Effect of precipitate–precipitate interaction on residual stress in welded structure

The residual stress analysis of a thick welded structure requires a lot of time and computer memory, which are different from those in thin welded structure analysis. This study investigated the effect of residual stress due to welding-pass grouping as a way to reduce the analysis time in multipass thick butt welding joint. For this purpose, the parametric analysis which changes the number of grouping passes was conducted in the multipass butt weld of a structure with a thickness of 25 mm and 70 mm. In addition, the residual stress by thermal elastoplastic FE analysis is compared with the results by the neutron diffraction method for verifying the reliability of the FE analysis. The welding sequence is considered in order to predict the residual stress more accurately when using welding-pass grouping method. The results of the welding-pass grouping model and half model occurred between the results of the left/right of the full model. If the total number of welding-pass grouping is less than half of that of welding pass, a large difference with real residual stress is found. Therefore, the total number of the welding-pass grouping should not be reduced to more than half.

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Influence of Welding Defects on Residual Stresses: Numerical Study

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.996.506 ◽

2014 ◽

Vol 996 ◽

pp. 506-511

Author(s):

Intissar Frih ◽

Pierre Antoine Adragna ◽

Guillaume Montay

Keyword(s):

Residual Stress ◽

Stress Distribution ◽

Residual Stresses ◽

Numerical Study ◽

Stress Gradient ◽

Residual Stress Distribution ◽

Welded Structure ◽

Critical Defect ◽

Welding Defects ◽

Residual Stress Gradient

This paper presents a study on the application of the finite element methods to predict the influence of a defect on the residual stress distribution in a T-welded structure. A defect is introduced in a numerical model firstly without residual stress to see its impact (size and position) on the stress distribution. Secondly the most critical defect (determined previously) is simulated with a residual stress gradient. The obtained results are useful for computation stress concentration factor due to weld residual stresses.

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Effects of Mechanical Loading on Residual Stress and Fracture: Part I — Background to the BS 7910:2013 Rules

Volume 1: Codes and Standards ◽

10.1115/pvp2014-28152 ◽

2014 ◽

Cited By ~ 1

Author(s):

Isabel Hadley ◽

Simon Smith

Keyword(s):

Residual Stress ◽

Stress Relaxation ◽

Mechanical Loading ◽

Mechanical Load ◽

Welding Residual Stress ◽

Assessment Procedure ◽

Welded Structures ◽

Interaction Factor ◽

Welded Structure ◽

The Uk

Failure of welded structures due to the presence of flaws is typically driven by a mixture of applied and residual stresses, yet in most cases only the former are known accurately. In as-welded structures, a typical assumption is that the magnitude of welding residual stress is bounded by the room temperature yield strength of the parent material. The UK flaw assessment procedure BS 7910:2013 also assumes that mechanical loading (either as a result of proof testing or during the initial loading of an as-welded structure) will bring about a relaxation in residual stress. Conversely, the UK structural assessment code for nuclear structures, R6, contains a warning on the ‘limited validation’ of the BS 7910 approaches for stress relaxation and suggests that they should be used ‘with caution’. The aim of this study was therefore to review the basis of the BS 7910 clauses on stress relaxation with a view to harmonising the BS 7910 and R6 rules for cases in which the original welding residual stress distribution is not known. The residual stress relaxation clauses of BS 7910:2013 date back to the 1991 edition of PD 6493 and have not changed substantially since then. A considerable programme of work was carried out by TWI at the time to justify and validate the clause, but the full underlying details of the work have not hitherto been available in the public domain, and are described in a separate companion paper. The approach proposed in BS 7910 combines ‘global’ relaxation of residual stress (Qm) under high mechanical load with ‘local’ enhancement of crack tip driving force through the adoption of a simplified primary/secondary stress interaction factor, ρ.

