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Volume 48, Issue 4
Displaying 1-8 of 8 articles from this issue
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Minoru Kobayashi1979 Volume 48 Issue 4 Pages 207-212
Published: April 05, 1979
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSDownload PDF (6426K) -
Studies on Brazability of Electric Contact Chip Materials (Report 2)Minoru Inamura, Kazuhiro Inukai, Shin Utsunomiya1979 Volume 48 Issue 4 Pages 213-218
Published: April 05, 1979
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSWetting phenomenon of steel(SPC) covered with powder metals by BAg filler metals was studied, in hydrogen atmosphere. The wettability was measured by spread test, and the wetting mechanism was investigated by SEM and EPMA technique.
Main results obtained were as follows.
1) On SPC covered with powder metals, the spread area of BAg-5 and BAg-8 is several ten times as large as that without powder.
2) Spread area is related to the mass of powder, and the smaller is the powder size, the larger the spread area is.
3) It is considered that melting filler metal wets powder, and its heat of immersion furnishes the driving force for wetting.
4) Spreading mechanism and improving rate of brazability were related to the kind of powder metals.It is because their mutual solubility to filler metals or base metal are different from another.
5) Fe and W powders have little mutual solubility, and the wetting mechanisms of them are simple.
6) Cu and Ni powders quickly melt in melting filler metal, change its composition, and rise its melting point. Their improving rate of brazability is small.
7) Ni has large mutual solubility to Fe. Interfacial layer can be observed. The layer is considered to be formed by "dissolution and deposition mechanism".
8) Co powder behaves as Ni powder, but Co dissolves little in BAg filler metals. The spread area is four times as large as that of Ni.View full abstractDownload PDF (5118K) -
Seam Welding with Direct Current Power SourceToshio Yamamoto, Takio Okuda1979 Volume 48 Issue 4 Pages 219-223
Published: April 05, 1979
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSA seam welder with direct current power source is produced by way of experiment and comparisons with seam welding by AC continious current are made. It is made clear that maximum welding speed for air tight welding is improved by DC seam welding especially in plate thickness less than 0.8 mm.View full abstractDownload PDF (4526K) -
Satoru Ohno, Masahiro Uda1979 Volume 48 Issue 4 Pages 223-229
Published: April 05, 1979
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSA study has been made of the effect of nitrogen and hydrogen in the arc atmosphere of blowhole formation in tungsten inert gas arc welding of nickel. The blowhole in specimen was detected by means of radiographical and cross-sectional methods. The results are summerized as follows:
1) Ni-H2O system; Pure nickel plates were welded in various water vapor contents of argon shielding gas. Any blowholes were not produced in the solidified specimens.
2) Ni-H system; It was found that the critical hydrogen concentrations of the atmospheres (Ar-H2) forming blowhole in solidified nickel are 50 % hydrogen for TIG welding method and 18 % hydrogen for leviation melting method (non-arc melting). It was only observed in the arc welding that the generation of fine nickel particles (vapor-like) from the melt increases with increasing the hydrogen concentration in the arc atmosphere, especially, this generation becomes more remarkable above 20 % hydrogen
3) Ni-N system; Blowholes by nitrogen were easily formed in this system as far as an arc was used. The critical nitrogen concentration of the atmosphere on blowhole formation of nickel by TIG welding was found to be 0.025 % nitrogen. On the other hand, any blowholes by nitrogen were not produced in nickel specimens which were melted under a 100 % nitrogen atmosphere by levitation melting method (non-arc melting). The difference of blowhole formation between arc welding and non-arc melting can be explained by the difference of nitrogen absorption mechanism into the molten nickel.
4) Ni-H-N system; The blowhole formation of this system was mainly dominated by nitrogen concentration in the arc atmosphere (N2-H2-Ar), however, hydrogen in the arc atmosphere had effects on .the shape of blowhole and the nitrogen content of welded nickel.View full abstractDownload PDF (5542K) -
Effects of Inserted Material to Weldment on the Weld StrengthJiromaru Tsujino, Eiji Mori1979 Volume 48 Issue 4 Pages 230-236
Published: April 05, 1979
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSIn the case of ultrasonic welding of metal specimens, special specimen surface treatments such as resistance welding are usually not required, and the fact is shown that the weld strength of ultrasonic welding specimens with clean surface is high.
The purpose of the study is to investigate the effects of specimen surface conditions on weld strength and input power to the welding system.
Welding tip vibration direction of ultrasonic welding is parallel to welding specimen surfaces, and it is expected that the contacting surface conditions of welding tip, welding specimens and welding anvil have direct effects upon the input power and the weld strength.
The welding system with 20 kHz resonance frequency autotracking & constant vibration velocity controller is used to weld aluminum plate specimens. Welding vibration amplitude, vibrating frequency, input high frequency current (fundamental frequency component) and input power to welding system are measured by detectors and recorded. with muliti-channel pen recorder.
The results obtained are as follows;
1) The clean condition of the specimen surfaces contacting with welding tip & anvil is desirable for successful welding.
2) Adequate material (such as certain polymer, thin plastics film, grease etc.) inserted to the welding surfaces is very effective to obtain high and stable weld strength.
