Limit loads of dissimilar metal welded joints for joining safe end to pipe-nozzle of nuclear pressure vessel

2021 ◽  
Vol 194 ◽  
pp. 104554
Author(s):  
T.F. Yan ◽  
G.Z. Wang ◽  
K. Wang ◽  
F.Z. Xuan ◽  
S.T. Tu
Keyword(s):  
Pressure Vessel ◽  
Welded Joints ◽  
Limit Loads ◽  
Dissimilar Metal

Effect of a Single Overload on the Fracture Behavior in Safe-End Dissimilar Metal Welded Joints in Nuclear Power Plant

2014 ◽  
Vol 1049-1050 ◽  
pp. 600-604
Author(s):  
He Xue ◽  
Yuan Kui Gui ◽  
Wei Bing Wang ◽  
Xiao Bo Li ◽  
Ying Ru Wang ◽  
...  
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Tensile Stress ◽  
Pressure Vessel ◽  
Welded Joints ◽  
Nuclear Power ◽  
Fracture Behavior ◽  
Welded Joint ◽  
Dissimilar Metal ◽  
Single Overload

To understand the effect of a single overload on the fracture behavior in welded joints, the stress and strain field at the crack tip in a safe-end dissimilar metal welded joint in nuclear pressure vessel is simulated and analyzed by using the elastic-plastic finite element method in the paper, in which the mechanical heterogeneity in welded joint is emphatically considered. The investigating results indicate that the tensile plastic strain at crack tip increases, but the tensile stress decreases as a single overload increases, and the influence of a single overload on tensile strain is larger than one on tensile stress, which provide a theoretical basis for quantitatively estimating the crack growth rate of environmentally assisted cracking in the welded structural material of pressure vessel and piping in the nuclear power plant.

scholarly journals Characterization of Mechanical Heterogeneity in Dissimilar Metal Welded Joints

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4145
Author(s):  
He Xue ◽  
Zheng Wang ◽  
Shuai Wang ◽  
Jinxuan He ◽  
Hongliang Yang
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Welded Joints ◽  
Structural Integrity ◽  
Material Interfaces ◽  
Mechanical Heterogeneity ◽  
Finite Element Software ◽  
Dissimilar Metal ◽  
Stress Changes

Dissimilar metal welded joints (DMWJs) possess significant localized mechanical heterogeneity. Using finite element software ABAQUS with the User-defined Material (UMAT) subroutine, this study proposed a constitutive equation that may be used to express the heterogeneous mechanical properties of the heat-affected and fusion zones at the interfaces in DMWJs. By eliminating sudden stress changes at the material interfaces, the proposed approach provides a more realistic and accurate characterization of the mechanical heterogeneity in the local regions of DMWJs than existing methods. As such, the proposed approach enables the structural integrity of DMWJs to be analyzed in greater detail.

Finite Element Analyses of Residual Stresses in Typical Welded Joints Used in Nuclear Power Plants and Comparisons With Experiments

2010 ◽  
Author(s):  
Dean Deng ◽  
Kazuo Ogawa ◽  
Nobuyoshi Yanagida ◽  
Koichi Saito
Keyword(s):  
Numerical Simulation ◽  
Residual Stress ◽  
Residual Stresses ◽  
Welded Joints ◽  
Nuclear Power ◽  
Power Plants ◽  
Butt Joint ◽  
Welding Residual Stress ◽  
Dissimilar Metal ◽  
Water Reactors

Recent discoveries of stress corrosion cracking (SCC) at nickel-based metals in pressurized water reactors (PWRs) and boiling water reactors (BWRs) have raised concerns about safety and integrity of plant components. It has been recognized that welding residual stress is an important factor causing the issue of SCC in a weldment. In this study, both numerical simulation technology and experimental method were employed to investigate the characteristics of welding residual stress distribution in several typical welded joints, which are used in nuclear power plants. These joints include a thick plate butt-welded Alloy 600 joint, a dissimilar metal J-groove set-in joint and a dissimilar metal girth-butt joint. First of all, numerical simulation technology was used to predict welding residual stresses in these three joints, and the influence of heat source model on welding residual stress was examined. Meanwhile, the influence of other thermal processes such as cladding, buttering and heat treatment on the final residual stresses in the dissimilar metal girth-butt joint was also clarified. Secondly, we also measured the residual stresses in three corresponding mock-ups. Finally, the comparisons of the simulation results and the measured data have shed light on how to effectively simulate welding residual stress in these typical joints.

