The Effect of Phase Transformations on Predicted Values of Residual Stresses in Welded Ferritic Components

2006 ◽  
Vol 524-525 ◽  
pp. 827-832 ◽  
Author(s):  
Alex P. Warren ◽  
Steve K. Bate ◽  
Richard Charles ◽  
C.T. Watson
Keyword(s):  
Finite Element ◽  
Residual Stresses ◽  
Phase Transformations ◽  
Welding Process ◽  
Heating And Cooling ◽  
Test Pieces ◽  
Property Data ◽  
Finite Element Package ◽  
Predicted Values ◽  
Welding Processes

The accurate prediction of the residual stresses present in welded structures can be of great importance to the fracture assessment of such components. Therefore, a large amount of benefit can be gained from improving techniques for measuring and numerically analysing these stresses. In recent years many advances have been made in the field of analysing residual stresses using finite element methods. That said, very little work has been conducted on the accurate modelling of welded ferritic components. This is largely due to the added complication of phase transformations that occur during the heating and cooling of such steels. The objective of the work presented in this paper was to improve understanding of the effect that phase transformations have on residual stresses present within welded ferritic structures. This was conducted by simulating such welding processes using the finite element package SYSWELD. An investigation was conducted to determine how phase transformations, and therefore residual stresses, are affected by the welding process used. Phase transformation and material property data available within SYSWELD were used for this analysis. An autogenously welded beam provided a simple basis for this qualitative investigation. In the future the manufacture and measurement of suitable test-pieces will enable these simulations to be validated.

The Prediction of Residual Stresses in an Autogenously Welded Ferritic Beams

2008 ◽  
Author(s):  
A. P. Warren ◽  
I. Symington ◽  
S. K. Bate ◽  
J. A. Francis ◽  
M. Turski ◽  
...  
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Residual Stresses ◽  
Phase Transformations ◽  
Structural Components ◽  
Reliable Operation ◽  
Viable Option ◽  
Heating And Cooling ◽  
Finite Element Package ◽  
Neutron Diffraction Technique

The continued safe and reliable operation of plant invariably has to consider the assessment of defects in welded structural components. This often requires some estimate of the residual stresses that have developed during the welding fabrication process. Increases in the computational power available to finite element analysts have made the prediction of welding residual stresses using finite element methods an increasingly viable option. Consequently recent years have seen many advances in the field of residual stress modelling. However, relatively little work has been conducted on the accurate modelling of welded ferritic components. This is largely due to the added complications associated with the solid-state phase transformations that occur during the heating and cooling of such steels. Against this background, a programme of work has been undertaken in order to investigate the effects that phase transformations have on the development of residual stresses in ferritic components and develop methods for their simulation. To facilitate this, generic components of increasing complexity are being studied. Reported in this paper is the first phase of this programme which considers SA508 beam specimens. These specimens have been subjected to autogenous TIG welds using two different torch travel speeds. In order to predict the resultant residual stresses, simulations have been conducted using the commercial finite element package SYSWELD. These predicted stresses are then compared with residual stress measurements conducted using the neutron diffraction technique.

The Effect of Modelling Simplifications on the Prediction of Residual Stresses in a Multi-Pass Plate Groove Weld

2007 ◽  
Author(s):  
A. P. Warren ◽  
S. K. Bate ◽  
P. Hurrell
Keyword(s):  
Finite Element ◽  
Heat Source ◽  
Residual Stresses ◽  
Finite Element Analyses ◽  
Computational Power ◽  
Test Pieces ◽  
Single Bead ◽  
Welding Processes

The inherent complexity of modelling welding processes and the lack of computational power available to analysts have resulted in simplified methods being commonly utilised when predicting residual stresses in welded components. Despite considerable advances in computational power, it is still often not possible to run detailed 3D analyses of complex welded geometries within practical timescales. Against this background, a programme of work has been undertaken in order to investigate the effect these simplifications will have on the prediction of residual stresses on a number of test-pieces. The geometry investigated in this paper is a plate containing a “V” groove, which runs the length of the plate and is filled with eight mechanised TIG weld passes. This paper presents the results of a number of finite element analyses conducted of this geometry. The analyses presented have been conducted using the commercial finite element packages SYSWELD and ABAQUS, using a number of modelling simplifications. These simplifications include modelling the plate in 2D and the use of the bead lumping technique to idealise a number of beads as a single bead. Also considered are various methods of heat source representation, namely; a moving ellipsoidal heat source, prescribed temperature and block dumping. These analyses are compared and qualitative conclusions are drawn.

