All issues
Volume 46, Issue 7
Displaying 1-14 of 14 articles from this issue
- |<
- <
- 1
- >
- >|
-
Yoshifumi Suezawa, Akira Koiso, Takeshi Okamura1977 Volume 46 Issue 7 Pages 381-386
Published: July 05, 1977
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSDownload PDF (5166K) -
Keizo Ishizaki, Shinichiro Yokoya1977 Volume 46 Issue 7 Pages 387-394
Published: July 05, 1977
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSConsidering the equilibrium condition among three kinds of interfacial tensions γsγ and γi acting on the liquid atoms at the contact line on the solid-liquid interface, it was deduced that the including angle of solidified layer or SOLIDIFICATION ANGLE φ is determined by the LIQUID PHASEANGLE θ through the following CHARACTERISTIC SOLIDIFICATION EQUATION.
γs cosgφ=γ cosθ+γi(6)
(6) The conclusions are as follows.
(1) In the new theory θ is always greater than φ, and φ tends to become zero very rapidly when θ comes near to CHARACTERISTIC SOLIDIFICATION CONSTANT θs which is θ in case of φ=0.
(2) Profile of solidified spatter of materials with various θs and initial contact area, were calculated by the computer using above eq. (6), and obtained figures were well reproduced the actual configuration patterns of solidified spatter including conical and ordinary round shape and irregular bead.
(3) θs estimated therefrom was 15-25° with mild steel, which was considered more reansonable than the estimated value of 60° for Young's contact angle in the former theory.
(4) 'Confinement' in the old theory remaines consistent at the melting front of the penetration interface. In the course of melting;
γs=γ cosθM+γi (22)
β+θM≥θ≥θM (23)
β; penetration angle, or angle between plate surface and solid-liquid interfaceView full abstractDownload PDF (4966K) -
Austenite Grain Growth of Steel in Weld-Heat Affected ZoneHiroshi Ikawa, Hiroaki Oshige, Shingo Noi1977 Volume 46 Issue 7 Pages 395-402
Published: July 05, 1977
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSIn this report, grain growth equation during thermal cycle, derived by the authors, was applied to the austenite grain growth during weld thermal cycles in TIG arc and submerged arc welding of steel. And then austenite grain growth phenomenon in weld-heat affected zone (HAZ) was investigated.
Main results obtained are as follows.
1) Value of austenite grain size calculated by applying grain growth equation during thermal cycle to the measured weld thermal cycles in HAZ of two-dimensional bead agreed with the measured asutenite grain size.
From this result, it became clear that austenite grain growth during weld thermal cycle could be calculated using grain growth equation during thermal cycle.
2) Austenite grain size in HAZ is influenced by weld heat input through the change in the distribution of peak temperature, heating and cooling rate. Effect of the latter factor is dominant near the fusion line and of the former one is dominant in the region away from fusion line.
3) In weld thermal cycle, 60-80% of the total amount of grain growth occurs on heating cycle. On cooling cycle, 20-40% of the total amount of grain growth occurs and grain growth is nearly completed when temperature falls down to the 90-95% of peak temperature.
4) During weld thermal cycle, grain growth rate increases rapidly as temperature rises, taking a maximumm value just before the peak temperature and decreases rapidly as temperature falls.View full abstractDownload PDF (2013K) -
Dissolution Phenomenon of Carbides During Weld Thermal CycleHiroshi Ikawa, Shigeo Shin, Yoshikuni Nakao, Kazutoshi Nishimoto, Taka ...1977 Volume 46 Issue 7 Pages 402-407
Published: July 05, 1977
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSIn the previous report, theoretical considreation was carried out in regard to the dissolution phenomenon of Nb(C, N) in SUS 347 under the isothermal heat treatment, and it was made clear that good agreement was obtained between experimental results and theoretical values.
In this report, the thoretical equation on the dissolution phenomenon during the thermal cycles was derived. By comparing experimental results with theoretical values, this theoretical equation was discussed.
The dissolution phenomenon of TiC in HAZ of SUS 321 was also considered experimentally.
