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Volume 47, Issue 7
Displaying 1-8 of 8 articles from this issue
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J. Ruge1978 Volume 47 Issue 7 Pages 402-408
Published: July 05, 1978
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSDownload PDF (8646K) -
Tohru Yoshida, Hirohiko Ohmura1978 Volume 47 Issue 7 Pages 409-412
Published: July 05, 1978
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSIn copper brazing of steels containing different quantities, respectively, of carbon under the narrow clearance, the columnar deposit of iron develops from high carbon steel to low carbon one in molten copper filler metal at a constant brazing temperature and finally links both steels by the dissolution and deposit of base metal.
Consequently, the shear strength of the joint increases remarkably up to the strength of steel. Longer holding time, narrower joint clearance and larger difference of carbon content, higher shear strength is.View full abstractDownload PDF (3856K) -
Takashi Yamaguchi, Motohide Okada1978 Volume 47 Issue 7 Pages 413-418
Published: July 05, 1978
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSThe present work has been undertaken for better understanding of the basic processes involved in the brazing of cemented tungsten carbides, and the interaction between Co-bonded tungsten carbide and molten copper has been studied referring especially to the effects of metal additives to copper. Techniques used for analyzing the obtained diffusion layers are EPMA and optical microscopy.
It is shown that the structures of diffusion layers are classified into three types depending on the additives. Manganese, Ni and Al have the most pronounced effect on the interaction yielding an additional carbide-free layer in the cemented carbide. Addition of Co and Fe checks the penetration of copper into the cemented carbide, whereas Ag has no detectable effect. The results have been interpreted in terms of the phase relationships between additives and copper as well as the solubility of cobalt into the liquid copper.View full abstractDownload PDF (1436K) -
Relation between Welding Conditions and Weld StructureYoshifumi Suezawa, Hideo Kuroda, Hideki Kobayashi, Makoto Takada, Taka ...1978 Volume 47 Issue 7 Pages 418-425
Published: July 05, 1978
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSThis report shows some experimental data concerning the electron beam welding of sintered steel having various kinds of porosity. The purpose of this investigation is to make clear the relation between the welding conditions and the weld structure, and shrinkage of weld zone of sintered steel. The results obtained in this investigation are summarized as follows:
(1) The pores of sintered steel zone which the electron beam had penetrated, were lost and turned to the solid state when the sintered structure had been melted by beam current. And the different between the structure of weld zone and that of base sintered steel was clearly observed.
(2) It was observed that several cracks which caused lowering the weld strength were created at the boundary of the weld zone owing to the high porosity of sintered steel or due to the high beam current.
(3) The penetrating depth of beam current was enlarged according to increased the beam current and the accelerating voltage, and also the porosity of sintered steel.
(4) The penetrating width of specimen was enlarged according to increased the beam current, however, concerning the accelerating voltage, reverse tendency was observed because the electron beam diameter was pinched due to increased accelerating voltage.
(5) It was observed that some blowhole which caused lowering the strength were created at the melt zone owing to insufficiency of gas exhausing.
(6) In order to prevent for pore creating at weld zone, it is very important that focus position must be placed at the lower side of specimen or use the specimen having a small hole at center to make easy gas exhausting from weld metal.View full abstractDownload PDF (6214K) -
Effect of P on the Deformability at the Tip of NotchHiroshi Ikawa, Yoshikuni Nakao, Toshiro Kikuchi, Hideyuki Takehara1978 Volume 47 Issue 7 Pages 425-432
Published: July 05, 1978
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSIn this report, the effect of P on the critical crack opening displacement at the tip of notch (Φc) in HT 80 steel was investigated in detail. The experimental results obtained in this study are as follows;
1) Φc at 600°C of synthetic bond depends on P content in the range of cooling time from 800°C to 500°C being 10 sec to 50 sec. Φc at 600°C decreases and intergranular cracking ratio becomes larger with increasing P content from 0.018 % to 0.074 %.
2) Φc at 600°C of synthetic bond decreases sharply when heating time from 450°C to 600°C becomes 15 min. However, decreasing tendency of Φc at 600°C becomes slow when the heating time is longer than 15 min. On the same heating conditions, Φc at 600°C decreases with increasing P content from 0.008 % to 0.097 %. Synthetic bond (0.008 % P) heated from 450°C to 600°C for 3 sec fractured in the grain interior. However, intergranular cracking ratio becomes larger with increasing heating time.
