Influence Of Welding Sequence Research Articles

Influence of welding sequence and external restraint on buckling distortion in thin-plate arc-welded joints

Buckling distortion as a troublesome engineering issue is easily generated in thin-plate arc-welded components (generally less than 4 mm in thickness). This study aims to clarify the impact of welding sequence and external restraint on out-of-plane deformation in thin plates for finding out an effective and practical strategy for the prevention of welding-induced buckling distortion. The experimental method was utilized for investigation here. The experimental results reveal that the external restraint cannot prevent buckling distortion in the thin-walled weldments, while it can significantly mitigate the amount of transverse (about 4 mm here) but not longitudinal bending. The welding sequence method can prevent buckling distortion, but it cannot eliminate the transverse bending induced by the non-uniform temperature field in the thin-plate thickness direction. In the present work, the transverse bending in the symmetrical welding is the lowest (about 4 mm), while that in the back-step welding is the largest (around 7 mm). Furthermore, symmetrical welding and continuous welding introduce the lowest (about 1 mm) and highest (about 4 mm) longitudinal bending, respectively. Both external restraint and welding sequence could affect the buckling distortion mode. For the thin-plate arc-welded components, symmetrical welding combined with external restraint is a very effective strategy for the prevention of buckling distortion.

Influence of welding sequences on induced residual stress and distortion in pipes

A three-dimensional (3D) finite element (FE) model based on thermal-elastic-plastic approach in SYSWELD® was employed to investigate the effects of welding sequences on induced residual stresses and radial distortion in AISI 316L stainless steel welded pipes. To mesh the model, the HYPERMESH® processor was utilized and the model was then exported to SYSWELD® for further thermo-mechanical analysis. The Goldak's double ellipsoidal moving heat source model was employed in SYSWELD® to obtain the volumetric heat flux density in the Gas Metal Arc Welding (GMAW) simulation process. A neural-network program was suitably trained and used to predict the parameters of Goldak's model. The obtained numerical models using predicted Goldak’s parameters were then successfully validated by experimental results in terms of size of welding pool and the temperature distribution. Four different welding sequences (concepts) were investigated and compared: three quarters and one full circumferential welding. These welding sequences were anticipated to create the least residual stress and distortion in pipe welding. The results demonstrate that the welding sequences significantly influence induced residual stresses and distortions in magnitude and in distribution. For the full circumferential welding concept, which was proposed in this study, the residual stresses and distortion present more uniform distribution along the circumferential direction than those in quarter welding sequences. The magnitude of welding distortion was also significantly lower in the full circumferential concept when compared to the quarter welding concepts. The FE results of residual stresses in the full circumferential welding sequences were accurately validated by experimental tests.

Study of Residual Stress Evolution in SUS304/Q235 Bimetallic Clad Plate Butt-Welded Joints Considering Welding Sequence

Abstract Residual stress prediction and controlling is important for structural integrity assessment of weldments. In this work, finite element (FE) and experimental methods were integrated to study the influence of welding sequence on the SUS304/Q235 bimetallic clad plate (BCP) joints during multilayer and multipass welding. The results show that the peak residual stress values on flyer plate surface are weakly affected by welding sequences but the width of high surficial longitudinal stress area of joint with base layer welded first is bigger. Meanwhile, welding sequence has a great influence on the longitudinal residual stress evolution law inside joints. When base seam layer is welded first, the highest stress concentration appears in the transition layer. However, it would be transferred into the first base seam layer due to martensite phase transformation when flyer seam layer is welded first. Residual stress controlling in the BCP joint should attract more attention from researchers.

