All issues
Volume 36, Issue 1
Displaying 1-8 of 8 articles from this issue
- |<
- <
- 1
- >
- >|
-
1967 Volume 36 Issue 1 Pages 3-6
Published: January 25, 1967
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSDownload PDF (5473K) -
Ken Ocho1967 Volume 36 Issue 1 Pages 9-28
Published: January 25, 1967
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSDownload PDF (7682K) -
Kunihiko Satoh, Shigetomo Matsui1967 Volume 36 Issue 1 Pages 29-34
Published: January 25, 1967
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSIn recent years high strength steels for low temperature use have been developed for application and increased importance has come to be attached to their welding In this report special attention was paid to evaluation of weld cracking sensitivities of the 9 percent nickel steel electrodes (Table 1). Four kinds of electrode (10N, 20N, 40N, 70N, see Table 2) with different nickel contents were selected for the test. The RRC-test1) was adopted for the cracking test. Two series of experiment were made; series I was to evaluate weld cracking sensitivity except for crater cracks and series II was to evaluate crater cracking sensitivity.
In the test series I, weld cracks as shown in Fig. 4 were observed on the bead surface and inner weld metal of the ION, 20N and 70N electrodes under high restraint. The critical gauge length of restraint (lcr) over which no weld cracks were observed was about 200 mm. Weld cracks as shown in Fig.4 were not observed in the 40N electrode weld metal even for 100 mm gauge length of restraint. Therefore lcr for the 40N electrode will be less than 100 mm. Crack formation temperature was estimated higher than about 900°C and may be near the solidus temperature of weld metal.
In the test series II, crater cracks were observed even in specimens almost free from restraint or with l>3000 mm. Crater cracking seems to be almost independent of the magnitude of restraint It will be important, therefore, to take away the crater for avoiding weld cracking of the 9% Ni steel weldments.View full abstractDownload PDF (1768K) -
Kimio Kimura, Sadasi Nisino, Tetuo Kanda1967 Volume 36 Issue 1 Pages 35-43
Published: January 25, 1967
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSIt was previously reported that the breaking of oxide film on the surface of sheets in Direct spot welding of Al alloy thick sheets should be done by application of ultrasonic vibration.
For successful application of this method, it is necessary to make clear the relation between applicable condition of this method and spot welding procedure, and to confirm that spot weld quality is equal, to that of chemical or mechanical pretreated one.
This report deals with the influence of various conditions such as material, thickness, or the cleaning of sheets to be spot welded, design factor of spot spacing, the arrangement and shape of vibrating tip, etc., upon the breaking of oxide film. In addition, comparative testing of mechanical or metallurgical property, corrosion resistance etc. of spot weld was carried out.
As the result, it has been clarified that this method can be practically applied and the quality of spot weld is as good as that of pretreated one.View full abstractDownload PDF (8580K) -
On the Effect of spraying conditon in the Ni-Cr-B-Si alloy coating, and the utilities of the shield nozzleMinoru Okada, Kimiyuki Nishiguchi, Hiroshi Maruo, Takayuki Tani1967 Volume 36 Issue 1 Pages 44-52
Published: January 25, 1967
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSAn excellent dense and oxide free coating of Ni-Cr-B-Si alloy was obtained by the shielded plasma spraying method as shown in the previous report. The present report describes certain effects of spraying conditions, such as spraying atmosphere and preheating of substrate surface, on the quality of coating. And the application of shield nozzle and its effect are also investigated in details.
Usually, plasma spraying of Ni-Cr-B-Si alloy in the air makes a porous and oxide inclusive deposit, even with use of pure argon plasma jet. It may be seen that some of these defects were caused by the oxidation of droplets in spraying. Air contamination into the plasma flame up to 90% was detected in the quantitative gas analysis of plasma flame at a distance of 90 mm from the torch.
Spraying in argon atmosphere gave a somewhat better coated layer compared with the spraying in the air, but is far from being perfect. These results suggest that the protection of particle and substrate from oxidation is necessary but is insufficient for obtaining perfect coating. Furthermore, thermal problems in a process should be considered at the same time. As the result of atmospheric, thermal and kinetic considerations in the processes, shield spraying method has been proposed.
In the shielded spraying of this alloy, the preheating of substrate has great effect on the bond between the coated layer and the substrate. For the specimen which is shield-sprayed without any preheating, a little amount of porosity was observed at the boundary. But almost perfect metallurgical bonding is accomplished with local preheating (300°C) of substrate surface.
As for the application of shield nozzle, a series of experiments were carried out to analize the effect of nozzle. Results as follows;
(1) Spraying atmosphere is kept perfectly inert.
(2) Shield nozzle has an effect of raising the heat transfer from the plasma flame to the particles and substrate, since the contamination of cold gas is completely shout off.
(3) Application of shield nozzle makes it easy to preheat the substrate surface with a high effluent of heat flux.
(4) Temperature and velocity of particle rise as a result of increase of thermal efficiency and velocity of plasma flame.View full abstractDownload PDF (6267K) -
Microstructures and Weld Cracking of Inconel 713CMinoru Okada, Shigeo Shin, Kimiyuki Nishiguchi, Yoshikuni Nakao, Hiroa ...1967 Volume 36 Issue 1 Pages 53-63
Published: January 25, 1967
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSInconel 713C is one of high strength Ni base heat resisting cast alloys.
The elevated temperature mechanical properties of this alloy are nearly equal to those of Nicrotung, Nimonic 115 and Udimet 700 but one of the weak points of this alloy is that it is sensitive to weld cracking.
In this study, the effect of carbon and aluminum+titanium content on weld cracking of this alloy was investigated in bead-on-plate test.
The effect of aluminum+titanium content on the elevated temperature (mechanical) properties was also inquired.