scholarly journals Electrochemical Impedance Analysis on Cryogenically Treated Dissimilar Metal Welding of 316L Stainless Steel and Monel 400 Alloy Using GTAW

Metals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1088 ◽  
Author(s):  
Cherish Mani ◽  
R Karthikeyan ◽  
Sathish Kannan
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
Welded Joints ◽  
Electrochemical Impedance ◽  
Cryogenic Treatment ◽  
Impedance Analysis ◽  
Oil Refining ◽  
Deep Cryogenic Treatment ◽  
Dissimilar Metal ◽  
Monel 400

An attempt was made to study the corrosion behavior of austenitic stainless-steel SS 316L/Monel 400 alloy dissimilar metal welded joints using gas tungsten arc welding. This combination of welded joints is used in re-heaters and heat exchangers in gas processing and oil refining industries. The welded specimens were subjected to post-weld treatments, such as annealing and deep cryogenic treatment. The welded specimens were sectioned into five different parts: SS 316L base, SS 316L HAZ, weld, Monel HAZ, and Monel base. The polarization method and electrochemical impedance analysis were used to analyze the corrosion resistance in a NaCl solution. A polarization graph, Nyquist plot, and Bode plot were constructed for all regions, separately, for the heat-treated and cryo-treated specimens, to analyze the variation in corrosion resistance in different regions, and then the results were compared. To validate the results of electrochemical impedance analysis, scanning electron microscope (SEM) and energy dispersive spectroscope (EDS) analyses were also performed. The results indicated that the cryo-treated specimens have better corrosion resistance when compared to the annealed ones. Weld region on both specimens exhibited better corrosion resistance when compared to other zones.

Constraint-Dependent J-R Curves of a Dissimilar Metal Welded Joint for Connecting Pipe-Nozzle of Nuclear Pressure Vessel

2015 ◽  
Vol 137 (2) ◽  
Author(s):  
J. Wang ◽  
G. Z. Wang ◽  
F. Z. Xuan ◽  
S. T. Tu
Keyword(s):  
Pressure Vessel ◽  
Nuclear Power ◽  
Power Plants ◽  
Structural Integrity ◽  
Welded Joint ◽  
Pressure Vessels ◽  
Stress Constraint ◽  
Dissimilar Metal ◽  
Local Strength ◽  
T Stress

In this paper, the J-R curves of two cracks (A508 HAZ crack 2 and A508/Alloy52Mb interface crack 3) located at the weakest region in an Alloy52M dissimilar metal welded joint (DMWJ) for connecting pipe-nozzle of nuclear pressure vessel have been measured by using single edge-notched bend (SENB) specimens with different crack depths a/W (different constraint). Based on the modified T-stress constraint parameter τ*, the equations of constraint-dependent J-R curves for the crack 2 and crack 3 were obtained. The predicted J-R curves using different constraint equations derived from the three pairs of crack growth amount all agree with the experimental J-R curves. The results show that the modified T-stress approach for obtaining constraint-dependent J-R curves of homogeneous materials can also be used for the DMWJs with highly heterogeneous mechanical properties (local strength mismatches) in nuclear power plants. The use of the constraint-dependent J-R curves may increase the accuracy of structural integrity design and assessment for the DMWJs of nuclear pressure vessels.

Creep-Fatigue Fracture of Dissimilar Metal Electron Beam Welded Joints at Elevated Temperature

1988 ◽  
Vol 110 (3) ◽  
pp. 212-218 ◽  
Author(s):  
M. Okazaki ◽  
Y. Mutoh ◽  
M. Yamaguchi
Keyword(s):  
Electron Beam ◽  
Fatigue Life ◽  
Welded Joints ◽  
Prediction Method ◽  
Strain Range ◽  
Local Strain ◽  
Base Metals ◽  
Dissimilar Metal ◽  
Creep Fatigue ◽  
Metal Electron

Creep-fatigue tests of dissimilar-metal electron beam welded joints between A387 Gr.22 ferritic low-alloy steel and AISI 405 ferritic stainless steel were carried out under strain-controlled cycling at a temperature of 873 K. It was found that the creep-fatigue life of a dissimilar metal welded joint was significantly shorter than those of its base metals. This resulted from the strain concentration on the AISI 405 side (with the lower deformation resistance.) It was also found that the hardness distribution was one of the important measures by which the local strain distribution was reflected. Furthermore, a simple prediction method for the creep-fatigue life of dissimilar metal welded joints was proposed based on the creep-fatigue life properties of its base metals by applying the strain range partitioning approach. The predicted lives were in good agreement with the experimental results.

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