Welding distortion prediction and mitigation in thick steel plate structures on ships

ABSTRACT In the ship fabrication process, welding distortion will affect the dimension accuracy. In this paper, an industrialisation prediction method for thick steel plate structures on ships is proposed based on a combination of thermal-elastic-plastic finite element method and inherent deformation theory to reduce the welding distortion in the design stage, and its applicability is verified through a comparison of measurements in the shipyard and numerical simulations. The thick plate models produced by multi-pass welding technology are selected to analyse the welding distortion. The results show that the numerical prediction results are in good agreement with the measurement on site. The transverse bending distortion is the main factor that affects the fabrication accuracy. To mitigate welding distortion, the influence of welding sequence and flame heating is examined. This research may provide a macro concept for understanding the distribution characteristics of welding distortion and serve as a mitigation reference for manufacturing engineers.

Influence of Interlayer Temperature and Welding Sequence on the Temperature Distribution and Welding Residual Stress of the Saddle-Shaped Joint of Weldolet-Header Butt Welding.

In this paper, based on Simufact Welding finite element analysis software, a numerical simulation of the temperature and residual stress distribution of the weldolet-header multi-layer multi-pass welding process is carried out, and the simulation results are verified through experiments. The experimental results are in good agreement with the numerical simulation results, which proves the validity of the numerical simulation results. Through the results of the numerical simulation, the influence of the welding sequence and interlayer temperature on the temperature and residual stress distribution at different locations of the saddle-shaped weld was studied. The results show that the temperature and residual stress distribution on the header and weldolet are asymmetric, and the high-stress area of the saddle-shaped welded joint always appears at the saddle shoulder or saddle belly position. When the interlayer temperature is 300 °C, the peak residual stress reaches a minimum of 428.35 MPa. Adjusting the welding sequence can change the distribution trend of residual stress. There is no high-stress area on the first welding side of the two-stage welding path-2. The peak values of residual stresses for continuous welding path-1 and two-stage welding path-2 are 428.35 MPa and 434.01 MPa, respectively, which are very close to each other.

Influence of welding sequence on the mechanical properties of a latticed shell formed by orthogonal and oblique members

With the development of economy and the improvement of people’s aesthetic level, large-span latticed shells are increasingly used. Such structures are commonly large in volume and huge in welding. In order to select an optimum welding sequence and avoid correcting complex welding deformation, a latticed shell formed by orthogonal and oblique members was taken as the research object in this paper. The finite element models of single and whole latticed shells were established respectively, and according to the equal deformation principle, the influence of different welding sequence on the deformation and internal force of the structure in each construction stage was quantitatively analyzed. The results show that in the welding and assembling stage of small assembling units in the single latticed shell, welding sequence has the greatest impact on the longitudinal deformation, and the change rate of the longitudinal deformation is up to 83.63%; whereas in the tension, sliding and closure stages of each piece of the latticed shell, the transverse deformation is most affected by welding sequence, and the change rate is 33.05%; in different construction stages, the axial stress of the latticed shell is less vulnerable to welding sequence. Furthermore, it is feasible to control the welding shrinkage deformation by selecting a reasonable welding sequence, and the symmetrical welding sequence from both ends to the middle should be adopted during construction.

Effect of welding sequence and welding current on distortion, mechanical properties and metallurgical observations of orbital pipe welding on SS 316L

Orbital pipe welding was often used to manufacture piping systems. In orbital pipe welding, a major challenge is the welding torch’s position during the welding process, so that additional methods are needed to overcome these challenges. This paper discusses the influence of welding sequence and welding current on distortion, mechanical properties and metallurgical observations in orbital pipe welding with SS 316L pipe square butt joints. The variation of the orbital pipe welding parameters used is welding current and welding sequence. The welding current used is 100 A, 110 A, and 120 A, while the welding sequence used is one sequence, two sequences, three sequences, and four sequences. The welding results will be analyzed from distortion measurement, mechanical properties test and metallurgical observations. Distortion measurements are made on the pipe before welding and after welding. Testing of mechanical properties includes tensile tests and microhardness tests, while metallurgical observations include macrostructure and microstructural observations. The results show that maximum axial distortion, transverse distortion, ovality, and taper occurred at a welding current of 120 A with four sequences of 445 µm, 300 µm, 195 µm, and 275 µm, respectively. The decrease in ultimate tensile strength is 51 % compared to the base metal’s ultimate tensile strength. Horizontal and vertical microhardness tests show that welding with one sequence produces the greatest microhardness value, but there is a decrease in the microhardness value using welding with two to four sequences. Orbital pipe welding results in different depths of penetration at each pipe position. The largest and smallest depth of penetration was 4.11 mm and 1.60 mm, respectively

