scholarly journals Numerical Investigation of Welding Residual Stress Field and its Behaviour under Multiaxial Loading in Tubular Joints

2014 ◽  
Vol 996 ◽  
pp. 788-793
Author(s):  
Kimiya Hemmesi ◽  
Majid Farajian ◽  
Dieter Siegele
Keyword(s):  
Residual Stress ◽  
Yield Strength ◽  
Residual Stresses ◽  
Structural Integrity ◽  
Weld Zone ◽  
Welding Residual Stress ◽  
Multiaxial Loading ◽  
Residual Stress Field ◽  
Tubular Joints ◽  
Welded Structure

The lack of clarities in estimating the residual stress threat to the structural integrity has led to conservative assumptions in the current design of welds. The complexities become more in the case of multiaxial loading of welded structure, considering fracture or fatigue. To what extent the residual stresses influence the performance of a welded structure, depends on how stable they are under service loads. Finite element analyses are used here to describe the development of welding residual stresses in tubular joints and their relaxation under multiaxial loading. It is observed that the effect of the torsion load is more significant than the effect of tension load in releasing of the residual stresses. For pure tensile loading, the relaxation of the residual stresses are negligible as long as the applied load is lower than 50% of the yield strength of the material. For a combined tension-torsion loading of 75% of the yield strength, the residual stresses are almost completely released, and in the weld zone they become compressive.

The Effects of Loadings on Welding Residual Stresses and Assessment of Fracture Parameters in a Welding Residual Stress Field

2011 ◽  
Author(s):  
Liwu Wei ◽  
Weijing He ◽  
Simon Smith
Keyword(s):  
Residual Stress ◽  
Stress Field ◽  
Residual Stresses ◽  
Path Dependence ◽  
Welding Residual Stress ◽  
Assessment Procedure ◽  
Fe Model ◽  
J Integral ◽  
Residual Stress Field ◽  
Growing Crack

The level of welding residual stress is an important consideration in the ECA of a structure or component such as a pipeline girth weld. Such a consideration is further complicated by their variation under load and the complexity involved in the proper assessment of fracture mechanics parameters in a welding residual stress field. In this work, 2D axi-symmetric FEA models for simulation of welding residual stresses in pipe girth welds were first developed. The modelling method was validated using experimental measurements from a 19-pass girth weld. The modeling method was used on a 3-pass pipe girth weld to predict the residual stresses and variation under various static and fatigue loadings. The predicted relaxation in welding residual stress is compared to the solutions recommended in the defect assessment procedure BS 7910. Fully circumferential internal cracks of different sizes were introduced into the FE model of the three-pass girth weld. Two methods were used to introduce a crack. In one method the crack was introduced instantaneously and the other method introduced the crack progressively. Physically, the instantaneously introduced crack represents a crack originated from manufacturing or fabrication processes, while the progressively growing crack simulates a fatigue crack induced during service. The J-integral values for the various cracks in the welding residual stress field were assessed and compared. This analysis was conducted for a welding residual stress field as a result of a welding simulation rather than for a residual stress field due to a prescribed temperature distribution as considered by the majority of previous investigations. The validation with the 19-pass welded pipe demonstrated that the welding residual stress in a pipe girth weld can be predicted reasonably well. The relaxation and redistribution of welding residual stresses in the three-pass weld were found to be significantly affected by the magnitude of applied loads and the strain hardening models. The number of cycles in fatigue loading was shown to have little effect on relaxation of residual stresses, but the range and maximum load together governed the relaxation effect. A significant reduction in residual stresses was induced after first cycle but subsequent cycles had no marked effect. The method of introducing a crack in a FE model, progressively or instantaneously, has a significant effect on J-integral, with a lower value of J obtained for a progressively growing crack. The path-dependence of the J-integral in a welding residual stress field is discussed.

