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알루미늄 대상 보빈-마찰교반 용접용 툴 디자인에 관한 리뷰
강상훈(Sanghoon Kang),차종환(Jonghwan Cha),강민정(Minjung Kang) 대한용접·접합학회 2021 대한용접·접합학회지 Vol.39 No.5
Friction stir welding using a bobbin tool (BT-FSW) is a kind of friction stir welding (C-FSW) process in which a lower shoulder is added to the general friction stir welding tool. It is known as the useful method to reduce the Z-axis load required during the tool insertion and traveling for FSW. In addition, it can eliminate the backing plate, and actively respond to part deformation. For this reason, research on the application of BT-FSW is expanding from low melting temperature materials such as aluminum and magnesium to high melting temperature materials. However, no relevant studies on BT-FSW can be found in Korea. This study aimed to present tool design guidelines specifically for BT-FSW. Summarized information on variables to be considered when designing the BT-FSW tool has been described, such as pin and shoulder diameter, shoulder gap, pin and shoulder feature. The design of the tool is a significant step in set-up the BT-FSW process, and should be considered according to the material characteristics (viscosity, plasticity…) and thickness. The pin diameter that is similar to the thickness of material, and the shoulder diameter that is 2 to 3 times wider than the pin diameter were recommended. The shoulder gap, the distance between the upper and lower shoulder, is generally machined to match the material’s thickness or fabricated to be shallower than. Since the pin shape directly affects the vertical and horizontal direction movement into the stir zone, the pins with 3 to 4 flat faces or threaded are more practical than the cylindrical pin shape.
Al/Fe 셀프피어싱 리벳 접합부의 부식특성 및 파괴거동
강상훈(Sanghoon Kang),윤진영(Jin Young Yoon),김철희(Cheolhee Kim) 대한용접·접합학회 2018 대한용접·접합학회지 Vol.36 No.3
In the automotive industry, light-weighting of chassis and car body is an inevitable trend to meet the fuel efficiency regulation. Therefore, the use of Al alloy is increasing and also joining with the conventional steel sheets is getting an important issue. The SPR(self-piercing rivet) joining kinds of mechanical fastening is preferred in Al/Fe joint due to different material properties between the Al and steel as like melting temperature, heat conduction coefficient and thermal expansion coefficient. However galvanic corrosion between rivet and materials is still a big issue to be solved in the SPR joint. In this study, salt spray test (SST) was performed for Al/Fe SPR joint in which 1 mm-thick of Al 6014-T4 and 1.2 mm-thick of GA 590DP steel sheets were joined with PFZn-Ni5L-B coated SPR. The steel sheet was electro-deposition coated prior to the SPR process. In SST up to 80 days, bearing load for tensile-shear test increased with increasing of exposure time, and fracture mode was not varied within the experimental period.