Residual Stresses Evaluation in Welds and Implications for Design for Pressure Vessel Applications

2006 ◽  
Vol 128 (4) ◽  
pp. 638-643 ◽  
Author(s):  
John W. H. Price ◽  
Anna M. Pardowska ◽  
Raafat Ibrahim ◽  
Trevor R. Finlayson
Keyword(s):  
Residual Stress ◽  
Neutron Diffraction ◽  
Residual Stresses ◽  
Pressure Vessel ◽  
Scale Up ◽  
Small Scale ◽  
Fatigue And Fracture ◽  
Single Bead ◽  
Key Issues ◽  
Neutron Diffraction Technique

Welding residual stresses have important consequences on the performance of engineering components. High residual stresses may lead to loss of performance in corrosion, fatigue, and fracture but as yet these consequences are poorly quantified. The major cause of this is that residual stress often remains the single largest unknown in industrial damage situations since it is difficult to measure or estimate theoretically. One of the key issues in the study of residual stress is that the detail of the stress distribution on a small scale (in the order of millimeters) can be important. In this paper, the neutron diffraction technique is used which while it is a very expensive technique, is capable of nondestructively measuring residual stresses at this scale up to a depth of 35mm. The investigation reported compares the residual stress characteristics due to various restraints for a single bead and in fully restrained samples with different numbers of beads. This paper considers the results of the neutron diffraction studies in relation to fitness for purpose guidance and implication for pressure vessel design.

Residual Stresses Evaluation in Welds and Implications for Design for Pressure Vessel Applications

2005 ◽  
Author(s):  
John W. H. Price ◽  
Anna Paradowska ◽  
Trevor Finlayson
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Residual Stresses ◽  
Scale Up ◽  
Small Scale ◽  
Fitness For Purpose ◽  
Fatigue And Fracture ◽  
Single Bead ◽  
Key Issues ◽  
Neutron Diffraction Technique

Welding residual stresses have important consequences on the performance of engineering components. High residual stresses lead to loss of performance in corrosion, fatigue and fracture but as yet these consequences are poorly quantified. The major cause of this is that residual stress often remains the single largest unknown in industrial damage situations since they are difficult to measure or estimate theoretically. One of the key issues in the study of residual stress is that the detail of the stress distribution on a small scale (in the order of millimetres) can be important. In this paper, the neutron diffraction technique is used which while it is a very expensive technique, is capable of non-destructively measuring residual stresses at this scale up to a depth of 35mm. The investigation reported compares the residual stress characteristics due to various restraints for a single bead and in fully restrained samples with different numbers of beads. The findings have important consequences with respect to design of welding procedures and fitness for purpose assessments.

Neutron Diffraction Evaluation of Residual Stress for Several Welding Arrangements and Comparison With Fitness-for-Purpose Assessments

2008 ◽  
Vol 130 (1) ◽  
Author(s):  
Anna M. Pardowska ◽  
John W. H. Price ◽  
Raafat Ibrahim ◽  
Trevor R. Finlayson
Keyword(s):  
Residual Stress ◽  
Neutron Diffraction ◽  
Assessment Procedure ◽  
Stress Distributions ◽  
Fitness For Purpose ◽  
Single Bead ◽  
Surface Measurements ◽  
Number Of Passes ◽  
Neutron Diffraction Technique ◽  
Level 2

In this research, the neutron diffraction technique was used to investigate and compare the residual stress characteristics in several weld arrangements. This research has focused on the effects on residual stress of restraint condition applied during welding, the start and end of the weld for a single bead, and increasing the number of passes. The measured residual stress distributions are normalized by the yield strength of the material and compared with distribution provided in fitness-for-purpose procedures. It is found that the current safety assessment procedure BS 7910 and R6 Level 1 significantly conservative for longitudinal stresses outside the weld and heat affected zone, and for transverse residual stress across the weldment for surface measurements. For a less conservative assessment, R6 Level 2 is recommended, however, even if this assessment is often conservative, in particular, for transverse residual stresses.

scholarly journals Advances in Neutron Diffraction for Engineering Residual Stress Measurements

1999 ◽  
Vol 33 (1-4) ◽  
pp. 151-171 ◽  
Author(s):  
A. N. Ezeilo ◽  
G. A. Webster
Keyword(s):  
Residual Stress ◽  
Neutron Diffraction ◽  
Residual Stresses ◽  
Measuring Method ◽  
Manufacturing Processes ◽  
Stress Measurements ◽  
Code Of Practice ◽  
Numerical Predictions ◽  
Engineering Materials ◽  
Neutron Diffraction Technique