The Effect of Modelling Simplifications on the Prediction of Residual Stresses in Thin-Walled Pipe Butt Welds

2006 ◽  
Author(s):  
A. P. Warren ◽  
S. K. Bate ◽  
R. Charles ◽  
D. M. O’Gara ◽  
P. M. Wood ◽  
...  
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Residual Stresses ◽  
Computational Power ◽  
Butt Weld ◽  
Butt Welds ◽  
Thin Walled Pipe ◽  
Thin Walled ◽  
Predicted Values ◽  
Welding Processes

The inherent complexity of modelling welding processes and the lack of computational power available to analysts has resulted in simplified methods being commonly utilised when predicting residual stresses. Despite considerable advances in computational power, it is still often not possible to run detailed 3D analyses of complex welded geometries within practical timescales. Against this background, a programme of work has been undertaken to develop a weld modelling procedure which can be followed by analysts. This procedure will account for how various modelling simplifications affect the predicted values of residual stress. One common geometry, which it is often necessary to analyse using modelling simplifications is that of a thin-walled pipe butt weld. Typically this geometry is simulated using a 2D axisymmetric analysis. Despite the popularity of this modelling simplification the effects of its use are not fully understood. In order to feed into this procedure, work has therefore been conducted to better understand the effects modelling simplifications will have on the residual stress levels that are predicted when simulating multi-pass pipe butt welds. The geometry considered in this study is the thin walled austenitic pipe butt weld specimen originally studied in VORSAC 5th Framework European Union project. This paper presents the results of a number of finite element analyses conducted of this geometry. These analyses have been conducted using a combination of the finite element codes SYSWELD and ABAQUS. The aim of this study was to understand the effect that the use of 2D axisymmetric analyses, and other modelling simplifications, namely block dumping and bead lumping will have on the predicted values of residual stress.

Numerical Analysis of Residual Stresses and Distortions in Aluminium Alloy Welded Joints

2015 ◽  
Vol 809-810 ◽  
pp. 443-448 ◽  
Author(s):  
Tomasz Kik ◽  
Marek Slovacek ◽  
Jaromir Moravec ◽  
Mojmir Vanek
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Aluminium Alloy ◽  
Thermal Cycle ◽  
Technology Development ◽  
Welding Process ◽  
Simulation Software ◽  
Structure Knowledge ◽  
Welding Processes ◽  
Element Method

Simulation software based on a finite element method have significantly changed the possibilities of determining welding strains and stresses at early stages of product design and welding technology development. But the numerical simulation of welding processes is one of the more complicated issues in analyses carried out using the Finite Element Method. A welding process thermal cycle directly affects the thermal and mechanical behaviour of a structure during the process. High temperature and subsequent cooling of welded elements generate undesirable strains and stresses in the structure. Knowledge about the material behaviour subjected to the welding thermal cycle is most important to understand process phenomena and proper steering of the process. The study presented involved the SYSWELD software-based analysis of MIG welded butt joints made of 1.0 mm thickness, 5xxx series aluminium alloy sheets. The analysis of strains and the distribution of stresses were carried out for several different cases of fixing and releasing of welded elements.

scholarly journals Prediction of Residual Stresses in a Multipass Pipe Weld by a Novel 3D Finite Element Approach

2018 ◽  
Author(s):  
Hui Huang ◽  
Jian Chen ◽  
Blair Carlson ◽  
Hui-Ping Wang ◽  
Paul Crooker ◽  
...  
Keyword(s):  
Finite Element ◽  
Residual Stresses ◽  
High Performance ◽  
Large Scale ◽  
Graphics Processing Unit ◽  
Computational Cost ◽  
Three Dimensional ◽  
Processing Unit ◽  
Girth Welds ◽  
Welding Processes

