• Title/Summary/Keyword: Welding Tensile Residual Stress

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A Study on the Residual Stress Distribution of Pure Titanium Welding Material (순수티타늄 용접재의 잔류응력분포에 관한 연구)

  • Choi Byung-ki;Chang Kyung-chun
    • Journal of the Korean Society of Safety
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    • v.19 no.4 s.68
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    • pp.8-13
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    • 2004
  • The purpose of this paper is to investigate the welding residual stress distribution according to the constraint or non-constraint welding condition with titanium commonly using power station, aircraft, and ship. The measuring method of the residual stress was applied stress release rating method with strain gages and a potable strain meter. The x direction residual stress generally showed the tensile residual stress in case of res03int welding. On the other hand, the x direction residual stress under non-restraint welding were changed tensile stress into compressive stress on 15mm away from welding bead center. Also, the y direction residual stress generally showed the tensile residual stress in case of non-restraint welding and the y direction residual stress under restraint welding were changed tensile stress into compressive stress about 60mm away from welding bead center.

The application of forman equation for fatigue crack propagation in welding residual stress region (溶接殘留應力領域에서의 疲勞균열傳播에 대한 Forman式의 適用)

  • 김상철;이용복
    • Journal of Welding and Joining
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    • v.5 no.1
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    • pp.42-56
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    • 1987
  • Fatigue Fracture behaviors of the TIG-welded aluminum alloys, such as Al 2024-T4, A1 5050-0 and Al 7075-T7 were investigated when a crack propagated from tensile residual stress region and compressive residual stress region. The experimental values were compared with the values expected by the Forman equation. The experimental results are summarized as the following: (1) In case of fatigue crack propagation from residual stress region, the values predicted by Forman equation were Found to exactly corresponded to the experimental values. (2) When the stress intensityfactors affected by compressive residual stress, Kres, were greater than the stress intensity factors by minimum applied stresses. Kmin, the Forman equation was found to be improper to be applied directly, but the equation appeared to be proper, if the stress ratio was modified to zero. (3) The experimental results confirmed that residual stress was relaxed by repeated tensile loading and the relaxing trend was greater in case of compressive residual stress than that of tensile residual stress.

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Redistribution of Welding Residual Stress and its Effects on Fatigue Crack Propagation (피로균열이 진전할 때 용접잔류응력의 재분포와 그 영향)

  • 이용복;조남익
    • Journal of Welding and Joining
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    • v.13 no.4
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    • pp.155-162
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    • 1995
  • Redistribution of residual stress and its effects during fatigue crack propagates from tensile residual stress region in weldment are investigated. Tests are performed by using welded CCT specimens of structual rolling steel (SS400) and it makes fatigue crack propagate from tensile residual stress region. For this study tension-tension loading type is selected by external loading condition and magnetizing stress indicator is used correctly to measure redistribution of residual stress according to fatigue crack growth and number of loading cycles. From this result, it is proved that redistribution of residual stress is mainly consist of residual stress released by fatigue crack growth. When fatigue crack propagates from tensile residual stress region residual stress are redistributed and it makes fatigue crack growth rate largely increase. Fatigue crack growth rate is low in case of redistributed residual stress compare with initial distributed residual stress.

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Reduction of residual stress for welded joint using vibrational load

  • Aoki, Shigeru;Nishimura, Tadashi;Hiroi, Tetsumaro
    • Steel and Composite Structures
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    • v.4 no.5
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    • pp.355-365
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    • 2004
  • A new reduction method of residual stress in welding joint is proposed where welded metals are shaken during welding. By an experiment using a small shaker, it can be shown that tensile residual stress near the bead is significantly reduced. Since tensile residual stress on the surface degrades fatigue strength for cumulative damage, the proposed method is effective to reduction of residual stress of welded joints. The effectiveness of the proposed method is demonstrated by the response analysis using one mass model with nonlinear springs.

Effect of Similar Metal Weld & Preemptive Weld Overlay On Residual Stress of Repair Weldment In Surge Nozzle (고리 원전 밀림관 노즐의 동종용접과 예방용접 Overlay가 보수용접 잔류응력에 미치는 영향)

  • Oh, Chang-Young;Song, Tae-Kwang;Shim, Kwang-Bo;Kim, Ji-Soo;Kim, Yun-Jae;Lee, Kyung-Soo
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.22 no.6
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    • pp.557-564
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    • 2009
  • Welding residual stress is occurred after welding process. Tensile residual stress is one factor of PWSCC. Repair welding usually happened during the manufacturing welding process. Repair welds cause strong tensile residual stress. In PWR, Repair weldments made by Alloy 82/182 is susceptible to PWSCC caused by tensile stress, material and environment. Therefore, mitigation of welding residual stress in weldments is important for reliable operating. PWOL is one of the methods for mitigation and verified for over twenty years. In this paper, residual stress distribution of repaired weldments and the effect of PWOL on mitigation is examined for surge nozzle.