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Evaluation of Crack Occurrence Probability of T-Shape Welded Structures

Journal of Mechanics ◽

10.1017/jmech.2011.31 ◽

2011 ◽

Vol 27 (2) ◽

pp. 279-286

Author(s):

Y. Hsu ◽

W.-F. Wu ◽

H.-T. Kuo

Keyword(s):

Residual Stress ◽

Chemical Composition ◽

Hydrogen Content ◽

Welded Joints ◽

Occurrence Probability ◽

Diffusible Hydrogen ◽

Element Analysis ◽

Welded Structures ◽

Welded Structure ◽

Major Factors

ABSTRACTWelded structures are vulnerable to fracture due to cracks, especially at the welds. To investigate the safety of T-Shape welded structures used in some construction sites, a method is proposed in this paper to evaluate the crack occurrence probabilities of the structures. Three major factors that affect the crack occurrence are taken into consideration. They are residual stress, diffusible hydrogen content and chemical composition of the weld metal. In the analysis, finite element analysis is performed to find the residual stress distribution of the structures. The uncertainties of diffusible hydrogen content and chemical composition are treated as random variables. The critical cooling time is found and utilized for evaluating the crack occurrence probability of the welded structure. Numerical results indicate that T-shape welded joints lead to higher residual stresses and higher crack occurrence probabilities in comparison with the traditional butt joints. Therefore, more attention should be paid to this kind of welded joints when they are used.

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Finite Element Modelling of Laser Stitch Welding Joints for Structural Dynamic Predictions

International Journal of Automotive and Mechanical Engineering ◽

10.15282/ijame.16.2.2019.7.0494 ◽

2019 ◽

Vol 16 (2) ◽

pp. 6556-6567

Author(s):

M. A. S. Aziz Shah ◽

M. A. Yunus ◽

M. N. Abdul Rani ◽

M. S. Mohd Zin ◽

W. I. I. Wan Iskandar Mirza

Keyword(s):

Residual Stress ◽

Finite Element ◽

Dynamic Behaviour ◽

Welding Process ◽

Shell Element ◽

High Strength ◽

Mode Shapes ◽

Finite Element Models ◽

Structural Dynamic ◽

Welded Structure

Laser stitch welding is a joining technique that has been increasingly popular in automotive industries, such as in the manufacturing and assembling of the car’s body-in-white (BiW) due to its advantages over the resistance spot weld, such as low heat application and high strength weld. The dynamic behaviour of a laser stitch welded structure is relatively difficult to predict accurately due to local parameters being induced during the laser welding process, such as heat affected zone (HAZ) and residual stress in the welded structure. This paper presents the idea of modelling the laser stitch weld by investigating different types of element connectors that can be used to represent laser stitch weld, such as rigid body element (RBE2), shell element (CQUAD4), bar element (CBAR) and area contact model (ACM2) format of element connectors. The accuracy of finite element models of laser stitch welded joints is compared in terms of natural frequencies and mode shapes with the experiment counterparts. The dynamic behaviour of the measured structure is obtained by using an impact hammer with free-free boundary conditions. It is found that the accuracy of the finite element models of the laser stitch welded structure highly depends on the involvement of residual stress and the heat affected zones that are generated from the welding process.

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Numerical Simulation and Experimental Investigation of Temperature and Residual Stress Distributions in a Circular Patch Welded Structure

Energies ◽

10.3390/en13205423 ◽

2020 ◽

Vol 13 (20) ◽

pp. 5423 ◽

Cited By ~ 1

Author(s):

Mato Perić ◽

Sandro Nižetić ◽

Zdenko Tonković ◽

Ivica Garašić ◽

Ivan Horvat ◽

...

