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Volume 50, Issue 4
Displaying 1-15 of 15 articles from this issue
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Nobuya Iwamoto1981 Volume 50 Issue 4 Pages 324-334
Published: April 05, 1981
Released on J-STAGE: August 05, 2011
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Toshio Enjo1981 Volume 50 Issue 4 Pages 335-342
Published: April 05, 1981
Released on J-STAGE: August 05, 2011
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Takashi Ohmac, Yasuhiro Fukaya1981 Volume 50 Issue 4 Pages 343-353
Published: April 05, 1981
Released on J-STAGE: August 05, 2011
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Shigeo Matsushima, Kouji Nozawa, Kenzo Nakamura, Toshio Enjo1981 Volume 50 Issue 4 Pages 354-361
Published: April 05, 1981
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSFrom a simple model of the bead weld constructed by three zones (base metal (BM) without heat affected zone, heat affected zone (HAZ) and weld metal (WM)), the approximate analysis for the tensile deformation of bead welds (mild steel (arc): three.zones, and copper (TIG and electron beam) and aluminum (TIG): two zones of BM and WM) have been carried out. And the confirmation for the propriety of this analysis is made by the tensile test of their bead welds.
As the results, it is found that absolute values of both ratios (σ/σx) and (ε/εx) are larger than 0.85 (σ and ε: equivalent stress and strain, and σx and εx: normal stress and longitudinal strain), and that the tensile deformation of bead weld is approximately expressed by the tensile deformation of the heterogeneity distribution. Moreover, it is found that initial yield for mild steel, copper (TIG) and aluminum occurs in BM in the vicinity of WM, and yield for copper (electron beam) occurs near the ditch (made by the weld), and that the yielding progresses along the boundary of HAZ (for arc and TIG). Also, it is recognized that the inclination (not perpendicular in the tensile direction) of boundary of HAZ and the contignity between HAZ and WM are necessary for the occurrence of the initial yield and for the yield progress and that the variations of the stress and the strain near boundaries between their zones occurs remarkably.View full abstractDownload PDF (2437K) -
Hironobu Nisitani, Hiroyuki Tanaka, Youichi Misawa, Nobuyuki Besho1981 Volume 50 Issue 4 Pages 362-366
Published: April 05, 1981
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSSince a fatigue crack of the butt welded joint with a backing strip initiates at the toe of root, fatigue strength of the joint may be strongly influenced by the form and size of the backing strip. Therefore, reversed bending tests were carried out to clarify the relation between stress concentration and fatigue strength of the butt welded joint with a backing strip, by varying the form. and size of the backing strip.
In a notched specimen, when a non-propagating crack exists at the root of a notch whose radius is smaller than the root radius of a notch at the branch point (the critical point where a non-propagating crack appears), the fatigue limit of the notched specimen can be estimated from the maximum stress at the root of a notch with no crack developing, whose radius is equal to that at the branch point.
As the butt welded joint with a backing strip can be considered as a kind of sharp notches, the fatigue limit of the joint is estimated in a similar manner as in the case of a sharp notch.
The specimens used are the simulated specimens cut out from a SS41 plate.
The main results obtained are as follows;
(1) As the thickness of a backing strip or the root opening decreases, fatigue strength of the butt welded joint increases.
(2) In the butt welded joint with a backing strip, the existence of reinforcement increases fatigue strength of the joint.
(3) When the notch radius at the toe of root is smaller than the critical radius for the existence of a nonpropagating crack, the fatigue limits of the joint are almost the same under the condition of constant thickness of the specimen and backing strip.View full abstractDownload PDF (1237K) -
Effect of Temperature on Strength of Welded JointKenji Seo, Shuzo Susei, Taketo Yamakawa, Hiroyuki Hirano, Kunihiko Sat ...1981 Volume 50 Issue 4 Pages 367-372
Published: April 05, 1981
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSThe present research deals with the fracture behavior and the strength of welded joints such as a side fillet welded joint which is loaded parallel to the axis of the weld at low temperature.