A study on the residual stresses in circumferential welds of the pipes (파이프 원주방향 용접부의 잔류응력 연구)

  • 남궁재관;홍재학
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.15 no.2
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    • pp.693-702
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    • 1991
  • The existence of residual stress in the circumferential butt welded pipes is one of the most important problems concerning stress corrosion cracking in service. In this paper, the residual stress distributions in three kinds of circumferential butt welded pipes were measured by the hole drilling strain gage method and calculation using finite element method is performed and its results are compared with the experiments. At the inner surface of the pipe region near the center line of welding is under high tensile residual stress. However, as the distance from the center line of welding increases, the tensile component decreases and finally becomes compressive residual stress at region far away from the center line of welding. The longitudinal residual stress at the outer surface is compressive regardless of the diameter of pipe and the circumferential stress is changed rom compressive to tensile as pipe diameter increases. The results also demonstrate that the residual stress is mainly caused by self restraint bending force in the pipe welding.

An Experimental Study on the Residual Stress Distribution at Circumferential Welds in Pipes (파이프 원주방향 용접부의 잔류응력분포 특성에 관한 실험적 연구)

  • Namkoong, Jae-Gwan;Hong, Jae-Hak
    • Journal of the Korean Society for Precision Engineering
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    • v.8 no.1
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    • pp.41-49
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    • 1991
  • A knowledge of the resdual stress distribution at circumferential weldments can normally increase the accuracy of a fracture assessment in pipe line. In this paper, we present the measurements about the residual stress distributions at three kinds of circumferential butt welded pipes using the holl drilling strain gage method. By this experiment, we have obtined the following characteristics. At the inner surface of the pipe region near the center line of welding is under high tensile residual stress. However, as the distance from the center line of welding increases, the tensile component decreases and finally becomes compressive residual stress at region far away from the center line of welding. The longitudinal residual stress at the outer surface is compressive regardless of the diameter of pipe and the circumferential stress is changed from compressive to tensile as pipe diameter increases. The results also demonstrate that the residual stress is mainly caused by self-restraint bending force in the pipe welding.

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Sensitivity Analysis of Heat Source Parameter for Predicting Residual Stress Induced by Electron Beam Welding (스테인리스강에 대한 전자빔 용접 잔류응력 예측을 위한 열원 변수 민감도 해석)

  • Shin Je Park;Hune Tae Kim;Yun Jae Kim
    • Transactions of the Korean Society of Pressure Vessels and Piping
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    • v.18 no.2
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    • pp.61-68
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    • 2022
  • Accurate evaluation of residual stress is important for stress corrosion cracking assessment. In this paper, electron beam welding experiment is simulated via finite element analysis and the sensitivity of the parameters related to the combined heat source model is investigated. Predicted residual stresses arecompared with measured residual stresses. It is found that the welding efficiency affects the size of the tensile residual stress area and the magnitude of maximum longitudinal residual stress. It is also found that the parameter related to the ratio of energy distributed to the two-dimensional heat source has little effect on the size of tthe tensile residual stress area, but affects the size of the longitudinal residual stress in the center of the weld.

The Effect of Residual Stress on Stress Intensity Factor and Fatigue Crack Growth Rate (잔류응력이 응력세기계수와 피로균열성장율에 미치는 영향)

  • Kang-Yong,Lee;Hong-Key,Kim
    • Bulletin of the Society of Naval Architects of Korea
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    • v.21 no.1
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    • pp.43-47
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    • 1984
  • The purpose of this paper is to investigate theoretically the effect of residual stress due to welding in stress intensity factor of a plate containing the Model I Crack in different crack size and location, and on fatigue crack growth rate. The initiation of crack is found to be possible only in the region of tensile residual stress. The most dangerous crack has the values of d/b and a/b equal to about 0.6 and 1.0, respectively, where d/b is the ratio of distance from the crack to welding bead and the width of tensile residual stress region and a/b is the ratio of crack length and tensile residual stress region. The crack perpendicular to and on the line of welding bead and with a/b equal to about 0.6 has maximum stress intensity factor. The theoretical fatigue crack growth rate under residual stress and applied stress, which is obtained from Forman's Law by stress superposition, is relatively in good agreement with Glinka's[8] experimental value. The fatigue crack growth is shown to be retarded due to residual stress distribution.

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A Study on the High Temperature Tensile Property and the Characteristics of Residual Stress in Welds of High Strength Steels (고강도강재의 고온인장특성 및 용접시 잔류응력특징에 관한 연구)

  • 장경호;이진형;신영의
    • Journal of Welding and Joining
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    • v.22 no.4
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    • pp.50-58
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    • 2004
  • In this study, high temperature tensile properties of high strength steels(POSTEN60, POSTEN80) were investigated. The three-dimensional thermal elastic-plastic analyses were conducted to investigate the characteristics of welding residual stresses in welds of high strength steels on the basis of thermal and mechanical properites at high temperature obtained from the experiment. According to the results, high temperature tensile strength of POSTEN60 steel deteriorated slowly to 10$0^{\circ}C$. As the temperature went up, the tensile strength became better because of blue shortness, and it deteriorated radically after reaching to the maximum value around 30$0^{\circ}C$. For the POSTEN80 steel, high temperature tensile strength deteriorated slowly to 20$0^{\circ}C$. As the temperature went up the tensile strength became better and it deteriorated slowly to $600^{\circ}C$ after reached to the maximum value around 30$0^{\circ}C$. Strain of high strength steels at the elevated temperature increased radically after the mercury rose to $600^{\circ}C$. The strain hardening ratio of POSTEN60 steel was larger then that of POSTEN80 steel at the elevated temperature as in the case at the room temperature and it became smaller radically after the mercury rose to 40$0^{\circ}C$. And, in the welding of high strength steels, increasing tensile strength of the steel (POSTEN60