The Experts below are selected from a list of 27 Experts worldwide ranked by ideXlab platform
Tohru Saito - One of the best experts on this subject based on the ideXlab platform.
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The effect of upsetting conditions on Flash Weld toughness. Study on toughness improvement of Flash Welded joints in high strength steel
Welding International, 2004Co-Authors: Yasutomo Ichiyama, Masashi Ichikawa, Tohru SaitoAbstract:Abstract An investigation was carried out of the factors influencing the toughness of Flash Welded high strength steel plate.1 It was explained that the major factors for toughness degradation can be summarised by the following: there is an inclusion factor, that is oxides which remain at the Weld interface and act as the starting point for fracture and the inclusions within steel which tend to be parallel to the Weld interface due to metal flow; there is a microstructural factor, that is degradation of the microstructure due to coarsening of former g grains, a localised softened layer at the Weld zone centre and the texture formed where there has been heavy rolling. Consequently, in order to secure toughness, a reduction of oxides at the Weld interface and an improvement of steel material purity are required for the former case and the post Weld heat treatment is required for the latter.
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effect of upsetting conditions on Flash Weld toughness study on toughness improvement of Flash Welded joint in high strength steel report 2
Quarterly Journal of The Japan Welding Society, 2003Co-Authors: Yasutomo Ichiyama, Masashi Ichikawa, Tohru SaitoAbstract:For the purpose of improving the toughness of Flash Weld, the effect of upsetting conditions on the Flash Weld of 980MPa grade high strength steel bar has been studied. The main results obtained are as follows; (1) Characteristic features have been observed in the displacement profile when the upsetting condition is set to higher current and lower pressure during upsetting. In case of higher current conditions, the upsetting speed increases rapidly and then goes down in a short time, which phenomena is repeated several times until its upsetting process is finished. (2) According to high-speed camera observation, such rapid increase in the upsetting speed is attributed to the extrusion of molten metal layer formed at the Weld interface due to excessive joule heating. The specimens showing the melting-extruding upsetting phenomena have revealed superior Weld toughness rather than those produced by conventional upsetting conditions. (3) The reason of toughness improvement in the high current condition where the melting and extruding upsetting mode is observed is considered to be the extrusion of both oxides defects and base metal inclusions, and the achievement of small upset deformation due to the lower upsetting pressure.
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Welding Phenomena and Process Control in the Flash Welding of Steel Sheets(Report 1). Weld Defects and Evaluation of Weld Quality.
QUARTERLY JOURNAL OF THE JAPAN WELDING SOCIETY, 1995Co-Authors: Tohru Saito, Yasutomo IchiyamaAbstract:Influence of chemical elements of base material has been investigated on interface quality of Flash Weld. Bend test of Welds was carried out for 43 kinds of sheet steels which included solid solution strengthened, dual phase and precipitation hardened high strength steels up to 590 MPa.Fractography anlysis indicated that cracks at Weld interface were caused by oxide inclusions. Aluminum, silicon and manganese were major elements of the inclusion, and whose influence were determined to be strong as 10:1:0.01 in the order. Carbon was also proved to affect cracking at interface by reducing ductility of Weld. Equivalent formula was experimentally established for the influence of those elements on interface cracking.The ordinary bend test was proved to be used as a simple and reliable method in quantitative evaluation of the interface quality of Flash Weld, while notch bend test showed higher ability in the evaluation than that.
Yasutomo Ichiyama - One of the best experts on this subject based on the ideXlab platform.
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The effect of upsetting conditions on Flash Weld toughness. Study on toughness improvement of Flash Welded joints in high strength steel
Welding International, 2004Co-Authors: Yasutomo Ichiyama, Masashi Ichikawa, Tohru SaitoAbstract:Abstract An investigation was carried out of the factors influencing the toughness of Flash Welded high strength steel plate.1 It was explained that the major factors for toughness degradation can be summarised by the following: there is an inclusion factor, that is oxides which remain at the Weld interface and act as the starting point for fracture and the inclusions within steel which tend to be parallel to the Weld interface due to metal flow; there is a microstructural factor, that is degradation of the microstructure due to coarsening of former g grains, a localised softened layer at the Weld zone centre and the texture formed where there has been heavy rolling. Consequently, in order to secure toughness, a reduction of oxides at the Weld interface and an improvement of steel material purity are required for the former case and the post Weld heat treatment is required for the latter.
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effect of upsetting conditions on Flash Weld toughness study on toughness improvement of Flash Welded joint in high strength steel report 2
Quarterly Journal of The Japan Welding Society, 2003Co-Authors: Yasutomo Ichiyama, Masashi Ichikawa, Tohru SaitoAbstract:For the purpose of improving the toughness of Flash Weld, the effect of upsetting conditions on the Flash Weld of 980MPa grade high strength steel bar has been studied. The main results obtained are as follows; (1) Characteristic features have been observed in the displacement profile when the upsetting condition is set to higher current and lower pressure during upsetting. In case of higher current conditions, the upsetting speed increases rapidly and then goes down in a short time, which phenomena is repeated several times until its upsetting process is finished. (2) According to high-speed camera observation, such rapid increase in the upsetting speed is attributed to the extrusion of molten metal layer formed at the Weld interface due to excessive joule heating. The specimens showing the melting-extruding upsetting phenomena have revealed superior Weld toughness rather than those produced by conventional upsetting conditions. (3) The reason of toughness improvement in the high current condition where the melting and extruding upsetting mode is observed is considered to be the extrusion of both oxides defects and base metal inclusions, and the achievement of small upset deformation due to the lower upsetting pressure.