The increasing awareness amongst engineers and designers, of the significance of residual stresses in influencing the useful lifetimes of engineering components, has resulted in more demanding expectations being placed on the methods used to obtain these stresses. The neutron diffraction technique is emerging as the most attractive measuring method as the residual stresses can usually be obtained non-destructively to depths of up to 40 mm in some common engineering materials. Although it is a relatively new technique it has been used to measure the residual stresses in a range of engineering materials introduced by a wide variety of manufacturing processes such as welding, quenching, machining, shot peening, cold hole expansion and autofrettage.In this paper the neutron diffraction technique for non-destructive residual stress measurements will be described including methods used to validate the measurements. Precautions that should be taken in order to obtain reliable measurements are outlined. Procedures being investigated in order to produce a code of practice will be presented. A representative selection of stress distributions developed by a range of manufacturing processes is examined. Some comparisons are made with strain gauge, X-ray and numerical predictions. It is shown how the results can be of benefit in engineering stress analysis.

Interpretation of residual stress distributions in previously loaded cracked beams

1992 ◽  
Vol 27 (2) ◽  
pp. 77-83 ◽  
Author(s):  
D J Smith ◽  
M A M Bourke ◽  
A P Hodgson ◽  
G A Webster ◽  
P J Webster
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Neutron Diffraction ◽  
Residual Stresses ◽  
Crack Tip ◽  
Stress Distributions ◽  
Element Analysis ◽  
Sampling Volume ◽  
Neutron Diffraction Technique ◽  
Good Agreement

The measurement and prediction of residual stress distributions in a fatigue pre-cracked and a plastically overloaded A533B steel beam are described. The residual stresses were obtained experimentally using the neutron diffraction technique. Finite element analysis was employed to predict the elastic-plastic response and residual stresses introduced after overloading. Comparison of the experimental results have been made with the finite element predictions (for both plane stress and strain conditions) averaged over the same sampling volume used to make the neutron diffraction measurements. It has been found that good agreement is achieved away from the near crack tip region. However, close to the crack tip the measured compressive residual stresses are significantly smaller than predicted. This difference is attributed to the A533B steel exhibiting a Bauschinger effect and yielding at a lower stress after a stress reversal.

Neutron diffraction analysis of the residual stress distribution in a bent bar

2000 ◽  
Vol 35 (4) ◽  
pp. 235-246 ◽  
Author(s):  
A. N Ezeilo ◽  
G. A Webster
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Neutron Diffraction ◽  
Residual Stresses ◽  
Residual Stress Distribution ◽  
Four Point Bending ◽  
Refinement Method ◽  
Nickel Based Alloy ◽  
Neutron Diffraction Technique ◽  
Profile Refinement

A well-characterized residual stress distribution resulting from four-point bending has been analysed using the neutron diffraction technique. Residual stresses were obtained from the strains measured at discrete positions through the bent bar on the (111) and (311) crystal planes of a nickel-based alloy using the appropriate diffraction elastic constants. In addition a profile refinement method was used to determine the residual stresses from average strains from all the diffraction peaks in the spectrum. The measured residual stress profiles have also been compared with strain gauge data and with analytical and finite element predictions. It has been established that the profile refinement approach gives stresses which most closely match those obtained by the non-diffraction techniques.

The Effectiveness of Cold Rolling for Residual Stress Reduction in Quenched 7050 Aluminium Alloy Forgings

2016 ◽  
Vol 716 ◽  
pp. 521-527 ◽  
Author(s):  
Ran Pan ◽  
Catrin Mair Davies ◽  
Wei Zhang ◽  
Zhusheng Shi ◽  
Thilo Pirling ◽  
...  
Keyword(s):  
Residual Stress ◽  
Neutron Diffraction ◽  
Residual Stresses ◽  
Cold Rolling ◽  
Stress Reduction ◽  
Stress Distributions ◽  
Effective Technique ◽  
The Core ◽  
Cold Rolled ◽  
Neutron Diffraction Technique

Residual stresses are often introduced into aluminum alloys through quenching processes performed to generate the required microstructure. Such residual stresses are known to be deleterious to the integrity of the component. Methods to mitigate residual stresses in quenched components are therefore of great importance. Cold rolling has been proposed as an effective technique to remove residual stresses in large components. In this work, the effectiveness of cold rolling in reducing the residual stresses in quenched blocks AA7050 has been quantified using the neutron diffraction technique. Neutron diffraction measurements have been performed on two blocks one quenched and the other quenched & cold rolled block. Comparing the residual stress distributions pre and post rolling it has been found that cold rolling almost eliminates the tensile residual stresses in the core of the block, however it generates large tensile residual stresses d in a shallow region near the surface of the block.

