• Title/Summary/Keyword: welding gap

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A Study on the Effect of Root Gap of Double Fillet Welded Joint Considering External Forces (외력을 고려한 양면 필릿용접이음부 루트갭의 영향에 관한 연구)

  • 방한서;김성환
    • Proceedings of the KWS Conference
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    • 1997.05a
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    • pp.107-111
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    • 1997
  • In this paper distribution of welding residual stress on the double fillet welded joint which exits and not exits root gap, i.e. full penetration and partial penetration is investigated by two dimensional cunduct and thermal elasto-plastic analysis. And stress distribution on notch-tip of the structure where welding residual stress regarded as initial stress and then external load is added is also investigated.

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Development of Low Frequency Pulse MIG Welding Process for AL and its alloy (AL 및 AL합금의 저주파 PULSE MIG 용접법의 개발)

  • 최병길;이사영;이승학;천성진
    • Proceedings of the KIPE Conference
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    • 1997.07a
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    • pp.45-48
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    • 1997
  • The low frequency pulsed MIG welding process of new current waveform control to switch over unit pulse conditions (pulse current, pulse duration) in the fixed cycle was developed and its effect were investigated for aluminium and its alloy. By using this new welding process, the bead appearance having clear ripple pattern, such as TIG welding bead can be obtained and the gap tolerance of lap and butt welding joint can be expanded.

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Study on the porosity formation in the lap joint CW Nd:YAG laser welds of 6K21 aluminum alloy sheet (6K21 알루미늄 판재의 레이저 겹치기 용접 시 발생하는 기공에 관한 연구)

  • Yang, Hyun-Seok;Lee, Kyoung-Don;Kim, Yong;Park, Ki-Young
    • Laser Solutions
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    • v.11 no.3
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    • pp.16-20
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    • 2008
  • The lap Joint welding of 6K21 aluminum sheets by Nd:YAG laser were performed with an aluminum 5183 filler wire or without a filler wire. The porosity of laser welding beads were observed through an optical microscope and X-ray photography with various levels of welding speed and gap size. The porosity was observed in the gap between upper and lower sheet near a heat affected zone when autogenous welding. Decrease of welding speed and use of AA5183 filler wire reduced porosity significantly.

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Prediction of Weld Residual Stress of Narrow Gap Welds (협개선 용접부에 대한 용접잔류응력 예측)

  • Yang, Jun-Seog;Heo, Nam-Su
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.34 no.1
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    • pp.79-83
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    • 2010
  • The conventional welding technique such as shield metal arc welding has been mostly applied to the piping system of the nuclear power plants. It is well known that this welding technique causes the overheating and welding defects due to the large groove angle of weld. On the other hand, the narrow gap welding(NGW) technique has many merits, for instance, the reduction of welding time, the shrinkage of weld and the small deformation of the weld due to the small groove angle and welding bead width comparing with the conventional welds. These characteristics of NGW affect the deformation behavior and the distribution of welding residual stress of NGW, thus it is believed that the residual stress results obtained from conventional welding procedure may not be applied to structural integrity evaluation of NGW. In this paper, the welding residual stress of NGW was predicted using the nonlinear finite element analysis to simulate the thermal and mechanical effects of the NGW. The present results can be used as the important information to perform the flaw evaluation and to improve the weld procedure of NGW.

LASER ARC HYBRID WELDING

  • Dilthey, Ulrich;Keller, Hanno
    • Proceedings of the KWS Conference
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    • 2002.10a
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    • pp.162-168
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    • 2002
  • Hybrid Welding means the coupling of the energy of two different energy sources in a common process zone. This paper describes prospects in laser-arc-hybrid-welding. Different kinds of lasers ($CO_2$ laser and Nd:YAG laser) and arc processes (TIG, Plasma and GMA) are considered.

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A Study on the Evaluation of the Fracture Toughness for the Narrow Gap Welding Part of Nuclear Piping (원전배관 협개선 용접재 파괴인성 평가에 관한 연구)

  • Huh, Yong;Park, Soo;Sin, In-Hwan;Seok, Chang-Sung
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.34 no.1
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    • pp.67-72
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    • 2010
  • The fracture toughness for the LBB analysis of piping is generally determined by the J-integral according to ASTM E1820. However, since this evaluates a base metal, the fracture toughness for narrow gap welding can be differently than the real value. This study evaluated the plastic  factor of the narrow gap welding part of a nuclear piping with SA508 Cl.1a and SA312 TP316. Also, it performed the fracture toughness test for the narrow gap welding part and applied the new plastic $\eta$ factor equation by Huh, et al. and then compared the results with those according with the ASTM standard.

Effects of Nd:YAG Laser Welding Parameters on Fatigue life of Lap Joint Structure in Stainless Steel (스테인리스강의 Nd:YAG 레이저 겹치기 용접부 피로수명에 미치는 용접변수의 영향)

  • Kim, Yang;Yang, Hyun-Seok;Park, Ki-Young;Lee, Kyoung-Don
    • Journal of Welding and Joining
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    • v.26 no.1
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    • pp.69-75
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    • 2008
  • Spot welding which use the main process for side block production of stainless steel railway vehicle is legged behind in laser welding about a quality and productivity. Although the laser welding has many potential advantages such as low heat input and aspect ratio of weld bead, its application to a new structural component still is required many engineering data including mechanical properties such as tensile, fatigue strength, etc on. Therefore, experimental analysis was carried out to understand the fatigue phenomena of different thickness stainless steel overlap joining panels by Nd:YAG laser welding. The fatigue life curves were obtained through fatigue tests with the various levels of applied load. The fatigue life is related with the parameters such as gap size and penetration depth through experiment. As the results, tensile strength and fatigue life were proportional in heat input level and gap was identified the major factor for fatigue life. Also we could know that deferent a-ferrite content at HAZ depend on welding heat input was important factor to determine a formation of initial crack and total fatigue life cycle.

A Study on an Electro-Magnetic System far Arc Rotating in MIAB Welding (MIAB용접에서 아크 회전을 위한 전자기 시스템에 관한 연구)

  • 최동혁;김재웅
    • Journal of Welding and Joining
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    • v.19 no.4
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    • pp.391-398
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    • 2001
  • MIAB welding method uses a rotating arc as its heat source and is known to be efficient in pipe butt welding. The arc is rotated around the weld line by the electro-magnetic force resulting from the interaction of arc current and magnetic field. This paper is concerned with the experiment of initial stage for process control, monitoring for weld quality, and the design of coil system which is efficient of flux generation and concentration. A coil system for the generation of magnetic flux was designed and constructed. Magnetic flux density and arc rotating behavior are important factors in MIAB welding, so the relations between these factors and process parameters were investigated. Various experiments were performed for the steel pipes(48.1mm O.D and 2.0mm thickness). The magnetic flux density is increased by increasing exciting current and decreasing gap size. The maximum of arc rotating frequency is affected by exciting current and gap size. However, the variations of arc rotating frequency during welding and then the melting process are mainly influenced by welding current. Thus, it is considered that the results of this study can be used as important data on the monitoring for weld quality and the design of efficient coil system.

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