Keyword(s):

Numerical Simulation ◽

Residual Stress ◽

Welding Process ◽

Infrared Camera ◽

Circular Disk ◽

Maximum Deviation ◽

Cooling Process ◽

Residual Stress Field ◽

Circular Patch ◽

Welded Structure

In this study, we performed a numerical simulation and experimental measurements on a steel circular patch welded structure to investigate the temperature and residual stress field distributions caused by the application of buried-arc welding technology. The temperature histories during the welding and subsequent cooling process were recorded for two locations, with the thermocouples mounted inside the plate close to the weld bead. On the upper surface of the welded model, the temperature-time changes during the cooling process were monitored using an infrared camera. The numerically calculated temperature values correlated well with the experimentally measured ones, while the maximum deviation of the measured and calculated temperatures was within 9%. Based on the numerical result analysis regarding circumferential and radial stresses after the completion of the welding process, it is concluded that both stresses are primarily tensile within the circular disk. Outside the disk, the circumferential stresses turn from tensile to compressive, while on the other hand the radial stresses disappear towards the ends of the plate.

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Study on Weld Fatigue Evaluation Incorporating Welding Induced Residual Stress Effect

Volume 4: Materials Technology ◽

10.1115/omae2016-55024 ◽

2016 ◽

Cited By ~ 1

Author(s):

Jeong K. Hong

Keyword(s):

Residual Stress ◽

Applied Load ◽

Fatigue Behavior ◽

Load Ratio ◽

Stress Effect ◽

Structural Stress ◽

Applied Loading ◽

Welded Structure ◽

Residual Stress Effect ◽

Weld Fatigue

For fatigue assessment of a welded structure, an important characteristic is the failure location. The fatigue crack begins from the pre-existing crack-like flaw which is an inherent feature of a weld toe or root. Residual stress in the welded joints is another important characteristic. It is also well known that tensile residual stress in welded structures can be as high as the material yield strength level and so the fatigue strength of the welded joint is governed by the applied stress range regardless of the applied load ratio. However, when the presumed conditions with high tensile residual stress in the weld regime are not satisfied, the fatigue behavior in welded structure deviates from the general weld fatigue behavior. In this paper, firstly the applied load ratio effect on fatigue behavior is investigated for two different residual stress levels of welds, i.e., as-welded and stress relieved. It has been observed that stress-relieving effect of welds is apparent when the applied loading introduces stress fluctuations in compressive loading. When the load ratio effect is considered in Battelle structural stress based fatigue parameter, the stress relieved weld fatigue data was consolidated within the master S-N curve. Based on this investigation, the Battelle structural stress based effective load ratio considering both applied loading and detailed residual stress is introduced for the weld fatigue behavior. The two-stage crack growth model is reformulated with the structural stress based effective load ratio, which is a function of crack length. Lastly, a fatigue life prediction procedure incorporating residual stress effect is proposed and validated using the existing fatigue test results. The proposed procedure clearly shows that the compressive residual stress distributions at the weld prone to crack provide great benefits for fatigue life improvement.

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Effects of Mechanical Loading on Residual Stress and Fracture: Part II — Validation of the BS 7910:2013 Rules

Volume 1: Codes and Standards ◽

10.1115/pvp2014-28092 ◽

2014 ◽

Cited By ~ 1

Author(s):

Isabel Hadley ◽

Simon Smith

Keyword(s):

