles from the selected issue
  • Tsugio Fujimoto
    1974 Volume 43 Issue 2 Pages 119-126
    Published: February 25, 1974
    Released: August 05, 2011
    As a second example of the applications of theoretical analysis of residual welding stresses based on the inherent strain, stress distributions in a finite circular plate with concentrically patch welded joint are calculated and compared with experimental results.
    In this report, the annular plastic region with finite width is considered to exist along the welded line corresponding to the patch welded joint.
    Both components of inherent strain εγ* and εθ* are assumed to be uniformly distributed along circumferential welded line. On this assumption the residual welding stresses in a patch welded circular plate are obtained as the inherent stresses caused by the inherent strain.
    Since the components of inherent strain are expressed as a function of only the variable γ, distance from the center of the circular plate, the results of the theory of axially symmetric inherent stresses presented in the first report can be applied in this case.
    In this report, taking the apparent elastic stress due to the 1 mm displacement of root gap of patch welded joint as the restraint coefficient, the transverse shrinkage is estimated from the welding conditions and restraint coefficient as in the butt welded joint. The inherent shrinkage is considered to be approximately equal to the transverse shrinkage. In contrast to the case of slit-type butt welded joint, described in the second report, the residual stresses are calculated here without reference to the experimental results of transverse shrinkage. Nevertheless, the theoretical results well agree with the experimental ones as shown in Figs. 4 to 6.
    The calculation method mentioned above makes it possible to estimate the rough distribution of residual stresses caused by circular patch welded joint.
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  • Masaki Imachi
    1974 Volume 43 Issue 2 Pages 127-134
    Published: February 25, 1974
    Released: August 05, 2011
    One of the principal problems in using polyethylene is the poor adhesion because of its nonpolarity and high crystallinity. There are various methods for surface treatment to improve adhesiveness of polyethylene and many ofthem are applied on purpose to make polyethylene oxydized and polarized.
    Relation between treatment conditions and adhesiveness or the effect of oxydation are not sufficiently clear. In this study, low density polyethylene film was exposed to pure oxygen gas under a pressure of 20kg/cm2-80kg/cm2 at 80°C-110°C for 5hours-30hours, and then degree of oxydation, wettability, adhesiveness and others were investigated. The effect of chromic acid treatment which is popularly used on account of its convenience was also examined.
    The results are summarized as follows:
    (1) Oxygen gas treatment even at a temperature below the melting point of polyethylene is somewhat effective on wettability and adhesiveness and more effective at a temperature above the melting point.
    (2) The adhesive strength of polyethylene increases owing to oxygen gas treatment but shows a decreasing tendency in excessive oxydation. One of the factors which cause this fact seems to be the weak boundary layer fomed with the advance of oxydation.
    (3) It becomes clear that the effect of only oxydation on adhesiveness is not so remarkable, i.e. polyethylene surface subjected to oxygen gas treatment dose not exhibit more increase in adhesive strength than that treated with chromic acid which is considered to be attended with some factors such as surface roughness in addition to oxydation.
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  • Isamu Koizumi, Muneyoshi Takeyama
    1974 Volume 43 Issue 2 Pages 135-140
    Published: February 25, 1974
    Released: August 05, 2011
    A study was carried out to seek the element which did not affect the HAZ cracking of 75Ni-15 Cr-Fe alloy remarkably and improve the forgeability of it instead of Mg.
    The main results obtained are as follows:
    1. Using Ca, the range where HAZ cracking does not occur can be extended.
    2. Using Ca, the mechanical and corrosion properties of 75 Ni-15 Cr-Fe alloy do not become worse.
    3. Consequently, a weldable 75 Ni-15 Cr-Fe alloy which does not cause HAZ cracking can be made more easily using Ca.
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  • Masanobu Hamasaki, Jituo Sakakibara, Fumikazu Tateiwa
    1974 Volume 43 Issue 2 Pages 141-146
    Published: February 25, 1974
    Released: August 05, 2011
    Authors have proposed an underwater welding pocess called water curtain type underwater CO2 arc welding method. It was already reported that may succeeded in single layer butt welding at 120 cm/min high speed as underwater welding by using flux cored wires in this process. Now, all deposited metal are made and thick plates are welded with multiple pass by using the said wires.
    The conclusions that may be drawn from this study are:
    1) Hardness of welds becomes lower under use of mixed shielding gas of O2 with Ar and CO2.
    2) In tensile tests of all deposited specimens executed by underwater welding, the elongation was 9-13%.
