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Volume 44, Issue 4
Displaying 1-11 of 11 articles from this issue
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Shinicni Kaku1975 Volume 44 Issue 4 Pages 275-277
Published: April 05, 1975
Released on J-STAGE: August 05, 2011
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Tomio Senda1975 Volume 44 Issue 4 Pages 278-286
Published: April 05, 1975
Released on J-STAGE: August 05, 2011
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Takashi Fuji1975 Volume 44 Issue 4 Pages 287-298
Published: April 05, 1975
Released on J-STAGE: August 05, 2011
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Shigeru Miyoshi1975 Volume 44 Issue 4 Pages 298-310
Published: April 05, 1975
Released on J-STAGE: August 05, 2011
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Masatoshi Kobayashi1975 Volume 44 Issue 4 Pages 311-313
Published: April 05, 1975
Released on J-STAGE: August 05, 2011
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Morio Onoe1975 Volume 44 Issue 4 Pages 314-316
Published: April 05, 1975
Released on J-STAGE: August 05, 2011
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Kunio Hasegawa, Hideaki Takahashi, Masahiko Suzuki1975 Volume 44 Issue 4 Pages 317-322
Published: April 05, 1975
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSWith reference to the particular aspect of the heat-affected zone, the fracture toughness of a welded low alloy steel has been examined. Test specimens have been prepared from a multiple-pass welded plate of 25 mm full thickness. The welding has been carried out under the heat input of 20 KJ/cm and interpass temperature 150°C. The hardness survey along the fusion boundary in heat-affected zone has shown that the hardness attains to the maximum value at the vicinity of the toe of weld. For this reason, the most critical feature of specimen machining has been concerned with the preparation and the location of the slit. The unusual shallow slits, such as 1 mm slit depth, have been also made. Furthermore, the tip of all the slits with various slit depth has been located in the heat-affected zone adjacent to the fusion line. Fracture testing has been carried out in four point bending over a wide temperature range.
Results of the present studies are summerized as follows.
(1) A typical result obtained at low temperature reveals that the plastic deformation near slit tip just before fracture decreases with decreasing slit depth. Especially, the plastic deformation and nominal fracture stress in the case of the most shallow slit exhibit remarkably low value.
(2) Fracture toughness value decreases with decreasing slit depth. The feature of the low fracture toughness with reference to the slit depth is remarkable at low temperature. For example, the fracture toughness value in 1 mm slit depth specimen at -133°C is only 23 kgmm-3/2 and this value is about 1/10 of the value in the case of the slit depth of 12.5 mm.
(3) In assessment of the fracture toughness in welded low alloy steel, the special attention should be paid to the location of the tip of the slit and its depth.
(4) It is revealed that there may be the risk of low stress level fracture even though the depth of the surface defect in the welded low alloy steel is shallow.View full abstractDownload PDF (2524K) -
Effect of Cr on SH-CCT diagram for weldingTakayoshi Kasugai, Michio Inagaki1975 Volume 44 Issue 4 Pages 323-331
Published: April 05, 1975
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSThe effect of Cr on transformation behaviour in synthetic weld heat-affected zone of steel was investigated using simplified steels made of pure metals and graphite. Cr element displaced ferrite and pearlite transformation regions to a longer time, and extended Zwischenstufengefüge (Zw) transformation region to a longer time in the SH-CCT diagram for welding. Each critical cooling time Cf', Cp' and Ce' increased with Cr content. Cz' was very small value.
Morphologies of ferrite, pearlite and Zw were strongly influenced by Cr. In the region of longer cooling time (cooling time from A3 to 500°C; above 60 sec), the growth of massive ferrite and ferrite sawteeth were controlled by the addition of Cr. Rodlike ferrite did not precipitate in austenite grain at 0.09%C-3.86%Cr steel which was most amount of Cr in this study. According to the addition of Cr, degenerate pearlite and fine colony pearlite precipitated more easily than lamellar pearlite. In the region of middle and shorter cooling time (cooling time; under 60 see), ferrite sideplate and rodlike ferrite or needlelike ferrite were more liable to develop with Cr than massive ferrite and ferrite sawteeth, and fine colony pearlite formed more easily than other pearlite. Zw accompanied with fine carbide precipitated easily in these region of cooling time by the addition of Cr.