The results obtained in this report are as follows;
(1) Good agreement between experimental results and theoretical values was found in the dissolution phenomenon of Nb(C, N) in SUS 347 under heating, and heating and cooling thermal cycles.
(2) The theoretical equation under the thermal cycles was applicable to the dissolution phenomenon of Nb(C, N) in HAZ of SUS 347.
(3) Over about 50% of Nb(C, N) in stabilized SUS 347 had dissolved in the knife line attacked region of HAZ during welding.
(4) Over about 55% of TiC in stabilized SUS 321 had also dissolved in the knife line attacked region of HAZ during welding.View full abstractDownload PDF (1992K) -
Yukio Ueda, Iwao Nishimura, Hideaki Iiyama, Naomichi Chiba1977 Volume 46 Issue 7 Pages 408-415
Published: July 05, 1977
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSIn corner joints, the occurrence of lamellar tearing of opening type (which implies here that the tearing reaches to the surface) is sometimes observed in addition to root cracking.
In this paper, the effect of the intensity of bending restraint on the lamellar tearing and root cracking in corner joints is investigated with the aid of a newly developed method of test which is named here "Corner Joint Weld Cracking Test (CJC-test)." The result of the CJC-test is compared with that obtained from an experiment carried out in this study on a large structural model.
The main results are as follows :
1) The lamellar tearing occurs where the intensity of bending restraint is above the critical value. Therefore, "the critical intensity of bending restraint for lamellar tearing" can be obtained for the specified materials and welding conditions from the CJC-test.
2) As the critical value is influenced by several factors, the following methods are effective to reduce the possibility of the occurrence of the lamellar tearing : to use steel plates of good ductility through thickness and to make the throat depth as small as possible.
3) The occurrence of the lamellar tearing in actual structures can be predicted by use of the intensity of bending restraint of the structures on the basis of the result of the CJC-test.View full abstractDownload PDF (5449K) -
Satoru Ohno, Masahiro Uda1977 Volume 46 Issue 7 Pages 415-421
Published: July 05, 1977
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSGlycerin is generally used as a collecting medium for the measurement of diffusible hydrogen in welded metal in japan, because the glycerin is defined by JIS Z 3113. However, it has been recognized that the measured values of diffusible hydrogen are different by a sort of collecting mediums such as glycerin, liquid paraffin, some alcohols and mercury.
In order to make clear the cause of this difference, the necessary conditions as a collecting medium and the behaviors of hydrogen bubbles in the collecting medium were discussed.
(1) A comparison of the amount of diffusible hydrogen by using the glycerin and mercury methods has been made and the amount of hydrogen by glycerin method showed always less values of about 50% than the mercury method.
(2) It was observed that small sizes of bubbles could not rise to the liquid surface within the difined time and suspended in the glycerin medium. As be understood from the Stokes's equation, the rate of rising a gas bubble in mediums is mainly related to the viscosity of medium and the size of gas bubble. The difference of viscosity between glycerin and mercury is remarkable, therfore the rate of rising a bubble in the mercury is calculated as about 104 times greater than that in the glycerin.
(3) An apparatus being able to collect the suspending bubbles in the glycerin medium were developed. From the use of this apparatus, it was found that the total amount of hydrogen (including the suspending bubbles) in the glycerin method agreed well with the result of mercury method. It is concluded that the glycerin method is not satisfied for the determination of diffusible hydrogen in the welded metals.View full abstractDownload PDF (492K) -
Observation of Growing Process of Penetration Depth Using Pulse Beam (Part 1)Hirosada Irie, Tatsuya Hashimoto, Michio Inagaki1977 Volume 46 Issue 7 Pages 421-428
Published: July 05, 1977
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSIn electron beam welding, it is well known the drilling action of electron beam dominates shape of fusion zone. In order to study this action, rectangular type pulse electron beams were impinged on Al-Zn-Mg alloy and shape of fusion zones were observed. Experiments were carried out using both rest and moving metals varying pulse duration time (0.02-3 sec) and energy density of electron beam. The results obtained are summerized as follows;
1) In most cases, a cavity is formed by electron beam.
