The Effect of Strength Mis-Match and Residual Stress in ECA of Girth Welds With Internal Circumferential Cracks

2009 ◽  
Author(s):  
Ali Mirzaee Sisan ◽  
Afshin Motarjemi
Keyword(s):  
Residual Stress ◽  
Stress Field ◽  
Driving Forces ◽  
Numerical Study ◽  
Welding Process ◽  
Detailed Comparison ◽  
Weld Strength ◽  
Residual Stress Field ◽  
Girth Welds ◽  
Welded Pipe

A numerical study was carried out to quantify the effect of a residual stress field on subsequent fracture behaviour of a girth welded pipe with an internal circumferential long crack when subjected to high applied strain loading. In order to introduce an initial residual stress field similar to a welding process in a pipe, a quenching process was numerically simulated and associated residual stress profiles were modified and mapped into the finite element (FE) models. A detailed comparison between the crack driving force for various cases with and without residual stress and weld strength mismatch was carried out for cases under a high plastic deformation regime. The BS7910 procedure was also used to predict crack driving forces using its current assumption of interaction of residual stress with primary loads. The results obtained from the FE analyses were compared with the BS7910 predictions.

scholarly journals A Time Saving Method to Compute Multi-Pass Weld Residual Stresses

2013 ◽  
Author(s):  
Lionel Depradeux ◽  
Frédérique Rossillon
Keyword(s):  
Residual Stress ◽  
Stress Field ◽  
Residual Stresses ◽  
Welding Process ◽  
Geometrical Parameters ◽  
Residual Stress Field ◽  
Time Saving ◽  
3D Geometry ◽  
Girth Welds ◽  
Number Of Passes

In order to obtain the residual stress field resulting from the welding process, numerical simulations of multi-pass welding have demonstrated their efficiency and have become an interesting alternative to practical measurements. However, in the context of engineering studies, it remains a difficult task to compute residual stresses for a very high number of passes with reasonable computation times. In this paper, a time-saving method is proposed to simulate the welding process, ensuring an accurate reproduction of the residual stress field with drastically reduced computation times. The method consists in including in the simulation only the last deposited pass, or a reduced number of appropriately selected passes. For a given material and a given heat input, the choice of remaining passes depends on the geometrical parameters. The method is applied to various geometries of austenitic pipes girth welds, which have been widely studied in the literature and standards. The results, confronted to multipass simulations including all the passes, and to literature results, are very satisfactory. Quasi-identical residual stress fields are computed in both cases with computation times divided by a factor comprised between 7 up to 12. Further computations are in progress on other configurations than girth-weld pipes, and more complex 3D geometry like J weld of bottom head nozzles.

scholarly journals Residual stresses in thermite welded rails: significance of additional forging

2020 ◽  
Vol 64 (7) ◽  
pp. 1195-1212
Author(s):  
B. Lennart Josefson ◽  
R. Bisschop ◽  
M. Messaadi ◽  
J. Hantusch
Keyword(s):  
Residual Stress ◽  
Stress Field ◽  
Residual Stresses ◽  
Weld Metal ◽  
Welding Process ◽  
Surface Zone ◽  
Fe Model ◽  
Uneven Surface ◽  
Residual Stress Field ◽  
High Dynamic

Abstract The aluminothermic welding (ATW) process is the most commonly used welding process for welding rails (track) in the field. The large amount of weld metal added in the ATW process may result in a wide uneven surface zone on the rail head, which may, in rare cases, lead to irregularities in wear and plastic deformation due to high dynamic wheel-rail forces as wheels pass. The present paper studies the introduction of additional forging to the ATW process, intended to reduce the width of the zone affected by the heat input, while not creating a more detrimental residual stress field. Simulations using a novel thermo-mechanical FE model of the ATW process show that addition of a forging pressure leads to a somewhat smaller width of the zone affected by heat. This is also found in a metallurgical examination, showing that this zone (weld metal and heat-affected zone) is fully pearlitic. Only marginal differences are found in the residual stress field when additional forging is applied. In both cases, large tensile residual stresses are found in the rail web at the weld. Additional forging may increase the risk of hot cracking due to an increase in plastic strains within the welded area.

