• Title/Summary/Keyword: Fillet Welding

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A Study on the Fatigue Crack Growth Behaviour for the Welded Configuration in Pressure Vessel Stiffener (압력용기 보강재의 용접 형태에 따른 피로균열성장 거동에 관한 연구)

  • 차용훈;김하식;성백섭
    • Journal of the Korean Society of Safety
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    • v.16 no.3
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    • pp.1-6
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    • 2001
  • The study is to investigate the influence on the fatigue crack growth behaviors for the welded configuration in pressure vessel stiffener. In order to perform this goal, the automatic welded specimens were prepared. The material is ASTM A516 grade 60 steel used in pressure vessel mainly. In skip welding of pad-on-plate, continuous fillet welding and PWHT specimen, fatigue crack is generally initiated at the starting and end old toe zone, and ruptured at the starting old toe zone. The fatigue life of pad-on-plate of the continuous fillet welding specimen is larger than that of pad-on-plate skip fillet welding specimen about 85% under low load, about 20% under high load and less than that of two-pad continuous fillet welding specimen about 85%. In da/dN-$\Delta$K curve under low load, skip fillet welding specimen of pad-on-plate showed retardation on the initial crack, and the fatigue crack growth rate at the low region of $\Delta$K greater specimen E($3.8 {\times} 10^{-6}mm/cycle$). And the fatigue life of welding specimen was smaller than that of PWHT specimen.

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A study on mathematical modeling and heat transfer analysis to predict weld bead geometry in horizontal fillet welding (수평필릿용접의 용접부 형상을 예측하기 위한 수학적 모델링 및 열전달 해석에 관한 연구)

  • 문형순;나석주
    • Journal of Welding and Joining
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    • v.14 no.6
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    • pp.58-67
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    • 1996
  • The horizontal filet welding is prevalently used in heavy and ship building industries to join the parts. The phenomena occurring in the horizonal fillet welding process are very complex and highly non-linear, so that its analysis is relatively difficult. Furthermore, various kinds of weld defect such as undercut, overlap, porosity. excess weld metal and incomplete penetration can be induced due to improper welding conditions. Among these defects, undercut, overlap and excess weld metal appear frequently in horizontal filet welding. To achieve a satisfactory weld bead geometry without weld defects, it is necessary to study the effect of welding conditions in the weld bead geometry. For analyzing the weld bead geometry with and without weld defects in horizontal fillet welding, a mathematical model was proposed in conjunction with a two-dimensional heat flow analysis adopted for computing the melting tone in . base metal. The reliability of the proposed model was evaluated through experiments. which showed that the proposed model was very effective for predicting the weld bead shape with or without weld defects in horizontal fillet welding.

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Study on the Simultaneous Control of the Seam tracking and Leg Length in a Horizontal Fillet Welding Part 1: Analysis and Measurement of the Weld Bend Geometry

  • Moon, H.S.;Na, S.J.
    • International Journal of Korean Welding Society
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    • v.1 no.1
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    • pp.23-30
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    • 2001
  • Among the various welding conditions, the welding current that is inversely proportional to the tip-to-work-piece distance is an essential parameter as to monitor the GMAW process and to implement the welding automation. Considering the weld pool surface geometry including weld defects, it should modify the signal processing method for automatic seam tracking in horizontal fillet welding. To meet the above necessities, a mathematical model related with the weld pool geometry was proposed as in a conjunction with the two-dimensional heat flow analysis of the horizontal fillet welding. The signal processing method based on the artificial neural network (Adaptive Resonance Theory) was proposed for discriminating the sound weld pool surface from that with the weld defects. The reliability of the numerical model and the signal processing method proposed were evaluated through the experiments of which showed that they are effective for predicting the weld bead shape with or without the weld defects in a horizontal fillet welding.

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A Study on Seam Tracking for Fillet Welding using High Speed Rotating Arc Sensor (고속회전 아크센서를 이용한 필렛 용접선 추적에 관한 연구)

  • Lee, Won-Ki;Lee, Gun-You;Oh, Myung-Seok;Kim, Sang-Bong
    • Proceedings of the KSME Conference
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    • pp.917-922
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    • 2003
  • In this paper, a high speed rotating arc sensor for automatic fillet welding is introduced. In order to track the welding seam, The high speed rotating arc sensor is used. The welding tip of a high speed rotating arc sensor rotates about 3000 rpm using DC motor. The rotating torch is driven by gear between welding torch body and wire guide. The welding current is measured by using the current sensor and rot at ing position sensor. To realize the welding seam tracking algorithm with accuracy, a software filter algorithm using the moving average method is applied to the measured welding current in the microprocessor. The welding mobile robot with two wheels and two sliders is developed for fillet welding. The welding mobile robot can control its traveling direction and turn itself around the corner. The effectiveness is proven through the experimental results conducted with varied fillet tracking patterns.

