JOURNAL OF THE JAPAN WELDING SOCIETY
Online ISSN : 1883-7204
Print ISSN : 0021-4787
ISSN-L : 0021-4787
Volume 36, Issue 4
Displaying 1-8 of 8 articles from this issue
  • Fumihito Itoh
    1967 Volume 36 Issue 4 Pages 386-394
    Published: April 25, 1967
    Released on J-STAGE: August 05, 2011
    JOURNAL FREE ACCESS
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  • Yuzuru Fujita
    1967 Volume 36 Issue 4 Pages 395-401
    Published: April 25, 1967
    Released on J-STAGE: August 05, 2011
    JOURNAL FREE ACCESS
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  • Itsuro Tatsukawa, Isamu Oda
    1967 Volume 36 Issue 4 Pages 402-408
    Published: April 25, 1967
    Released on J-STAGE: August 05, 2011
    JOURNAL FREE ACCESS
    Transverse-weld bending tests under alternating loads beyond the elastic range were carried out on the welds of a quenched and tempered high strength steel indicated in Table 1 for the purpose of evaluating the stress-strain characteristics of the individual zones of weld, such as base metal, heat-affected zone and deposit metal. The test specimens were cut out of different types of welds, viz. bead, semi-circle-groove and U-groove welds, as shown in Figs. 1 to 3. After hardness tests, microscopy and tension test, bending tests were performed, in which the strain at each zone and the deflection in parallel part were measured with a strain gage of 1 mm gage length and a dial gage respectively and then the elastic limits at 0.002% offset as well as the mode of hysteresis loops of the stress-strain diagrams, for example, represented in Fig. 8 were observed under repeated stress cycles. The results obtained are as follows:
    Both the over-heated and the softened base metals in the heat-affected zones, -both of them having been most hardened and softened respectively in each weld, -exhibit generally lower elastic limits than the unaffected base metal and deposit metal, as illustrated in Figs. 6, 10 and 15. Figs. 10 and 15 show also that the reversal of direction of stress in cyclic bending noticeably decreases the elastic limits of all zones, especially those of the over-heated and the softened zones, to a fraction of the initial value of the base metal, owing to the Bauschinger effect and the internal stresses caused by the previous bending. And then, in Figs. 11 and 13, the widths of hysteresis loops of these heat-affected zones are considerably larger than those of the base metal at the same stress cycles. These properties of the over-heated zones seem to be accounted for by their microstructures consisting of coarse-grained proeutectoid ferrite and matrix of bainite plus martensite, as shown in Photo. 4 2 6, the former being responsible for the lower elastic limits as well as wider hysteresis loops and the latter for the high hardness.
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  • Minoru Okada, Hiroshi Maruo, Masakatsu Uchida
    1967 Volume 36 Issue 4 Pages 409-415
    Published: April 25, 1967
    Released on J-STAGE: August 05, 2011
    JOURNAL FREE ACCESS
    In the welding technology, it may be interesting to examine the magnetic control of a plasma jet flame. In this report is described the experimental result on the fundamental properties of plasma jet flame in a magnetic field.
    The distribution of field strength in the cusp type or mirror type magnetic field, each of them were made by two coils Ml and M2, was measured as a preliminary research. The plasma jet was injected to the low pressure vessel along the axis of magnetic field, as shown in Fig. 1.
    Photographic observations show that the plasma jet flame flows in the direction of magnetic line of force. Radial distribution of total pressure of the plasma jet flame was measured with use of a pitot tube on the mid-plane between coil Mt and coil M2. In general, the total pressure of plasma jet in the mirror type magnetic field was higher than that in cusp type field. Higher values were observed at relatively constricted region near the central axis of plasma jet.
    Total pressure rises as the are current incrases, but is almost invariant with the arc voltage in this experiment.
    The thermal efficiency of the plasma jet torch was also investigated. The amount of energy contained in plasma flame is expressed as ηVI, η being thermal efficiency of torch.
    It has been found that the total pressure varies with the amount of plasma energy ηVI.
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  • Interfacial Tention Theory on the Phenomena of Arc Welding (Chapter 11)
    Keizo Ishizaki, Kazuo Murai, Yoshio Kanbe
    1967 Volume 36 Issue 4 Pages 416-424
    Published: April 25, 1967
    Released on J-STAGE: August 05, 2011
    JOURNAL FREE ACCESS
    The author has discusssed about various phenomena in penetration with paraffin and stearic acid in case of the heat source directly contacting them, and concludes as follows:
    1. Strong convection flowing within the molten pool is caused by the strong surface flow due to the difference of surface tension by heating a part of molten surface.
    2. The type of convection changes according to the shape of heat source, heat input, heating time and the kind of material, and this determines the shape of penetration.
    The same shape of penetration is obtained by the same type of convection regardless of its cause.
    1) There occurs a very little convection if the surface of molten pool is immovable.