2) At the initial time of welding, electron beam penetrates into metal at very high speed (about lm/sec, for instance, when electron beam of average energy density of about 5 × lO5 Watt/cm2 is projected) and this speed depends largely upon energy density of electron beam.
3) In rest metal, penetration depth of welding continues to increase at a decreasing rate after the above initial step and that in moving metal it also increases in the same manner, but until a stationary state.
4) At the same time, penetration depth in moving metal is often superior to that in rest metal. This phenomenon is more considerable at lower energy density of electron beam.
Those results show that the movement of metal promotes the drilling action of electron beam because molten metal in moving metal is more easily pushed away to the cavity formed behind electron beam impinging point and electron beam can penetrates into deeper portion of metal.View full abstractDownload PDF (3324K) -
Development and Function of 100KW Class Electron Beam WelderYoshiaki Arata, Michio Tomie1977 Volume 46 Issue 7 Pages 429-436
Published: July 05, 1977
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSA 100KW-class electron beam welder was designed and assembled for the first time in the world with the maximum output power of 120KW. Typical material qualities of a thermionic emission type cathode and its life time were tested and discussed for such a high power electron beam production. Various properties of the bead penetration were investigated for each output level of the beam up to 100KW. Some fundamental discussions were given for the penetration depth of the bead.View full abstractDownload PDF (8363K) -
Seishin Kirihara, Tsutomu Onuma, Kiyoshi Watanabe1977 Volume 46 Issue 7 Pages 437-443
Published: July 05, 1977
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSWith the demand for the increasingly large capacity of machines and equipment, structural dimensions are growing large, and design stress is becoming higher eventually. This naturally necessitates the use of high-strength steel possessing high tensile strength and high toughness.
Although mild steel is generally adopted for welded structures, it needs an exceedingly large gauge to give sufficient strength and involves difficulites in builiding up welded structures. In this report an examination was conducted on the effects of intensity of restraint, restraint stress, and the groove shape influencing delayed cracks during manual are welding on high-strength steel.View full abstractDownload PDF (2503K) -
Sadao Nobuhara, Takefumi Kubota, Isamu Ukita1977 Volume 46 Issue 7 Pages 444-449
Published: July 05, 1977
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSIn our previous paper, we described some of reignition phenomena in which a rectangular current pulse having variable width 1-500 microsec was impressed to the gap for restriking at every reverse polarity, using alminum, mild steel and copper as a base metal.
It is supposed that the reignition process with a rectangular current pulse depends only on the thermal energy due mainly to a pulsed arc discharge. Then we have defined those thermal energy as the Reignition Energy, and calculated these values in the critical conditions that the arc reignition was caused by minimum pulse voltage, pulse width and pulse current. The calculated results are compared with them of ordinary method in which the higher frequencies are superimposed.View full abstractDownload PDF (413K) -
Seishin Kirihara, Tsutomu Onuma, Kiyoshi Watanabe1977 Volume 46 Issue 7 Pages 450-455
Published: July 05, 1977
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSIt has been reported that increasing weld heat input is effective in preventing delayed fracture because it would delay cooling after welding and consequently lengthen the time of structural improvement and discharge of diffusive hydrogen. On the other hand, a higher weld heat input tends to increase thermal stress and restraint stress, which in turn can promote delayed fracture.
In the present study, the relationships of weld heat input to delayed fracture (cracking) and restraint stress are investigated experimentally.
The result are as follows;
(1) In the formula σw=mK, the value of m varies with heat input.
(2) Increase of weld heat input result in a higher restraint stress, which promotes cracking.
(3) Increase of weld heat input does not lead to a lower preheating temperature.View full abstractDownload PDF (2576K) -
Kohei Ando, Yutaka Nakane1977 Volume 46 Issue 7 Pages 456-463
Published: July 05, 1977
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSUsing some reasonable assumptions, temperature curve of nugget part produced by condenser discharge type spot welder is calculated in dimensionless form for various circuit constant m (equ.1) of the welder, and various thermal time constant T (equ. 6) of the plate.
Fig. 4 shows the results.