Abrasive Waterjet Peening With Elastic Prestress: Subsurface Residual Stress Distribution

2007 ◽  
Author(s):  
Balaji Sadasivam ◽  
Alpay Hizal ◽  
Dwayne Arola
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Stress Field ◽  
Yield Strength ◽  
Residual Stresses ◽  
Residual Stress Distribution ◽  
Abrasive Waterjet ◽  
Residual Stress Field ◽  
Surface Residual Stress ◽  
Compressive Residual Stresses

Recent advances in abrasive waterjet (AWJ) technology have resulted in new processes for surface treatment that are capable of introducing compressive residual stresses with simultaneous changes in the surface texture. While the surface residual stress resulting from AWJ peening has been examined, the subsurface residual stress field resulting from this process has not been evaluated. In the present investigation, the subsurface residual stress distribution resulting from AWJ peening of Ti6Al4V and ASTM A228 steel were studied. Treatments were conducted with the targets subjected to an elastic prestress ranging from 0 to 75% of the substrate yield strength. The surface residual stress ranged from 680 to 1487 MPa for Ti6Al4V and 720 to 1554 MPa for ASTM A228 steel; the depth ranged from 265 to 370 μm for Ti6Al4V and 550 to 680 μm for ASTM A228 steel. Results showed that elastic prestress may be used to increase the surface residual stress in AWJ peened components by up to 100%.

Finite Element Welding Residual Stress Analysis of CRDM Penetration Nozzles

2021 ◽  
Vol 144 (1) ◽  
Author(s):  
Seung-Jae Kim ◽  
Eui-Kyun Park ◽  
Hong-Yeol Bae ◽  
Ju-Hee Kim ◽  
Nam-Su Huh ◽  
...  
Keyword(s):  
Residual Stress ◽  
Yield Strength ◽  
Residual Stresses ◽  
Nuclear Reactor ◽  
Reactor Vessel ◽  
Welding Residual Stress ◽  
Alloy 600 ◽  
Stress Distributions ◽  
Control Rod ◽  
Residual Stress Analysis

Abstract This article investigates numerically welding residual stress distributions of a tube with J-groove weld in control rod drive mechanisms of a pressurized nuclear reactor vessel. Parametric study is performed for the effect of the tube location, tube dimensions, and material's yield strength. It is found that residual stresses increase with increasing the inclination angle of the tube, and the up-hill side is the most critical. For thicker tube, residual stresses decrease. For material's yield strength, both axial and hoop residual stresses tend to increase with increasing the yield strength of Alloy 600. Furthermore, axial stresses tend to increase with increasing yield strength of Alloys 82/182.

Welding Residual Stress Analysis Using Axisymmetric Modeling for Shroud Support Structure

2008 ◽  
Author(s):  
Kazuo Ogawa ◽  
Yukihiko Okuda ◽  
Toshiyuki Saito ◽  
Takahiro Hayashi ◽  
Rie Sumiya
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Large Scale ◽  
Structural Integrity ◽  
Plastic Material ◽  
Welding Residual Stress ◽  
Stress Distributions ◽  
Surface Residual Stress ◽  
Actual Structure ◽  
Elastic Plastic Material

Recently, several cracks caused by stress corrosion cracking (SCC) have been found on welds of shroud supports in Boiling Water Reactor (BWR) plants. The major cause of SCC in a weld joint is considered due to welding residual stress generated in the fabrication processes of the components. For continuous safety operations, it is necessary to estimate the structural integrity of such shroud supports with cracks based on the distribution of residual stresses induced by welding. In order to know and to validate the numerical method of residual stresses induced by welding of large scale and complex shaped components, a BWR shroud support mock-up with a hemispherical base of reactor pressure vessel (RPV) was fabricated by Japan Nuclear Energy Safety Organization (JNES) as a national project. The mock-up has a 32° section of actual BWR shroud supports with approximately the same configurations, materials and welding conditions of an actual component. During welding in the fabrication process of the mock-up, temperature was measured and after completion of the mock-up fabrication, surface residual stress distributions for each weld were also measured by the sectioning method. In addition, through-thickness residual stress distributions were investigated. Residual stress for each weld was calculated by using axisymmetric models considering temperature dependent elastic-plastic material properties. Though the actual structure of shroud supports is essentially complex, we simplified axisymmetric models in the center of the cross section. The analysis results show a similar profile and good agreement with the measured results on the surface of all the welds and through the welds at the upper and lower joints of the shroud support leg.