    In this case, the shape of penetration is a semicircle which seems to be explained by "Heat Conduction Theory".
    2) "Pa" type penetration by point heat source and peripheral penetration by disk heat source have a strong resemblance to the shape of penetration with mild steel by fixed TIG arc, and all of these penetration shapes seem to be brought about by the same cause.
    3) Deep simple penetration shape with mild steel can not be explained by the surface tension convection radially flowing from center part. For explaining this type of penetration, the existence of another type of convection such as flows vertically at center part may be necessary.
    3. As for the temperature, it is the highest at the center part of vortex, and goes gradually down toward the surface of penetration, when the convection due to surface tension exists in the molten pool.
    4. From the results of various measurements on the angle of penetration and the shape of molten drop, the reasonable contact angle of molten paraffin and stearic acid as well as of solid state is estimated. This fact shows that the shape of penetration can be anticipated from the contact angle of the material.
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  • Toshikage Ikkai, Yasuo Ishimaru
    1967 Volume 36 Issue 4 Pages 425-428
    Published: April 25, 1967
    Released on J-STAGE: August 05, 2011
    JOURNAL FREE ACCESS
    This report relates to a fusion upset welding method effected using molten slag as resistance-exo-thermic medium.
    It is known that most of conventional welding methods effect their welding by means of molten deposit metal formed in a number of ways, but it may also happen that, in the case of welding ordinary and special steels, mechanical properties of deposited metal invariably drop to a considerable extent under all circumstances. On the other hand, the resistance butt welding and flash butt welding methods in which no metal is deposited, necessitate provision of large capacity power source facilities, so that it is difficult to weld a large cross section using normal welding facilities in these welding systems.
    The objective of developing this new welding method is to solve above mentioned problems. This method enables effective welding of large cross sectional materials with I-shape welding grooves under small current densities, utilizing the resistance-exothermic heat developed as a small current passes through the molten slag.
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  • Isamu Ueda, Masaaki Kawamura
    1967 Volume 36 Issue 4 Pages 429-434
    Published: April 25, 1967
    Released on J-STAGE: August 05, 2011
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    We have concluded already in Report 1 that embrittlement of 2 1/4% Cr-1% Mo steel caused by immersion in 0.5% acetic acid solution saturated with hydrogen sulphide can be regarded as the hydrogen embrittlement.
    This report describes the influence of corrosive environment, i.e., temperature of 0.5% acetic acid and hydrogen sulphide concentration, and heat treatment on hydrogen sulphide corrosion.
    In this research, we shall also try to clarify the effect of test specimen diameter on absorbed hydrogen and embrittlement.
    The conclusions of this report are follows.
    1. In the case of the immersion test, the volume of absorbed hydrogen is greatly dependent on the hydrogen sulphide concentration used and solution temperature more sensitive to corrosion loss.
    2. The volume of absorbed hydrogen decreases with diameter of test specimen and the embrittlement caused by immersion is not related with the diameter.
    3. The effect of heat treatment on the absorbed hydrogen and others, involve complex problems, so that we suppose the relation between the volume of absorbed hydrogen and corrosion loss or the mechanical properties is non-existent.
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  • Masaki Watanabe, Kin-ichi Nagai, Akio Otsuka, Yoshiya Nagata
    1967 Volume 36 Issue 4 Pages 435-443
    Published: April 25, 1967
    Released on J-STAGE: August 05, 2011
    JOURNAL FREE ACCESS
    It is well known that the fatigue strength of welded part reduces to almost half that of base metal of a mild steel. The conceivable factors to reduce the fatigue strength of welded part are the metallugical discontinuity and the stress concentration at the toe, the undercut of reinforcement etc.
    In this study, basic experiments were carried out with small notched plate specimens subjected to plane bending in order to determine whether the metallugical discontinuity or the stress concentration at welded joint plays more important parts on their fatigue strength. The notch was located respectively at the base metal, the weld metal and the heat-affected zone (fine-grained zone, spheroidized pearlite zone and embrittled zone) of butt welded joint, the reinforcement cut off by machine.
    From the test results, it is clear that the fatigue strengths of weld metal and heat-affected zone are larger than that of base metal unless they contain defects like a notch (Fig. 8). The weld metal and heat affected zone are more notch-sensitive than the base metal, especially the spheroidized pearlite zone (Fig.10). The rate of crack propagation on respective zones is less in the intermediate stage of stationary crack growth because of work hardening, while it is large at the initial stage of crack and the prior stage to fracture. The fatigue strength of welded parts depends on the rate of crack propagation in the stationary stage and the crack propagation rate is largest in the spheroidized pearlite zone of welded part (Figs.14, 15). This fact corresponds to the lowest fatigue strength of this structure. It is observed by microscope that the cracks in the heat-affected zone propagate along grain boundary more remarkably than those on base metal.
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