3) In HT 80 steel, P segregates to grain boundaries during heating to 600°C after affecting synthetic weld thermal cycle and as a result, intergranular cracking at reheating temperature is promoted.View full abstractDownload PDF (6060K) -
Effect of Welding Method and Welding Condition on Welding Arc SoundYoshiaka Arata, Hiroshi Maruo, Katsunori Inoue, Masami Futamata, Tetsu ...1978 Volume 47 Issue 7 Pages 432-440
Published: July 05, 1978
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSThe sound signal of arc welding seems to provide a useful information for the elucidate of welding arc phenomena, the observation of behavior and the control of arc welding. Afterwards we call this sound the welding arc sound through the investigation.
In this paper we describe an experimental study about the characteristics of welding arc sound with the various methods of welding and welding conditions.
The results obtained are summerized as follows;
1) The welding arc sound has a good competence for the useful source of the information with high level of SPL and good S/N.
2) The welding arc sound emits an unique frequency spectrum according to the welding methods and the spectrum has a very wide-band frequency in CO2 arc welding, MIG arc welding and CO2+Ar arc welding. Otherwise the spectrum of TIG arc welding has a simple frequency state that means nearly "pure sound."
3) The instantaneous sound pressure synchronized with the extinction and the reignition of arc is very strong and the sound wave has a characteristic of the shock wave's propagation.
4) The welding arc sound is closely related to the supplied electric power, welding speed, gas flow rate and electrode extension.
5) The welding arc sound provides the informations about the contraction and expansion of arc, the phenomenon of the molten pool and the transfer of droplets.View full abstractDownload PDF (4458K) -
Hiroshi Ikawa, Yoshikuni Nakao, Toshinori Isai1978 Volume 47 Issue 7 Pages 440-445
Published: July 05, 1978
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSIn this study, bonding mechanism of diffusion brazing of Ni-base superalloys was considered theoretically based on the experimental results. Main experimental results obtained in this research are as follows;
1) In the diffusion brazing joint using Ni-P plating film as an insert metal, a Ni-P film melted at a bonding temperature and a thin liquid film was formed at the bonding region. P in the liquid film diffused into base metal with holding at the bonding temperature and as the result, the width of the liquid film decreased with increasing holding time.
2) From the theoretical considerations on the disappearing process of the liquid film, it was clarified that this process was controlled by the diffusion process of P in the base metal.
3) The elements contained in the base metal diffused into the bonding interlayer in the homogenizing process and finally, the concentration difference of these elements between base metal and bonding interlaver vanished.
4) It is concluded that in the diffusion brazing joints of Ni-base superalloys, both isothermal solidication processes controlled by the diffusion processes of depressants and mutual diffusion processes of main .alloying elements of base metal have important roles in the diffusion brazing process.View full abstractDownload PDF (3458K) -
Plastic Zone, Through-the-thickness Deformation and their Relation to COD ValueHiroshi Tamura, Noboru Kato, Young Sik Kim1978 Volume 47 Issue 7 Pages 446-451
Published: July 05, 1978
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSUsing an optical interference method, the plastic strain behaviours and the progress of the through-the-thickness deformation close to the crack tip were observed continuously on 3-point bending test specimens, made of nitrogen containing mild steel and HT 80 steel. The plastic zones on plate surface and interior section were determined also by etching technique for comparison.
In addition, the fracture criterion, COD, was discussed based on the observed plastic strain behaviours and the progress of the through-the-thickness deformation.
Main results are summarized as follows:
(1) The plastic zone and the through-the-thickness deformation close to the crack tip both loading and unloading could be measured by optical interference technique using sodium light source.
(2) At local yielding stage near the crack tip, the length of plastic zone on plate surface was larger than that on interior section. But when the hinge type plastic strain widely spreaded on both cases, the length of plastic zone on plate surface was about the same or rather smaller than that on interior section.
(3) The crack opening displacement was proportional to the through-the-thickness deformation near the crack tip. Moreover, the crack opening displacement was confirmed to be proportional to the size of plastic zone. But its proportionality was different each other at local yielding stage near the crack tip and hinge type plastic strain stage.View full abstractDownload PDF (4368K)
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