A Numerical Study on the Redistribution of Residual Stress After Machining

2017 ◽  
Author(s):  
Kunyang Lin ◽  
Wenhu Wang ◽  
Ruisong Jiang ◽  
Yifeng Xiong
Keyword(s):  
Residual Stress ◽  
Stress Field ◽  
Residual Stresses ◽  
Numerical Study ◽  
Cutting Speed ◽  
Machining Process ◽  
Stress Profile ◽  
Residual Stress Field ◽  
Machining Processes ◽  
Residual Stress Profile

Machining induced residual stresses have an important effect on the surface integrity. Effects of various factors on the distribution of residual stress profiles induced by different machining processes have been investigated by many researchers. However, the initial residual, as one of the important factor that affect the residual stress profile, is always been ignored. In this paper, the residual stress field induced by the quenching process is simulated by the FEM software as the initial condition. Then the initial residual stress field is used to study the residual stress redistribution after the machining process. The influence of initial stress on the stress formation is carried out illustrating with the mechanical and thermal loads during machining processes. The effects of cutting speed on the distribution of residual stress profile are also discussed. These results are helpful to understand how initial residual stresses are redistributed during machining better. Furthermore, the results in the numerical study can be used to explain the machining distortion problem caused by residual stress in the further work.

Key Technology Research of the Temperature Field Simulation Based on the Flat Butt Weld

2012 ◽  
Vol 562-564 ◽  
pp. 729-732 ◽  
Author(s):  
Yu Wen Li ◽  
Fu Xing Wang
Keyword(s):  
Residual Stress ◽  
Temperature Field ◽  
Stress Field ◽  
Field Distribution ◽  
Welding Process ◽  
Residual Stress Field ◽  
Butt Weld ◽  
Temperature Method ◽  
Simulation Based ◽  
Direct Loading

Aluminum as solder, in the flat welding process, the temperature field and the residual stress field distribution was the main problem of the study; According to the actual situation of the welding process, using the direct loading temperature method and the indirect loading temperature method , the main path of temperature field distribution curves and the residual stress field distribution were gained by 2D numerical simulation respectively; Through comparison, the indirect loading method can get more accuracy of residual stress field distribution than that of the direct loading temperature method; The above methods were useful in practical production.

Impact of Intensity of Residual Stress Field Upon Re-Yielding and Re-Autofrettage of an Autofrettaged Thick Cylinder

2010 ◽  
Author(s):  
Anthony P. Parker ◽  
John H. Underwood ◽  
Edward Troiano
Keyword(s):  
Residual Stress ◽  
Stress Field ◽  
Hoop Stress ◽  
Bauschinger Effect ◽  
Numerical Study ◽  
Fatigue Cracks ◽  
Maximum Pressure ◽  
Residual Stress Field ◽  
Intensity Effect ◽  
Elastic Plastic

Re-autofrettage has been identified as a significant, cost-effective method to achieve higher re-yield pressure (RYP) and/or weight reduction in large caliber gun tubes. For a given overstrain, residual stress profiles for hydraulic and for swage autofrettage may differ significantly in their intensity. The simplest representation of this ‘intensity’ effect is the magnitude of the bending moment ‘locked in’ via the residual hoop stress. Hill’s analytical, plane strain, Von Mises, analysis predicts a larger ‘locked-in’ moment than does the equivalent open-end condition. By assuming a range of stress-field intensities (f) scaleing from 1.0 to 1.4 times that produced by open-end hydraulic autofrettage, it was possible to assess re-yield behavior following initial autofrettage via a generic numerical study. In cases where Bauschinger effect is absent, re-yield initiates at the original elastic plastic interface. This includes the ideal Hill distribution. When Bauschinger effect is present, re-yield for f ≤ 1.1 initiates at the bore and after further pressurization at the original elastic plastic interface within two zones. For f ≥ 1.2 the reverse is the case, with initial yield at the original elastic plastic interface and subsequently at the bore. RYP increases with increasing f up to f = 1.175 and then decreases significantly. This loss of RYP may be mitigated by hydraulic re-autofrettage. At f = 1.0 re-autofrettage increases RYP by 4%. At f = 1.4 RYP is increased by 19%. There are modest increases in safe maximum pressure as a result of re-autofrettage. RYP closely approaching re-autofrettage pressure is achievable for f ≥ 1.3. Within this range, re-autofrettage offers a significant benefit. Re-autofrettage also produces beneficial effects via increased bore hoop compressive stress, this increase varying from 20% for f = 1 to zero for f = 1.4. Such increased compression will benefit fatigue lifetime for fatigue cracks initiating at the bore. Conversely, tensile OD hoop stress increases, with increasing f, by a maximum of 6%.

scholarly journals Numerical study on the effect of welding and heating treatments on strength of high strength steel column

2018 ◽  
Author(s):  
Jiang Jin ◽  
Wei Bao ◽  
J. Liu ◽  
Z.Y. Peng
Keyword(s):  
Residual Stress ◽  
High Strength Steel ◽  
Arc Welding ◽  
Numerical Study ◽  
Welding Process ◽  
High Strength ◽  
Residual Stress Field ◽  
Heating Treatment ◽  
Welding Processes ◽  
Box Columns

High strength steel box columns are usually fabricated from steel slab by applying welding. The welding process can introduce residual stresses and geometric imperfections into the columns and influence the column strength. In this study, a numerical investigation on the behavior of high strength steel thin-walled box columns under the compression force was carried out. The welding processes were firstly simulated with commercial package ABAQUS in this study to find out the residual stress distributions in high strength steel box column. After that, the column behaviors under the compression were modelled with predefined field from the previous step. The effect of the welding process (including flux-core arc welding and submerged arc welding), heating treatment (including preheating and post-weld heat treatment) and geometrical imperfection on the residual stress field and box column strength was investigated and discussed.   