Due to enormous computation cost, current residual stress simulation of multipass girth welds are mostly performed using two-dimensional (2D) axisymmetric models. The 2D model can only provide limited estimation on the residual stresses by assuming its axisymmetric distribution. In this study, a highly efficient thermal-mechanical finite element code for three dimensional (3D) model has been developed based on high performance Graphics Processing Unit (GPU) computers. Our code is further accelerated by considering the unique physics associated with welding processes that are characterized by steep temperature gradient and a moving arc heat source. It is capable of modeling large-scale welding problems that cannot be easily handled by the existing commercial simulation tools. To demonstrate the accuracy and efficiency, our code was compared with a commercial software by simulating a 3D multi-pass girth weld model with over 1 million elements. Our code achieved comparable solution accuracy with respect to the commercial one but with over 100 times saving on computational cost. Moreover, the three-dimensional analysis demonstrated more realistic stress distribution that is not axisymmetric in hoop direction.

In Situ Observation of Phase Transformations during Welding of Low Transformation Temperature Filler Material

2010 ◽  
Vol 638-642 ◽  
pp. 3769-3774 ◽  
Author(s):  
Arne Kromm ◽  
Thomas Kannengiesser ◽  
Jens Gibmeier
Keyword(s):  
Residual Stresses ◽  
Phase Transformations ◽  
Volume Change ◽  
Transformation Temperature ◽  
High Energy ◽  
Filler Materials ◽  
Transformation Temperatures ◽  
Welding Processes ◽  
Compressive Residual Stresses

Tensile residual stresses introduced by conventional welding processes diminish the crack resistance and the fatigue lifetime of welded components. In order to generate beneficial compressive residual stresses at the surface of a welded component, various post-weld treatment procedures are available, like shot peening, hammering, etc. These post-weld treatments are, however time and cost extensive. An attractive alternative is to generate compressive stresses over the complete weld joint in the course of the welding procedure by means of so-called Low Transformation Temperature (LTT) filler materials. The volume change induced by the transformation affects the residual stresses in the weld and its vicinity. LTT fillers exhibit a relatively low transformation temperature and a positive volume change, resulting in compressive residual stresses in the weld area. In-situ measurements of diffraction profiles during real welding experiments using Gas Tungsten Arc (GTA)-welding process were realized successfully for the first time. Transformation temperatures during heating and subsequent cooling of LTT welding material could be assessed by means of energy dispersive diffraction using high energy synchrotron radiation. The results show that the temperature of martensite start (Ms) is strongly dependent on the content of alloying elements. In addition the results indicate that different phase transformation temperatures are present depending on the welding depth. Additional determination of residual stresses allowed it to pull together time and temperature resolved phase transformations and the resulting phase specific residual stresses. It was shown, that for the evaluation of the residual stress state of LTT welds the coexisting martensitic and austenitic phases have to be taken into account when describing the global stress condition of the respective material in detail.

Fast Three-Dimensional Finite Element Analysis of Weld Overlay Application on a Formed Feeder Elbow

2011 ◽  
Author(s):  
Francis H. Ku ◽  
Pete C. Riccardella
Keyword(s):  
Residual Stress ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Residual Stresses ◽  
Nuclear Reactor ◽  
Three Dimensional ◽  
Fe Method ◽  
Element Analysis ◽  
Weld Overlay ◽  
Welding Processes

This paper presents a fast finite element analysis (FEA) model to efficiently predict the residual stresses in a feeder elbow in a CANDU nuclear reactor coolant system throughout the various stages of the manufacturing and welding processes, including elbow forming, Grayloc hub weld, and weld overlay application. The finite element (FE) method employs optimized FEA procedure along with three-dimensional (3-D) elastic-plastic technology and large deformation capability to predict the residual stresses due to the feeder forming and various welding processes. The results demonstrate that the fast FEA method captures the residual stress trends with acceptable accuracy and, hence, provides an efficient and practical tool for performing complicated parametric 3-D weld residual stress studies.

