JOURNAL OF THE JAPAN WELDING SOCIETY
Online ISSN : 1883-7204
Print ISSN : 0021-4787
ISSN-L : 0021-4787
Volume 48 , Issue 11
Showing 1-19 articles out of 19 articles from the selected issue
  • Yoshihiko Mukai, Masato Murata
    1979 Volume 48 Issue 11 Pages 903-910
    Published: November 05, 1979
    Released: August 05, 2011
    JOURNALS FREE ACCESS
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  • Masanobu Hamasaki, Fumikazu Tateiwa
    1979 Volume 48 Issue 11 Pages 911-915
    Published: November 05, 1979
    Released: August 05, 2011
    JOURNALS FREE ACCESS
    The authors have developed a stud welding as one of the underwater welding methods, the stud welding set for surface use as it is can be applied for underwater use, but the gun must be modified to watertight and an air shroud must be added to gun in which air is fed and expells water and in addition fine porous material was set around the slots of the shroud, preventing water pushed back in the welds.
    Fundamental study was conducted at 0.3m and 50m deep. Welded strength obtained underwater, even though 50 m deep underwater, was no weaker than that made on the surface. Application study was conducted in an 8 m long × 4 m wide × 2 m deep pool, where a welder in a diving suit carried out stud welding with successful result.
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  • Atsushi Hasui, Yasuo Suga, Shinsuke Kishi, Mitsuo Teranishi
    1979 Volume 48 Issue 11 Pages 916-920
    Published: November 05, 1979
    Released: August 05, 2011
    JOURNALS FREE ACCESS
    Underwater welding by the submerged-arc welding process is investigated by using the 1.6 and 2 mm diameter flux cored wires and a flux MF43 mixed with water glass.
    Welding experiments are done by using SM41 and SM50 steel base metals of 6, 9 and 12 mm in thickness and it is ascertained that this process may be pat to practical use.
    Main results are summerized as follows:
    (1) Sound weld can be obtained easily by using flux cored wires and a special flux mixed water glass with MF43, due to stable arc.
    (2) Weld metal does not include a blowhole. And cracks are not obserbed at heat-affected zone and in weld metal.
    (3) The welds resulting from this process have excellent mechanical properties in both tensile strength and notch toughness.
    (4) Cooling rate at 500°C at bond is 13-15°C/s and it eems to be much lower value than those by any other underwater welding processes.
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  • Isao Masumoto, Jun Takano, Atsushi Yoshida
    1979 Volume 48 Issue 11 Pages 921-925
    Published: November 05, 1979
    Released: August 05, 2011
    JOURNALS FREE ACCESS
    An algorithm and program for determination of CO2 arc welding parameters of flat position fillet joint has been studied under given fillet sizes and welding speeds. Two torch angles examined were at 45° and 25°. The proposed program is applicable to the globular transfer condition using wier of 1.6 mm in diameter. Calculated parameters were confirmed experimentally to give good bead appearance for fillet sizes from 5.5 to 12 mm. Effect of welding parameters on the relation between effective throat thickness Te and theoretical throat thickness T was also calculated.
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  • Isao Masumoto, Hirohito Hira
    1979 Volume 48 Issue 11 Pages 926-931
    Published: November 05, 1979
    Released: August 05, 2011
    JOURNALS FREE ACCESS
    Very fine structure of the friction welded joint interface can be attributed to the result of heavy working above recrystallization temperature.
    The purpose of this study is to know the mechanism of formation and the properties of such fine structure of pure aluminium, varying working temperature, strain rate, and strain by hot torsion testing machine.
    Main results are as follows,
    (1) Deformation resistance increases with a increment of strain up to a definite value, at which the deformation resistance becomes almost constant value. This value depends mainly on working temperature.
    (2) Dynamically formed fine structure at various working condition consists of subgrains, and the subgrain size depends both on working temperature and on strain rate.