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Finite Element Analysis for Prediction of Bead Shape of Nd:YAG Laser Fillet Welding (Nd:YAG 레이저 필렛 용접의 비드형상 예측에 관한 유한요소해석)

  • Kim, Kwan-Woo;Lee, Jae-Roon;Suh, Jeong;Cho, Hae-Yong
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.31 no.8
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    • pp.839-846
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    • 2007
  • Nd:YAG pulse laser fillet welding of stainless steel plate was simulated to find welding condition by using commercial finite element code MARC. Full model of AISI 304 stainless steel plate was considered and user subroutines were applied to boundary condition for the heat transfer. Material properties such as conductivity, specific heat, mass density and latent heat were given as a function of temperature. As results, Three dimensional heat source model for pulse laser beam conditions of fillet welding has been designed by the comparison between the finite element analysis results and experimental data on AISI 304 stainless steel plate. Nd:YAG laser welding for AISI 304 stainless steel was successfully simulated and it should be useful to determine optimal welding condition.

A Study on Horizontal Fillet Welding by Using Rotating Arc (I) - Relation Between Welding Parameters and Weld Bead Shape (회전아크를 이용한 수평필릿 용접에 관한 연구 (I) - 공정변수와 용접비드형상의 관계 -)

  • 김철희;나석주
    • Journal of Welding and Joining
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    • v.21 no.3
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    • pp.40-45
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    • 2003
  • The high-speed rotating arc process forms a flat bead surface with decreased penetration depth because the molten droplets are deflected by centrifugal force. Therefore the rotating arc welding for horizontal fillet welding increases the leg length with the increase of rotation frequency and prevents the deflection of weld bead and overlap. In this study, the relationship between the welding parameters and the weld bead shape - leg length and undercut - are investigated experimentally. Consequently, the weld quality could be improved by rotating arc welding, and sound weld bead was achieved when applied to horizontal fillet welding with 4mm gap by avoiding the undercut which is inevitable for the conventional GMA welding methods.

A Study on Horizontal Fillet Welding by Using Rotating Arc (II) - Development of High-speed Welding Process - (회전아크를 이용한 수평필릿 용접에 관한 연구 (II) - 고속용접공정의 개발 -)

  • 김철희;나석주;이현철;김세환
    • Journal of Welding and Joining
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    • v.21 no.3
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    • pp.46-50
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    • 2003
  • The horizontal fillet joint is one of the most important weld joints in the shipbuilding industry. High-speed rotating arc welding, which can increase the leg length, is an effective way to improve the weld productivity and quality for the horizontal fillet welding. Based on the Taguchi method, the effects of welding parameters on bead characteristics - leg length, asymmetry, undercut, overlap - are investigated fur high-speed welding process. As a result, the adequate welding parameters are selected for the required leg length, symmetric bead and no undercut. Besides, considerably consistent leg length is observed for the horizontal fillet welding with gap variation up to 3mm.

A Study on Mechanical Properties of Fillet Weldment in Pipeline Repair Welding Using Sleeve (슬리브덮개를 이용한 배관 보수용접시 필릿용접부의 기계적특성에 관한 연구)

  • 김영표;김형식;김우식;홍성호
    • Journal of Welding and Joining
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    • v.14 no.5
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    • pp.49-58
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    • 1996
  • In Korea Gas Corporation, as one of the pipeline repairing methods, damaged pipelines are sometimes treated with a temporally employment of split sleeve. On conducting the repair process, circumferential fillet and longitudinal groove welding usually must be included. For the case of groove welding, a considerable amount of R&D have been carried out related to property changes, while few study on the property change in fillet welding has been conducted. In this paper, so as to confirm the specification of fillet welding in terms of safety and reliability, properties changed by fillet welding were investigated for two welding processes. Qualifying tests such as reviewing macrostructure and nick-break tests were performed according to API 1104 and ASME section IX. In addition, tensile properties and hardness were evaluated according to KS B0841 and BS 4515. The fillet weld prepared by the qualified procedure showed melting depth of 0.8∼1.3mm and heat affected zone of 2.8∼3.4mm length. No crack and lack of penetration were observed. And the results of hardness and nick-break tests satisfied code requirements. The area crossed by fillet and groove welding line was found to have minimal tensile strength.

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An Analysis of the Cause of Porosity Generation and Reduction Plan in Fillet Welding (필렛용접에서의 결함발생 원인 분석 및 저감 방안)

  • Choi, K.Y.;Kim, Y.P.;Kim, K.J.;Kim, D.S.;Bae, S.D.
    • Special Issue of the Society of Naval Architects of Korea
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    • pp.128-133
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    • 2006
  • Generally, porosity which was formed by pyrolysis of the primer is usually generated in the weld metal in respect of increase of the welding speed. in order to analyze the cause of porosity generation, this study was performed using FCAW(flux cored arc welding) process for three kinds of inorganic.zinc primer. in addition the evaluation by influence of welding method on porosity generation is conducted to compare between FCAW and MAG(metal active gas) welding with the same inorganic zinc primer. As the result of this investigation, not only primer of lower organic binder and zinc but also FCAW process than MAG in fillet welding have been verified the excellent resistance to the porosity generation for horizontal fillet welding.

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