Biaxial Residual Stress Mapping in a PWR Dissimilar Metal Weld

2013 ◽  
Author(s):  
Michael R. Hill ◽  
Mitchell D. Olson
Keyword(s):  
Residual Stress ◽  
Axial Stress ◽  
Image Correlation ◽  
Contour Method ◽  
Pressurized Water Reactor ◽  
Pressurized Water ◽  
Dissimilar Metal ◽  
Stress Mapping ◽  
Metal Weld ◽  
Alloy Weld

This paper describes a sequence of residual stress measurements made to determine a two-dimensional map of biaxial residual stress in a dissimilar metal welded nozzle typical of a nuclear pressurized water reactor (PWR). The present experimental work follows on the numerical analysis reported earlier, in PVP2012-78885. The measurement subject is a cylindrical nozzle, removed from a PWR pressure vessel, having a nickel alloy weld joining a stainless steel safe end to a low-alloy steel vessel. Biaxial residual stress was determined in a series of experimental steps using strain gage measurements, the contour method, and slitting. Confirmatory measurements were also performed (including digital image correlation and neutron diffraction). The paper includes descriptions of the experimental steps, data reduction, and residual stress results, along with a comparison between measurements and output from a weld simulation. The measured hoop stress in the weld region is tensile near the OD (300 MPa) and compressive near the ID (−400 MPa); the measured axial stress is tensile near the OD (150 MPa) and compressive near the ID (−150 MPa).

Biaxial Residual Stress Mapping for a Dissimilar Metal Welded Nozzle

2014 ◽  
Author(s):  
Michael R. Hill ◽  
Mitchell D. Olson ◽  
Adrian T. DeWald
Keyword(s):  
Residual Stress ◽  
Hoop Stress ◽  
Axial Stress ◽  
Welding Residual Stress ◽  
Cylinder Wall ◽  
Two Dimensional ◽  
Pressurized Water Reactor ◽  
Steel Cylinder ◽  
Pressurized Water ◽  
Dissimilar Metal

This paper describes a sequence of residual stress measurements made to determine a two-dimensional map of biaxial residual stress in a nozzle mockup having two welds, one a dissimilar metal (DM) weld and the other a stainless steel (SS) weld. The mockup is cylindrical, designed to represent a pressurizer surge nozzle of a nuclear pressurized water reactor (PWR), and was fabricated for Phase 2a of the NRC/EPRI welding residual stress round robin. The mockup has a nickel alloy DM weld joining a SS safe end to a low-alloy steel cylinder and stiffening ring, as well as a SS weld joining the safe end to a section of pipe. The biaxial mapping experiments follow the approach described earlier, in PVP2012-78885 and PVP2013-97246, and comprise a series of experimental steps and a computation to determine a two-dimensional map of biaxial (axial and hoop) residual stress near the SS and DM welds. Specifically, the biaxial stresses are a combination of a contour measurement of hoop stress in the cylinder, slitting measurements of axial stress in thin slices removed from the cylinder wall, and a computation that determines the axial stress induced by measured hoop stress. At the DM weld, hoop stress is tensile near the OD (240 MPa) and compressive at the ID (−320 MPa), and axial stress is tensile near the OD (370 MPa) and compressive near the mid-thickness (−230 MPa) and ID (−250 MPa). At the SS weld, hoop stress is tensile near the OD (330 MPa) and compressive near the ID (−210 MPa), and axial stress is tensile at the OD (220 MPa) and compressive near mid-thickness (−225 MPa) and ID (−30 MPa). The measured stresses are found to be consistent with earlier work in similar configurations.

