• 제목/요약/키워드: Welding Residual Stress

검색결과 593건 처리시간 0.034초

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

  • 최병기;장경천
    • 한국안전학회지
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    • 제19권4호
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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.

304 스테인레스강 용접부 잔류응력에 미치는 예열 효과의 유한요속 해석 (Finite Element Analysis of Effect of Preheating on the Residual Stress in 304 Stainless Steel Weldment)

  • 장경복;김하근;강성수
    • Journal of Welding and Joining
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    • 제16권5호
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    • pp.67-75
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    • 1998
  • This study aimed at he experimental and finite element analytic investigation of the effect of preheating on he residual stress of weldment. In this study, an autogenous arc welding was used on type 304 stainless steel and MARC as F.E.M. common code was utilized in analysis The analyses include transient and moving heat source and thermal properties as function of temperature. During welding, the thermal cycles of four locations in the weldment were recorded to investigate of the behavior of thermal stress and residual stress. The experimental and analytic results had good coincidence and show that there are two factors influencing the formation of welding residual stress in preheat process. One is the elevation of welding equilibrium temperature and the other is the increase of amount of heat input. The former decrease welding residual stress and the latter increase welding residual stress. Therefore, the cumulative effects result in the welding residual stress not being improved significantly with preheating in 304 stainless steel.

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PREFLEX BEAM 제작시의 용접부 역학적 특성에 관한 연구 (A Study on the Analysis for Welding Residual Stress of Preflex Beam)

  • 방한서;주성민;안해영
    • 한국해양공학회지
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    • 제17권6호
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    • pp.65-71
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    • 2003
  • Since the preflex beam is fabricated through welding, the pre-compressive stresses that should occur over the concrete pier are diminished by the welding residual stresses. Therefore welding residual stresses must be relieved during the fabrication. Therefore, the analysis and examination of the accurate welding residual stress distribution characteristics are necessary. In this study, accurate distribution of welding residual stress of the preflex beam is analyzed by the finite element method, using 2 dimensional and 3 dimensional elements. Further, the thermo-mechanical behavior of the preflex beam is also studied. After the finite element analysis, real distribution of welding residual stress is measured using the sectioning method, and then is compared with the simulation results. The distribution of welding residual stress by finite analysis agreed well with the experimental results.

피로강도해석을 위한 용접잔류응력 이완의 정량적 평가 (A Quantitative Estimation of Welding Residual Stress Relaxation for Fatigue Strength Analysis)

  • 한승호;이탁기;신병천
    • 대한기계학회논문집A
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    • 제26권10호
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    • pp.2018-2025
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    • 2002
  • It is well known that the strength and the fatigue life of welded steel components are affected extensively by welding residual stresses distributed around their weldments under not only monotonic but also cyclic loads. The externally applied loads are to be superimposed with the welding residual stresses, so that unexpected deformations and failures of the components might occur. These residual stresses are not kept constant, but relaxed or redistributed during in service. Under monotonic loads the relaxation takes place when the sum of external and welding residual stress exceeds locally the yield stress of material used. By the way, it is shown that under cyclic loads the welding residual stress is considerably relieved by the first or the early cycles of loads, and then gradually relaxed with increasing loading cycles. Although many investigations in this field have been carried out, the phenomenon and mechanism of the stress relaxation are still not clear, and there are few comprehensive models to predict amount of relaxed welding residual stress. In this study, the characteristics of the welding residual stress relaxation under monotonic and cyclic loads were investigated, and a model to predict quantitatively amount of welding residual stress relaxation was proposed.

용접잔류응력장 중에서의 Aluminum-Alloy용접재료의 피로균열성장거동 연구 (A study on the fatigue crack growth behavior of aluminum alloy weldments in welding residual stress fields)

  • 최용식;정영석
    • Journal of Welding and Joining
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    • 제7권1호
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    • pp.28-35
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    • 1989
  • The fatigue crack growth behavior in GTA butt welded joints of Al-Alloy 5052-H38 was examined using Single Edge Notched(SEN) specimens. It is well known that welding residual stress has marked influence on fatigue crack growth rate in welded structure. In the general area of fatigue crack growth in the presence of residual stress, it is noted that the correction of stress intensity factor (K) to account for residual stress is important for the determination of both stress intensity factor range(.DELTA.K) and stress ratio(R) during a loading cycle. The crack growth rate(da/dN) in welded joints were correlated with the effective stress intensity factor range(.DELTA.Keff) which was estimated by superposition of the respective stress intensity factors for the residual stress field and for the applied stress. However, redistribution of residual stress occurs during crack growth and its effect is not negligible. In this study, fatigue crack growth characteristics of the welded joints were examined by using superposition of redistributed residual stress and discussed in comparison with the results of the initial welding residual stress superposition.

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재분포된 용접잔류응력이 충격흡수에너지에 미치는 영향 (Effect of the welding residual stress redistribution on impact absorption energy)

  • 양조예;이영석
    • Journal of Welding and Joining
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    • 제33권1호
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    • pp.72-79
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    • 2015
  • Evaluation of fracture toughness of welded structures has a significant influence on the structural design. However the residual stresses is redistributed while the welded structures is cut for preparing specimens. This study investigated an effect of the welding residual stress redistribution on the impact absorption energy of Charpy specimen. SA516Gr70 steel plate by at the flux cored arc welding (FCAW) and gas tungsten arc welding(GTAW) was cutting. Specimens for Charpy impact testing were taken from the welded plate. Two material removal mechanisms (wire cutting and water jet) were used to make the specimens. Welding residual stress and redistribution residual stress were measured using the XRD (X-Ray Diffraction) method. The amount of redistribution of residual stress depends on the different material removal mechanism. Redistribution of residual stress of reduced the impact absorption energy by 15%.

