JOURNAL OF THE JAPAN WELDING SOCIETY
Online ISSN : 1883-7204
Print ISSN : 0021-4787
ISSN-L : 0021-4787
Volume 44, Issue 9
Displaying 1-8 of 8 articles from this issue
  • Shigetomo Matsui, Yuji Ohkuma
    1975 Volume 44 Issue 9 Pages 716-727
    Published: September 05, 1975
    Released on J-STAGE: August 05, 2011
    JOURNAL FREE ACCESS
    Download PDF (5267K)
  • Relationship Between Charpy Impact Properties and Micro Structures of Si-Mn Weld Metals
    Yoshinori Ito, Mutsuo Nakamishi
    1975 Volume 44 Issue 9 Pages 728-733
    Published: September 05, 1975
    Released on J-STAGE: August 05, 2011
    JOURNAL FREE ACCESS
    Relations among Charpy impact properties microstructures and Si, Mn or O content about Si-Mn weld metal with submerged arc welding were investigated for the purpose of finding out the way to improve Charpy impact properties of weld metal.
    Results can be summarized as follows.
    (1) In Si-Mn weld metals, effects of Si and Mn content on Charpy impact properties are related with the change of microstructure and the decrease of oxigen content. And when the chemical composition of weld metal is the range of 0.10-0.25% Si and 0.8-1.0% Mn Charpy impact properties of weld metal is the best.
    (2) The growth of coarsened-grain ferrite and needle like ferrite on the microstructure deteriorate the Charpy impact properties, the growth of the mixed structure of them and fine-grain ferrite improve the Charpy impact properties.
    From these results it is thought the control of micro-structure is the most important factor for the improvement of Charpy impact properties on the weld metals.
    Download PDF (4403K)
  • Effect of the grain size and cementite configuration of steels on the corrosion fatigue of steel
    Isao Masumoto, Tohru Akaishi
    1975 Volume 44 Issue 9 Pages 734-738
    Published: September 05, 1975
    Released on J-STAGE: August 05, 2011
    JOURNAL FREE ACCESS
    The effect of some alloyed elements was described in the previous report. In this report, the effect, of grain size, distribution of cementite of steel plates and dissolved oxygen in 3% NaCl aq. solution on the corrosion fatigue was investigated and compared with the fatigue strength in air.
    Results obtained are as follows:
    1)In the case of fatigue test in air, slight difference of fatigue strength was observed by the difference of grain size, but there was no difference in the corrosion fatigue test.
    2)The fatigue strength in air of the steel with dispersed cementite was slightly higher than that of the steel with lamellar perlite, but in the case of corrosion fatigue strength there was no difference by cementite distribution in steel test specimen.
    3)The corrosion potential changed abruptly at the early cycles of corrosion fatigue test, and the damage due to corrosion fatigue reached to 80% at the same time.
    4)Effect of dissolved oxygen on corrosion fatigue life was remarkable below 0.01cc/l of dissolved oxygen, but there was no linear relationship between dissolved oxygen and corrosion fatigue life over 0.01cc/l dissolved oxygen.
    Download PDF (2894K)
  • Continuous method of lay down welding
    Yoneo Kikuta, Nobuaki Miyao, Saijiro Yoshida, Hiroshi Tanimoto, Masayo ...
    1975 Volume 44 Issue 9 Pages 739-744
    Published: September 05, 1975
    Released on J-STAGE: August 05, 2011
    JOURNAL FREE ACCESS
    For the practical use of the continuous lay down arc welding method, the effects of the joint part and the current supplying part of the lay down electrode on bead appearance and penetration condition were studied. With the information by this study, the automatic motion mechanism to breakaway the current supplying part from the lay down electrode by perceiving arc heat was developed. The results are sum-marized as follows:
    (1)The jointing method of electrode that the electrodes with a projected part and a hollowed part at the side edges is jointed successively by fitting the projected part to the hollowed part is available, and good bead and good penetration are obtained if the topp clearance for the fitting is kept in zero and the side clearance is kept within 0.05 mm.
    (2)The current supplying method to the lay down electrode in which the flux is eliminated at the place where the automatic current supplying machine is set, and supply the current under pressing the current supplying element on the current receiving place, and the element is breakaway from the electrode before the arc current arrive on the element, is recommended. The eliminating length of the flux of 10mm and the exposed area of the core wire of 24mm2 is most preferable for the electrode of 6mm diameter to obtain good bead and good penetration.
    Download PDF (4383K)
  • Brittle Fracture Initiation from Surface Notch in Fusion Line of Welded Joints with Augular Distortion
    Isao Masaoka, Ryoichi Sasaki, Masami Yada, Shizuka Shimanuki, Masao Is ...