Biaxial Residual Stress Mapping for a Dissimilar Metal Welded Nozzle

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Michael R. Hill ◽  
Mitchell D. Olson ◽  
Adrian T. DeWald
Keyword(s):  
Residual Stress ◽  
Hoop Stress ◽  
Stress Measurement ◽  
Axial Stress ◽  
Cylinder Wall ◽  
Two Dimensional ◽  
Pressurized Water Reactor ◽  
Steel Cylinder ◽  
Pressurized Water ◽  
Dissimilar Metal

This paper describes a sequence of residual stress measurements made to determine a two-dimensional map of biaxial residual stress in a nozzle mockup having two welds, one a dissimilar metal (DM) weld and the other a stainless steel (SS) weld. The mockup is cylindrical, designed to represent a pressurizer surge nozzle of a nuclear pressurized water reactor (PWR), and was fabricated as part of a weld residual stress measurement and finite-element (FE) modeling round-robin exercise. The mockup has a nickel alloy DM weld joining an SS safe end to a low-alloy steel cylinder and stiffening ring, as well as an SS weld joining the safe end to a section of SS pipe. The biaxial mapping experiments follow an approach described earlier, in PVP2012-78885 and PVP2013-97246, and comprise a series of experimental steps and a computation to determine a two dimensional map of biaxial (axial and hoop) residual stress near the SS and DM welds. Specifically, the biaxial stresses are a combination of a contour measurement of hoop stress in the cylinder, slitting measurements of axial stress in thin slices removed from the cylinder wall, and a computation that determines the axial stress induced by measured hoop stress. At the DM weld, hoop stress is tensile near the OD (240 MPa) and compressive at the ID (−320 MPa), and axial stress is tensile near the OD (370 MPa) and compressive near the midthickness (−230 MPa) and ID (−250 MPa). At the SS weld, hoop stress is tensile near the OD (330 MPa) and compressive near the ID (−210 MPa), and axial stress is tensile at the OD (220 MPa) and compressive near midthickness (−225 MPa) and ID (−30 MPa). The measured stresses are found to be consistent with earlier work in similar configurations.

scholarly journals Experimental Characterisation and Numerical Modelling of Residual Stresses in a Nuclear Safe-End Dissimilar Metal Weld Joint

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1298
Author(s):  
Shuyan Zhang ◽  
Zhuozhi Fan ◽  
Jun Li ◽  
Shuwen Wen ◽  
Sanjooram Paddea ◽  
...  
Keyword(s):  
Residual Stress ◽  
Neutron Diffraction ◽  
Residual Stresses ◽  
Weld Joint ◽  
Steel Tube ◽  
Contour Method ◽  
Fe Modelling ◽  
Dissimilar Metal ◽  
Dissimilar Metal Weld ◽  
Metal Weld

In this study, a mock-up of a nuclear safe-end dissimilar metal weld (DMW) joint (SA508-3/316L) was manufactured. The manufacturing process involved cladding and buttering of the ferritic steel tube (SA508-3). It was then subjected to a stress relief heat treatment before being girth welded together with the stainless steel tube (316L). The finished mock-up was subsequently machined to its final dimension. The weld residual stresses were thoroughly characterised using neutron diffraction and the contour method. A detailed finite element (FE) modelling exercise was also carried out for the prediction of the weld residual stresses resulting from the manufacturing processes of the DMW joint. Both the experimental and numerical results showed high levels of tensile residual stresses predominantly in the hoop direction of the weld joint in its final machined condition, tending towards the OD surface. The maximum hoop residual stress determined by the contour method was 500 MPa, which compared very well with the FE prediction of 467.7 Mpa. Along the neutron scan line at the OD subsurface across the weld joint, both the contour method and the FE modelling gave maximum hoop residual stress near the weld fusion line on the 316L side at 388.2 and 453.2 Mpa respectively, whereas the neutron diffraction measured a similar value of 480.6 Mpa in the buttering zone near the SA508-3 side. The results of this research thus demonstrated the reasonable consistency of the three techniques employed in revealing the level and distribution of the residual stresses in the DMW joint for nuclear applications.