Cr element raised the hardenability curves in synthetic weld heat-affected zone of steels. It seems that the hardness is influenced considerably by the morphological change of microstracture. The effect of Cr on the hardness of martensite was a little.View full abstractDownload PDF (13509K) -
Change of tensile shear strength with increasing of member of spots in case of continuous dischargeMasanobu Hamasaki, Satosi Matuoka1975 Volume 44 Issue 4 Pages 332-336
Published: April 05, 1975
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSSpot welding is the most commonly used, because it is the simpliest, the lowest cost and the highest welding speed. On the other hand, the spot welding has the limitation that is demanded relatively heavy current for an extremely, usually, cycle unit.
Therefore, the substation transformer or power supply becomes larger with increasing of welding transformer. In the point of this disadvantage it could not be applied to minor enterprises and field shops.
In order to dissolve these problems, the battery type spot (electrochemical stored energy spot) welding system has been studied. In this system, the storage battery is connected to the primary of welding transformer and comprises the underlying principle that the electrical energy is stored at a low rate during a night, then discharge it at a high rate as required for welding during a day.
This investigation evaluated the effect of the increasing of number of spots on the tensile shear strength in 1.0-3.2 mm thick mild steel.View full abstractDownload PDF (2921K) -
Application to Vertical WeldingAtsushi Hasui, Yasuo Suga, Hideo Toma1975 Volume 44 Issue 4 Pages 337-344
Published: April 05, 1975
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSThe feasibility of underwater vertical welding by gravity arc welding process is investigated by using 4 mm dia. coated electrodes of five types. SM41 steel plate of 6 mm thickness is used as base metal. And it is ascertained that this process may be put to practical use.
Main results are summerized as follows:
(1) Sound weld can be got easily without skillness of welder, if only proper welding conditions are selected. Especially both high titanium oxide type electrode and high cellulose type electrode have good weldability for vertical welding.
(2) The proper range of combinations of electrode angle and ratio of bead length to electrode length for the high titanium oxide type electrode seems to be relatively wide. For example the proper range of electrode angle is 45°-80° and that of ratio of bead length to electrode length is 0.8-1.2.
(3) Fillet welded joints got by high titanium oxide type electrode and high cellulose type electrode have sufficient tensile strength.
(4) The maximum hardness of weld got by vertical welding is higher than that by flat welding.
(5) As the base metal angle increases, the cooling rate of weld becomes higher. For example, cooling rate at bond at 500°C is about 230°C/sec in vertical welding and 145°C/sec in flat welding, and the former is about 1.6 times higher than the latter.View full abstractDownload PDF (8199K) -
Hydrogen Distribution in Thick Weldment and its Change with Post-heatingYasuhiro Nishio, Yasuyuki Yoshida, Yuzuru Miura1975 Volume 44 Issue 4 Pages 345-350
Published: April 05, 1975
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSThis paper deals with the diffusible hydrogen in multilayer weldment with plate thickness 100 mm to 200 mm.
The hydrogen distribution in thick weldment are examined by the experiment. The following facts were clarified.
(1) Diffusible hydrogen content in weld metal is raised with an increase of the number of welding layer. The maximum position of diffusible hydrogen content in thickness direction exists at just under the last layer and its distribution can be shown as Fig. 5 and Fig. 7. The hydrogen contents of maximum position was raised with an increase of the number of welding layer.
(2) Maximum hydrogen contents, above mentioned, is reduced about 30 per cent with locally postheating for 0.5 hr at 300°C, and diffusible hydrogen is almost removed with furnace annealing for 2 hr at 625°C.
(3) Diffusible hydrogen remains for a long period in thick weldment, for example, it remains over 60 days in 100 mm thick weldment of A 387 Gr D steel (2 1/4Cr-1 MO Steel).View full abstractDownload PDF (2633K)
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