In this paper, the effect of temperature on the fracture behavior in these welded joints are investigated experimentally.
Experiments are made with five types of welded specimen in a temperature range from 20°C to -170°C. In the series of experiment, the results obtained are as follows:
1) Three different types of fracture mode are appeared according to the different temperature.
2) It is cleared that the critical shear displacement which depends on temperature can be applied as the engineering fracture criteria for fracture of these welded joints.
3) In these welded joints, small scale of fractures of weld metal by shear force at low temperature induce the fatal brittle fracture of base metal.View full abstractDownload PDF (5489K) -
Shuji Nakata, Nobuharu Sakabata, Minoru Mouko1981 Volume 50 Issue 4 Pages 373-378
Published: April 05, 1981
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSInfluence of the cross-sectional area of consumable nozzle on the penetration in base plate and its stability and the possibility on the control of welding phenomena by changing the nozzle current is investigated using the mild steel plate with the thickness of 30 mm to develop narrow gap electroslag welding process with high efficiency and low heat input.
It is experimentaly shown that the nozzle with large crosssectional area is useful in stable and high current welding process because of dispersing the welding current in slag pool by increasing the nozzle current. So, the method for estimating the nozzle current during welding is designed and, by this method, the nozzle current is estimated under various conditions in connection with the cross-sectional area of the nozzle.
Adopting above results to high current narrow gap welding process, it is clarified that more stable and uniform penetration can be obtained by using the nozzle with large cross-sectional area. This result is due to the preheating effect at root faces of base plate in slag pool and dispersing the heat source in slag pool by increase of nozzle current.View full abstractDownload PDF (2176K) -
Factors on Bead Shape and Sound Weld MetalKiyoteru Hirabayashi, Tada-aki Taira, Hiroyuki Ichinose1981 Volume 50 Issue 4 Pages 379-386
Published: April 05, 1981
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSThe development of three wires submerged arc welding techniques was carried out to produce line-pipes in the large-diameter and heavy-wall-thickness from 20 to 50 mm by UOE process. Some factors on a sound weld metal and a bead shape have been clarified as follows.
(1) The good correlation between the penetration depth of the weld bead and the sum of 3√ I4/v⋅V2a at the leading and the middle wire could be obtained. The bead width had the good correlation with the heat input, and it was spread by an increase of the welding current and/or the arc voltage at the middle and the trail wire or by a decreasing of the welding speed.
(2) The stable arc voltage and the good bead appearance can be obtained in the use of a large diameter welding wire because of lowering down the current density in it. The wire of 4.0 mm in diameter is too small to get a good weld bead, but the wire of 6.4 mm in diameter is so rigid that undercuts in the weld bead are sometimes caused by the unstable wire feeding. As a result the optimum wire may be 4.8 mm in diameter.
(3) As lengthening a wire spacing, nitrogen and oxygen content in a weld metal are increased and they deteriorate the Charpy value, so that each wire spacing is desired to set within about 30 mm.
(4) To get the high welding speed due to increasing a melting rate may be to weld at a high welding-current, but in this case, weld defects of the bead appearance such as undercuts are caused because of the hunting of the arc voltage happened by higher welding-current. Therefore sums of the welding current in three wires are desired to be about less than 3000 Amp. and the welding current at each wire is limited in the use of the fused flux.View full abstractDownload PDF (515K) -
Nobuyuki Shinohara1981 Volume 50 Issue 4 Pages 387-392
Published: April 05, 1981
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSThe relation was investigated, between nondestructive tests (electro resistance method and ultrasonic method) and destructive tests (shear strength test and ram tensile strength test), with explosively bonded steel, SUS316L (6.5 mm) +ASTMA204(22 mm), which contains unbonded area.