Influence of welding sequence on residual stress distribution and deformation in Q345 steel H-section butt-welded joint

Abstract Based on Marc. MSC software, this paper developed a thermo-elastic-plastic finite element method (FEM) to simulate the welding residual stresses and deformation in the low alloy high strength steel joints. The welding residual stresses and deformation in the Q345 Steel H-section butt-welded joints were calculated using this method. An H-section butt-welded joint was fabricated and the welding residual stresses were measured. Based on the simulation and experiment, the influence of welding sequence on the residual stress distribution and deformation in the Q345 steel H-section butt-welded joint was investigated. The results indicate that the welding sequence has a relatively small effect on the residual stress distribution in the flanges of the H-section joints, but a significant influence on that in the web. Under three different welding sequences, the welding deformations in the joints were similar. In the view of controlling welding residual stress, welding the web first is recommended in the fabrication of the H-section butt-welded joint.

Prediction and mitigation of out-of-plane welding distortion of a typical block in fabrication of a semi-submersible lifting and disassembly platform

Out-of-plane welding distortions of block structures during fabrication of offshore structure will significantly influence its dimensional accuracy and production schedule. Taking a B514 block of a semi-submersible lifting and disassembly platform as research object, typical welded joints and their welding conditions were summarized based on actual welding procedure specification (WPS). Effective thermal elastic plastic (TEP) finite element (FE) analysis with parallel computation technology was carried out to examine thermal-mechanical response. Welding inherent deformations, which are considered as the elementary cause of welding distortion, were then evaluated. With welding inherent deformations as mechanical loading, elastic finite element (FE) analysis was then employed to predict dimensional accuracy of examined B514 block, which has a good agreement with measurement data. In order to ensure the fabrication accuracy with less out-of-plane welding distortion, inverse deformation approach was applied to reduce the out-of-plane welding distortion, and influence of welding sequence on out-of-plane welding distortion was also examined. Both mitigation practices have obvious effect on dimensional accuracy of examined B514 block, while corresponding mechanical mechanisms were also clarified.

Experimental and numerical investigation of hybrid laser arc welding process and the influence of welding sequence on the manufacture of stiffened flat panels

Hybrid laser arc welding (HLAW) has gained growing attention from both industry and academic laboratories for its high efficiency and weld quality. The objective of the present paper is to develop a nonlinear finite element method for predicting the weld-induced deflection and residual stress of semi-industrial scale stiffened panel, using a novel heat source model. The novel hybrid heat source consists of a Goldak's double-ellipsoid mathematical model representing the arc source, combined with a truncated cone Gaussian mathematical model to simulate the laser source. For this purpose, three-dimensional coupled thermo-elastic-plastic finite element model has been developed with ABAQUS using an additional numerical subroutine of DFLUX written in the Fortran programming language to simulate the volumetric heat flux distributions of the HLAW process. The finite element method (FEM) is verified by comparison with experimental measurements of T-joint small-scale naval EH36 steel specimens, welded in horizontal position with full penetration using hybrid laser-arc welding process (HLAW). A good agreement is observed between the numerical results and the experimental measurements, confirming that the model developed in the present paper can be used effectively to predict the deformation behaviour of the stiffened plate structures during shipbuilding. The effect of changing welding sequence on the semi-industrial scale stiffened panel has been also studied. It is concluded that the welding sequence plays an important role in the deformation of the structures. A change of direction in the middle section, in combination with alternation of the welding paths between two consecutive reinforcements welding, leads to a significant decrease of distortion.

