Standardized Through-Wall Distributions of Dissimilar Metal Weld Residual Stress

2015 ◽  
Author(s):  
John E. Broussard
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Residual Stresses ◽  
Crack Growth ◽  
Welding Process ◽  
Wall Stress ◽  
Residual Stress Distribution ◽  
Analytical Models ◽  
Stress Distributions ◽  
Dissimilar Metal

The residual stresses imparted by the welding process are a principal factor in the process of primary water stress corrosion cracking (PWSCC) of Alloy 82/182 nickel-alloy (i.e., dissimilar metal or DM) piping butt welds in PWRs. While Section XI of the ASME Code requires that residual stresses are considered in crack growth calculations, there is little guidance or requirement on how to calculate them. Analytical models are frequently used to simulate the welding process in order to predict the residual stress distribution in the weld and base material as an input to crack growth calculations. The crack growth calculations, in turn, have demonstrated a high sensitivity to the welding residual stress distribution inputs. While significant progress has been made in understanding and reducing the variability in calculated residual stress among modelers as well as the variability in measured residual stress among different techniques, there remains some uncertainty regarding any given measured or calculated distribution. A feasible alternative to calculating through-wall stress distributions with analytical models on a case-by-case basis is to develop a set of standardized through-wall stress distributions that are applicable to DM welds. Examples of standardized through-wall distributions for residual stress are found in numerous consensus code and standards. The benefit of established through-wall stress distributions is that evaluations for flaws in welds would start from a uniform basis on one of the key inputs to the crack growth calculation, reducing the time required to perform and review flaw evaluations. This paper presents and describes the technical basis for a set of through-wall distributions for common DM welds found in the US nuclear industry. The basis of the distributions include the results of analytical models, including uncertainty, as well as measured data for through-wall stress in DM welds.

Important Residual Stress Features in Reactor Nozzle Dissimilar Metal Welds

2011 ◽  
Author(s):  
Jinmiao Zhang ◽  
Shaopin Song ◽  
Pingsha Dong
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Nuclear Reactor ◽  
Residual Stress Distribution ◽  
Stress Distributions ◽  
Weld Overlay ◽  
Dissimilar Metal ◽  
Nozzle Length ◽  
Dissimilar Metal Weld ◽  
Metal Weld

This paper is focused on the study of residual stress distribution at a dissimilar metal weld (DMW) of nuclear reactor nozzle. The paper extends some of the recent research on this subject by investigating the effect of weld sequence and nozzle length design on the residual stress distributions. It also investigates the effect of a partial excavation repair and a weld overlay on the residual stress distribution. As a result, some of the important residual stress features at DMW are revealed and these features are discussed and summarized in the paper.

A numerical prediction of residual stress for a thin-walled part with geometrical features fabricated by GMA-based additive manufacturing

2019 ◽  
Vol 26 (2) ◽  
pp. 299-308
Author(s):  
Rong Li ◽  
Jun Xiong
Keyword(s):  
Residual Stress ◽  
Additive Manufacturing ◽  
Stress Distribution ◽  
Residual Stresses ◽  
Residual Stress Distribution ◽  
Stress Distributions ◽  
Content Type ◽  
Geometrical Features ◽  
Longitudinal Residual Stress ◽  
Thin Walled

Purpose An accurate prediction of process-induced residual stress is necessary to prevent large distortion and cracks in gas metal arc (GMA)-based additive manufactured parts, especially thin-walled parts. The purpose of this study is to present an investigation into predicting the residual stress distributions of a thin-walled component with geometrical features. Design/methodology/approach A coupled thermo-mechanical finite element model considering a general Goldak double ellipsoidal heat source is built for a thin-walled component with geometrical features. To confirm the accuracy of the model, corresponding experiments are performed using a positional deposition method in which the torch is tilted from the normal direction of the substrate. During the experiment, the thermal cycle curves of locations on the substrate are obtained by thermocouples. The residual stresses on the substrate and part are measured using X-ray diffraction. The validated model is used to investigate the thermal stress evolution and residual stress distributions of the substrate and part. Findings Decent agreements are achieved after comparing the experimental and simulated results. It is shown that the geometrical feature of the part gives rise to an asymmetrical transversal residual stress distribution on the substrate surface, while it has a minimal influence on the longitudinal residual stress distribution. The residual stress distributions of the part are spatially uneven. The longitudinal tensile residual stress is the prominent residual stress in the central area of the component. Large wall-growth tensile residual stresses, which may cause delamination, appear at both ends of the component and the substrate–component interfaces. Originality/value The predicted residual stress distributions of the thin-walled part with geometrical features are helpful to understand the influence of geometry on the thermo-mechanical behavior in GMA-based additive manufacturing.

