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허동운,이세헌,Huh, Dong-Woon,Rhee, Se-Hun 대한용접접합학회 2011 대한용접·접합학회지 Vol.29 No.5
Stainless steels are alloy steels with a nominal chromium content of at least 11 percent, with other alloy additions. The stainlessness and corrosion resistance of these alloy steels are attributed to the presence of a passive oxide film on the surface. When exposed to conditions like Resistance Spot Welding (RSW) process that remove the passive oxide film, stainless steels are subject to corrosive attack. And exposure to elevated temperatures causes oxidation (discoloration) of areas around indentation in Spot welding. In this paper, deal with the effect of shielding gas (Ar) preventing the corrosion, oxidation of stainless steel. And find the optimal shielding gas flow rate. In addition, suggest effective purging method for direct/indirect spot welding process.
허동운(Dong Woon Huh),서진원(Jin Won Seo),곽태호(Tae Ho Kwak) 한국철도학회 2013 한국철도학회 학술발표대회논문집 Vol.2013 No.5
스테인리스 강은 Fe성분에 Cr, Ni 등을 첨가하여 내부식성을 향상시킨 재료로써 소재 표면에 형성된 부동태 피막(Cr₂O₃) 층의 우수한 방청성으로 인해 주로 철도차량 외판에 사용한다. 철도차량의 주요 접합 방법인 저항 용접을 이용할 경우 용접부 주변의 표면에 형성되어 있던 부동태 피막은 고온 열에 의해 저항성을 잃고 대기중의 산소와 반응하여 용접부 주변 영역이 검은색, 갈색 등으로 산화된다. 이러한 용접부 산화 현상을 제거하기 위한 기존 전해연마 방법 대신 본 연구에서는 기존 불활성 기체와 Purging 장치에 대한 연구를 바탕으로 스테인리스 철도차량 용접에 적합한 장치를 개발, 적용하여 스테인리스 철도차량의 감성 품질 및 방청성 향상, 제조 공정 시간을 단축하였다. The conventional stainless steel spot weld is oxidized around Weld by high temperature and atmospheric oxygen when the Spot welding carried out. According to the goal of improvement like emotional qualities (no oxidation mark and good appearance) and the efficiency of manufacturing, the stainless steel has been partially applied to other welding methods recently. However, due to the high cost of device and equipment, design constraints, there is no choice but to use the existing Spot welding. In order to resolve the oxidation issue, after welded, the electrolytic polishing process has been held. In spite of this process, the weld around was not still enhanced emotional qualities. In this paper, the chronic oxidation problem of spot weld is fundamentally eliminated by using inert Gas and the improved Ar purging device.
가공 전극 팁을 이용한 스테인레스 저항 용접 외판 변형 저감
허동운(Dong Woon Huh),이세헌(Sehun Rhee) 한국생산제조학회 2011 한국생산제조학회지 Vol.20 No.6
Recently, STS 301L joints of side panels to frames for stainless steel rolling stock have been made out by using existing welding methods including Resistance Spot Welding, Laser Welding and Arc Welding. Most of the processes were jointed by spot welding because it is faster at welding and comparatively less expensive for investment in welding facilities than other methods. During spot welding, however, indentation of the metal surface was made due to pressure and melting property of welding. Moreover, since the melting metal was forced to periphery of the plate as indentation was made, sheet separation, which cracked apart between jointed sheets, was carried out. A slight deformation which resulted from sheet separation deteriorated the emotional quality of railway vehicles. This paper suggests that by processing conventional spot electrode tip appropriately, melting metal is able to push up around the processed part (Hollow Spot Electrode Tip) and prevent from being dislodged from first place to periphery. Consequently, sheet separation is remarkably decreased. Also, the emotional quality of appearance of stainless steel rolling stock is enhanced considerably.