    (3) Hot-heavy-worked specimen at 350°C-500°C showed higher strength and enough elongation, and its microstructure was similar as that of friction welds.
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  • Hiroshi Tamura, Tadao Onzawa, Susumu Uematsu, Kiyoaki Maekawa
    1979 Volume 48 Issue 11 Pages 931-936
    Published: November 05, 1979
    Released: August 05, 2011
    JOURNALS FREE ACCESS
    The retained austenite and V-Charpy toughness of the weld metal, the weld bond and the heat-affected zone (HAZ) of 9 % Ni steel welds were investigated. 20 mm thick test plates were welded using the automatic gas tungsten-arc process and a ferritic filler metal having chemical compositions similar to those of the base metal. The weld specimens were prepared by deposition of aingle pass and multi-pass weld beads into single bevel groove of the base metal. Some of the single pass weld specimens were heated at 550°C, 600°C, and 650°C for 1 hr in order to evaluate the influence of the post weld heat treatment. The heat treatment at 600°C resulted in peak value of toughness at the weld bond as well as large amounts of retained austenite, 10-17 %, at the weld bond and the HAZ. The austenite produced in this condition, however, was unstable and decreased in less than 10 % by sub-zero treatment at -196°C. In the multi-pass weld specimens, both the HAZ and the weld metal showed the good toughness comparable with those of the base metal, and then the bond toughness of half size specimen including the primary bead was excellent because of being adequently affected heat histories of the subsequent passes. A sufficient amount of the austenite was present in whole weld of the multi-pass specimen as a consequence of tempering due to the subsequent passes, though the weld heat cycles were in relatively short time comparing with furnace heat cycles. From the results obtained above, it was found that there was the considerable correlation between the thermally stabled austenite and the notch toughness in the weld zone.
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  • Yoshihiko Mukai, Masato Murata
    1979 Volume 48 Issue 11 Pages 937-944
    Published: November 05, 1979
    Released: August 05, 2011
    JOURNALS FREE ACCESS
    The effect of temperature of 42 % MgCl2 solution on crack propagation feature of stress corrosion cracking (SCC) of SUS 304 stainless steel was investigated. It was observed that the threshold value of stress intensity factor KISCC was not clearly influenced by temperature, while crack growth rate da/dt increased with temperature in the range of 109°C-143°C. The effect of temperature on crack growth rate was able to be evaluated by Arrhenius equation. Apparent free energy of activation was about 22.6 Kcal/mol which scarcely had K dependence.
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  • Toshio Kitani, Tuneo Toyooka, Yoshihiko Wakino
    1979 Volume 48 Issue 11 Pages 944-949
    Published: November 05, 1979
    Released: August 05, 2011
    JOURNALS FREE ACCESS
    Recently the production of thick wall pressure vessels with corrosion resistant stainless steel clading for atomic and chemical application has been incresing rapidly. Some large sized pressure vessel have been repeated stress-relief heat treatment up to 50 hrs. As a result of heat treatment, the hardened layer is formed due to carbon migration from low alloy steel (base metal) to stainless steel, which may cause cracking in the bend test. Such problem takes place not only in the rectangular electrode process but also in other overlay arc welding processes.
    From the observation on the netallurgical study, the boundary layer formed during welding has width of about 20-45μ (martensite structure), but in this case no cracking is found in the bend test. When the boundary layer is received stress-relif annealing, the hardened layer is formed near the bond line of the weld metal by carbide precipitation. If the meximum hardness of the hardened layer exceeds Hv400, the bend ductility of metal decreases.
    According to the examinations of heat treatment condition for various austenitic stainless steels, it is reasonable that the process of 309 stainless steel for the 1st layer and 308 or 347 stainless steel for the 2nd layer is preferable to a single-pass welding of 308 or 347 stainless steel.
    In any case, since higher annealing temperature may cause problemes, so the anneling should be performed at temperature below 625°C.