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Welding Phenomena and Process Control in the Flash Welding of Steel Sheets(Report 1). Weld Defects and Evaluation of Weld Quality.
QUARTERLY JOURNAL OF THE JAPAN WELDING SOCIETY, 1995Co-Authors: Tohru Saito, Yasutomo IchiyamaAbstract:Influence of chemical elements of base material has been investigated on interface quality of Flash Weld. Bend test of Welds was carried out for 43 kinds of sheet steels which included solid solution strengthened, dual phase and precipitation hardened high strength steels up to 590 MPa.Fractography anlysis indicated that cracks at Weld interface were caused by oxide inclusions. Aluminum, silicon and manganese were major elements of the inclusion, and whose influence were determined to be strong as 10:1:0.01 in the order. Carbon was also proved to affect cracking at interface by reducing ductility of Weld. Equivalent formula was experimentally established for the influence of those elements on interface cracking.The ordinary bend test was proved to be used as a simple and reliable method in quantitative evaluation of the interface quality of Flash Weld, while notch bend test showed higher ability in the evaluation than that.
Masashi Ichikawa - One of the best experts on this subject based on the ideXlab platform.
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The effect of upsetting conditions on Flash Weld toughness. Study on toughness improvement of Flash Welded joints in high strength steel
Welding International, 2004Co-Authors: Yasutomo Ichiyama, Masashi Ichikawa, Tohru SaitoAbstract:Abstract An investigation was carried out of the factors influencing the toughness of Flash Welded high strength steel plate.1 It was explained that the major factors for toughness degradation can be summarised by the following: there is an inclusion factor, that is oxides which remain at the Weld interface and act as the starting point for fracture and the inclusions within steel which tend to be parallel to the Weld interface due to metal flow; there is a microstructural factor, that is degradation of the microstructure due to coarsening of former g grains, a localised softened layer at the Weld zone centre and the texture formed where there has been heavy rolling. Consequently, in order to secure toughness, a reduction of oxides at the Weld interface and an improvement of steel material purity are required for the former case and the post Weld heat treatment is required for the latter.
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effect of upsetting conditions on Flash Weld toughness study on toughness improvement of Flash Welded joint in high strength steel report 2
Quarterly Journal of The Japan Welding Society, 2003Co-Authors: Yasutomo Ichiyama, Masashi Ichikawa, Tohru SaitoAbstract:For the purpose of improving the toughness of Flash Weld, the effect of upsetting conditions on the Flash Weld of 980MPa grade high strength steel bar has been studied. The main results obtained are as follows; (1) Characteristic features have been observed in the displacement profile when the upsetting condition is set to higher current and lower pressure during upsetting. In case of higher current conditions, the upsetting speed increases rapidly and then goes down in a short time, which phenomena is repeated several times until its upsetting process is finished. (2) According to high-speed camera observation, such rapid increase in the upsetting speed is attributed to the extrusion of molten metal layer formed at the Weld interface due to excessive joule heating. The specimens showing the melting-extruding upsetting phenomena have revealed superior Weld toughness rather than those produced by conventional upsetting conditions. (3) The reason of toughness improvement in the high current condition where the melting and extruding upsetting mode is observed is considered to be the extrusion of both oxides defects and base metal inclusions, and the achievement of small upset deformation due to the lower upsetting pressure.
Shinji Kodama - One of the best experts on this subject based on the ideXlab platform.
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Flash butt Welding of high strength steels
2007Co-Authors: Yusuke Ichiyama, Shinji KodamaAbstract:Welding technologies with high productivity is very attractive in the field of Welding. Flash Welding is essentially very fast Welding and can meet this requirement. However, their Weld properties, especially fracture toughness, have not been acceptable and thus the application has been limited. In this study, factors governing Flash Weld qualities have been studied using high strength steels. The effects of Welding conditions and base metal chemical compositions on the Weld defects are summarized. The effects of inclusions and microstructures on Weld toughness are also discussed. Through these results, quality improvement methods by applying special upsetting conditions have been observed and these are presented in this paper.
Yusuke Ichiyama - One of the best experts on this subject based on the ideXlab platform.
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Flash butt Welding of high strength steels
2007Co-Authors: Yusuke Ichiyama, Shinji KodamaAbstract:Welding technologies with high productivity is very attractive in the field of Welding. Flash Welding is essentially very fast Welding and can meet this requirement. However, their Weld properties, especially fracture toughness, have not been acceptable and thus the application has been limited. In this study, factors governing Flash Weld qualities have been studied using high strength steels. The effects of Welding conditions and base metal chemical compositions on the Weld defects are summarized. The effects of inclusions and microstructures on Weld toughness are also discussed. Through these results, quality improvement methods by applying special upsetting conditions have been observed and these are presented in this paper.