Numerical Methods to Predict Distortion in Welded Components

2008 ◽  
Author(s):  
N. A. Leggatt ◽  
R. J. Dennis ◽  
P. J. Bouchard ◽  
M. C. Smith
Keyword(s):  
Residual Stress ◽  
Numerical Methods ◽  
Structural Integrity ◽  
Large Strain ◽  
Stress Fields ◽  
Specimen Thickness ◽  
Single Bead ◽  
Stress Profiles ◽  
Welding Processes ◽  
Integrity Assessments

Numerical methods have been established to simulate welding processes. Of particular interest is the ability to predict residual stress fields. These fields are often used in support of structural integrity assessments where they have the potential, when accurately characterised, to offer significantly less conservative predictions of residual profiles compared to those found in assessment codes such as API 579, BS7910 and R6. However, accurate predictions of residual stress profiles that compare favourably with measurements do not necessarily suggest an accurate prediction of component distortions. This paper presents a series of results that compare predicted distortions for a variety of specimen mock-ups with measurements. A range of specimen thicknesses will be studied including, a 4mm thick DH-36 ferritic plate containing a single bead, a 4mm thick DH-36 ferritic plate containing fillet welds, a 25mm thick 316L austenitic plate containing a groove weld and a 35mm thick esshete 1250 austenitic disc containing a concentric ring weld. For each component, distortion measurements have been compared with the predicted distortions with a number of key features being investigated. These include the influence of ‘small’ vs ‘large’ strain deformation theory, the ability to predict distortions using simplified analysis methods such as simultaneous bead deposition and the influence of specimen thickness on the requirement for particular analysis features. The work provides an extremely useful insight into how existing numerical methods used to predict residual stress fields can be utilised to predict the distortions that occur as a result of the welding fabrication process.

Numerical Simulation of a Single Bead on Plate and Three Pass Slot Welds in Austenitic Stainless Steel

2011 ◽  
Author(s):  
Jijin Xu ◽  
Philippe Gilles
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Structural Integrity ◽  
Steel Plate ◽  
Task Group ◽  
Stress Fields ◽  
Stainless Steel Plate ◽  
First Case ◽  
Welding Processes

This paper provides the numerical simulations of two welding benchmark cases defined in the frame of the European Network on Neutron Techniques Standardization for Structural Integrity. The network involves over 35 organizations from industry and promotes the application of modern experimental and numerical techniques to problems related to the determination of residual stress and distortion in components. The first case issued by Task Group 1, addresses the estimation of residual stress fields around a single weld bead deposited on an austenitic stainless steel plate. The second case issued by Task Group 4, deals with the estimation of residual stress fields in a three-pass slot weld in an austenitic stainless steel plate. In both cases, the welding processes and types of material are same: tungsten-inert-gas welding and AISI 316 stainless steel. It is therefore of interest to compare these two studies in terms of differences between calculated / measured and in terms of the influences of the number of welding pass and heat input.

Analysis of circumferentially welded thin-walled cylinders to study the effects of tack weld orientations and joint root opening on residual stress fields

2009 ◽  
Vol 223 (5) ◽  
pp. 1037-1049 ◽  
Author(s):  
N U Dar ◽  
E M Qureshi ◽  
A M Malik ◽  
M M I Hammouda ◽  
R A Azeem
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Arc Welding ◽  
Operating Conditions ◽  
Stress Fields ◽  
Welded Structures ◽  
Prime Concern ◽  
Thin Walled ◽  
Tack Weld ◽  
Welding Processes

In recent years, the demand for resilient welded structures with excellent in-service load-bearing capacity has been growing rapidly. The operating conditions (thermal and/or structural loads) are becoming more stringent, putting immense pressure on welding engineers to secure excellent quality welded structures. The local, non-uniform heating and subsequent cooling during the welding processes cause complex thermal stress—strain fields to develop, which finally leads to residual stresses, distortions, and their adverse consequences. Residual stresses are of prime concern to industries producing weld-integrated structures around the globe because of their obvious potential to cause dimensional instability in welded structures, and contribute to premature fracture/failure along with significant reduction in fatigue strength and in-service performance of welded structures. Arc welding with single or multiple weld runs is an appropriate and cost-effective joining method to produce high-strength structures in these industries. Multi-field interaction in arc welding makes it a complex manufacturing process. A number of geometric and process parameters contribute significant stress levels in arc-welded structures. In the present analysis, parametric studies have been conducted for the effects of a critical geometric parameter (i.e. tack weld) on the corresponding residual stress fields in circumferentially welded thin-walled cylinders. Tack weld offers considerable resistance to the shrinkage, and the orientation and size of tacks can altogether alter stress patterns within the weldments. Hence, a critical analysis for the effects of tack weld orientation is desirable.

