Advanced Post Weld Treatment of a Repair Weld in an Austenitic Header

2005 ◽  
Author(s):  
T. B. Brown ◽  
T. A. Dauda ◽  
C. E. Truman ◽  
D. J. Smith
Keyword(s):  
Residual Stress ◽  
Nuclear Power ◽  
Electricity Production ◽  
Hole Drilling ◽  
The European Union ◽  
Suitable Alternative ◽  
Before And After ◽  
Development And Validation ◽  
Outside Diameter ◽  
Repair Techniques

The repair or replacement of nuclear power components outwith code is a very cumbersome, costly and time consuming exercise which is responsible for long plant shut down time and corresponding loss of electricity production. The aim of the European Union sponsored project ENPOWER was to produce advanced repair techniques and procedures for application in such circumstances to improve the integrity and life of the component and eliminate the need for expensive and sometimes difficult to execute global Post Weld Heat Treatment (PWHT). This paper describes the development and validation of an Alternative Post Weld Treatment (APWT) for a repair weld in an austenitic header component consisting of a 217mm outside diameter by 202mm thick tube plate welded to a 64mm thick cylindrical header. The development of the method using finite element (FE) analysis and the predicted residual stresses before and after application of the APWT are given. Application of the method to a full size mock up of the header is described. Comparison is made between the FE predictions and Deep Hole Drilling through thickness residual stress measurements. This leads to the conclusion that the APWT method is a suitable alternative to a standard PWHT for the control of residual stress in repair welds.

An Analysis of Residual Stress Improvement for a Dissimilar Metal Nozzle-to-Pipe Weld by Using the Heat Sink Method

2008 ◽  
Author(s):  
J.-S. Park ◽  
J.-M. Kim ◽  
G.-H. Sohn ◽  
Y.-H. Kim
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Heat Sink ◽  
Nuclear Power ◽  
Power Plants ◽  
Base Alloy ◽  
Fatigue Cracking ◽  
Hole Drilling ◽  
Fe Model ◽  
Dissimilar Metal

This study is concerned with the mechanics analysis of residual stress improvement by the heat sink method applied to a dissimilar metal weld (DMW) for the use in nuclear power plants. The DMW joint considered here is composed of ferritic low-alloy steel nozzle, austenitic stainless steel safe-end, and nickel-base alloy A52 weld metal. To prepare the DMW joint with a narrow-gap, the gas tungsten arc welding (GTAW) process is utilized, and the heat sink method is employed to control thermal gradients developed in the critical region of work pieces during welding. Weld residual stresses are computed by the non-linear thermal elasto-plastic analysis using the axisymmetric finite element (FE) model, for which temperature-dependent thermal and mechanical properties of the materials are considered. A full-scale mock-up test is conducted to validate analytical solution for the DMW joint, and residual stresses are measured by using the hole-drilling method. Results of the FE modeling and mock-up test for the DMW joint are compared and effects of the heat sink method are discussed. It is found that a significant amount of residual compressive stresses can be developed on the inner surface of the DMW joint by using the heat sink method, which can effectively reduce the susceptibility of the welded materials to stress corrosion or fatigue cracking.

Residual Stresses in Steel-Titanium Composite Manufactured by Explosive Welding

2012 ◽  
Vol 726 ◽  
pp. 125-132 ◽  
Author(s):  
Aleksander Karolczuk ◽  
Krzysztof Kluger ◽  
Mateusz Kowalski ◽  
Fabian Żok ◽  
Grzegorz Robak
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Residual Stresses ◽  
Hole Drilling ◽  
Element Analysis ◽  
Welded Steel ◽  
Hole Drilling Method ◽  
Drilling Method ◽  
Before And After ◽  
Stress States

The main aim of the paper is determination of residual stresses in explosively welded steel-titanium bimetal. The analysis considers two bimetallic specimens: before and after the heat treatment. In residual stress determination the hole drilling method along with finite element analysis were applied. The results show different residual stress states depending on the heat treatment. The obtained results are confirmed by thermal stress calculation.

A Study of Redistribution of Residual Stress and Hardness Due to Welding and Surface-Machining at Girth Welded Joint

2009 ◽  
Author(s):  
Masahito Mochizuki ◽  
Jinya Katsuyama ◽  
Ryohei Ihara ◽  
Hiroaki Mori ◽  
Yoshiki Mikami ◽  
...  
Keyword(s):  
Residual Stress ◽  
Nuclear Power ◽  
Power Plants ◽  
Crack Growth Behavior ◽  
Internal Diameter ◽  
Butt Weld ◽  
Butt Welding ◽  
Surface Machining ◽  
Inner Surface ◽  
Before And After

