3D finite element analysis and optimization of welding residual stress in the girth joints of X80 steel pipeline

Zhao, Weimin; Jiang, Wei; Zhang, Hongjie; Han, Bo; Jin, Haicheng; Ping, Qi

doi:10.1016/j.jmapro.2021.04.009

Cited by 36 publications

(16 citation statements)

References 22 publications

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“…On the one hand, formation of compressive stress is due to the heat treatment of latter welds. 20 On the other hand, when carrying out the filling welding of thick weld, the melted weld metal is constrained by the root weld, resulting in the generation of compression stress.…”

Section: Microstructure Distribution In Q690 Hss Butt-welded Jointmentioning

confidence: 99%

“…[17][18][19] The results demonstrate that SSPT during cooling process has a considerable contribution to the final welding residual stress distribution in thin plate and the effect of transformationinduced plasticity on residual stress is inferior to that of volume change. A few numerical models 1,[20][21][22] have been used to simulate the residual stress in thick welds, but the effects of SSPT and initial stress have not been taken into account. Therefore, it is meaningful to clarify the influence of SSPT and initial stress on the formation of the throughthickness distribution of residual stress during multi-pass butt welding of HSS thick plates.…”

Section: Introductionmentioning

confidence: 99%

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Accurate evaluation on residual stress considering solid-state phase transformation and initial stress in thick weld

Zhang

Wang

2022

Proceedings of the Institution of Mechanical Engineers, Part C:

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During the welding process of thick plates, it is difficult to evaluate the residual stress distribution in thick welds accurately because complicated residual stress is generated by multi-thermal cycles. In this study, a multi-pass butt joint was fabricated using Q690 high strength steel with the thickness of 75 mm, meanwhile experiments were carried out to characterize the microstructure and measure the through-thickness distribution of longitudinal residual stress in a butt-welded joint by the contour method. Then numerical methods were developed to predict the through-thickness distribution of residual stress in butt-welded joints. To evaluate residual stress accurately and efficiently, the effects of solid-state phase transformation (SSPT) and initial stress were taken into consideration, and the parallel computation technology and iterative substructure method were employed. The root-mean-square error (RMSE) was employed to evaluated the prediction accuracy of numerical methods between measurement and numerical results of residual stress. Through comparing the simulated results with experimental data, the validity of the developed numerical methods was verified. Numerical results indicate that the through-thickness distribution of residual stress in butt-welded joints is very complex and peak value of tensile stress can be found in the area adjacent to the heat-affected zone (HAZ). Moreover, the RMSE is significantly decreased from 307 to 8 when considering the effect of SSPT on residual stress in weld vicinity, and the RMSE is apparently decreased from 137 to 11 when considering the effect of initial stress on residual stress in base metal.

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Section: Microstructure Distribution In Q690 Hss Butt-welded Jointmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Accurate evaluation on residual stress considering solid-state phase transformation and initial stress in thick weld

Zhang

Wang

2022

Proceedings of the Institution of Mechanical Engineers, Part C:

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“…In order to obtain the residual stress and deformation results of the base metal after welding, it is first necessary to divide the three-dimensional structure model into a finite element model [15]. The meshing of the model selected solid 70 for a multi-physics coupling solution.…”

Section: The Development Of Finite Element Model Of Welding Objectmentioning

confidence: 99%

FEM Research on Welding Thermal Deformation of Copper Alloy Sheet and Optimization of Welding Sequence

et al. 2021

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To reduce the residual stress and deformation of the copper alloy sheet after welding, and improve the welding quality of the copper alloy sheet, the finite element method (FEM) research on welding thermal deformation and welding sequence optimization was carried out. First, a finite element model of copper alloy sheet welding was established based on ANSYS, the mechanical property parameters of the model at high temperature were determined, and the thermal–structural coupling calculation was performed on the model. Then, the change trend and magnitude of the residual stress and deformation of the model after welding were analyzed. Finally, different welding sequence schemes were designed, and numerical simulation calculations were carried out. The results of the welding sequence solution show that the change trend of the residual stress after welding of the base metal under different welding sequences is basically the same; repeated heating of the base metal at the same position causes large residual stress; the weldment vertical plate is subjected to opposing forces in the x-axis and y-axis directions at the same time. Among four welding schemes, the welding scheme that alternately welds symmetrically from the start and end positions of the weld seam to the middle position of the plate causes the least welding deformation. Compared with the other three schemes, its deformation reduces by 26.6%, 18.3%, and 19.4%, respectively.

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“…Non-linear transient heat transfer equation was expressed as follows [ 27 ]:

where

is the material density,

is the specific heat thermal conductivity,

is thermal conductivity,

is mainly the latent heat of phase transition.…”

Section: Finite Element Modelingmentioning

confidence: 99%

Effects of Fillet Weld Size and Sleeve Material Strength on the Residual Stress Distribution and Structural Safety While Implementing the New Sleeve Repair Process

et al. 2021

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The process optimization and structural safety improvement of the in-service repair welding of the X80 pipeline are very important. In this paper, the temperature, microstructure, and stress distribution were analyzed using the combination of TMM (thermal-metallurgical-mechanical) simulations and the corresponding verification experiments. The effects of the sleeve material strength and the fillet weld size were discussed. The results showed that the fillet weld zone was mainly composed of ferrite and bainite when the material of the sleeve pipe was Q345B. Furthermore, the sleeve pipe’s HAZ (heat affected zone) was dominated by lath martensite, lath bainite, and granular bainite. Moreover, granular bainite and a small amount of ferrite were found in the HAZ of the X80 pipe. It was found that, as the fillet weld size increased, the welding residual stress distribution became more uniform. The hoop stress at weld toe reduced from ~860 MPa of case A to ~680 MPa of case E, and the axial stress at weld toe reduced from ~440 MPa of case A to ~380 MPa of case E. From the viewpoint of welding residual stress, fillet weld size was suggested to be larger than 1.4T. The stress concentration and the stress distribution showed a correlation with the cracking behavior. Weld re-solidification ripples on the weld surface and weld ripples between welding passes or near the weld toe could cause stress concentration and the corresponding crack initiation. Furthermore, when the material of the sleeve pipe changed from Q345B to X80, the high-level tensile stress zone was found to be enlarged. The hoop stress at weld toe increased from ~750 to ~800 MPa, and the axial stress at weld toe increased from ~500 to ~600 MPa. After implementing the new sleeve repair welding process where X80 replaces the material of sleeve pipe, the cracking risk in sleeve pipe will improve. From the perspective of the welding residual stress, it was concluded that the fillet weld size reduction and the sleeve material strength improvement are harmful to in-service welded structures’ safety and integrity.

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3D finite element analysis and optimization of welding residual stress in the girth joints of X80 steel pipeline

Cited by 36 publications

References 22 publications

Accurate evaluation on residual stress considering solid-state phase transformation and initial stress in thick weld

Accurate evaluation on residual stress considering solid-state phase transformation and initial stress in thick weld

FEM Research on Welding Thermal Deformation of Copper Alloy Sheet and Optimization of Welding Sequence

Effects of Fillet Weld Size and Sleeve Material Strength on the Residual Stress Distribution and Structural Safety While Implementing the New Sleeve Repair Process

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