3) The input power and the welded area of the specimens with the inserted material to weldment become larger and the welded area is more concentrated than clean surface specimens without the inserted material.
4) By X-ray diffraction method, it is shown that recrystallization is present in the successfully welded area, and it is suggested that the mutual velocity of welding surfaces become larger by insertion of material such as grease etc. and successful welding becomes possible.View full abstractDownload PDF (2093K) -
Effect of Fluxes Mixed with NiCl2 or FeCl3Ikuo Okamoto, Akira Ohmori, Tadashi Takemoto, Masaaki Miyake, Keisuke ...1979 Volume 48 Issue 4 Pages 237-241
Published: April 05, 1979
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSAuthors had reported already that the spreading of BAg alloy on mild and stainless steels could be improved by adding small amounts of NiCl2 or FeCl3 to KCl-LiCl cut. salt flux. In this study, then, when a 18Cr-8Ni stainless steel plate was pre-coated with the mixed salt fluxes and was heated, the corrosion products formed on the plate surface were analized by SEM and X-ray diffractometer. On the other hand, a spreading test of BAg-5 on the same treated plate was done, using only KCl-LiCl eut. salt flux.
From these experiments, the effect of used fluxes on the spreading of BAg-5 was concluded as follows;
1) The addition of NiCl2 to KCI-LiCl eut. salt promotes the dissolution of chromium and iron from the stainless steel and the resultant corroded surface becomes spongy intermetallic compound, FeNi3, furthermore, the particles layers of nickel were precipitated on the compound owing to electrochemical reaction.
2) The addition of FeCl3 to the eut. salt also promotes the corrosion of stainless steel and the surface becomes the spongy compound, FeNi3.
3) The spread area of BAg-5 on the particles layer of nickel was considerably larger than that on the compound, FeNi3. This result showed that the wettability of intermetallic compound, FeNi3, is not superior to the each wettability of both constituent elements, Fe and Ni.
4) The spread area of BAg-5 on the particles layer of nickel was larger than that on a nickel plate, because the former was larger than the latter in a real surface area to be wet. Furthermore, since the spread area depended on the total surface area of particles distributed on the most outside layer, the amount of NiCl2 necessary to form mono-particle layer was considered to be about 10wt%.
5) "De-chromiumnisztion" phenomenon on the surface of stainless steel may be one of the important effect of flux used.View full abstractDownload PDF (6041K) -
Stress Corrosion Cracking in Weld Metal of SUS 304 (Report 1)Yoshihiko Mukai, Masato Murata1979 Volume 48 Issue 4 Pages 242-248
Published: April 05, 1979
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSCrack propagation behavior of stress corrosion cracking was studied in 42 % MgCl2 solution (143°C) on two kinds of weld metals of SUS 304 stainless steel which exhibited duplex (ferrite-austenite) and only austenite structures. As the results, it was made clear that the crack growth directions were only parallel or vertical for columnar crystal directions. The fracture modes in both materials were transgranular cracking and their fracture surfaces were mainly constituted with {100} plane. Accordingly, it would be sure that the selectivity of crack growth directions were caused by coherent preferential crystal orientations in weld metals. The crack growth rate was delayed by keying effect of δ-ferrite, although, it was scarcely affected with preferential crystal orientation.View full abstractDownload PDF (6523K) -
Kunihiko Satoh, Toshio Terasaki, Yuji Ohkuma1979 Volume 48 Issue 4 Pages 248-252
Published: April 05, 1979
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSThere are few studies on relationship between critical stress and residual diffusible hydrogen content HR when the temperature on bond line becomes the crack initiating temperature. It'seems that residual hydrogen content HR relates with critical stress of HAZ cracking more closely than initial hydrogen content HIIW, HJIS.
This paper describes relationship between critical stress and residual hydrogen content at tern perature 100°C on bond line. Residual hydrogen content HR is measured by means of mercury method and experimental equations between HR and thermal factor ΣDΔt which relates with thermal cycle on bond line are deduced. Conventional equation of thermal factor ΣDΔt is deduced from 100 data on thermal cycles by use of regression analysis. Implant tests are carried out under various conditions of initial hydrogen content H0. It is shown that critical stress is approximately obtained from residual hydrogen content HR at temperature 100°C on bond line under various initial hydrogen contents.
The conclusions obtained in this report are summarized as follows:
1. Experimental equation between thermal factor ΣDΔt and ratio of hydrogen content HR to initial hydrogen content H0 is deduced.
Bead-on-plate HR=H0exp (-75ΣDΔt) Y-groove HR=H0exp (-95ΣDΔt)
2. Thermal factor ΣDΔt)100 at cooling temperature 100°C on bond line is given by following equation; (ΣDΔt100)=(0.76t100+6.3t200)×10-5(cm2)
where tθ=cooling time from 1500°C to θ (°C) on bond line, sec
3. Critical net stress of implant test is considered to be a function of residual hydrogen content HR=H0 exp (-7.5×10-4(0.76t100+6.3t200)).View full abstractDownload PDF (324K)
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