    1975 Volume 44 Issue 9 Pages 745-754
    Published: September 05, 1975
    Released on J-STAGE: August 05, 2011
    JOURNAL FREE ACCESS
    The brittle fracture initiation characteristics from surface notch in weld fusion line of the welded joints, both manual arc welded and submerged arc welded made of 80kg/mmz high strength steel with a plate thickness of 50mm, were investigated using the wide plate tension test specimen with an angular distortion and a surface notch. And the results were analyzed by application of the conventional fracture mechanics. The main results are summarized as follows:
    (1) In case the joint has a notch (defect) in weld fusion line, its brittle fracture strength is lowered as. its angular distortion and notch length increase. It also diminishes with a temperature drop.
    (2) The test results can be adjusted quantitatively by stress intensity factor of Eq. (5). However in. the tests with a specimen with angular distortion the results show a large variation depending on the end. restraint condition of the specimen, so this difference should be introduced in the calculation concerned, using km of Eq. (6). Generally, the end restraint condition proves to give an intermediate value between the two different theoretical values, one for the fixed condition and the other for the supported condition. km is obtained from the bending moment of the weld zone estimated from the deformation behavior of the specimen which is measured by strain gages.
    (3) The fracture toughness of the weld fusion line is high if the specimen is left as welded, but drops extremely low when the specimen is annealed for stress relief. In the specimens as welded, the manual arc welded joints show higher fracture toughness than the submerged arc welded joints.
    (4) Characteristics of fracture initiated from the weld toe can be calculated by assuming that the crack is continuous and has an equivalent crack depth of about lmm.
    (5) The effectiveness of preloading in increasing fracture stress was verified.
    (6) We calculated relation between fracture stress and crack depth of infinite plate for welded structure in the stress field where bending stress is twice as much as tensile stress.
    Download PDF (3850K)
  • The Mechanism of Knife Line Attack Phenomenon(1)
    Hiroshi Ikawa, Shigeo Shin, Yoshikuni Nakao, Kazutoshi Nishimoto
    1975 Volume 44 Issue 9 Pages 755-762
    Published: September 05, 1975
    Released on J-STAGE: August 05, 2011
    JOURNAL FREE ACCESS
    In previous report, the influence of welding heat inputs and heat treatment conditions after welding on knife line attack phenomenon in stabilized austenitic stainless steels was investigated and it was suggested that there was the intimate relation between the cause of the above phenomenon and the microstructure in knife line attacked region.
    In this report, electron microscopic investigations in HAZ were conducted and the behaviour of carbides was studied in order to make clear the cause and the mechanism of knife line attack phenomenon.
    The experimental results obtained in this study are as follows;
    (1) MC type carbides in HAZ dissolved partially or almost perfectly during welding.
    (2) Under sensitizing heat treatment, M23C6 type carbide precipitated at austenite grain boundaries.
    (3) According to the fact that the net work of M23C6 around the austenite grain boundaries causes intercrystalline corrosion, M23C6 type carbide precipitated in HAZ near the weld interface was considered to be the cause of knife line attack phenomenon.
    Download PDF (10124K)
  • Rolled Steel for General Structute SS41
    Shozaburo Ohta, Shoichi Satoh
    1975 Volume 44 Issue 9 Pages 763-770
    Published: September 05, 1975
    Released on J-STAGE: August 05, 2011
    JOURNAL FREE ACCESS
    Pulsating tension stress high cycle fatigue tests were carried out on mild steel plates with various Unotches (form factor α=1-6) cut at base metal and at welded bond, and the following conclusions were obtained.
    (1) Fatigue limit of crack initiation (σI) is slightly higher in weld than in base metal, and the α-dependency of σI is strong. But with an increase in α, a decrease in σI shows a tendency to saturate gradually.
    (2) In welded specimens, fatigue limit of crack propagation (σp) is considerably greater than σI because of crack propagation being inhibited; and σp is seemingly independent of α and nearly constant at 14kg/mm2. It seems that the non-propagating crack in weld is dependent on structural change, hardness change and residual stress due to welding and loading conditions etc. In this experiment, σp branched off from σI at around α=3 (branching point).
    (3) Generally, in weld the crack propagates ladder like at a far lower velocity than in base metal. Therefore, it can be considered that the resistance to crack propagation is greater in weld than in base metal.
    (4) The notch sensitivity factor for crack initiation (qI) increases rapidly from α=1 to about 3, in the range of 3<α<6 being nearly constant (0.61-0.65) regardless of α. While the notch sensitivity factor for crack propagation (σp) almost linearly drops with an increasing α (3<α<6).
    (5) From the facts described above, we may conclude that the geometrical form of notch has decisively effect on crack initiation, while the various changes due to welding have greater effect on crack propagation than on crack initiation.
    (6) Fatigue limit (σI) at least at α<1.3 is supposed not to be very different between notched and plain specimens.
    (7) ε0 tends to be smaller, as α is larger, and as the stress gradient is steeper or the notch radius ρ is smaller when α is same.
    (8) In the first stage of crack propagation, the crack propagating rate is slower as the stress gradient at the notch is steeper.
    Download PDF (545K)
  • 1975 Volume 44 Issue 9 Pages 771-773
    Published: September 05, 1975
    Released on J-STAGE: August 05, 2011
    JOURNAL FREE ACCESS
    Download PDF (5492K)
feedback
Top