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Volume 37, Issue 7
Displaying 1-11 of 11 articles from this issue
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Yugoro Ishii, Tadao Onzawa1968 Volume 37 Issue 7 Pages 658-667
Published: July 25, 1968
Released on J-STAGE: August 05, 2011
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Ikuo Okamoto1968 Volume 37 Issue 7 Pages 667-677
Published: July 25, 1968
Released on J-STAGE: August 05, 2011
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Tsuguyasu Wada1968 Volume 37 Issue 7 Pages 677-690
Published: July 25, 1968
Released on J-STAGE: August 05, 2011
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Keizo Tezuka1968 Volume 37 Issue 7 Pages 691-698
Published: July 25, 1968
Released on J-STAGE: August 05, 2011
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Electrode Force Change on Continous Spot WeldingTakashi Nakamura, Masanobu Hamasaki, Sadao Obokata1968 Volume 37 Issue 7 Pages 699-704
Published: July 25, 1968
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSThe reducing valve used for a spot welder is characterized by producing a large pressure drop at a lettle discharging range when the welding speed (number of spots/sec.) is increased in a spot welder having a pneumatic system with an air reservior, it is noticed that the electrode pressure with pneumatic system become lower than the pre-set value by following welding when the air reservior is connected to the cylinder nearer than the reducing valve.
This pressure drop can be prevented if the air reservior is inserted between air source (compressor) and reducing valve.View full abstractDownload PDF (6651K) -
Messurement of the Initial Local Melting Temperature of Inconel 713C by Microscopic ObservationMinoru Okada, Hiroshi Ikawa, Shigeo Shin, Yoshikuni Nakao, Isao Fukuna ...1968 Volume 37 Issue 7 Pages 705-710
Published: July 25, 1968
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSWeld crackings of Inconel 713C were initiated at grain boundaries. These weld crackings are considered to be the same kind of hot crackings as repoted on the other Ni base super alloys.
Inconel 713C being a cast alloy, the alloying elements in it are easy to segregate. at grain boundaries and dendrite boundaries. Segregated elements are helpful to form low melting point particles.
Consequently, it is important to identify the location and temperature of local melting and thereby clarify the causes of weld crackings.
According to the microscopic observations of the same area before and after rapid heating in the vacuum, the temperature of local melting recognized in Alloy V-3 (low carbon Inconel 713°C), is particularly low compared with the other alloys, i.e., about 1235°C.
In Alloy V-3, a massive "White Constituent" exists at the grain boundaries and dendrite boundaries, and a fine "White Constituent" is formed continuously at the grain boundaries. The melting point of this constituent is lower than that of matrix.
It is considered that the "White. Constituent" is one of the causes of the weld crackings of Inconel 713C.View full abstractDownload PDF (8331K) -
Masaki Watanabe, Yoshihiko Mukai, Hajime Matsuyama, Akira Matsuda1968 Volume 37 Issue 7 Pages 711-719
Published: July 25, 1968
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSWe discussed the susceptibility for sulfide corrosion cracking of pre-strained mild steel and high-strength steels.
The tested materials were four kinds of steels (SB42B, HT50, HT60 and HT80), and the test pieces, which were circular rods, were strained by tension test at room temperature before being submitted to sulfide corrosion test. Sulfide corrosion test was carried out under constant tensile load in the solution' of 0.5% acetic acid saturated with hydrogen sulfide at the temperature of 35°C, and the time to failure was measured
It became clear that the effect of pre-strain on the time to failure was closely associated with the structure o each steel. In the material like HT80 of which the structure was tempered martensite, the time to failure shortened with the increase of pre-strain until the test piece began local shrinkage, but conversely the time to failure lengthened with the increase of pre-strain beyond the uniform elongated zone. In the material like HT60, the time to failure shortened with the increase of pre-strain all over the zone of pre-strain. In the materials like SB42B and HT50 of which the structure was ferrite plus pearlite, the time to failure lengthened with the increase of pre-strain until the test piece began local shrinkage, but beyond this region of pre-strain the time to failure already did not practically change.
The volume of the diffusible hydrogen absorbed in steel increased with the increase of pre-strain, and this relation was observed with all kinds of steels.
Though it is believed that sulfide corrosion carcking is introduced by the diffusible hydrogen absorbed in steel, there is not any relation established between sulfide corrosion susceptibility and the volume of absorbed hydrogen.
As far as the local shrinkaged HT80 is concerned, the failure occurred at the part separated from the center of local shrinkage.