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  • Katsunori Inoue, Yoshiaki Arata
    1979 Volume 48 Issue 11 Pages 950-954
    Published: November 05, 1979
    Released: August 05, 2011
    JOURNALS FREE ACCESS
    The results of measurement of the parameters which represent the fluctuating properties of the light from arc plasma are described, following the previous report, and some considerations are made in order to clarify the mechanism of the fluctuation.
    The rasults are as follows;
    1) The fluctuation of the light of comparatively high frequency (angular frequency >30) is due to the repeating process, in which the tip of the wire melts and grows up to the globule, then the globule parts from the wire, and that of comparatively low frequency (angular frequency=2π-6π) is due to the alternation of the arc generating point which is caused by globular transfer.
    2) The fluctuation of the light in dip transfer CO2 arc is caused by the short and refiring cycle of the wire to the work piece.
    3) The arc becomes stable and the fluctuation disappears gradually according as the gas mixing ratio of Ar to CO2 becomes large and the melted metal of the wire begins spray transfer.
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  • Shuji Nakata, Masahiro Nishikawa, Hiroaki Agoh
    1979 Volume 48 Issue 11 Pages 955-960
    Published: November 05, 1979
    Released: August 05, 2011
    JOURNALS FREE ACCESS
    The effect of projection height on nugget formation and growth has been examined using projections with the constant diameter, embossed on a cold rolling sheet of low carbon steel of 1 mm in thickness (SPCC).
    Using the high projection, the splash during the collapse of projection occurs extensively under the low electrode force, and causes to decrease the tensile shear strength. Using the low projection, the current shunting occurs in the other part near the projection. A rate of occurrence of the current shunting in the weld specimens. is found to increase with the electrode force. This shunting also causes the tensile shear strength to decrease the value near the critical weld current.
    Under the high electrode force, the bonding part like a torus is formed at the initial period of weld time by using high projections. The tensile shear strength is related to the nugget diameter and the saturated diameter of nugget depends only on the weld current above the critical current as a function of the cold collapsed area and the electrode force.
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  • Toshiro Kikuchi, Iwao Onishi
    1979 Volume 48 Issue 11 Pages 960-966
    Published: November 05, 1979
    Released: August 05, 2011
    JOURNALS FREE ACCESS
    This report is discussed the method of improvement at the sensitivity of steel to reheat cracking.
    Namely, a plan of improvement that be decrease the impurity element, P in steel is discussed.
    The experimental materials used the commercial HT80, A387-12, A533B steels and trial producted steels that be decrease the impurity element, P in those steels.
    The results of the study obtained are summaraized as follows:
    1) From results of reheat cracking test by specimens of synthetic HAZ test or y-slit crack test; to decrease the impurity element, P in steel could be improve the sensitivity to reheat cracking.
    2) The above results well be support a new mechanism of reheat cracking that take into consideration the embrittlement of grain boundary.
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  • Shigetsugu Asakura, Masayasu Nihei
    1979 Volume 48 Issue 11 Pages 966-971
    Published: November 05, 1979
    Released: August 05, 2011
    JOURNALS FREE ACCESS
    In his study, experiments were performed to make clear the influence of the contentious cooling transformation in heat affected zone (HAZ) of the 1Cr-1/4Mo (SCM4 and SCM22) steels on notch toughness, tensile properties and HAZ cracking by making the SH-CCT diagram, heat cycle simulating tests and slit type cracking tests. The results of these test are summarised as follows.
    (1) The impact value falls strikingly when the single heat cycle of 1, 350°C is given, and those values (vE20) are 0.5-1 kg-m/cm2 for SCM4 and 2-3 kg-m/cm2 for SCM22. However, the influence of the cooling rate in the heat cycle cannot be especially recognized.
    (2) The impact value will be remarkably improved when the cooling time of the heat cycle from 800 to 500°C is made less than 20s for SCM4 and 10s for SCM22 (the area percentage of the martensite are in the range 80-100%) and then postheated at 600°C for 2 or 3 hours.