    3) After heat treatment of these specimens at 350°C for 1 hr, the elongation became 14-24%.
    4) Welds executed by two layer butt welding of 6mm thick plates and six layer butt welding of 20mm thick plates turned out satifactory in tensile test and bending test.
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  • Itsuro Tatsukawa, Akira Oda
    1974 Volume 43 Issue 2 Pages 147-155
    Published: February 25, 1974
    Released: August 05, 2011
    Low-cycle fatigue process and failure at high stresses beyond elastic range are investigated for individual weld zones, namely base metal, heat-affected zones and weld metal, of an 80kg/mm2 class heat-treated highstrength steel weld.
    The specimens, shape of which is transverse-weld cantilever beam of uniform strength in bending, are divided into three types, that is, a plain plate as cut out from a weldment and similar plates with transverse small circular holes acting as stress raisers in each weld zone or with a reinforcement. In the fatigue processes at alternating stresses applied by displacement-controlled repeated loading, the stress-strain behaviours for each weld zone and propagation of macroscopic cracks initiated from stress raisers are observed at different numbers of cycles of stress. The main results are summarized as follows:
    As fatigue proceeds, stress-strain hysteresis loops, areas of which are equivalent to absorbed energy per unit cycle of stress, become progressively wider for all the weld zones with a decreasing elastic limit and an increasing plastic strain except that in the first stages of fatigue both the elastic limits and plastic strains of over-heated zone and weld metal vary reversely to the above. The magnitudes of absorbed energy in heataffected softened zones are so great that main macroscopic cracks which led to fracture take place in these zones of all the specimens regardless of presence of stress raisers.
    In notched specimens macroscopic cracks appear at every stress raiser early in the cycles of loading, and propagate similarly with approximately linear relation to cycles of stress but at different growth rates in the weld zones such as the greatest of the softened zones until the crack growth rates in the softened zones begin to increase rapidly at the final stages of fatigue.
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  • Hiroshi Kihara, Ikuo Okamoto, Yoichi Shibata, Takehiko Iuchi
    1974 Volume 43 Issue 2 Pages 156-161
    Published: February 25, 1974
    Released: August 05, 2011
    This investigation was made to know the effect of complex ion and compound present in a flux aqueous solution on the spreading of solder. The used flux solution is ZnCl2-NH4Cl system, and the equivalent conductances were measured at various concentrations and mixing ratios for the mixing system. Results show that the equivalent conductance of the solution with 5.77N concentration deviates to negative side from the mixing rule at 50°C, probably because of the formation of the complex compound showed by the following equation;
    [ZnCl4]2- +3NH4++Cl- (NH4)3[ZnCl4] Cl
    On the other hand, the spreading test of a low melting point solder on copper base plate was made by using the 5N solution at 60°C. This experimental result shows that the formed complex compound indirectly affects to the spreading of the solder. Namely, though the activity of Cl- in the solution decreases with an increasing of the compound, the spreading is found when the aC1- and pH of the solution satisfy the relation that is shown by the following equation;
    log aC1-=-4.65+pH (where 1<pH<4.4)
    and if the pH is constant, the spread area is about equal at each mixing ratio.
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  • Hiroshi Ikawa, Shigeo Shin, Masahiro Inui
    1974 Volume 43 Issue 2 Pages 162-173
    Published: February 25, 1974
    Released: August 05, 2011
    In the welding of dissimilar metals such as α-steels (carbon steel, Cr-Mo steel, low alloying steel, etc.) to γ-steels and alloys (austenite stainless steel, Ni alloys, etc.), martensite-like structure at weld bound and macroscopic segregation in weld metal are observed by unsuitable welding procedures and its conditions, and these structures result in lower ductilities of the welds and lead to weld crackings.
    Taking notice of such metallurgical phenomena at weld bound and in weld metal, the authors investigated on the substance of martensite-like structure and the effects of chemical compositions of the electrodes and welding conditions on the formation of this structure. Some metallurgical considerations on the macroscopic segregation in weld metal were also discussed.
    The formation of martensite-like structure at weld bond in the welding of above dissimilar metals was reduced and the ductility of the welds was improved with increasing Ni content in the electrodes.
    Martensite-like structure at weld bond will be formed due to the diffusion of alloying elements such as Ni, Cr, Mo, C, etc. at a stagnation area where flow of the molten metal contacting with the fusion line does not occur. In lower range (less than 35%) of Ni content in weld metal, martensite-like structure at weld bond was formed in large quantity with pre-heating.