An Efficient Modelling Approach for Predicting Residual Stress in Power-Beam Welds

2019 ◽  
Author(s):  
Graeme Horne ◽  
Danny Thomas ◽  
Andrew Collett ◽  
Andrew Clay ◽  
Martin Cott ◽  
...  
Keyword(s):  
Residual Stress ◽  
Structural Integrity ◽  
Welding Residual Stress ◽  
Contour Method ◽  
Element Analysis ◽  
Stress Measurements ◽  
316L Austenitic Stainless Steel ◽  
Important Input ◽  
Integrity Assessments ◽  
Modelling Approach

Abstract The prediction of welding residual stress in components is often an important input to structural integrity assessments. An efficient modelling approach was developed for predicting residual stress in power-beam welds, including validation against residual stress measurements. Specifically, sequentially coupled thermo-mechanical finite element analysis was conducted using a simplified heat source that was tuned to the observed fusion zone from a weld macrograph and thermocouple data for a series of electron beam welds in 316L austenitic stainless steel with a variety of geometries. The predicted residual stresses were compared with contour method and neutron diffraction residual stress measurements.

Experimental Residual Stress and Geometric Imperfections on Pressure Hull Instability Analysis

2018 ◽  
Vol 140 (3) ◽  
Author(s):  
Paulo Rogério Franquetto ◽  
Miguel Mattar Neto
Keyword(s):  
Residual Stress ◽  
Numerical Models ◽  
Experimental Results ◽  
Pressure Reduction ◽  
Collapse Pressure ◽  
X Ray ◽  
Cold Bending ◽  
Portable System ◽  
Stress Profiles ◽  
Welding Processes

Residual stress produced by cold bending and welding processes contributes to the collapse pressure reduction of submarine hulls. Usually, the residual stress profiles used to quantify this reduction are obtained from analytical or numerical models. However, such models have limitations to take into account cold bending and welding in the same time. Hence, experimental analyses are necessary to better quantify the residual stress. Based on that, this paper presents residual stress experimental results obtained at six points on a pressure hull prototype using X-ray portable system. Based on these results, the residual stress profiles through the material thickness were estimated for each region on the frame by using a polynomial approximation. These profiles were introduced in a nonlinear finite element numerical model to study the collapse pressure reduction. Experimental results available on the literature were also used. Material and geometric nonlinearities were considered in the analysis. The results show that the residual stress reduces the collapse pressure as part of the frame web has stress level higher than the material yield. The preload introduced by the residual stress plays a less important role for the collapse pressure reduction at higher out-of-roundness and out-of-straightness defect amplitudes.

Pipe Girth Weld Residual Stress Intensity Factor Profiles for Structural Integrity Assessment

2013 ◽  
Author(s):  
P. John Bouchard
Keyword(s):  
Residual Stress ◽  
Stress Intensity Factor ◽  
Stainless Steel ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Structural Integrity ◽  
Steel Pipe ◽  
Stress Fields ◽  
Stainless Steel Pipe ◽  
Girth Welds

The influence of the residual stress field in a welded structure on crack growth and fracture is commonly assessed through its contribution to the stress intensity factor (SIF) for the crack of interest. This contribution is most often calculated by assuming a bounding through-thickness residual stress profile for the specific type of weldment with an appropriate SIF solution for the crack location, shape and structure of concern. Although more realistic residual stress profiles for stainless steel pipe girth welds have been developed recently their use, in some cases, leads to an underestimate of the SIF. A new approach is developed for determining bounding SIF values for cracks in residual stress fields of stainless steel pipe girth welds. The forms of the proposed SIF profiles are based on recently published SIF solutions for cracks in periodic residual stress fields [1]. It is shown that the SIF profiles bound those based on a large database of residual stress measurements without being excessively conservative. The outcome is a simple new method for defining more realistic SIF profiles for use in structural integrity assessments of stainless steel pipe girth welds.

Residual Stresses Measurement in Various Joint Weldments

2013 ◽  
Author(s):  
Xavier Ficquet ◽  
Sayeed Hossain ◽  
Ed J. Kingston
Keyword(s):  
Experimental Data ◽  
Residual Stress ◽  
Structural Integrity ◽  
Stress Measurement ◽  
Nuclear Industry ◽  
Residual Stress Measurement ◽  
Stress Measurements ◽  
First Case ◽  
Offshore Industry ◽  
Welding Processes

Published experimental data from residual stress measurements are generally limited or difficult to find. Experimental data in the offshore industry are even more scarce and difficult to access to. The oil and gas industry can benefit from research done in other industries. For example, the nuclear industry has published a multitude of residual stress measurements that could be beneficial to the offshore industry, gaining more understanding and confidence in the structural integrity of critical components. For the past year VEQTER Ltd has been developing a web access database for storing and comparing residual stress measurement and modelling results. This paper presents a comparison of through thickness residual stress measurement results that are published. The first case will show numerous measurements using different techniques on girth welded joints. Then, measurements on the temper bead welding processes which have been developed to simulate the tempering effect of post-weld heat treatment will be presented and compared with cladding. Finally, comparison of residual stress measurements on T-section plate fillet weld will be made.