Furthermore, the influences of various heat treatments on the behavior of precipitated phases, micro-structures and hardness of Inconel 713C were investigated.
The results obtained in this study are summarized as follows:
(1) There are γ' phase [Ni3(Al, Ti)], Nb(C, N) and Cr23C6 in the precipitated phases of Inconel 713C.
γ' phase is almost dissolved into matrix after solution treatment at 1150°C for 5h and the hardness of this alloy falls from Hv 400-430 about Hv 330.
(2) The aging time to reach max. hardness of this alloy becomes shorter, as the aging temperature is higher.
Max. hardness is about Hv 450-470 under proper aging conditions.
The hardness does not drop so much after aging treatment at the temperature below 750°C for 500h.
This alloy is overaged after heat treatment at 800°C for 20h or at 900°C for 10h; its hardness is about Hv 350-360.
Hardness change is mainly affected by the particle size and distribution of γ' phase.
(3) The elevated temperature tensile properties of this alloy increases with increasing AI+Ti content as shown in Fig. 7 and 8.
Tensile strengthes at 700°C of 3.26(2.81Al, 0.45Ti), 4.85(3.58Al, 1.27Ti), 5.36(4.45Al, 0.91Ti) and 6.95(6.00Al, 0.95Ti) % Al+Ti alloy are respectively 39, 66, 72 and 74 kg/mm2 and at 800°C, are 37, 64, 69 and 78 kg/mm2.
(4) The reduction of area at 1100°C and 1200°C of this alloy decreases with increasing Al+Ti content.
(5) According to the result of bead-on-plate test, the effect of carbon content on weld cracking of this alloy is not clarified in the range of this study but the effect of Al+Ti content on that of this alloy is observed.
Dendrite boundary cracks, grain boundary cracks and recrystallized grain boundary cracks in H.A.Z. are found in 6.95% Al+Ti alloy but no cracks are detected in Inconel 713C of which Al+Ti content is less than 5.36%.View full abstractDownload PDF (10407K) -
Characteristics of commercial high tensile steelsMakoto Sato, Hajime Nakasugi1967 Volume 36 Issue 1 Pages 64-76
Published: January 25, 1967
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSPreparatory study was conducted in a series of researches on the characteristics of weld heat-affected zone, especially on the embrittlement in grain coarsened region adjacent to weld and softening in spheroidized zone welded with submerged arc process for quenched & tempered high tesile steel, based on the fact that decrease of notch toughness in weld heat-affected zone for Q & T steel was great when welded with large heat input such as in submerged arc welding.
In this study submerged arc single bead weld was deposited on an unsymmetrical single Vee groove of 20 mm plate, and a 2 mm V Charpy and small tensile specimen was taken out of HAZ.
Results show that decrease of notch touhgness caused by large heat input welding is greatest in bonded region HAZ and the slower the rate of cooling, the lower the notch toughness.
Ni is effective for improving bonded region HAZ notch toughness; however, other elements such as Mn, Cr, Mo and V, all show the tendency to decrease it.
Carbon equivalent which was described in Suzuki et al papers does not always appear to be suitable for predicting the notch toughness in large heat input weld HAZ and further study is needed.
By contrast, joint strength is hardly affected by Ni, but other elements increase this strength. Carbon equivalent which represents heat-affected zone hardnability is more useful to predict joint strength than notch toughness.
Microstructures in bonded zone are mostly bainitic except the case of 60 kg/mm2 grade high tensile steel, i.e., steel A; and grains grow up to extreme size and their boundaries are intermittent, which is presumed to be due to the burning effect.
In higher strength steel, maximum hardness in HAZ is detected at 1 mm inside of HAZ from bond, which seems to be caused by diffusion of alloying element into weld and burning in grain boundaries.
Inspection by electron microprobe analyser indicates the diffusion region around bond approximately 120 μ for submerged arc welding and shows that it is located in HAZ.View full abstractDownload PDF (6841K) -
Minoru Okada, Kimiyuki Nishiguchi, Kazumasa Tashiro, Teruhiro Hayashi, ...1967 Volume 36 Issue 1 Pages 77-84
Published: January 25, 1967
Released on J-STAGE: August 05, 2011
JOURNAL FREE ACCESSAn investigation was made to determine the heat transfer intensity distribution obtained when an argon plasma jet impinged on cylindrical and flat surfaces. Some discussions were also made about the results, from the standpoint of heat transfer theory. The plasma jets used were in two conditions, (I) nozzle diameter d=5 mm, argongas flow rate G=5 l/min, the output of the plasma jet Pf=420 cal/s (laminar flow), (II) d=5 mm, G=10 l/min, Pf=680 cal/s (turbulent flow).
A water cooled stainless tube whose outer diamerer was 1 mm, was used as the Cylindrical surface. And two sections of water cooled copper plate were used as the flat surface. These two sections were separated by a sheet of mica about 0.2 mm thick, thermally insulating them from each other. Conclusions obtained from experimental results are as follows:
(1) The experimental equation of heat transfer for the low temperature gas flow (below 1000°C) around the cylinder can be sued for the plasma flow, if it is for a roughly approximate value.
(2) Heat diffusion into the atmosphere from a turbulent plasma jet is larger than that from a laminar one. Therefore, the degree of concentration of heat transfer on cylindrical and flat surfaces from the turbulent one falls more rapidly with the distance from the nozzle exit, than that from the laminar one.
(3) In the conditions of this experiment, the distribution of heat transfer intensity qf on the flat surface from the plasma jet, can be roughly expressed as qf=exp (-γ) with the radius r centered on the jet axis.View full abstractDownload PDF (3199K)
- |<
- <
- 1
- >
- >|