    (3) In slit type cracking tests on the tested steels, when the bainite structure of the HAZ was made approximately more than 40-60% by preheating, the HAZ cracking cannot be recognized even though wet coated electrode (12cc H/100g) was used.
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  • Koichi Akizono, Ri-ichi Murakami
    1979 Volume 48 Issue 11 Pages 971-979
    Published: November 05, 1979
    Released: August 05, 2011
    JOURNALS FREE ACCESS
    The impact and non-impact fatigue crack propagation tests were conducted on butt welded mild steel specimens. The impact fatigue tests were carried out using the rotating disk type impact fatigue testing machine. The influence of local constraint in the weld zone which was produced by the residual stress and the difference of microstructure and mechanical properties between heat-affected zone and weld metal on imact fatigue crack growth rate was investigated by means of fracture mechanics and fractography, and the results of impact fatigue tests were compared with the non-impact fatigue test results. The important conclusions were as follows.
    (1) In non-impact fatigue, it was found that the crack growth rate into the direction perpendicular to the weld bead were almost equal to that in parent metal or weld metal.
    (2) In impact fatigue, it was found that he crack growth rate in weld metal was almost equal to that in parent metal. But, the crack growth rate into the direction perpendicular to the weld bead showed a drastic decrease in the vicinity of the bond. This drastic decrease of crack growth rate was primarily caused by the residual compressive stresses in heat-affected zone.
    (3) The dominant fracture appearance in impact fatigue was striation as in non-impact fatigue. It was found that the fatigue crack growth rate for all specimen regions except that which propagated into the direction perpendicular to the weld bead in impact fatigue almost agreed with striation spacing.
    (4) Comparing impact fatigue test results with non-impact fatigue test results, quite large difference of crack growth rates arises from the difference of striation spacings which should be attributed to the impact load wave and impact loading. Therefore, the impact fatigue crack growth rates, (da/dN)imp, could be expressed as follows,
    (da/dN)imp=C'(K'max)m'=αC(βKmax)m =αβm(da/dN)non.
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  • Hiroshi Ikawa, Hiroaki Oshige, Hirohiko Date
    1979 Volume 48 Issue 11 Pages 980-984
    Published: November 05, 1979
    Released: August 05, 2011
    JOURNALS FREE ACCESS
    The method to calculate the hardness distribution in weld-heat affected zone of cold rolled materials was examined using commercial-purity nickel and aluminum.
    That is, the method to calculate the fraction of recrystallization during thermal cycle was proposed, based on isothermal recrystallization equation. Then, the validity of this method in calculation of hardness distribution in weld-heat affected zone was confirmed experimentally.
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  • Hiromu Ogawa, Shigeru Tominaga, Takeshi Maruyama
    1979 Volume 48 Issue 11 Pages 985-991
    Published: November 05, 1979
    Released: August 05, 2011
    JOURNALS FREE ACCESS
    Dynamic fracture toughness KId is generally considered as one of the most important mechanical properties, but it is not so easy to obtain KId. While statical fracture toughness is easily obtained comparatively. If the relation between KIc, and KId can be cleared, it may be very useful for engineering. In this paper, the temperature dependence of KIc, and KId of 2 1/4Cr-lMo steel weld joint were investigated at both states of as weld and as heat treated. Furthermore, the correlations between Charpy impact value Cv and KIc, KId were studied. Main results obtained are as follows.
    (1) KIc, and KId values as weld state are considerably low, and their increasing ratios as temperature rise are little. But by heat treatment, the former are improved remarkably and the latter are increased.
    (2) The temperature dependence curves of KId are located at the temperatures which shifted parallelly those of KIc, to their higher sides. The amounts of shifts determined by the section transition temperatures of Cv tests are over a range of 74-84°C.