Residual Stress ◽

Stress Relaxation ◽

Stress Distribution ◽

Mechanical Loading ◽

Welding Residual Stress ◽

Numerical Work ◽

Welded Structures ◽

Interaction Factor ◽

Welded Structure ◽

The Uk

Failure of welded structures due to the presence of flaws is typically driven by a mixture of applied and residual stresses, yet in most cases only the former are known accurately. In as-welded structures, a typical assumption is that the magnitude of welding residual stress is bounded by the room temperature yield strength of the parent material. The UK flaw assessment procedure BS 7910:2013 also assumes that mechanical loading (either as a result of proof testing or during the initial loading of an as-welded structure) will bring about a relaxation in residual stress. Conversely, the UK structural assessment code for nuclear structures, R6, contains a warning on the ‘limited validation’ of the BS 7910 approaches for stress relaxation and suggests that they should be used ‘with caution’. The aim of this study was therefore to review the basis of the BS 7910 clauses on stress relaxation with a view to harmonising the BS 7910 and R6 rules for cases in which the original welding residual stress distribution is not known. A companion paper describes the history of the residual stress relaxation clauses of BS 7910. A considerable programme of work was carried out in the late 1980s to justify and validate the clauses, using a range of experimental and numerical work. This included analysis of work carried out by the UK power industry and used in the validation of the R6 procedure. The full underlying details of the work have not hitherto been available in the public domain, although the principles were published in 1988. The approach proposed in BS 7910 combines ‘global’ relaxation of residual stress (Qm) under high mechanical load with ‘local’ enhancement of crack tip driving force through the adoption of a simplified primary/secondary stress interaction factor, ρ. This is different from the method adopted by R6, but appears to be equivalent to allowing negative values of ρ under conditions of high primary stress. A re-analysis of the original TWI work, using the current version of BS 7910, has shown nothing to contradict the approach, which represents a workable engineering solution to the problem of how to analyse residual stress effects in as-welded structures rapidly and reasonably realistically when the as-welded stress distribution is unknown.

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Microstructure and residual stress analysis of Strenx 700 MC welded joint

Production Engineering Archives ◽

10.30657/pea.2020.26.09 ◽

2020 ◽

Vol 26 (2) ◽

pp. 41-44

Author(s):

Libor Trško ◽

Ján Lago ◽

Michal Jambor ◽

František Nový ◽

Otakar Bokůvka ◽

...

Keyword(s):

Residual Stress ◽

Heat Affected Zone ◽

Microstructural Analysis ◽

Fatigue Crack Initiation ◽

Welding Process ◽

High Strength ◽

Carbon Steels ◽

Fatigue Properties ◽

Residual Stress Field ◽

Welded Structure

AbstractHigh strength low alloy (HSLA) steels are a new generation of plain carbon steels with significantly improved mechanical properties while maintaining good weldability with common commercial techniques. Residual stress and microstructural analysis of welded HSLA Strenx 700 MC was carried out in this research. Results have shown that the welding process causes significant grain coarsening in the heat affected zone. The microstructural changes are also accompanied with creation of tensile residual stress field in the weld metal and heat affected zone, reaching up-to depth of 4 mm. Tensile residual stresses are well known for acceleration of fatigue crack initiation and together with coarse grains can lead to significant decrease of the fatigue properties of the welded structure.

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Can a Weld in Welded Structure Be Made With Zero Residual Stress?

Volume 6B: Materials and Fabrication ◽

10.1115/pvp2015-45991 ◽

2015 ◽

Author(s):

Stanislav Tchernov ◽

John A. Goldak

Keyword(s):

Residual Stress ◽

Optimization Problem ◽

Design Space ◽

Design Parameters ◽

Cpu Time ◽

Welded Structure ◽

Transverse Distance ◽

Heated Area ◽

Open Question ◽

Heater Design

While solving a sequence of seventeen optimization projects to predict the values of the side heater parameters that would be expected to minimize camber distortion in an edge welded bar, the design parameters that reduced distortion to effectively zero were not unique. This raised the question if any of the designs that minimized the distortion effectively to zero also minimized the residual stress. To answer this question three different measures of residual stress were evaluated for all 1451 designs. The Computational Weld Mechanics (CWM) optimization problem is to find the best point in the 4D space of side heater design parameters: flux, heated area, longitudinal and transverse distance from the weld such that the final residual stress is as low as possible (minimized). To evaluate the objective function for each point in the 4D design space, the associated 3D transient non-linear thermal visco-elastic-plastic stress analyzes was solved. A FEM mesh with 6600 8-node brick elements and 9438 nodes was solved for 166 time steps in 10 minutes of single-core CPU time. In the seventeen optimization projects, 1451 weld analyses were solved in 75 quad-core CPU hours by one person in two calendar weeks. The residual stress was effectively reduced to zero in some designs. These designs also reduced distortion to effectively zero. Whether a design that effectively reduces the residual stress to zero is unique remains an open question.

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