The effect of initial stress induced during the steel manufacturing process on the welding residual stress in multi-pass butt welding

  • Park, Jeong-ung;An, Gyubaek;Woo, Wanchuck
    • International Journal of Naval Architecture and Ocean Engineering
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    • 제10권2호
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    • pp.129-140
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    • 2018
  • A residual stress generated in the steel structure is broadly categorized into initial residual stress during manufacturing steel material, welding residual stress caused by welding, and heat treatment residual stress by heat treatment. Initial residual stresses induced during the manufacturing process is combined with welding residual stress or heat treatment residual stress, and remained as a final residual stress. Because such final residual stress affects the safety and strength of the structure, it is of utmost importance to measure or predict the magnitude of residual stress, and to apply this point on the design of the structure. In this study, the initial residual stress of steel structures having thicknesses of 25 mm and 70 mm during manufacturing was measured in order to investigate initial residual stress (hereinafter, referred to as initial stress). In addition, thermal elastic plastic FEM analysis was performed with this initial condition, and the effect of initial stress on the welding residual stress was investigated. Further, the reliability of the FE analysis result, considering the initial stress and welding residual stress for the steel structures having two thicknesses, was validated by comparing it with the measured results. In the vicinity of the weld joint, the initial stress is released and finally controlled by the weld residual stress. On the other hand, the farther away from the weld joint, the greater the influence of the initial stress. The range in which the initial stress affects the weld residual stress was not changed by the initial stress. However, in the region where the initial stress occurs in the compressive stress, the magnitude of the weld residual compressive stress varies with the compression or tension of the initial stress. The effect of initial stress on the maximum compression residual stress was far larger when initial stress was considered in case of a thickness of 25 mm with a value of 180 MPa, while in case of thickness at 70 mm, it was 200 MPa. The increase in compressive residual stress is almost the same as the initial stress. However, if initial stress was tensile, there was no significant change in the maximum compression residual stress.

전기저항 점용접부의 용접잔류응력 해석에 관한 연구 (A Study on the Welding Residual Stress Analysis of the Spot Welding Point)

  • 손일선;배동호
    • 대한용접접합학회:학술대회논문집
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    • 대한용접접합학회 1999년도 특별강연 및 춘계학술발표대회 개요집
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    • pp.233-236
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    • 1999
  • The welding residual stress should be considered in fatigue stress analysis because it develope during the process of the electric resistance spot welding and it causes bad affect on the fatigue crack initiation and growth at nugget edge of spot welded points. Therefore the accurate estimation of residual stress is crucial. In this study, nonlinear finite element analysis on welding residual stress generated during the process of the spot welding was conducted, and their results were compared with the experimental data measured by X-ray diffraction method. From the results, it was found that welding residual stress existed as tension in the nugget center and as compression around the nugget edge.

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용접잔류응력 이완 및 노치변형률법을 적용한 십자형 필렛용접 이음부의 피로수명 평가 (Fatigue Life Evaluation Based on Welding Residual Stress Relaxation and Notch Strain Approach for Cruciform Welded Joint)

  • 한정우;한승호;신병천;김재훈
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2003년도 추계학술대회
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    • pp.1103-1108
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    • 2003
  • The fatigue strength of welded joint is influenced by the welding residual stress which is relaxed depending on local stress distributed in vicinity of stress raisers, eg. under cut, overlap and blow hole. To evaluate its fatigue life the geometry of the stress raisers and the welding residual stress should be taken into account. The several methods based on notch strain approach have been proposed in order to consider the two factors above mentioned. These methods, however, have shown considerable differences between analytical and experimental results. It is due to the fact that the amount of the relaxed welding residual stress evaluated by the cyclic stress-strain relationship do not correspond with that occurred in reality. In this paper the residual stress relaxation model based on experimental results was used in order to reduce the discrepancy of the estimated amount of the relaxed welding residual stress. Under an assumption of the superimposition of the relaxed welding residual stress and the local stress, a modified notch strain approach was proposed and verified to the cruciform welded joint.

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보수용접에 따른 이종금속 용접부의 잔류응력 해석 (Residual Stress Analysis for Repair Welding in Dissimilar Metal Weld)

  • 이승건;진태은;강성식;권동일
    • Journal of Welding and Joining
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    • 제27권4호
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    • pp.32-37
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    • 2009
  • Alloy 600 and Alloy 82/182 materials have been used widely in PWR plants. But these materials are known to be susceptible to PWSCC(Primary Water Stress Corrosion Cracking). Recently, there have been several PWSCC events in major components due to repair welding, because repair welding in the dissimilar metal welds during the construction increases residual stress significantly on the inner surface of welds. In this paper, various residual stress analyses for repair welding were performed using FEM to check the effect of repair welding on residual stress distributions in PZR safety/relief nozzle. The results indicate that for inside surface repair welding, high tensile residual stress is developed on the inside surface of the nozzles.