    (3) The temperature dependence curves of KIc, KId and Cv are shifted to lower sides by heat treatment. The amounts of shifts determined by the transition temperatures show some differences between the locations of weld joint, but coincide considerably well so far as any one location concerns.
    (4) The formula representing the correlation between Cv and KIc, KId are presented.
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  • Kozo Okita, Waichiro Kishimoto
    1979 Volume 48 Issue 11 Pages 991-995
    Published: November 05, 1979
    Released: August 05, 2011
    JOURNALS FREE ACCESS
    The charpy V-nocth impact characteristics of friction welded joints have been studied with attention to the influences of testing temperature, solution treatment and base metal characteristics.
    The results are summarized as follows.
    (1) The ductile-brittle transition of friction welded joints from -196°C to 20°C was not observed.
    (2) The main cause of the decrease in the charpy absorbed energy of the friction welded joint was considered to be the reorientation of the non-metallic inclusions contained in the base metal.
    (3) Solution treatment at 1050°C of charpy absorbed energy of friction welded joint gave at most 55% value of that of the base metal, remainning the fiber structure present on the fracture surface.
    (4) Charpy V-notch impact characteristics of base metal was considered to be transmitted to those of the friction welded joint.
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  • Jun Matumoto, Ren Obata, Tomihiko Teramoto, Hedehiko Ono
    1979 Volume 48 Issue 11 Pages 996-1000
    Published: November 05, 1979
    Released: August 05, 2011
    JOURNALS FREE ACCESS
    Effect of groove width on wire melting rates and characteristics of welding arcs have been studied in DCSP and DCRP-MIG welding (shielding gas composition;80 %Ar+20 % CO2).
    In DCSP, it was found that wire melting rate increased as groove width increased, and wire melting rate became a constant value as groove width was wider than some boundary width. In cases where groove width was narrow, welding arcs burned not only at groove bottom but also on both groove faces. Their arc flames were extended and wire tapered end had a tendency to be lengthened and sharpened. At the same time droplets became small and transfered smoothly (spray transfer).
    On the other hand, in DCRP, characteristics of arc and wire melting rates were not affected by groove width.
    The results are explained in terms of the change of magnetic force and wandering area of cathode spot around the conical tapered wire end.
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  • Isao Masumoto, Hirohito Hira
    1979 Volume 48 Issue 11 Pages 1001-1005
    Published: November 05, 1979
    Released: August 05, 2011
    JOURNALS FREE ACCESS
    In order to examine the effect of base metal condition of pure aluminium of friction weldability, full annealed and cold-worked aluminium were prepared.
    Vickers hardness of the cold-worked aluminium was 27-30 compared with 20-22 of the annealed. Experimental results were as follows;
    Cold-worked base metal for friction welding reduced the defect to weld interface, and gave better reproducibility of sound joint, compared with annealed base metal. And suitable welding condition can be broadend by using cold-worked base metal.
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  • Hirosada Irie, Tatsuya Hashimoto, Michio Inagaki
    1979 Volume 48 Issue 11 Pages 1005-1011
    Published: November 05, 1979
    Released: August 05, 2011
    JOURNALS FREE ACCESS
    During the drilling process of an electron beam, whose energy was less than 30 keV, measurement of power for drilling, taking tine films by a high speed camera (about 4000 frames/sec), and capturing sputters and electrons emitted from molten metal were carried out. Results are summerized as follows:
    1) Most of power during drilling is dissipated to heat and melt metal which occupied the drilled hole.
    2) The high speed movies show that metal vapor is emitted from molten metal at the next frame after a brilliant point is recognized at the metal surface.
    3) Sputters captured during very short beaming with high energy density beam is very fine and the larger with the lower energy density beam, and
    4) About I msec later of the start of beaming, much amount of electrons is emitted from molten metal. This electron current has high frequency components often superimposed on low frequency components (less than 300 Hz).
    From these results, it is concluded that the drilling progresses mainly through sputtering of superheated molten metal by boiling phenomenon.
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