Influence of welding sequences on the microstructure and mechanical properties of dual-pass electron beam welded Ti60/V/Cu/GH3128 joints

Electron beam welding of Ti60 titanium alloy to GH3128 nickel-base superalloy was realized by using V/Cu composite interlayers, based on the element metallurgical compatibility. The effects of welding sequences on the microstructures and properties of the joints were analyzed. Microstructures and energy spectrum analysis shown that the reaction of Ti and Ni atoms to form brittle intermetallic compounds (IMC) can be effectively prevented by the interlayers. When the electron beam was first focused on the V foil, the copper foil was melted due to the high melting point of vanadium (1890 °C). Continuously distributed CuTi IMCs were produced near the Ti60 side. When the electron beam was first focused on the Cu foil, CuTi IMCs were replaced by the formation of (Ti,V) solid solutions at the interface of Ti60. A joint with a maximum tensile strength of 392 MPa, 49% of that of the GH3218 alloy was obtained. The fracture morphology proved that the fracture type belonged to brittle fracture.

Accuracy of computational welding mechanics methods for estimation of angular distortion and residual stresses

This study estimates the angular distortion and residual stresses due to welding using the following methodologies: thermo-elastic-plastic, inherent strain (local-global), and substructuring on two types of welded joints (T-type fillet weld and butt weld). The numerical results are compared with the experimental measurements and these methodologies are evaluated in terms of accuracy and computational time. In addition, the influence of welding sequence on distortion and transverse residual stresses has been studied numerically by implementing the thermo-elastic-plastic and inherent strain (local-global) methods on the T-type fillet weld. For the T-type fillet weld, the estimated angular distortion from these methods is much the same and in good agreement with the experimental measurements. For the butt weld, the angular distortion calculated by the inherent strain (local-global) method is largely underestimated. In order to gain a better understanding of where the underestimation of angular distortion in the inherent strain (local-global) method comes from, the study discusses the influence of block length and welding speed on angular distortion. It is found that for long weld length or slow welding speed, activating the plastic strain gradually by dividing the weld bead into an appropriate number of blocks can reduce the level of underestimation of angular distortion.

Enhanced idealized explicit FEM for predicting welding deformation in complex large-scaled structure and application to the real structure

ABSTRACT In the fabrication of steel structures, welding is widely utilized to join the materials. Due to the welding, distortions are inevitably generated, and these distortions may cause problems in accuracy or labour costs. In this research, to establish an analysis method which can predict the welding distortions in complex large-scale structures, we proposed a new analysis method based on the Idealized Explicit FEM. In the proposed method, an algebraic multigrid method was introduced to the Idealized Explicit FEM to achieve an efficient analysis in realistic structures. The proposed method was applied to the prediction of the welding distortion in the base structures of the construction machine. The number of welding passes was 28. The predicted and measured distortions were compared. As a result, it was demonstrated that the proposed method has a high analysis accuracy. The analysis finished within the realistic time within 35 h. The influence of welding sequence on the deformation was also investigated by changing welding sequence. The result indicated that the welding sequence may have considerable effect on the welding distortion and is necessary to be investigated in advance of the production.

Correlation between laser welding sequence and distortions for thin sheet structures

Thin ultra-high strength steel shaped as 700 mm long U-beams have been laser welded in overlap configuration to study the influence of welding sequence on distortions. Three different welding directions, three different energy inputs as well as stitch welding have been evaluated, using resistance spot welding (RSW) as a reference. Transverse widening at the ends and narrowing at the centre of the beam were measured. A clear correlation was found between the weld metal volume and distortion. For continuous welds there was also a nearly linear relationship between the energy input and distortion. However, the amount of distortion was not affected by a change in welding direction. Stitching and RSW reduced distortion significantly compared to continuous laser welding.