Study of the Effect of Boundary Conditions on Residual Stresses in Welding Using Element Birth and Element Movement Techniques

2003 ◽  
Author(s):  
Ihab F. Z. Fanous ◽  
Maher Y. A. Younan ◽  
Abdalla S. Wifi
Keyword(s):  
Finite Element ◽  
Residual Stresses ◽  
Boundary Conditions ◽  
Welding Process ◽  
Computation Time ◽  
3D Models ◽  
The Other ◽  
3D Analysis ◽  
The Media ◽  
Element Movement

The structure in which the welding process is performed highly affects the residual stresses generated in the welding. This effect is simulated by choosing the appropriate boundary conditions in modeling the welding process. The major parameters of the boundary conditions are the method by which the base metal is being fixed and the amount of heat being applied through the torch. Other parameters may include the coefficients of thermal heat loss from the plate which may simulate the media in which the welding is taking place. In modeling the welding process, 2D forms of approximation were developed in analyzing most of the models of such problem. 3D models analyzing the welding process were developed in limited applications due to its high computation time and cost. With the development of new finite element tools, namely the element movement technique developed by the authors, full 3D analysis of the welding process is becoming in hand. In the present work, three different boundary conditions shall be modeled companng their effect on the welding. These boundary conditions shall be applied to two models of the welding process: one using the element birth technique and the other using the element movement technique showing the similarity in their responses verifying the effectiveness of the latter being accomplished in a shorter time.

Estimation of Residual Stresses in Steel Welded Joints Using Three Dimensional Finite Element Analysis

2018 ◽  
Author(s):  
Shivdayal Patel ◽  
B. P. Patel ◽  
Suhail Ahmad
Keyword(s):  
Residual Stress ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Residual Stresses ◽  
Boundary Conditions ◽  
Welding Speed ◽  
Welded Joints ◽  
Plate Thickness ◽  
Welding Process ◽  
Element Analysis

Welding is one of the most used joining methods in the ship industry. However, residual stresses are induced in the welded joints due to the rapid heating and cooling leading to inhomogenously distributed dimensional changes and non-uniform plastic and thermal strains. A number of factors, such as welding speed, boundary conditions, weld geometry, weld thickness, welding current/voltage, number of weld passes, pre-/post-heating etc, influence the residual stress distribution. The main aim of this work is to estimate the residual stresses in welded joints through finite element analysis and to investigate the effects of boundary conditions, welding speed and plate thickness on through the thickness/surface distributions of residual stresses. The welding process is simulated using 3D Finite element model in ABAQUS FE software in two steps: 1. Transient thermal analysis and 2. Quasi-static thermo-elasto-plastic analysis. The normal residual stresses along and across the weld in the weld tow region are found to be significant with nonlinear distribution. The residual stresses increase with the increase in the thickness of the plates being welded. The nature of the normal residual stress along the weld is found to be tensile-compressive-tensile and the nature of normal residual stress across the weld is found to be tensile along the thickness direction.

Reconditioning of Crankshaft in the Automotive Industry by Using TIG Welding

2015 ◽  
Vol 1111 ◽  
pp. 43-48
Author(s):  
Oana Roxana Chivu Vîrlan ◽  
Corneliu Rontescu ◽  
Dumitru Titi Cicic ◽  
Mihai Vasile
Keyword(s):  
Residual Stresses ◽  
Automotive Industry ◽  
Heat Affected Zone ◽  
Structural Changes ◽  
Welding Process ◽  
Heat Energy ◽  
Zone Structure ◽  
Welding Processes ◽  
Very High ◽  
Deposit Layer

It is well known that, due to their working under severe conditions, the crankshafts in the automotive industry yield in the area of the crankpin journals and that buying a new crankshaft means high costs. Due to these reasons, various welding processes are frequently used for repairs. Certain welding processes are difficult to apply because the heat energy introduced into the parts during the welding process is very high and will lead to deformations and residual stresses and to structural changes. The paper contains the experimental results related to the effect of applying the WIG welding process to certain characteristics of the deposit layer: hardness, heat affected zone, structure etc.

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