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Volume 44, Issue 11
Displaying 1-9 of 9 articles from this issue
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Toshio Yamamoto1975 Volume 44 Issue 11 Pages 870-872
Published: November 05, 1975
Released on J-STAGE: August 05, 2011
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Takashi Nakamura1975 Volume 44 Issue 11 Pages 873-880
Published: November 05, 1975
Released on J-STAGE: August 05, 2011
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Eiichi Yoshida, Hideo Nakao1975 Volume 44 Issue 11 Pages 881-888
Published: November 05, 1975
Released on J-STAGE: August 05, 2011
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Makoto Ohsumi1975 Volume 44 Issue 11 Pages 889-894
Published: November 05, 1975
Released on J-STAGE: August 05, 2011
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Tohru Tohmoto, Akira Sakaguchi1975 Volume 44 Issue 11 Pages 895-901
Published: November 05, 1975
Released on J-STAGE: August 05, 2011
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Yukio Ueda, Keiji Fukuda1975 Volume 44 Issue 11 Pages 902-908
Published: November 05, 1975
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSIn order to analyze theoretically creep behaviors accompanied by stress relief annealing, the authors extended their theory of thermal elastic-plastic analysis based on the finite element method. In the present analytical method, the increment of creep strain is evaluated with an additional term, [Cc] {dσ}, since changes of the creep properties and variation of stresses in a time increment are considered. If their .changes are considered, that is, [Cc] is adopted, the convergence of solutions by the present method is assured even for a comparatively large time increment. But unless the above mentioned changes can be included, that is, [Cc] is not adopted, the convergence of solutions is attained only for a sufficiently small time interval.
Examples are analyzed for two kinds of creep laws, the power and the exponential laws, which are observed in such a material as quenched and tempered H.T.60. From this study, the following information is obtained.
(1) The entire behavior during thermal cycles, not only welding but also stress relief annealing, can be analyzed consistently by the present method.
(2) In this method, the temperature dependency of the mechanical properties of metal during creep behavior can be also taken account.
(3) Any creep law can be adopted in the present method. If appropriate creep laws are adopted, the result of analysis of creep behavior shows good coincidence with that of experiment. This indicates that this method is useful and can be applied for analysis.
(4) If changes of the creep properties and variation of stresses in a time increment are considered, the convergence of solutions by the'present method is assured even for a comparatively large time increment.
(5) In the plane stress state, assuming that the temperature increases uniformly over the specimen for annealing, the stress ratio, σx/σy along the axes of symmetry, hardly changes in the entire course of annealing.View full abstractDownload PDF (439K) -
Automatic control method and the deviceYoneo Kikuta, Nobuaki Miyao, Saijiro Yoshida, Hiroshi Tanimoto, Masayo ...1975 Volume 44 Issue 11 Pages 909-913
Published: November 05, 1975
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSThe automatic control equipment was developed to control the disturbance in the lay down welding method. It was necessary to keep a constant value of voltage in the range of arc current in which good bead and good penetration coexisted.
The arc voltage was regulated by moving the movable core or by means of feed back control system by which the phase of thyristor was controled in the range of proper intensity of current when the variations of arc voltage and arc current was detected by means of a meter relay.View full abstractDownload PDF (2914K) -
Effects of Residual Stress and Repair Welding on Brittle Fracture Initiation from Surface Notch in Fusion Line of Welded JointsIsao Masaoka, Masami Yada, Ryoichi Sasaki1975 Volume 44 Issue 11 Pages 914-922
Published: November 05, 1975
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSEffects of residual stress and repair welding on the brittle fracture initiation in weld fusion line of the manual arc welded joints for 80kg/mm2 high strength steel 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 fracture mechanics. The main results are summarized as follow:
(1) The maximum residual stress of T-shaped welded joints is about 50kg/mm2 in the direction of weld line. That of repair weld zone is about 35kg/mm2 in the direction of right angle with weld line and is about 50kg/mm2 in the direction of weld line.
(2) The brittle fracture strength of the T-shaped welded wide plate specimen with a surface notch, is lower than that of the transversely welded W(1) specimen. The test results with the specimen in which residual stress is superimposed can be adjusted quantitatively by taking stress intensity factor KR of Eq. (4) into consideration. The fracture toughness obtained by the above procedure agrees with that of a transversely welded W(1) specimen without residual stress.
(3) The fracture toughness of the repair welded wide plate specimen almost equals to the minimum values of stress relieved welded joints when the notch tip is heated to the temperature range, 300-550°C, in repair welding. Therefore, the fracture stress of the repair welded joints is extremely lowered if defects remain in the fusion line. But it is as high as the fracture stress of the transversely welded W(1) joints as welded, when the maximum temperature of notch tip is below 250°C in repair welding.
(4) It is important that the maximum heat temperature of fusion line is below 250°C in repair welding. Removal ofhydrogen by heating is effective, but its temperature should be below 250°C.
(5) We calculated relation between fracture stress and crack length of T-shaped welded joint and repair weld zone for welded structure.View full abstractDownload PDF (3342K) -
Shizuo Mukae, Mitsuaki Katoh, Yasumasa Nakayama1975 Volume 44 Issue 11 Pages 923-930
Published: November 05, 1975
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSThe development of new crystals in weld metals was investigated. The welding was performed by following two methods. The first method was that bead-on-plate welding was performed on specimens. The specimens were obtained by arc-spot-welding a piece of Al-4.90% Mg alloy on 99.999% Al sheets. The other method was that butt-welding was performed on 99.999% Al and Al-Mg alloys.
In these weld metals new crystals unlike stray crystals were observed to develop along a curve of puddle isotherm besides columnar crystals grown from fusion boundary. These crystals were named "ripple crystals". Hence, the ripple crystals were elliptical-shaped when the welding was performed at a low speed. Subgrains were also developed in the ripple crystals and were observed to grow in the direction of ‹100›. Moreover, the concentration of magnesium was observed near the grain boundaries of the ripple crystals. It would be concluded, therefore, that magnesium contributed mainly to the development of the ripple crystals.View full abstractDownload PDF (10173K)
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