Residual Stress Fields after Heat Treatment in Cladded Steel of Process Vessels

2011 ◽  
Vol 681 ◽  
pp. 364-369
Author(s):  
Maria José Marques ◽  
António Castanhola Batista ◽  
Joana Rebelo-Kornmeier ◽  
Michael Hofmann ◽  
Joao P. Nobre ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Arc Welding ◽  
Submerged Arc Welding ◽  
The Other ◽  
Steel Plates ◽  
Stress Fields ◽  
Stress Profiles ◽  
Filler Metals ◽  
Submerged Arc

The influence of the heat treatment on the residual stress fields of weld cladded samples is discussed in this paper. The samples were elaborated from carbon steel plates, cladded in one of the faces with stainless steel filler metals by submerged arc welding. After the cladding process some of the samples were submitted to heat treatments with different parameters: one at 620° C for a holding time of 1 hour and the other at 540° C for a period of ten hours. The in‑depth residual stress profiles were determined by neutron diffraction. The results shown that the sample treated to 620 °C, presented the highest residual stress relaxation. The corresponding heat treatment has the industrial benefit to be shorter than the other heat treatment.

Effect of Partial Welding on the Residual Stress and Structural Integrity of Piping Welds

2013 ◽  
Vol 135 (6) ◽  
Author(s):  
Jinya Katsuyama ◽  
Koichi Masaki ◽  
Kunio Onizawa
Keyword(s):  
Residual Stress ◽  
Structural Integrity ◽  
Cutting Depth ◽  
Butt Welding ◽  
Repair Welding ◽  
Partial Repair ◽  
Compressive Stresses ◽  
Weld Residual Stress ◽  
Mechanical Cutting ◽  
Integrity Assessments

When weld defects are observed during an inspection after welding, repair welding is performed after removing the defects. However, partial repair welding can potentially complicate the weld residual stress distribution. In this study, we performed thermal-elastic-plastic analyses to evaluate the weld residual stress produced by repair welding after pipe butt-welding. The analysis results were validated through comparison with actual measurements. In addition, based on the analysis results for varying repair-welding conditions, we also performed structural integrity assessments related to stress corrosion cracking using the probabilistic fracture mechanics analysis code pascal-sp. It was clearly observed that the tensile stress in the repair-welded region increased and that compressive stresses occurred outside the repair-welded region. A deeper mechanical cutting depth caused larger increases in the tensile residual stress of the repair-welded region. It was also concluded that partial repair welding may favorably affect the break probability of piping welds.

A Study of the Effects of Scaling on Structural Integrity Assessment

2015 ◽  
Author(s):  
Paulo Orrock ◽  
David J. Smith ◽  
Christopher E. Truman
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Scaling Laws ◽  
Structural Integrity ◽  
Driving Forces ◽  
Scaling Law ◽  
Stress Fields ◽  
Complex Nature ◽  
Integrity Assessment ◽  
And Performance

For nuclear welded components the complex nature of the residual stresses involved means it is often advantageous to produce mock-ups in order that the structural integrity and performance may be assessed. The weight and size of these components can make the production of mock-ups prohibitively expensive, and so the use of scaled models is considered here. Numerical analysis and finite element simulations have been carried out to investigate the scaling laws encountered affecting the applied loads, stress fields and crack driving forces that are of interest in the full sized component. To illustrate the effects of scaling we consider the introduction of a residual stress through prior plastic deformation in rectangular beams of different sizes. A simple scaling law provides the loads required to introduce the same magnitude and distribution of residual stresses in different sized specimens. This is pertinent to uncracked beams. In contrast, if a crack is introduced this scaling law is no longer applicable and the stress intensity factor associated with residual and applied stresses differ for different sized specimens. Alternatively, to create the same crack driving force in different sized specimens different initial residual stress fields are required. The implications of these findings are discussed in the context of future work.

Effect of Partial Welding on Residual Stress and Structural Integrity in Piping Welds

2012 ◽  
Author(s):  
Jinya Katsuyama ◽  
Koichi Masaki ◽  
Kunio Onizawa
Keyword(s):  
Residual Stress ◽  
Structural Integrity ◽  
Cutting Depth ◽  
Butt Welding ◽  
Repair Welding ◽  
Partial Repair ◽  
Compressive Stresses ◽  
Weld Residual Stress ◽  
Mechanical Cutting ◽  
Integrity Assessments

When weld defects are found by inspection after welding, repair welding after removing the defects is performed. The partial repair welding has a possibility to make weld residual stress distribution complicated. In this study, we have performed thermal-elastic-plastic analyses to evaluate the weld residual stress produced by repair welding after piping butt-welding. The analysis results were validated by the comparison with measurements. From the analysis results with varying the repair welding conditions, we also performed structural integrity assessments related to stress corrosion cracking using probabilistic fracture mechanics analysis code PASCAL-SP. It was clearly shown that tensile stress in repair-welded region was increased and compressive stresses occurred outside the repair-welded region. Deeper mechanical cutting depth caused larger increases in tensile residual stress of repair-welded region. It was also clarified that partial repair welding might have a beneficial influence on the break probability of piping welds.

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