In the figures, time t is expressed in form of t/tp, tp being the time of maximum current Ip as shown in Fig. la, and temperature rise θ0 of nugget is expressed in form of θ0/θ0f, θ0f being the final temperature rise when the current is constant of magnitude Ip (see equ. (4) ), and g is the ratio of T and tp.View full abstractDownload PDF (582K) -
Kin-ichi Nagai, Mitsumasa Iwata, Katsuhiko Ogiso, Yuji Okumoto1977 Volume 46 Issue 7 Pages 464-469
Published: July 05, 1977
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSIn sin2, ψ method used in X-ray stress measurement, the stress is analysed on the basis of information about the strain obtained from the diffracted beam in the specified direction on Debye-Scherrer ring. Any diffracted beam in other directions on the same Debye-Scherrer ring can also give information about the strain on normal to diffraction plane. Therefore, it is possible to estimate the stress more accurately, since any information on Debye-Scherrer ring can be adopted to φ-sin2ψ method suggested by the authors. In order to improve the accuracy of stress measured at such a portion where the direction of incident X-ray is confined, the authors examine to evaluate the stress by φ-sin2ψ method on the basis of the information about strains obtained from diffracted beam in various directions on Debye-Scherrer ring. Moreover, the accuracy of residual stress on fillet welded joint measured by φ-sin2ψ method is also discussed in this report. The results obtained are summarized as follows:
(1) In measurement of a diffraction angle by counter method, the direction (Φ, Ψ) of normal to a diffraction plane in an arbitrary direction on a Debye-Scherrer ring is given by following equations,
sin2Ψ = 1-(cosψ0cosη0-sinψ0sinη0cosω)2
Φ=tan-1{ sinΦ0(sinψ0cosη0+cosψ0sinη0cosω)+cosφ0sinη0sinω/cosΦ0(sinψ0cosη0+cosψ0sinη0cosω)-sinφ0sinη0sinω }
where Φ0 and ψ0 show the directions of incident X-ray, ω is the rotating angle of the plane of counter scanning about the axis of incident X-ray and η0 the complement of diffraction angle on strain-free crystal. Therefore the information about the strain required to stress analysis in φ-sin2ψ method consists of the direction of normal to diffraction plane given by above equations and the measured diffraction angle.
(2) The stresses, which are estimated by φ-sin2ψ method on the basis of information about the strain obtained from diffraction beam in arbitrary directions on Debye-Scherrer ring, are accurate enough for practice.
(3) In a fillet weld, since the domain of direction of adopted normal to diffraction planes with measurable diffraction angle is larger in the case where the direction of the plane of counter scanning is variable than in the case of the fixed plane of counter scanning, it is possible to estimate more accurate value of residual stresses on the basis of the information about strains obtained from the larger domain.View full abstractDownload PDF (1975K) -
Influence of Weld Current and Electrode Force on Nugget FormationShuji Nakata, Masahiro Nishikawa, Takanori Suematsu, Jiro Mizutani, Ta ...1977 Volume 46 Issue 7 Pages 470-477
Published: July 05, 1977
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSUsing embossed projection, influence of weld current and electrode force on nugget formation was approched basically from a viewpoint how to supply the input power to the projection part in order.to form efficiently the nugget and obtain the good weldment with stable mechanical strength. The power source with low impedance circuit was prepared in this experiment.
For the weld current near over a suitable value, the tensile shear strength became a stable value with small amount of scatter and the weld failed only in the tear fracture. Increasing the weld current, the initial nugget with the diameter corresponding to that of the cold collapsed area became early formed and the saturation value of nugget diameter increased.
Under low electrode force where the projection is scarcely collapsed, the initial small nugget was stably formed in the center of the projection part and grew up around its center near the critical weld current. With excessive weld current, the initial splash during collapse of projection did not only occur but the splash in the latter half weld time. The welds even for this condition, however, were found to, have stable tensile shear strength with small amount of scatter and to fail in the tear fracture.
Scuh a critical weld current increased with electrode force due to the enlargement of the initial current area. Under high electrode force, the periphery of projection was tend to be initially heated, so that the heat affected zone or the nugget was found to be formed like a torus at, the initial weld time.View full abstractDownload PDF (4158K)
- |<
- <
- 1
- >
- >|