Simulation of Triaxial Residual Stress Mapping for a Hollow Cylinder

2012 ◽  
Author(s):  
Mitchell D. Olson ◽  
Wilson Wong ◽  
Michael R. Hill
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Nuclear Power ◽  
Complex Geometry ◽  
Cylindrical Body ◽  
Pressurized Water Reactor ◽  
Pressurized Water ◽  
Weld Residual Stress ◽  
Novel Method ◽  
Stress Mapping

This paper describes a novel method to determine a two-dimensional map of the triaxial residual stress on a radial-axial plane of interest in a hollow cylindrical body. With the description in hand, we present a simulation to validate the steps of the method. The simulation subject is a welded cylindrical nozzle typical of a nuclear power pressurized water reactor pressurizer; in the weld region, the nozzle inner diameter is roughly 132 mm (5.2 inch) and the wall thickness is roughly 35 mm (1.4 inch). The pressure vessel side of the nozzle is carbon steel (with a thin stainless steel lining), the piping side is austenitic stainless steel, and between the two are weld and buttering deposits of nickel alloy. Weld residual stresses in such nozzles have important effects on crack growth rates in fatigue and stress corrosion cracking, therefore measurements of weld residual stress can help provide inputs for managing aging reactor fleets. Nuclear power plant welds often have large and complex geometry, which has made residual stress measurements difficult, and this work provides a proof of concept for a new experimental technique for measurements on welded nozzles.

Experimental Study of the Weld Residual Stress in Manually and Mechanically Fabricated Dissimilar Metal Weld

2018 ◽  
Author(s):  
Xinjian Duan ◽  
Andrew Glover ◽  
Dongmei Sun ◽  
Sanjooram Paddea
Keyword(s):  
Residual Stress ◽  
Experimental Study ◽  
Stress Measurement ◽  
Welding Process ◽  
Contour Method ◽  
Inconel 600 ◽  
Dissimilar Metal ◽  
Weld Residual Stress ◽  
Dissimilar Metal Weld ◽  
Metal Weld

The dissimilar metal welds between the Inconel 600 flow element and the SA-106 Grade B carbon pipe with Alloy 82 or Alloy 182 filler material of some CANDU® designs have been identified as being susceptible to Primary Water Stress Corrosion Cracking (PWSCC). Initiation and growth of PWSCC in a Dissimilar Metal Weld (DMW) are driven primarily by Welding Residual Stresses (WRS). The present paper focuses on the experimental study of weld residual stress distribution in manually and mechanically fabricated DMWs with emphasis on the effect of repair. A series of DMW samples are firstly fabricated in accordance with the original welding procedures for those DMWs in the field, which were fabricated in 1970s and 1980s. Multiple thermocouples were used to record the temperature evolution during the entire welding process. These samples were then examined by ASME qualified personnel in accordance with the requirements for Class 1 weld in Article 9 of Section V of ASME BVPC using Visual Testing (VT) and Radiography Testing (RT). Repair was then performed in some samples, and further NDE examinations were performed. The qualified samples (with and without repair) were finally subject to destructive weld residual stress measurement using contour method. It is observed that weld repair dramatically changes the distribution of weld residuals tress. The use of a constant through-thickness WRS of 60,000 psi (415 MPa) is justified as the bounding case.

Prediction of Weld Residual Stress in a Pressurized Water Reactor Pressurizer Surge Nozzle

2015 ◽  
Vol 138 (2) ◽  
Author(s):  
Akira Maekawa ◽  
Atsushi Kawahara ◽  
Hisashi Serizawa ◽  
Hidekazu Murakawa
Keyword(s):  
Residual Stress ◽  
Heat Source ◽  
High Speed ◽  
Nuclear Regulatory Commission ◽  
Round Robin ◽  
Welding Residual Stress ◽  
3D Analysis ◽  
Pressurized Water Reactor ◽  
Pressurized Water ◽  
Water Reactor

Primary water stress corrosion cracking (PWSCC) phenomenon in dissimilar metal welds is one of the safety issues in ageing pressurized water reactor (PWR) piping systems. It is well known that analysis accuracy of cracking propagation due to PWSCC depends on welding residual stress conditions. The U.S. Nuclear Regulatory Commission (NRC) and the Electric Power Research Institute (EPRI) carried out an international round robin validation program to evaluate and quantify welding residual stress analysis accuracy and uncertainty. In this paper, participation results of the authors in the round robin program were reported. The three-dimensional (3D) analysis based on a fast weld simulation using an iterative substructure method (ISM), was shown to provide accurate results in a high-speed computation. Furthermore, the influence of different heat source models on analysis results was investigated. It was demonstrated that the residual stress and distortion calculated using the moving heat source model were more accurate.