Moreover, small longitudinal cracks were observed at the core of local shrinkage for all kinds of steels. It is thought that these cracks occurred only though the diffusible hydrogen in steel.View full abstractDownload PDF (7234K) -
Rupture properties of 1Cr-1/2Mo steel and their weldsMasaki Watanabe, Seiroku Ogawa1968 Volume 37 Issue 7 Pages 720-729
Published: July 25, 1968
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSThe previous report has shown the rupture characteristics of mild steel at 450°C under the stress conditions of a relatively small pulsating stress being superimposed on the static tensile stress which is sufficient to produce a creep rupture.
The work described in this paper is concerned with the rupture properties of 1Cr-1/2 Mo steel and their welds at 550°C under the similar conditions of stress to those mentioned above.
The amplitude-to-mean stress ratios A (σa/σm) selected for this experiment were 0(static), 10, 20 and 40%.
The results ogtained are summarized as follows:
1. The mean stress versus time for rupture diagram in log-log plots showed that the rupture life decreased with an increasing stress amplitude ratio A and the static stress rupture had the longest life.
2. The stress-rupture diagram plotted on the basis of maximum (crest) stress in the stress cycle in view of fatigue behavior showed that the rupture life increased with an increasing stress ratio A and the static stress rupture had the shortest life, being incompatible with fatigue behavior.
3. Rupture characteristics under pulsating stress were investigated from creep behavior by the same method of analysis as reported in previous paper. The superposition of alternating stress resulted in a decline of rupture strength, supposedly due to the dynamic effect, for the base metal but in no decline in the welded joint except for the shot-life tests.
4. Ductilities of test specimen, determined by true strain at the fractured section, did not show remarkable difference in static and pulsating stress rupture between base metal and welded joint.
Welded joint showed lower ductilities than base metal.
5. There was no remarkable difference in situation of fracture in welded specimens between static and pulsating stress rupture. Most of their fractures occured at the base metal adjoining the heat affected zone in short-life test and approached the deposit metal with an increase of rupture life.View full abstractDownload PDF (4656K) -
Schlieren Photographs and Oxygen Purity DistributionMinoru Nakanishi1968 Volume 37 Issue 7 Pages 730-735
Published: July 25, 1968
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSRegarding the purity of cutting oxygen jet, the relation between schlieren photographs and the oxygen purity has been studied experimentally, with the following results.
a: Jet boundary printed on schlieren photographs shows only the supersonic zone of jet and there is none of discontinuities of oxygen purity at the boundary.
b: With the increasing of nozzle inlet pressure Po, the sonic boundary distance Xs increased proportionally to the value of Po and the oxygen purity at Xs decreased.
Some other experiments have been made regarding the effect of preheating flame on cutting oxygen purity with the following result:
c: The oxygen purity was kept at a long distance from nozzle exit with preheating flame as well as the case of oxygen momentum described in the report 2.View full abstractDownload PDF (5464K) -
Electromotive force of gas flameYoshiaki Arata, Katsunori Inoue1968 Volume 37 Issue 7 Pages 736-743
Published: July 25, 1968
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSIn a combustion gas flame, the electron concentration is larger than that calculated from gas temperature and ionization potential assuming a thermodynamic equilibrium. This difference is attributed to the combustion reaction in a flame, i.e., a combustion gas flame shows more remarkable electrical properties than an incombustible hot gas of the same temperature.
A voltage generation effect such as the Klein Effect of a combustion flame may be a typical example of the electrical properties.
In this paper, description is made of the effect of potential difference between nozzle and metal plate, induced by a combustion gas flame of a mixture of C2H2 and O2 which is blown vertically on the plate.
First, the volt-ampere (V-I) characteristics due to the effect in a steady state are investigated.
These V-I characteristics are affected by the temperature of the metal plate, the distance between nozzle and plate and the mixing ratio of C2H2 and O2.
No-load voltage, short-circuit current are in the order of one volt and of several micro amperes respectively under the condition of this experiment.
Second, in a transiant state including the case of gas cutting, the voltages caused by this effect are measured.
The theory of plasma sheath potential is applied to the analysis of the voltage generation. And discussions are made on the influences of the electron concentration in the flame, and of the temperature and the thermionic emission of the surface at the each plate on this effect.
Experimental results fairly agree with theoretical analysis.View full abstractDownload PDF (494K) -
1968 Volume 37 Issue 7 Pages 750-767
Published: July 25, 1968
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSDownload PDF (8091K)
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