Residual Stress Modeling of Warm-Bent Tight-Radius CANDU Feeder Bends

2008 ◽  
Author(s):  
Y. Ding ◽  
M. Yetisir
Keyword(s):  
Residual Stress ◽  
Neutron Diffraction ◽  
Residual Stresses ◽  
Thickness Distribution ◽  
Measurement Data ◽  
Future Research ◽  
Cross Sectional ◽  
Simulation Results ◽  
Sectional Shape ◽  
Neutron Diffraction Technique

In one CANDU® nuclear station, a few feeder piping failures have occurred because of stress corrosion cracking. All the cracks were located in tight-radius bends. Root cause analyses indicated that the residual stress played a significant role in these failures. Residual stress measurements using the neutron diffraction technique have been performed to quantify the residual stresses for a large number of feeder bends. Numerical simulations have also been performed to supplement the measurement data. This paper presents the modeling work carried out for 2.5” warm-bent tight-radius feeder bends using LS-DYNA®. The warm-bending process was divided into heating, bending, springback and cooling stages. The simulation results were compared to the measurement data using the neutron diffraction technique. Good agreement was achieved between the trends of simulation results and the measured residual stresses in feeder bends. Additionally, it was found that the predicted cross-sectional shape and wall thickness distribution agreed well with the measurements. Limitations of the simulation work were summarized and recommendations for future research were made based on this study.

Neutron Diffraction Evaluation of Residual Stress for Several Welding Arrangements and Comparison With Fitness-for-Purpose Assessments

2006 ◽  
Author(s):  
Anna M. Paradowska ◽  
John W. H. Price ◽  
Raafat Ibrahim ◽  
Trevor Finlayson ◽  
Richard Blevins ◽  
...  
Keyword(s):  
Residual Stress ◽  
Neutron Diffraction ◽  
Assessment Procedure ◽  
Stress Distributions ◽  
Fitness For Purpose ◽  
Single Bead ◽  
Level 1 ◽  
Number Of Passes ◽  
Neutron Diffraction Technique ◽  
Level 2

In this research the neutron diffraction technique was used to investigate and compare the residual stress characteristics in a several weld arrangements. This research has focused on the effects on residual stress of: • restraint condition applied during welding, • the start and end of the weld for a single bead, and • increasing the number of passes. The measured residual stress distributions are normalized by the yield strength of the material and compared with distribution provided in fitness-for-purpose procedures. It is found that the current safety assessment procedure BS 7910 and R6 Level 1 are significantly conservative. For a less conservative assessment R6 Level 2 is recommended, however even this assessment is often conservative, in particular for transverse residual stresses.

Characterization of Welding-Induced Residual Stress Using Neutron Diffraction Technique

2017 ◽  
Vol 139 (6) ◽  
Author(s):  
M. Clyde Zondi ◽  
Andrew Venter ◽  
Deon Marais ◽  
Clinton Bemont
Keyword(s):  
Residual Stress ◽  
Neutron Diffraction ◽  
Pressure Vessel ◽  
Pressure Vessels ◽  
Stress Effect ◽  
Industrial Operations ◽  
Plant Equipment ◽  
Hoop Stresses ◽  
Neutron Diffraction Technique

Pressure vessels comprise critical plant equipment within industrial operations. The fact that the vessel operates under pressure, and may carry toxic, dangerous, or hazardous contents, necessitates that care is taken to ensure safety of humans operating it and the environment within which it operates. Residual stress developed during welding of pressure vessel structures can adversely affects fatigue life (mean stress effect) of such structure and lead to corrosion crack growth. The present study applies the neutron diffraction (ND) technique to formulate the stress field distribution of a nozzle-to-shell weld joint of a pressure vessel. A number of experiments are conducted using the submerged arc welding (SAW) process at various parametric combinations to develop a number of specimens with different stress profiles. It is shown that the hoop stresses close to the weld center line (WCL) are highly tensile and have values close to the yield strength of the material. The ideal parametric combination is also determined based on the results with lowest stresses. The results obtained in this study are congruent to the results of similar studies in the literature.

scholarly journals Residual Stress Measurements in Mo/CuCrZr Tiles Using Neutron Diffraction

2008 ◽  
Vol 59 ◽  
pp. 299-303
Author(s):  
K. Mergia ◽  
Marco Grattarola ◽  
S. Messoloras ◽  
Carlo Gualco ◽  
Michael Hofmann
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Neutron Diffraction ◽  
Residual Stresses ◽  
Heat Sink ◽  
High Yield ◽  
Fusion Reactors ◽  
Plasma Facing Components ◽  
Induced Stresses ◽  
Compliant Layer

In plasma facing components (PFC) for nuclear fusion reactors tungsten or carbon based tiles need to be cooled through a heat sink. The joint between the PFC and the heat sink can be realized using a brazing process through the employment of compliant layer of either a low yield material, like copper, or a high yield material, like molybdenum. Experimental verification of the induced stresses during the brazing process is of vital importance. Strains and residual stresses have been measured in Mo/CuCrZr brazed tiles using neutron diffraction. The strains and stresses were measured in Mo tile along the weld direction and at different distances from it. The experimental results are compared with Finite Element Simulations.

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