Neutron Diffraction Studies of Residual Stresses Around Gouges and Gouged Dents

2012 ◽  
Author(s):  
Lynann Clapham ◽  
Vijay Babbar ◽  
Thomas Gnaeupel-Herold ◽  
Remi Batisse ◽  
Mures Zarea
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Neutron Diffraction ◽  
Stress Field ◽  
Residual Stresses ◽  
Wall Stress ◽  
Outer Wall ◽  
Stress Distributions ◽  
Wall Surface ◽  
Residual Stress Field

The residual stress pattern surrounding gouges is complex and, to date, has not been accurately modeled using stress modeling software. Thus measurement of these stress distributions is necessary. Neutron diffraction is the only experimental method with the capability of directly evaluating residual strain throughout the entire thickness of a pipe wall, in and around dent or gouged regions. Neutron diffraction measurements were conducted at the NIST reactor on three gouged dents in X52 pipeline sections. These were part of a larger sample set examined as part of the comprehensive MD4-1 PRCI/DOT PHMSA project. Gouges contained in pipeline sections were termed BEA161 (primarily a gouge with little denting), and BEA178 (mild gouging, very large dent). Measurements were also conducted on a coupon sample – P22, that was created as part of an earlier study. For the moderate gouges with little or no associated denting (BEA161 and P22) the residual stress field was highly localized around the immediate gouge vicinity (except where there was some denting present). The through wall stress distributions were similar at most locations — characterized by neutral or moderate hoop and axial stresses (50–100MPa) at the outer wall surface (i.e. at the gouge itself) gradually becoming highly compressive (up to −600MPa) at the inner wall surface. The other sample (BEA178) exhibited a very mild gouge with significant denting, and the results were very different. The denting process associated with this kind of gouge+dent dominated the residual stresses, making the residual stress distribution very complex. In addition, rather than having a residual stress field that is localized in the immediate gouge vicinity, the varying stress distribution extends to the edge of the dented region..

Crack Analysis of a Pressure Vessel Using the API 579-1/ASME FFS-1

2017 ◽  
Author(s):  
Jose de Jesus L. Carvajalino ◽  
José Luiz F. Freire ◽  
Vitor Eboli L. Paiva ◽  
José Eduardo Maneschy ◽  
Jorge G. Diaz ◽  
...  
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Stress Distribution ◽  
Residual Stresses ◽  
Duplex Stainless Steel ◽  
Pressure Vessel ◽  
Welding Process ◽  
Residual Stress Distribution ◽  
The Other ◽  
Austenitic Steels

This paper presents a structural integrity evaluation of a duplex stainless steel pressure vessel containing several flaws detected in a longitudinal weld. The evaluation had the objective of determining whether the pressure vessel was suitable to continue in operation or whether it should be immediately repaired or even replaced. Due to timely issues, a first analysis was conducted in accordance with the 2007 edition of the API 579-1/ASME FFS-1 Standard [1]. A second analysis was later repeated based on the 2016 edition [1]. Results obtained from both analyses were compared and presented relevant differences caused by the other calculation procedures used to determine residual stresses generated in the longitudinal welding. The assessment was based on the Failure Assessment Diagram (FAD). The existing indications were detected by ultrasonic examination and were located in one longitudinal weld. The assessment evaluations used stress intensity factors for the opening mode I, KI, obtained for two cases: 1) the combination of the several supposedly interacting cracks into an equivalent crack using the interaction criteria presented in [1]; 2) the allocation of the multiple cracks into a finite element model that took into consideration, more realistically, the interaction among the individual cracks. The total loads and stresses considered in the analysis resulted from a superposition of the design pressure stress and the residual stresses induced by the welding process. Due to lack of information on the material fracture toughness for the duplex stainless steel used in the vessel, the material toughness was estimated using a lower bound value suggested in [1] for common welded stainless austenitic steels, although higher values can be predicted for duplex steels by extending the use of a transition master curve as presented and discussed elsewhere [2–7] and by employing specific Charpy test results for the vessel material. One of the key aspects of the problem was the calculation of the residual stress distribution imposed by the welding process. Two procedures were adopted: one available in the API/ASME Standard issued in 2007, and the other in the 2016 release. The results presented in this paper have demonstrated that the limits of the Standard 2007 are conservatively satisfied when the Level 3 assessment is applied. The re-analysis of the vessel when subjected to the residual stress distribution presented in the newest 2016 edition leads to consider the vessel safe under an assessment Level 2. The overall conclusion was that the damaged pressure vessel could continue in service under restrictions of the development of an inspection plan to verify the absence of future crack growth.

SCC Assessment Based on Probability Fracture Mechanics Considering SCC Initiation and Propagation Under Residual Stress Fields Generated by Machining and Welding Process of Pipes

2013 ◽  
Author(s):  
Masahito Mochizuki ◽  
Ryohei Ihara ◽  
Jinya Katsuyama ◽  
Makoto Udagawa
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Crack Growth ◽  
Welding Process ◽  
Residual Stress Distribution ◽  
Initiation Time ◽  
Butt Welding ◽  
Surface Machining ◽  
Inner Surface ◽  
Growth Analyses

Stress corrosion cracking (SCC) has been observed near the welded zones of pipes made of austenitic stainless steel type 316L. Residual stress is an important factor for SCC. In the joining processes of pipes, butt welding is conducted after surface machining. Residual stress is generated by both processes, and the residual stress distribution by surface machining is varied by the subsequent butt-welding process. In this study, numerical analysis of the residual stress distribution by butt welding after surface machining was performed by the finite element method. The SCC initiation time was estimated by the residual stress obtained at the inner surface. SCC growth analyses based on probability fracture mechanics were performed by using the SCC initiation time and the residual stress distribution. As a result, the residual stress distribution in the axial direction due to butt welding after surface machining has high tensile stress exceeding 1000 MPa at the inner surface. The effect of SCC initiation on leakage probability is not as significant as the effect of plastic strain on the crack growth rate. However, to perform crack growth analyses considering SCC initiation, evaluation of the residual stress due to surface machining and welding is important.