    Here, the weld bond in the bead-on-plate test specimen of above dissimilar metals, it is not merely as a fusion line, will be defined as a wide semi-melted zone of the base metal that was melted by the molten metal after arc travelling.
    Macroscopic segregation in weld metal was greatly observed with increasing welding speed and content of carbide formers as Cr, Mo, V etc. in α-steels, the segregation area was identified as martensite structure partially including carbide.
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  • Tetsuo To, Masami Futamata
    1974 Volume 43 Issue 2 Pages 174-179
    Published: February 25, 1974
    Released: August 05, 2011
    We have made investigation for the improvement of wind resistance in gas shielded arc welding and extend our experiments of the welding nozzles which we mentioned in our previous paper. In the previous paper, the distribution of the shielding gas velocities, variation of the shape of gas jets and the influence of gas flows on the welds were examined.
    In the present paper, the relation between the construction of the nozzles and the wind resistance is discussed based on the X-ray photographs of the welds under windy conditions and the CO2 concentration in the shielding gas jets without arc. Moreover the effect of the distance between the nozzle and the base metal is checked.
    The welding nozzles classified in 3 types, i.e. A, B and C, are the same as used in the previous paper. The results are summarized below.
    (1) It becomes clear that C type nozzle is most effective to the wind resistance followed by A and B in this order. The limit of the wind velocity is assumed to be 6m/sec in A type, 4m/sec in B type and 6.5m/sec in C type nozzle. Especially in C type nozzle, it is proved that the most suitable ratio of flows (the axial [QZ] and the tangential flows [QR]) exist within 2/1-3/1).
    (2) The performance of wind resisting nozzle is proved by measuring the concentration of the shielding gas without arc. When the CO2 concentration is found over 80% in the gas jets, we can obtain a fine weld.
    (3) It is desirable that the distance between nozzle and base plate be shorter in the same nozzle to increase the wind resistance in gas shielded arc welding.
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  • Hiroshi Kihara, Ikuo Okamoto, Akira Omori, Hirohumi Nakano, Yoshio Aoy ...
    1974 Volume 43 Issue 2 Pages 180-188
    Published: February 25, 1974
    Released: August 05, 2011
    In this report, the effect of dissolution of metal into solder on spreadability was studied. The experimental results obtained are as follows:
    The active metal atom, produced by the reaction of molten Sn-Pb eutectic alloy solder with various metal stearates, dissolves easily into molten Sn-Pb alloy solder, and the dissolution may be most important factor in spreading of solder on the base metal.
    But, the addition of various metal to Sn-Pb alloy solder and the dissolution of base metal into solder, had little effect on improvement of spreading of Sn-Pb alloy solder.
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  • Junichi Kinugawa, Takeshi Fukushima, Sadao Fukushima
    1974 Volume 43 Issue 2 Pages 189-196
    Published: February 25, 1974
    Released: August 05, 2011
    In underwater wet welding using a plasma arc as a heat source, the process using both water and gas as the shielding materials has been developed as a way to protect the plasma arc and the part being welded from the water environment. In this process, the periphery of the cavity which is formed around the plasma arc with an annular flow of shielding gas is surrounded and restricted with fanwise streams of water.
    Then, the effects of the process mentioned above and the phenomena following this have been investigated by comparing with those of the process without shielding materials and the process using shielding gas.
    The experiments have been done at a depth of 20 cm in city water. Steel for welded structure (SM41A) having a thickness of 12 mm has been used as the base metal.
    Adding the process using viscous liquid as a shielding material to the three processes mentioned above, merits and demerits of each process have been evaluated.
    Main results are summarized as follows:
    (1) The process using both water and gas as shielding materials enables the cavity formed around the plasma arc to remain stable. Consequently, the stable plasma arc can be obtained by this process as well as that of the process using viscous liquid.
    (2) In spite of the fact that water stream has an effect to cool the weld rapidly, the weld produced by this process using both water and gas includes less blowholes and has better appearance than that produced by the process using shielding gas.
    From the results mentioned above, it is concluded that the process using both water and gas as shielding materials is effective as a wet welding process which is free from water pollution caused by use of shielding materials.
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  • Kunio Norita
    1974 Volume 43 Issue 2 Pages 197-204
    Published: February 25, 1974
    Released: August 05, 2011
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  • Shozaburo Ohta, Noboru Kimata
    1974 Volume 43 Issue 2 Pages 204-214
    Published: February 25, 1974
    Released: August 05, 2011
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  • Yugoro Ishii
    1974 Volume 43 Issue 2 Pages 215-220
    Published: February 25, 1974
    Released: August 05, 2011
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