Stress corrosion cracking (SCC) near the welded zone of core internals and recirculation piping of Type 316L stainless steel in BWR nuclear power plants has been observed at the surface where tensile residual stress exists due to welding and/or surface-machining. It is well-known that butt-welding of austenitic piping causes the tensile stress in the inner surface of the pipe and that surface-machining is usually conducted before and after piping butt-welding to match the internal diameter (ID) of pipes and to provide a smooth surface finish but some amount of hardening. The SCCs near the welds of Ni-based alloys have been observed in the environment of primary water coolant, which is so called PWSCC. In this case, both residual stress and hardening are also the most important factors induced by welding as well as surface-machining in the regions of interest. In this work, therefore, Vickers hardness and residual stress distributions at work hardened layer such as inner surface of piping butt-weld by surface-machining before and after welding were experimentally evaluated. A simulation using a local micron-scale finite element method (FEM) model has been performed to support the understanding of experimental data by a model which was proposed in previous paper (PVP2006 and 2008 [1, 2]). Redistribution behavior of residual stress by welding after surface-machining will be discussed based on experimental and analytical results with regard to crack growth behavior.

Reduce the Residual Stress of Welded Structures by Post-Weld Vibration

2005 ◽  
Vol 490-491 ◽  
pp. 102-106 ◽  
Author(s):  
De Lin Rao ◽  
Zheng Qiang Zhu ◽  
Li Gong Chen ◽  
Chunzhen Ni
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Residual Stresses ◽  
Mechanical Vibration ◽  
Welding Process ◽  
Hole Drilling ◽  
Welded Structures ◽  
Hole Drilling Method ◽  
Drilling Method ◽  
Before And After

The existence of residual stresses caused by the welding process is an important reason of cracking and distortion in welded metal structures that may affect the fatigue life and dimensional stability significantly. Heat treatment is one of the traditional methods to relieve the residual stresses. But it is often limited by the manufacturing condition and the size of the structures. In this paper a procedure called vibratory stress relief (VSR) is discussed. VSR is a process to reduce and re-distribute the internal residual stresses of welded structures by means of post-weld mechanical vibration. The effectiveness of VSR on the residual stresses of welded structures, including the drums of hoist machine and thick stainless steel plate are investigated. Parameters of VSR procedure are described in the paper. Residual stresses on weld bead are measured before and after VSR treatment by hole-drilling method and about 30%~50% reduction of residual stresses are observed. The results show that VSR process can reduce the residual stress both middle carbon steel (Q345) and stainless steel (304L) welded structures effectively.

scholarly journals Finite Element Analysis and Experimental Evaluation of Residual Stress of Zr-4 alloys Processed through Swaging

Metals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1281 ◽  
Author(s):  
Gaurav Singh ◽  
Bijit Kalita ◽  
K. I. Vishnu Narayanan ◽  
Umesh Kumar Arora ◽  
Manas M. Mahapatra ◽  
...  
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Nuclear Power ◽  
Zirconium Alloy ◽  
True Strain ◽  
Three Dimensional ◽  
Element Model ◽  
Hole Drilling ◽  
Element Analysis ◽  
Hole Drilling Method

Zirconium alloy has been extensively used as a cladding material in nuclear power reactors due to its low neutron absorption cross section, excellent mechanical properties, and corrosion resistance. The influence of the swaging parameter, feed rate (0.7, 1.25, 2 m/min) on residual stress induced in Zr-4 alloy is investigated in the present work. A three-dimensional finite element model was implemented in the Deform 3D software to simulate the rotary swaging (RS) process over a circular rod of Zr-4 alloy. The simulation results based on the 3D framework provide a detailed insight of residual stress, true stress versus true strain and force applied over the rod during the multiple pass swaging process; the results are compared with experimental results. The experimental hole drilling method is used to determine the residual stresses on swaged zirconium alloy at different feed rates (0.7, 1.25, and 2 m/min). A similar trend of residual stress between experimental and numerical results from the surface to the center on the swaged rod samples is observed. The same magnitude of residual stress at the surface of the swaged Zr-4 rod is also observed. It is found to be compressive at the surface and tensile in the center of the samples, as observed in the present work.