The effect of high compressive loading on residual stresses and fatigue crack growth at cold expanded holes

2003 ◽  
Vol 38 (5) ◽  
pp. 419-427 ◽  
Author(s):  
D Stefanescu ◽  
M Dutta ◽  
D Q Wang ◽  
L Edwards ◽  
M. E Fitzpatrick
Keyword(s):  
Residual Stress ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Stress Distribution ◽  
Residual Stresses ◽  
Crack Growth ◽  
Compressive Loading ◽  
Residual Stress Distribution ◽  
Residual Stress Field ◽  
X Ray

The effect of monotonic compressive loading on the residual stresses developed at cold expanded fastener holes has been investigated using the neutron and X-ray diffraction techniques. Monotonic loading models the effect of the peak of a fatigue loading sequence experienced before a crack is initiated. It was found that the compressive loading significantly affected the residual stress distribution. A low load relaxed only the stresses near to the bore of the hole, whereas a larger load affected the stress distribution over a greater area. Residual stresses measured at the mandrel entrance face were more affected by the compressive loading than the residual stresses measured at the other segments of thickness. The comparison between the X-ray and neutron diffraction results showed that the techniques complemented each other well, enabling a three-dimensional residual stress distribution to be derived. This distribution was used for modelling the effect of compressive loading on fatigue crack growth, using a linear elastic fracture mechanics approach and assuming a stabilized residual stress field.

Residual Stress Evaluation of Dissimilar Weld Joint Using Reactor Vessel Outlet Nozzle Mock-Up Model (Report-1)

2008 ◽  
Author(s):  
Itaru Muroya ◽  
Youichi Iwamoto ◽  
Naoki Ogawa ◽  
Kiminobu Hojo ◽  
Kazuo Ogawa
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Welding Process ◽  
Reactor Vessel ◽  
Residual Stress Distribution ◽  
Test Model ◽  
Alloy 600 ◽  
Outlet Nozzle ◽  
Stress Evaluation ◽  
Weld Region

In recent years, the occurrence of primary water stress corrosion cracking (PWSCC) in Alloy 600 weld regions of PWR plants has increased. In order to evaluate the crack propagation of PWSCC, it is required to estimate stress distribution including residual stress and operational stress through the wall thickness of the Alloy 600 weld region. In a national project in Japan for the purpose of establishing residual stress evaluation method, two test models were produced based on a reactor vessel outlet nozzle of Japanese PWR plants. One (Test model A) was produced using the same welding process applied in Japanese PWR plants in order to measure residual stress distribution of the Alloy 132 weld region. The other (Test model B) was produced using the same fabrication process in Japanese PWR plants in order to measure stress distribution change of the Alloy 132 weld region during fabrication process such as a hydrostatic test, welding a main coolant pipe to the stainless steel safe end. For Test model A, residual stress distribution was obtained using FE analysis, and was compared with the measured stress distribution. By comparing results, it was confirmed that the FE analysis result was in good agreement with the measurement result. For mock up test model B, the stress distribution of selected fabrication processes were measured using the Deep Hole Drilling (DHD) method. From these measurement results, it was found that the stress distribution in thickness direction at the center of the Alloy 132 weld line was changed largely during welding process of the safe end to the main coolant pipe.

Experimental Analysis of Repair Welding Alternatives for Shipbuilding DH36 Plates

2020 ◽  
Vol 64 (04) ◽  
pp. 384-391
Author(s):  
Tetyana Gurova ◽  
Segen F. Estefen ◽  
Anatoli Leontiev ◽  
Plinio T. Barbosa ◽  
Valentin Zhukov ◽  
...  
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Best Practice ◽  
Welding Process ◽  
Offshore Structures ◽  
Residual Stress Distribution ◽  
Shipbuilding Industry ◽  
Repair Welding ◽  
Ship Construction ◽  
Repair Techniques

Repair by welding is widely used in the shipbuilding industry during ship construction. The effect of the residual stress distribution induced by the welding process on the ship structure is important for the repair effectiveness. This article presents an experimental study of the residual stress distribution induced by repair welding in the plates that are typically used in ships and offshore structures. Different repair techniques are evaluated to identify the best practice associated with residual stress values. Recommendations for repair welding are discussed, and modifications to the present practice are proposed.

Sign in / Sign up

Export Citation Format

Share Document