Influence of welding sequence on welding deformation and residual stress of a stiffened plate structure

An important consideration in the safe and efficient manufacture and operation of marine structures is the possible distortion, and consequential induced residual stress, owing to welding. This paper deals with welding simulation of a stiffened plate structure with longitudinal and transverse stiffeners using a thermal elasto-plastic FE method. Shell elements with section integration features are adopted to model the plate and stiffeners and solid elements to model the local detail of weld line region. Linear constraint equations are established between degrees of freedom of the shell and solid elements. Welding parameters of heat input, welding speed and welding sequence are considered in the analysis. A typical fillet-welded joint is studied and the thermal and mechanical results are compared with experimental values. Six welding sequences are simulated. The results demonstrate the specific influences of the different welding parameters on residual distortion and stress in a stiffened plate structure.

A new algorithm on welding process of T-shaped plates in ship hull structure to minimize distortion based on thermal simulation

In this paper, the influence of welding sequence on the distribution of distortion on a T-shaped plate bar is investigated. The simulation consists of sequentially coupled thermal and mechanical analyses using an element birth and death technique to model the addition of welding metal to the work piece. Thermal distribution in steel T-shaped plate subjected to gas metal arc welding is determined through finite element method (FEM) in numerical simulations. Three-dimensional (3D) thermal model is simulated in ANSYS FEM commercial code. A macro code programme based on Goldak model is developed to apply thermal loading generated by the heat sources. The analyses are planned to be performed for 3D, transient and non-linear conditions. Temperature distribution during welding, welding-induced distortion fields and thermal graphs are predicted. The results are compared with the predictions from mechanical analyses. The results of four welding sequences on the magnitude of distortion in the plate are discussed and their effects on the thermal smooth distribution for special points in the plate are studied. Evaluation of the results with minimum distortion represents proper predictions and proves applicability and simplicity of the new introduced algorithm in this paper.

Numerical Simulation for Residual Stress and Deformation of Surface Welding on Membrane Water-Wall

Automatic MIG was adopted to weld Inconel 625 alloy on 20 G Membrane Waterwall, which can improve the capacities of high temperature corrosion resistance and wear resistance. To study the influence of Membrane Waterwall surface welding sequences on residual stress and residual deformation, this paper utilized finite element software ABAQUS and segmented moving heat source model to simulate the sequence welding, balanced welding from the middle to sides, balanced welding from sides to the middle, balanced skip welding from middle to sides and balanced skip welding from sides to the middle and studied their residual stresses and deformations. The simulation results indicated that there was a great influence of welding sequences on the residual stress and deformation. The optimal welding sequence was balanced skip welding from middle to sides and balanced skip welding from sides to the middle, which could change the stress distribution, decrease the welding residual stress by 17%, realize the even deformation of the whole welding section and decrease the bending deformation by 50%.

Numerical Simulation of Welding for Box Beam Structure on Bogie of High Speed Train

In this paper a typical box beam structure on certain high speed power car was taken as study object, Based on the finite element analysis software SYSWELD, established the material parameters database for SMA490BW weathering steel, and performed the numerical simulation for the welding of typical box beam structure of side beam of high speed bogie, comparison between the simulation results and that of experiment test verified the existing welding procedures. For the purpose of studying the influence of welding sequence on the residual stress and providing theoretical support for actual production, the residual stress under different welding sequences was investigated then.

Numerical Simulation of Welding Distortion under Different Sequences

Finite element software ANSYS was used to study the influence of welding sequences on the distortion generated in the welding process of a Q345 plate with V-groove. The simulation of the welding process consists of sequentially coupled thermal and structural analyses using element birth and death technique. The results show that the backstep welding makes the distortion decrease. But back welding with too many steps makes the distortion increase. For a structure, the most reasonable number of steps can be found.

Influence of welding sequence on welding distortions in pipes

This paper presents a three-dimensional thermo-mechanical analysis to investigate the effect of welding sequence on welding deformations in pipe–pipe joints of AISI stainless-steel type. Single-pass TIG welding with V-joint geometry in pipes having a diameter of 274 mm and a thickness of 6.2 mm is studied here. Nine different welding sequences are analysed. The finite element results are compared with experimental data. It has been shown that selecting a suitable welding sequence can substantially decrease the amount of welding distortions in this pipe geometry.