• Title/Summary/Keyword: TIG Welding

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A Study on the Micro-Focus X-Ray Inspection for Confirming the Soundness of End Closure Weld of DUPIC Fuel Elements (DUPIC 핵연료봉 봉단 용접부 건전성 확인을 위한 미세초점 X-선 투과시험에 관한 연구)

  • 김웅기;김수성;이정원;양명승
    • Journal of Welding and Joining
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    • v.19 no.1
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    • pp.88-94
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    • 2001
  • DUPIC (Direct use of spent PWR fuel in CANDU reactors) nuclear fuel is a CANDU fuel fabricated remotely from spent PWR fuel materials in a hot cell. The soundness of the end closure welds of nuclear fuel elements is an important factor for the safety and performance of nuclear fuel. To evaluate the soundness of the end closure welds of DUPIC fuel element, a precise X-ray inspection system is developed using a micro-focus X-ray generator with an image intensifier and a real time camera system. The fuel elements made of Zircaloy-4 and stainless steel by an Nd:YAG laser welding and a TIG welding aye inspected by the developed inspection system. The soundness of the welds of the fuel elements was confirmed by the X-ray inspection process, and the irradiation test of DUPIC fuel elements has been successfully completed at the HANARO research reactor.

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A Study on Plasma Arc Weldability by Root Gap and Misalignment (루트 갭과 단차에 의한 플라즈마 아크 용접성에 관한 연구)

  • Kim, Dae-Ju;Kim, Gyeong-Ju;Baek, Ho-Seong
    • Proceedings of the KWS Conference
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    • pp.138-140
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    • 2005
  • Plasma arc welding(PAW) technology is a proven process that has already been adopted by other industrial fields and recently has been considered to join the tank structure of LNG carrier. The purpose of this study is to introduce PAW process for the root welding of stainless steel pipes instead of TIG welding. There are distinctive features of the PAW compared to TIG welding; higher energy density that can increase welding speed by more than twofold, and longer arc length that can be controlled to trace seam line easily because of allowable gap between workpiece and torch. However, PAW process is also very sensitive to the root gap and misalignment due to the characteristics of long and narrow arc shape. So, we have done various experiments to establish the allowable fit-up condition by changing welding parameters including arc length, with or without filler metal, groove shape, and obtained satisfactory result.

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Weldability Increase of Aluminum by Variable Polarity Arc (가변 극성 아크의 알루미늄 용접성 향상에 관한 연구)

  • Cho, Jungho
    • Journal of Welding and Joining
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    • v.32 no.1
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    • pp.108-111
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    • 2014
  • Low arc weldability of aluminum alloy is enhanced by applying variable polarity TIG and the result is theoretically investigated to figure out the mechanism. Conventionally, it is well known fact that DCEP (reverse polarity) arc is effective on aluminum welding. The reason is due to oxide layer removal by plasma ion bombardment and therefore it is named as cleaning effect. Another fact of polarity characteristic is that DCEN shows higher heat input efficiency therefore conventional variable polarity arc used to apply DCEP portion as small as possible. However, higher DCEP portion shows bigger weldment in this research and it is explained by adopting a theory of arc concentration on oxide layer with tunneling effect which was not clearly mentioned before in several variable polarity TIG welding research. Disagreement between variable polarity TIG welding result and conventional arc polarity theory is rationally explained for the first time with help of electron emission theory.

A Study on the Analysis of the Thermal Stress and Residual Stress in Process of STS304 TIG Welding (STS304 TIG 용접시 발생하는 잔류응력과 열응력 해석에 관한 연구)

  • Ko, Jun-Bin;Park, Hee-Sang
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.17 no.5
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    • pp.1-10
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    • 2008
  • Residual stress caused in the weldments with high restraint force are often during welding observed in the weldments of large size nozzles or radial tanks. The reason is that quantitative analysis about thermal stresses during welding is lack for this weldments. To verify Finite Elements Method(FEM) theory, the temperature was measured with thermocouple in a real time in this paper. Also analysis of the thermal stress for welding condition is performed by ABAQUS program package on various welding condition in 304 stainless steel butt welding.

Fatigue Damage Behavior in TIG Welded Joint of F82H Steel under Low Cycle Fatigue Loading (저주기 피로부하에서 F82H 강 TIG 용접 접합부의 피로손상거동)

  • Kim, Dong-Hyun;Park, Ki-Won
    • Journal of Welding and Joining
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    • v.33 no.6
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    • pp.42-48
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    • 2015
  • Reduced activation ferritic/martensitic steels are recognized as the primary candidate structural materials for fusion blanket systems. Welding is an inevitable for breeding blanket for pressure tightness and radioisotope confinement. Especially, TIG welding was chosen for sealing because it has the largest gap allowance compared to the other welding methods, and its properties are controllable by feed wire and welding conditions. In this study, the low cycle fatigue test using two-type gage such as extensometer and strain gage was applied to the TIG welded joint of F82H steel, for evaluating fatigue damage accumulation behavior of the HAZs. As the result, the over-tempered HAZ have shown a higher fatigue damage accumulation compared with other materials at all the testing conditions.

A Study on the Bead Stability in High Speed TIG Welding (고속 TIG 용접의 비드 안정성에 관한 연구)

  • 조상명
    • Journal of Advanced Marine Engineering and Technology
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    • v.18 no.3
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    • pp.68-77
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    • 1994
  • TIG welding process is applied for the active metal such as aluminum and titanium, also sometimes for overlay welding of superalloy. However the welding speed to be applied is very low because of the unstable bead formed in the region of high current and high welding speed. The present study was carried out to examine the basic phenomena of high speed TIG melt run welding by the 2% Th - W electrode(dia.3.2mm) of various tip shapes.

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