Effect of Reeling Installation on Weld Residual Stress in Pipeline Girth Welds

2013 ◽  
Author(s):  
T. Sriskandarajah ◽  
Graeme Roberts ◽  
Daowu Zhou
Keyword(s):  
Residual Stress ◽  
Plastic Deformation ◽  
Residual Stresses ◽  
Axial Strain ◽  
Saddle Points ◽  
Parent Material ◽  
Welding Residual Stress ◽  
Residual Stress Field ◽  
Weld Residual Stress ◽  
Girth Welds

A characteristic of pipeline installation by the reeling technique is the generation of high plastic strain around the majority of the pipeline’s circumference as it is spooled onto a drum, under displacement controlled conditions. It is well-known that the application of sufficiently high amounts of mechanical or thermal energy will “anneal” (relax) weld residual stresses and, therefore, under the gross plasticity experienced during reeling it should be expected that initial girth weld residual stresses will be entirely relaxed during the first reel cycle. The residual stress state needs to be taken into account in Engineering Critical Assessment (ECA) procedures of girth welds when predicting allowable defect dimensions. ECA codes such as DNV-OS-F101 and BS7910 assume the welding residual stress to be equal to the yield strength of the parent material and relaxation of welding residual stress under overload is allowed. However, the treatment specified in DNV is established from load-controlled scenarios and may result in un-realistic allowable defect dimensions in displacement-controlled situations such as reeling. Welding residual stress in reeling ECA is concerning to the subsea pipeline industry. By performing reeling simulations with 3D finite element analyses (FEA), this paper examines the welding residual stress before and after reeling and assesses the extent of residual stress relaxation. It was found that reeling axial strain causes significant relaxation of the weld residual stress at the pipe intrados and extrados. At the saddle points there is a slight disruption to the residual stress field. The full weld residual stress is relaxed from a value equal to the material yield stress, and is replaced by a plastic deformation induced stress of much lower magnitude, typically in the order of 100 MPa or less. The plastic deformation stress is of equal magnitude whether or not the pipe section contains initial weld residual stress and, therefore, it is concluded that weld residual stress can be ignored following the first reel cycle.

Numerical Analysis of Residual Stresses in Hyperbaric Welding

2012 ◽  
Author(s):  
Xiaobo Ren ◽  
Odd M. Akselsen ◽  
Sigmund K. Ås ◽  
Bård Nyhus
Keyword(s):  
Residual Stress ◽  
Numerical Analysis ◽  
Residual Stresses ◽  
Pressure Range ◽  
Structural Integrity ◽  
Sea Water ◽  
Welding Residual Stress ◽  
Transformation Plasticity ◽  
Micro Structure ◽  
Welding Procedure

Hyperbaric welding residual stress is one of the main concerns for deep water operation. This study presents the numerical investigation of residual stresses in hyperbaric welding by using WeldsimS code. The pressure range investigated in this study is from 3 to 35 bar, which corresponds to 30 to 350 msw (Meters of Sea Water). Experiments results indicate that the welding procedure might be significantly influenced within the pressure range studied. A 2D axisymmetric model has been considered in this study to simulate circumferential welding of a pipe. Phase transformations and transformation plasticity during the welding procedure have been taken into account. The main aim of the study is to predict the hyperbaric welding residual stresses. The temperature evolution and the micro-structure were also studied. Results show that residual stresses induced by hyperbaric welding are significant within the pressure range investigated, which should be assessed for the sake of structural integrity.