Residual Stresses Redistribution in Girth Weld Pipe After Reduction of the Wall Thickness

2017 ◽  
Author(s):  
Xavier Ficquet ◽  
Remi Romac ◽  
Karim Serasli ◽  
Ed J. Kingston
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Wall Thickness ◽  
Hole Drilling ◽  
Gas Oil ◽  
Internal Corrosion ◽  
The North ◽  
Before And After ◽  
The North Sea ◽  
Welded Pipe

Girth welded pipes, such as those located offshore on platforms in the North Sea, are subjected to highly corrosive environment. The need to consider welding residual stresses in the assessment of the fitness for service and damages to these pipes when investigating local corrosion damages across a welded region is therefore important for the operators of the platforms and the manufacturers of the pipes. This paper presents a review of work carried out to ascertain the welding residual stresses present within a thin-walled girth welded pipe mock-up made from steel API 5LX Grade 52 before and after reduction of the wall thickness. The mock-up was manufactured to replicate typical pipes used to convey gas, oil and water through the platforms. The mock-up was of diameter 30” and of thickness 19mm. The incremental deep hole drilling (iDHD), contour, hole drilling, XRD, and ultrasonic technique were applied to characterise the residual stresses in the weld and heat affected zone of the specimen. The residual stresses were then measured during the manufacture of a groove located on the weld at the ID and were compared to an FE prediction. Ultrasonic measurements were then carried out on the outer surface of the pipe and show a significant increase in the residual stress and could be used to monitor the changes in the residual stress caused by internal corrosion.

Effect of Ageing on Residual Stresses in a Girth Welded Stainless Steel 316 L Pipe

2019 ◽  
Author(s):  
R. J. Coulthard ◽  
M. Mostafavi ◽  
C. E. Truman
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Residual Stresses ◽  
Service Use ◽  
Hole Drilling ◽  
Stainless Steel 316L ◽  
Weld Residual Stress ◽  
Before And After ◽  
Maximum Residual Stress ◽  
Stainless Steel 316

Abstract Residual stresses within welded components can redistribute when exposed to high temperatures and large levels of loading. The ageing process for a specimen attempts to replicate the temperature regime experienced during typical service use of the component, redistributing stresses from the as-welded condition to post-ageing. The aim of this investigation was to study the effects of ageing on weld residual stress redistribution and to evaluate the changes in the residual stress profiles before and after the pipe had been aged. In this investigation the through thickness residual stresses within a narrow gap girth TIG welded stainless steel 316L pipe were measured. The ageing of the pipe specimen involved heating to 400°C for 3000 hours. To measure residual stress the incremental Deep-Hole Drilling (iDHD) method was employed; two measurements were taken, once before and after ageing. Analysis of the measured pre and post-ageing residual stresses showed a consistent reduction in the magnitude of approximately 50 MPa, corresponding to the change in the yield stress of the material at room and elevated (400°C) temperatures; the maximum residual stress, of 450 MPa, was measured at 4 mm from the external surface of the pipe.

Effect of Ageing on Residual Stresses in Welded Stainless Steel Cylinders

2012 ◽  
Author(s):  
Son Do ◽  
David Smith ◽  
Mike Smith
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Residual Stresses ◽  
Hole Drilling ◽  
Hole Drilling Method ◽  
Power Stations ◽  
Before And After ◽  
Girth Welds ◽  
Effects Of Aging ◽  
Hoop Stresses

Operation of components at high temperature in power stations leads to the relaxation of residual stresses created in welded stainless steel cylinders. In this work a number of Esshete 1250 stainless steel cylinders containing girth welds and repair welds were manufactured. Two cylinders were then put to a furnace for 10,000hrs and 20,000hrs at 650°C. These conditions simulated the effects of aging. The residual stresses in the girth welds and repair welds before and after aging were measured using a number of methods based around the Deep Hole Drilling method. This paper describes the experiments carried out to obtain the through-wall distribution of stresses. It is evident that there was significant relaxation of the residual stresses due to aging. The peak tensile residual stress in girth welds was relaxed from 500MPa to 110MPa and the peak compressive residual stress in girth welds was relaxed from −301MPa to −135MPa after 10,000 hours at 650°C. The repair weld residual stresses were not only relaxed at the peak stresses but relaxed average levels from 220MPa to 140MPa for hoop stresses and from 180MPa to 145MPa for axial stresses. The implications of these findings are discussed in the context of future fracture tests.

Analysis on Residual Stresses of the Casing Part in Aeroengine Based on Hole-Drilling Method

2013 ◽  
Vol 770 ◽  
pp. 159-163
Author(s):  
Dian Ye Cao ◽  
Yin Fei Yang ◽  
Zhi Wu Liu ◽  
Jie Yu ◽  
Liang Li
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Residual Stresses ◽  
Annealing Treatment ◽  
Residual Stress Distribution ◽  
Hole Drilling ◽  
Hole Drilling Method ◽  
Measurement Results ◽  
Drilling Method ◽  
Before And After

In order to study the residual stress distribution of the casing part in aeroengine, the hole-drilling method was used to measure the residual stress before and after the annealing treatment. The measurement results indicated that the annealing treatment significantly improved the residual stress distribution in the part, and the residual stresses were showed as compressive stress. Meanwhile, the measured residual stress distribution would provide the basis for controlling the machining distortion of the casing part in aeroengine.

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