• Title/Summary/Keyword: 이종금속용접

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Investigation on the Effect of Strength Mismatch on Residual Stresses in Welds with Different Strength Used in Buried Natural Gas Pipeline (매설 가스 배관 이종금속 용접부의 강도 불일치가 잔류응력에 미치는 영향 고찰)

  • Kim, Jong-Sung;Kim, Woo-Sik;Baek, Jong-Hyun
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.34 no.4
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    • pp.413-421
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    • 2010
  • In this study, residual-stress distributions in welds with different strength used in natural gas pipelines are calculated by using finite-element analysis and simulating a realistic welding process. The temperature and residual-stress analysis results are compared with the real fusion profile and the application results of the Fitness-For-Service assessment code, API 579 in order to validate the finite-element analysis model and procedure. Parametric study is performed to assess the effect of welding and material variables such as mechanical strength mismatch, the strength of weld metal, reinforcement, and heat input on the residual stress distributions. Finally, on the basis of the parametric study results, the effects of these variables on residual stress distributions are investigated. In particular, the strength mismatch between base metals has an insignificant effect on residual-stress distributions.

Effects of Hybrid Welding Conditions on Impact Toughness of Weld Metal in Ship Structural Steel (조선용강재의 하이브리드 용접금속부 충격인성에 미치는 용접조건의 영향)

  • Hong, Seung-Gap;Lee, Jong-Bong
    • Proceedings of the KWS Conference
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    • 2006.10a
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    • pp.130-132
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    • 2006
  • In passenger ship building where thin plates are mainly used, conventional arc welding processes result in significant post-weld reworking due to thermal distortion of welded joints. In order to solve this problem, European shipbuilding industries introduced hybrid welding process since the 1990's. for passenger ship, first of all, stability is very important. So, in this study, we investigated effects of hybrid welding conditions on impact toughness of weld metal in passenger ship building using DH36 steel.

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The Weldability of 6mm$^{t}$ Primer-coated Steel for Shipbuilding Using $CO_2$ Laser (III) - Real-time X-ray Imaging Observation of Defect Formation of Laser Welding - (6mm$^{t}$ 조선용 Primer코팅강판의 $CO_2$레이저 용접성 (III) - X-선 투과영상시스템에 의한 결함형성거동의 리얼타임관찰 -)

  • 김종도;박현준;이종봉;김영식
    • Proceedings of the KWS Conference
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    • 2004.05a
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    • pp.103-105
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    • 2004
  • 키홀 용접현상에 관한 연구는, 키홀 현상이 용융금속내부에서 아주 빠른 속도로 과도적으로 이루어지기 때문에 그 계측과 해석이 곤란하여 수 많은 가정이나 가설 하에서 용입형상과 키홀의 거동에 관한 해석이 국한된 영역에서 이루어지고 있는 것이 현실이다. (중략)

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A study on the residual stress relieving for dissimilar metal weld under weld overlay (Overlay 용접을 통한 원전 이종 금속 용접부 잔류응력 완화효과에 대한 연구)

  • Song, Tae-Gwang;Bae, Hong-Yeol;Kim, Yun-Jae;Lee, Gyeong-Su;Park, Chi-Yong
    • Proceedings of the KWS Conference
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    • 2007.11a
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    • pp.260-262
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    • 2007
  • In nuclear power plants, residual stress of dissimilar metal weld propagates cracks in the weld metal which is susceptible to stress corrosion cracking. Overlay welding is a process widely used to mitigate residual stress replacing inside tensile stress by compressing stress. The purpose of this paper is to predict the effect of weld overlay by finite element analysis.

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Investigation on the Effects of Preventive Maintenance Schemes for Dissimilar Metal Welds on the Residual Stress Distribution (이종금속용접부 예방정비 방법에 따른 잔류응력 분포 고찰)

  • Song, Tae-Kwang;Choi, Young Hwan;Park, Jeong Soon;Chung, Hae-Dong;Oh, Chang-Young
    • Transactions of the Korean Society of Pressure Vessels and Piping
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    • v.7 no.4
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    • pp.1-11
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    • 2011
  • This paper presents the effects of preventive maintenance schemes on the residual stress distributions in dissimilar metal welds. Dissimilar metal weld is known susceptible to PWSCC and thus, effective maintenance schemes to prevent PWSCC are needed. Three preventive maintenances schemes, i.e. weld overlay, MSIP and inlay weld which are widely used in nuclear power plants, are selected and their effects on welding residual stresses are investigated via finite element analyses. As results, weld overlay and MSIP were proved effective method to mitigate residual stresses and inlay weld, on the other hand, produces strong tensile residual stresses in the inner surface. Although Alloy 690 known to be resistant to PWSCC are used in inlay weld, continuous careful observation are needed since tensile welding residual stresses are key parameter for PWSCC.

A Study on the Diffusion Behaviors in Weld Interface of Cr-Mo Steel/Austenitic Stainless Steel (Cr-Mo강/오스테나이트계 스테인리스강 용접재의 용접계면에서의 확산거동에 관한 연구)

  • 김동배;이상율;이종훈;이상용;양성철
    • Journal of Welding and Joining
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    • v.17 no.4
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    • pp.46-52
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    • 1999
  • Some of the pressurized reactor pressure vessels used in many chemical plants are made of low alloy carbon steel plates internally clad with an austenitic stainless steel for improved anti-corrosion properties. In this study, metallurgic structure of the weld interface of A 387 Grade12Class1 low alloy carbon steel claded with A182-F321 austenitic stainless steel after thermal exposure simulation heat treatment was investigated to display a characteristic behavior of dissimilar metal weld interface with thermal exposure during service at high temperature and pressure. EPMA, STEM, vickers-hardness test were performed and the results were correlated with the microstructure. To estimate the depth of the carburized/decarburized bands quantitatively, a model for carbon diffusion was proposed. The validity of the proposed theoretical relationships was confirmed by the directly measured data from the welded parts failed during service.

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