Impact of Intensity of Residual Stress Field Upon Reyielding and Re-Autofrettage of an Autofrettaged Thick Cylinder

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
Anthony P. Parker ◽  
Edward Troiano ◽  
John H. Underwood
Keyword(s):  
Residual Stress ◽  
Stress Field ◽  
Hoop Stress ◽  
Bauschinger Effect ◽  
Numerical Study ◽  
Fatigue Cracks ◽  
Maximum Pressure ◽  
Residual Stress Field ◽  
Intensity Effect ◽  
Elastic Plastic

Re-autofrettage has been identified as a significant, cost-effective method to achieve higher reyield pressure (RYP) and/or weight reduction in large caliber gun tubes. For a given overstrain, residual stress profiles for hydraulic and swage autofrettage may differ significantly in their intensity. The simplest representation of this “intensity” effect is the magnitude of the bending moment “locked in” via the residual hoop stress. Hill’s analytical, plane strain, Von Mises analysis predicts a larger “locked-in” moment than does the equivalent open-end condition. By assuming a range of stress-field intensities (f) scaling from 1.0 to 1.4 times that were produced by open-end hydraulic autofrettage, it was possible to assess reyield behavior following initial autofrettage via a generic numerical study. In cases where Bauschinger effect is absent, reyield initiates at the original elastic–plastic interface. This includes the ideal Hill distribution. When Bauschinger effect is present, reyield for f≤1.1 initiates at the bore and after further pressurization at the original elastic–plastic interface within two zones. For f≥1.2, the reverse is the case, with initial yield at the original elastic–plastic interface and subsequently at the bore. RYP increases with increasing f up to f = 1.175 and then decreases significantly. This loss of RYP may be mitigated by hydraulic re-autofrettage. At f = 1.0 re-autofrettage increases RYP by 4%. At f = 1.4, RYP is increased by 19%. There are modest increases in safe maximum pressure (SMP) as a result of re-autofrettage. RYP closely approaching re-autofrettage pressure is achievable for f≥1.3. Within this range, re-autofrettage offers a significant benefit. Re-autofrettage also produces beneficial effects via increased bore hoop compressive stress, this increase varying from 20% for f = 1% to 0% for f = 1.4. Such increased compression will benefit fatigue lifetime for fatigue cracks initiating at the bore. Conversely, tensile outside diameter (OD) hoop stress increases, with increasing f, by a maximum of 6%.

An Inverse Method for Reconstruction of the Residual Stress Field in Welded Plates

2010 ◽  
Vol 132 (6) ◽  
Author(s):  
G. H. Farrahi ◽  
S. A. Faghidian ◽  
D. J. Smith
Keyword(s):  
Residual Stress ◽  
Stress Field ◽  
Residual Stresses ◽  
Stress Function ◽  
Welding Process ◽  
Fatigue Loading ◽  
Least Square ◽  
Residual Stress Field ◽  
Inverse Approach ◽  
Residual Stress State

Welding process is widely used in manufacturing of many important engineering components. For such structures, the most important problem is the development of residual stresses and distortion due to welding. Welding tensile residual stresses have a detrimental effect and play an important role in an industrial environment. Crack initiation and propagation in static or fatigue loading, or in stress corrosion can be greatly accelerated by welding tensile stresses. Practically, however, it is often very difficult to characterize the residual stress state completely, while the knowledge of the complete residual stress distribution in structures is essential for assessing their safety and durability. In this research, based on the concept of the Airy stress function, an inverse approach would be presented to reconstruct the residual stress field from limited incomplete measurements of the residual stresses existing in a welded plate. In contrast to the published methods, a general solution based on the approximated stress function would be proposed together with satisfying all of the requirements of continuum mechanics; also, there exist a flexibility to impose the type of the physical behavior of residual stresses to attain the meaningful stress field. The efficiency of the method has been demonstrated by achieving an excellent agreement between the model prediction and experimental measured stresses in the sense of least-square approximation; also, the solution of the inverse problem has been stabilized using the Tikhonov–Morozov stabilization theory.

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