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Nagai T.,Kobe Steel | Kasai R.,Kobe Steel | Ueno K.,Tosei Electrobeam Co. | Mochizuki M.,Osaka University | Suga T.,Osaka University
ISIJ International | Year: 2015

The effect of metal types on the residual stresses has been researched through X-ray stress measurement for the electron-beam welding joints made of sheet metals with a thickness of approximately 10 mm. The finite-element method (FEM) has also been used to analyze the experimental results and verify the residual stress characteristics. Consequently, it has been revealed that the residual stress near the weld toe in the longitudinal direction along the weld axis becomes tensile to a larger extent as the yield strength of the testing material is higher. By contrast, in the transverse direction, the residual stress close to the weld toe has been found to be compressive to a higher degree as the yield strength of the testing material is bigger. These correlations can be observed not only for ferritic and martensitic steel materials but also for other types of metals such as austenitic stainless steel of SUS304 and aluminum alloy of A5052. © 2015 ISIJ.


Nagai T.,Kobe Steel | Kasai R.,Kobe Steel | Ueno K.,Tosei Electrobeam Co. | Mochizuki M.,Osaka University | Suga T.,Osaka University
ISIJ International | Year: 2016

The relationship between residual stress and fatigue strength has been researched for electron beam welded joints made of sheet metals with a thickness of approx. 10 mm. Residual stresses were analyzed by the Finite Element Method, and fatigue strength was obtained by the three-point bending fatigue test. From the results of examining the effect of heat input, a particular relationship was observed between fatigue strength and residual stress, but the effect of stress concentration on fatigue strength was not significant within the tested range of stress concentration factors with varied bead shapes. As a result of testing the effect of steel type, the correlation between fatigue strength and residual stress was confirmed with exception of S50C steel that resulted in lower fatigue strength deviating from the correlation, the deviation of which can presumably be attributed to localized hardening and narrowed area where compressive residual stress was induced. © 2016 ISIJ.


Ueno K.,Tosei Electrobeam Co. | Shindo M.,Tosei Electrobeam Co. | Mochizuki M.,Osaka University
Keikinzoku Yosetsu/Journal of Light Metal Welding and Construction | Year: 2012

The electron beam welding with pulse control is mentioned as one of the possibilities that the scope of electron beam welding will be expandable. However, while the electron beam welding of pulse control can generally control a heat input as compared with the electron beam welding of continuous irradiation, it is known especially in welding of an aluminium alloy that generating of porosity is remarkable. In this paper, we carry out a pulsed electron beam welding to which a beam spot position is moved with doing one pulse irradiation of the electron beam, and also examine the effect which the amount of beam spot movements exerts on the number of porosity. As a result, it turned out that the number of porosity is reduced with the increase in the amount of beam spot movements.


Suga T.,Osaka University | Murai Y.,Shinko Welding Service Co. | Kobashi T.,Shinko Welding Service Co. | Ueno K.,Tosei Electrobeam Co. | And 3 more authors.
Welding International | Year: 2016

In many industries, there are applications that require the joining of stainless steel and copper components; therefore, the welding of dissimilar stainless steel/copper joints is a common process. For this investigation, the optimal brazing conditions and suitable filler metals for laser brazing of stainless steel/copper lap joints were studied. Tensile shear force increases with increases in the laser spot diameter or in the laser irradiation angle, which is associated with increased bonding width; however, as bonding width approaches 2 mm, tensile shear force reaches a saturated value due to fracturing at the HAZ of the Cu base plate. In order to obtain joints with high tensile shear strength, laser brazing was optimized by using Cu–Si-based filler metal under the following conditions: laser power, 4 kW; spot diameter, 3 mm; laser irradiation angle, 80°; irradiation position shift, 0.6 mm; brazing speed, 0.30 m/min; and filler metal feed speed, 0.30 min. Concerning filler metals, it was found that the Ni–Cu type showed relatively large tensile shear force even at high welding speeds in comparison with those of the Cu–Si, Cu, Cu–Ni, Ni–Cu and Ni types, respectively. © 2016, © 2015 Taylor & Francis.


Suga T.,Osaka University | Murai Y.,Shinko Welding Service Co. | Kobashi T.,Shinko Welding Service Co. | Ueno K.,Tosei Electrobeam Co. | And 3 more authors.
Yosetsu Gakkai Ronbunshu/Quarterly Journal of the Japan Welding Society | Year: 2014

In many industries, there are applications that require the joining of stainless steel and copper components; therefore, the welding of dissimilar stainless steel/copper joints is a common process. For this investigation, the optimal brazing conditions and suitable filler metals for laser brazing of stainless steel/copper lap joints were studied. Tensile shear force increases with increases in the laser spot diameter or in the laser irradiation angle, which is associated with increased bonding width; however, as bonding width approaches 2 mm, tensile shear force reaches a saturated value due to fracturing at the HAZ of the Cu base plate. In order to obtain joints with high tensile shear strength, laser brazing was optimized by using Cu-Si-based filler metal under the following conditions: laser power: 4 kW; spot diameter: 3mm; laser irradiation angle: 80 degrees; irradiation position shift: 0.6 mm; brazing speed: 0.30 m/min; and filler metal feed speed: 0.30 min. Concerning filler metals, it was found that the Ni-Cu type showed relatively large tensile shear force even at high welding speeds in comparison with those of the Cu-Si, Cu, Cu-Ni, Ni-Cu and Ni types, respectively.

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