The electro resistance method, the JIS ultrasonic method by the reference block and Cross's ultrasonic method by the amplitude difference provide quantitative results, while the JPI ultrasonic method by the damping of multiple reflection produces only qualitative results and requires some delicate manipulations. The indicate voltage of electro resistance method represents the shear strength, and the amplitude difference of Cross's ultrasonic method corresponds to the shear strength and ram tensile strength.
For the nondestructive tests at the boundary between completely bonded area and unbonded area, the position of the probe has significant influence on the test results.View full abstractDownload PDF (1646K) -
3rd Report: In Case of Butt Weld Joints with Tack WeldsKunihiko Satoh, Kazuhiro Nohaara1981 Volume 50 Issue 4 Pages 392-398
Published: April 05, 1981
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSThe present paper deals with the effect of welding conditions, plate length and tack weld pitch on changes of root gap during welding in butt weld joints. The calculations of changes of root gap during welding are carried out under various conditions of heat input, plate length and tack weld pitch, using the finite element method explained in the previous report. In this case it is assumed that the rigidity of tack weld is infinite.
The main conclusions obtained in this report are summarized as follows:
(1) In case of butt weld joints with tack welds under the condition of relative small tack weld pitch, the root gap at heat source closes between the weld start position and the first tack weld position. The behaviour of released displacement at tack weld position is devided into the following classes. In the first case the released displacement at tack weld position increases as the heat source moves. In the second case the released displacement increases after decreasing as the heat source moves.
(2) The maximum closing displacement between the weld start position and the first tack weld position ((uH)s) and the released displacement at the end tack weld ((uH)e) have the following characteristics.
The remarcable displacement ((uH)s) increases as the heat input (q/υh) increases under the condition of constant molten pool length lead from the mechanical point of view (lM). It decreases as the molten pool length (lM) increases under the condition of constant q/hυ.
The remarkable displacement ((uH)e) increases as the heat input (q/υh) increases under the condition of constant lM.
Effect of plate length(L) on (uH)e depends on the welding conditions (q/υh, lM) and the range of plate length.
The remarkable displacement (uH)e increases as the tack weld pitch increases.View full abstractDownload PDF (468K) -
Fracture from Notch of Poor Penetration TypeShigeo Akashi, Mitsuhiro Natsume, Makoto Fukuzawa1981 Volume 50 Issue 4 Pages 398-403
Published: April 05, 1981
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSThe brittle fracture from a weld defect of through-thickness type (crack length 2a=10-30 mm) for mild steel, which had relatively low toughness, was investigated and compared with the behavior of base metal with machined notch. Results are summarized as follows:
1) In bending COD tests, δc(-10)=0.3 mm and δc(-40)=0.2 mm were obtained for a weld defect notch on the manual arc welding. While for the same notch on non-gas arc welding, δc(-10)=0.3 mm and S δc(-40)=0.09 mm were obtained. For the latter, COD characteristic depended well on the temperature.
2) In tensile tests on notched specimen of welded joint and base metal at -10°C and -40°C, low stress fracture did not occur and overall strain el exceeded yielding strain ey. But the value of e1 for welded joint was larger than that for base metal. In welded joints, the yielding of parent metal adjacent to weld occured preceding to yielding in the net ligament of weld metal which had higher yielding stress than parent metal. Consequently, for these overmatched joints the Burdekin's design curve gave a conservative estimate in the yielding range.View full abstractDownload PDF (3367K) -
Effect of traveling Velocity on Bead ShapeHiroshi Maruo, Isamu Miyamoto, Fumimaru Kawabata, Yoshiaki Arata1981 Volume 50 Issue 4 Pages 404-409
Published: April 05, 1981
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSIn CO2 laser welding of stainless steel plate, correlation between travelling velocity and dimensions of the weld bead is examined over a wide range of 0 2-200 m/min. The interaction between the cavity and the incident beam is analyzed. The penetration depth and joining rate are estimated on the basis of this correlation and the heat conduction theory. Results obtained are summerized as follows:
(1) Under fixed focussing condition, cyclic change in the beam intensity at the bottom of the cavity occurs, producing step-like change in the dimensions of the bead with the travelling velocity.