Welding Residual Stresses in Tubular Joints

2013 ◽  
Vol 768-769 ◽  
pp. 605-612 ◽  
Author(s):  
Majid Farajian ◽  
Thomas Nitschke-Pagel ◽  
Klaus Dilger
Keyword(s):  
Residual Stress ◽  
Fatigue Crack ◽  
Crack Initiation ◽  
Residual Stresses ◽  
Structural Integrity ◽  
Fatigue Crack Initiation ◽  
Welding Residual Stress ◽  
Structural Safety ◽  
Welding Parameters

In spite of an increased awareness of welding residual stress threat to structural integrity, the extent of its influence on fatigue especially under multiaxial loading is still unclear and is a matter of debate. One important reason for this lack of clarities is that the determination of the initial welding residual stress field in welded structures even at the fatigue crack initiation sites is difficult and requires complementary instruments. Since the fatigue crack initiation in sound welds almost always occurs on the surface, the determination of surface residual stresses could increase the awareness of the extent of their threat to the structural safety. In this paper the development of residual stresses in different TIG-welded tubular specimens out of S355J2H and S690QL steel is studied and compared. The mechanisms of the development of residual stresses based on heat input and cooling rate are discussed. The welding parameters and thus heat inputs are varied and the mechanisms leading to different residual stress states are investigated. X-ray method was used for residual stress state characterization.

Analysis of Welded Joint Under Residual Stresses

2014 ◽  
Author(s):  
H. P. Jawale ◽  
Rahul Singh
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Welded Joint ◽  
Weld Zone ◽  
Welding Process ◽  
Fatigue Behaviour ◽  
Hole Drilling ◽  
Building Structures ◽  
Residual Stress Field ◽  
Stress Relieving

Welded joint is most commonly used for building structures and machine components. Welding process involves heating followed by uneven cooling causing residual stress field. In conjunction with stresses due to external loads, in-service behaviour is affected due to residual stress in welded components. It induces defects, also alters crack initiation life, fatigue behaviour, breaking strength, corrosion resistance and increases the susceptibility of structure to failure by fracture. The residual stress is function of cooling rate and the size of weld. The role of residual stress associated with welding is therefore very important while designing mechanical parts. Conventional methods like heat treatment and shot-peening techniques becomes difficult to be applied for reduction of residual stress in general purpose applications. The work presented in this paper describes the measurement of residual stress using stress relieving method, based on hole-drilling technique. Subsequently, residual stresses are relived and measured using strain rosette near the weld zone. These strains value is converted in to stress value. Residual stress is quantified with respect to yield strength, making it possible to be considered for safe designing of weld components.

Effects of Repair Weld Residual Stresses on Wide-Panel Specimens Loaded in Tension

1998 ◽  
Vol 120 (2) ◽  
pp. 122-128 ◽  
Author(s):  
P. Dong ◽  
J. K. Hong ◽  
J. Zhang ◽  
P. Rogers ◽  
J. Bynum ◽  
...  
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Residual Stresses ◽  
Structural Integrity ◽  
Space Shuttle ◽  
Tensile Tests ◽  
External Loading ◽  
Residual Stress Field ◽  
Fabrication Procedure ◽  
Loading Effects

As a part of the welding fabrication procedure development for the next generation space shuttle external tank, aluminum-lithium wide-panel specimens were used to assess the interactions between repair weld residual stresses and external loading conditions. The detailed residual stress development in the wide panel specimens with a repair weld was analyzed using an advanced finite element procedure. External tension loading effects were then incorporated in the residual stress model to study the interactions between the residual stress field and external tensile loading. Wide-panel tensile tests were also performed to extract photo strain and strain-gage results. A good agreement between the finite element and experimental results was obtained. The results demonstrate that the presence of high tensile residual stresses within a repair weld has a drastic impact on the stress/strain distribution in the wide panel specimens subjected to external loading. Its implications on structural integrity are discussed in light of the wide-panel results. The effects of post-welding mechanical treatment such as planishing were also examined.

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