High-Temperature Constitutive Behavior of Austenitic Stainless Steel for Weld Residual Stress Modeling

2012 ◽  
Author(s):  
Dongxiao Qiao ◽  
Wei Zhang ◽  
Zhili Feng
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Stainless Steel ◽  
High Temperature ◽  
Residual Stresses ◽  
Constitutive Rule ◽  
Dissimilar Metal ◽  
Weld Residual Stress ◽  
Dissimilar Metal Weld ◽  
Metal Weld

Weld residual stress is a major driving force for initiation and growth of primary water stress corrosion cracking (PWSCC), which is a critical challenge for weld integrity of reactor pressure vessel nozzles in nuclear industry. Predicting weld residual stresses for the purpose of understanding and mitigating PWSCC requires the knowledge of material constitutive rule especially strain hardening behavior over a wide range of temperatures. Though it is adequate for describing deformation at low temperature, the conventional, rate-independent, elastic-plastic constitutive rule falls short in predicting the strong microstructure-mechanical interaction such as the softening due to recovery (dislocation annihilation and realignment) and recrystallization at elevated temperature in welding. To quantify the extent of softening under temperature and strain conditions relevant to welding, a framework has been developed by combining advanced experimental techniques and finite element modeling. First, physical simulation in a Gleeble testing machine is used to simulate the temperature transients typical of dissimilar metal weld by subjecting round tensile bar shaped specimens to rapid heating and cooling. Second, the digital image correlation (DIC) technique is used to map the non-uniform strain field and extract local strain history needed for accurately determining the true stress vs. true strain curve of softened material. Third, the thermally-mechanically processed specimens are characterized metallographically to correlate the microstructure changes to the measured stress-strain behavior. Finally, a thermal-stress finite element model of three-bar frame is used to study the effect of softening on the predicted weld residual stresses. As a first step toward developing the much-needed, comprehensive material constitutive relation database for dissimilar metal weld, the framework has been applied to study AISI 304L austenitic stainless steel. The extent of softening due to different duration of high-temperature exposure is studied and its influence on final residual stresses is discussed.

Effect of Strain Hardening Constitutive Relations on Weld Residual Stress Simulation of Dissimilar Metal Weld

2015 ◽  
Author(s):  
Jian Chen ◽  
Gaoqiang Chen ◽  
Xinghua Yu ◽  
Zhili Feng ◽  
Paul Crooker
Keyword(s):  
Residual Stress ◽  
Strain Hardening ◽  
Elevated Temperatures ◽  
Measurement Data ◽  
Dynamic Strain ◽  
Dissimilar Metal ◽  
Hardening Rule ◽  
Weld Residual Stress ◽  
Dissimilar Metal Weld ◽  
Metal Weld

Weld residual stress (WRS) in dissimilar metal welds (DMWs) has been identified as an important driver for primary water stress corrosion cracking, which is observed in nuclear power plant safety-related components. In this work, a newly developed dynamic strain hardening rule is implemented in finite element (FE) thermal-mechanical model to simulate the residual stress distribution in a dissimilar metal weld studied in a recent NRC/EPRI Round Robin study. This new dynamic strain hardening constitutive rule takes into account the effect of dynamic recovery and recrystallization at elevated temperatures on the strain hardening behavior during welding. Weld residual stresses calculated using the new dynamic strain hardening rule are compared to those with the conventional strain hardening ones (isotropic and kinematic), as well as the experimental measurement data. The new dynamic strain hardening rule results in improvements in WRS prediction.

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