(2) Under optimal focussing condition, the ratio of penetration depth to mean bead width is almost constant in a wide travelling speed range of 1-40 m/min. In this range, the penetration depth is inversely proportional to the square root of the travelling velocity.
(3) The maximum joining rate, 320 mm/kJ, has been obtained at a penetration depth about 0.5 mm. The joining rate is inversely proportional to the penetration depth.View full abstractDownload PDF (443K) -
Masanobu Hamasaki, Fumikazu Tateiwa1981 Volume 50 Issue 4 Pages 409-414
Published: April 05, 1981
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSThe authors have developed a consumable electrode water jet cutting technique as a underwater cutting method. Underwater cuttings of mild steel and aluminum were at this time carried out at a water depth up to 200 m. Welding machine and electrode wire used were DC constant voltage characteristic and 2.4 mm diam. steel wire. Cutting result at a deep water depth obtained was the same that at a shallow water depth, in case no load voltage was heightend 0.5-1.0 v every 10 m deep with increasing of water depth.
Underwater cutting of mild steel by aluminum wire was also achieved at water depth up to 90 m. The dross was not recognized at cut surface, which was better than that by steel wire.View full abstractDownload PDF (8369K) -
Experiments of Circumferentially Notched Round Bar SpecimenShigeru Kitamura, Eisuke Fujii1981 Volume 50 Issue 4 Pages 415-421
Published: April 05, 1981
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSOne of problems relating to the dynamic fracture toughness of heary section, structural steel plates is the effects of looding rate on it. The authors have studied experimentally on the dynamic fracture phenomena in high speed tensile test using notched round bar specimens. The results obtained were as follows.
1) The stress ratio of σNet/σy has transition phenomerna against test temperature. This transition temperature shifts to higher side for higher notch acuity and for faster tensile rate.
2) An increase of σNet/σY value for increasing tensile rate was smaller for fatigue cracked (FC) specimen than for machine notched (MN) specimen. While an increase of transition temperature was smaller for MN specimen than for FC specimen.
3) The critical dynamic COD value δdc defined at fibrous crack initiation for both FC and MN specimens was observed to remain approximately constant up to tensile rate of 20 m/sec and δdc increased ahrupthy for larger tensile rate than 30 m/sec.
4) There are following relationships between transition temperatures for dynamic and static test for FC specimen.
TdS-TS(0.2)≅20 TdS=-40°C
TdJ-TJ(10)≅30 TdJ=-50°C
The authors can also estimate the transition temperature of FC specimen from the data of MN specimen.View full abstractDownload PDF (2866K) -
Comparison of Submerged Arc Welding with Covered Arc WeldingYukio Ueda, Keiji Fukuda, Iwao Nishimura, Hideaki Iiyama, Naomichi Chi ...1981 Volume 50 Issue 4 Pages 421-427
Published: April 05, 1981
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSLamellar tearing of opening type and root cracking occasionally occur in multipass welded corner joints.
In this paper, the influence of welding methods such as submerged arc welding (SAW) and covered arc welding (SMAW) is investigated on the occurrence of these weld cracks. The main results obtained in this study are as follows.
(1) When SAW is applied, the transverse welding residual stress (σx) is less on the edge surface of the vertical plate and the lamellar tearing is less probable to occur in comparison with SMAW.
(2) By SAW, σx, induced at the root is less and root cracking is less probable to occur against SMAW.
Accordingly, in order to prevent occurrence of the weld cracks in multipass welded corner joints, it is effective to use SAW whose deposited metal weight per unit welding pass is large and which enables to fill up a given groove with smaller number of passes.View full abstractDownload PDF (3754K)
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