Three-dimensional welding residual stress distribution of thick-plate T-joints in steel bridge tower

Fatigue behavior assessment of AA2219 TIG butt joints considering weld reinforcement geometry and residual stresses measurements

In this work, a laser lap-welded joint of galvanized steel/Mg and a laser lap-welded joint of galvanized steel/Mg assisted by ultrasonic vibration were compared. By adjusting the laser beam power and ultrasonic amplitude, the appropriate welding process parameters were obtained. The weld formation, microstructure and mechanical properties were studied and analyzed. The results indicated that the addition of ultrasonic vibration generated an excitation force with a certain frequency and amplitude on the weldment, making the molten metal in the molten pool produce ultrasonic forced vibration, and producing the effects of cavitation, acoustic streaming, mechanical stirring and heat, thus reducing welding residual stress and welding-deformation, porosity and incomplete-fusion defects. In addition, it can make the fusion zone transition evenly, improve the wettability, refine the weld grain, and reduce the average grain area from 583 μm2 to 324 μm2. Moreover, the distribution of Mg-Zn reinforcing phase at the interface was more uniform and denser, and the maximum tensile shear strength increased from 179.9 N/mm to 290 N/mm, indicating that the addition of ultrasonic vibration was conducive to improving the comprehensive mechanical properties of the joint.

To reduce the computational cost associated with traditional moving heat source methods, a segmented approach is proposed for simulating the welding process of T-joints in large-scale infrastructure steel modules. Firstly, the hole-drilling method was employed to measure the welding residual stresses in a 2400 mm T-joint. Subsequently, a three-dimensional finite element model was established in ABAQUS, and a user-defined subroutine for the segmented moving heat source was developed in Fortran to calculate the welding residual stresses. The numerical simulation results were compared with experimental data, showing high consistency and further validating the accuracy of the finite element model. Furthermore, the distribution patterns of residual stresses along the thickness direction and the effects of different welding sequences on temperature, stress, and deformation were investigated to optimize the welding sequence. The results indicated that the residual stresses along the weld seam exhibited a compressive–tensile–compressive distribution, with the maximum tensile stress reaching approximately 347 MPa. Additionally, the simulation results demonstrated that the double-ellipsoidal heat source method was computationally intensive and failed to provide accurate results for long weld seams, whereas the segmented moving heat source approach reduced the computation time to only 38 h. Moreover, different welding sequences had a significant impact on residual stresses and deformation. Through comprehensive analysis, it was found that Case 1 (sequential welding in the forward direction) achieved the best performance in minimizing welding residual stresses and deformation.

The bogie serves as a critical structural component in high-speed trains, subjected to dynamic loads throughout its operational lifecycle. Enhancing the fatigue life of the bogie necessitates not only ensuring welding quality but also effectively managing welding residual stresses during the manufacturing process. In this study, an efficient and simplified thermal–elastoplastic finite element method was developed based on the ABAQUS software platform, and its reliability and applicability were validated through comparison with measured data. The computational approach was employed to investigate the distribution characteristics of welding residual stresses in a weathering steel bogie beam, with particular emphasis on the influence of different welding sequences on residual stress distribution. Simulated results demonstrate that the welding sequence significantly influences the residual stress distribution and magnitude within the beam. The numerical simulation methodology developed in this study offers a powerful tool for optimizing welding sequences to regulate residual stresses during the fabrication of bogie structures.

Finite element thermo-elasto-plastic (FEM TEP) analysis, commonly used to evaluate welding deformation and residual stress, requires high computational cost due to sequential calculation from welding start to full cooling. In contrast, the thermal shrinkage technique predicts welding deformation more efficiently by modeling only the thermal contraction that occurs during cooling and performing a one-step elastic–plastic analysis. However, it can reproduce only angular distortion. In this study, a modified thermal shrinkage technique is proposed to reproduce both angular and transverse deformation by introducing multiple shrinkage parameters. The method is applied to bead-on-plate welding, and the shrinkage area and shrinkage temperature are identified to reproduce transverse shrinkage and angular distortion under various heat input conditions. Using these parameters, deformation in a six-pass multi-layer weld is predicted accurately. The proposed technique successfully reproduces the deformation history of all passes with good agreement to FEM TEP analysis, achieving more than 250 times faster computation. This demonstrates that the modified thermal shrinkage technique is a simple yet accurate and highly efficient method for predicting welding deformation.

Abstract Marine engineering welded structures are prone to stress corrosion cracking (SCC) under the combined influence of complex marine environments and welding residual stresses. This study focuses on the heat-affected zone (HAZ) of DH36 steel welded joints. It investigates the stress corrosion mechanism under different welding residual stresses using four-point bending immersion experiments, scanning electron microscopy (SEM), X-ray diffraction (XRD), and electrochemical testing. The results show that the stress corrosion resistance of the heat-affected zone (HAZ) of DH36 steel welded joints is significantly reduced under residual stress. Under the condition of no residual stress, a compact passive film forms on the HAZ surface. Residual stress accelerates the formation rate of the passive film. At 50% R el , the surface of the sample first undergoes deformation-induced passivation, followed by film rupture and even spalling. Without residual stress, corrosion products consist predominantly of α-Fe 2 O 3 , whereas under residual stress, γ-FeOOH becomes the dominant phase. At 50% R el , the high residual stress makes the passivation film completely rupture, resulting in the exposure of the Fe matrix. The corrosion mechanism is primarily governed by anodic dissolution. The research provides theoretical guidance for improving welding processes in marine engineering equipment.

Mechanism analysis of welding distortion and residual stress induced by repair welding in thin-walled pipes

The Contour Method is a well-established destructive technique for determining cross-sectional maps of residual stress in manufactured metallic components. The validity of the technique is dependent on linear elastic relaxation of residual strains across the plane of interest as the component is progressively cut into two parts across the plane of interest. However, for some welded components, redistribution of the residual stress field during the contour cutting step can result in local plastic deformation of the cut faces, giving errors in the measured residual stress map. This article describes a novel implementation of the Contour Method for welded components that can mitigate the risk of introducing such strain relief errors in the measured residual stress field. An orthogonal cutting sequence is applied where the component is first cut along the weld centreline (in the longitudinal direction) into two mirror-symmetric halves. Each one-half component is then cut transversely towards the weld line at mid-length. The out-of-plane deformation contours of the four cut faces are then measured, and the original residual stresses present on each cut section are determined using the multiple cut contour method. The efficacy of implementing the new contour measurement approach to fusion-line weldments is demonstrated both numerically and experimentally.

This investigation explores the friction stir welding of dissimilar AA6061-AA5083 aluminum alloy joints using experimental methods and numerical modeling techniques. The objective was to assess the effects of welding parameters on heat distribution and their impact on residual stress, microstructure, and hardness. To validate the model, a comparison was made between the simulation results and the experimental data. The modeling results and residual stress measurements obtained through the XRD method indicated that increasing the number of welding passes from one to two at a constant rotational speed of 1100 rpm, while reducing the tool traverse speed from 32 to 25 mm/min, led to an increase in the thermal gradient and residual stresses. An analysis of longitudinal and transverse residual stress values revealed a combination of tensile and compressive stresses. In single-pass welding, heat distribution was skewed toward the retreating side; however, altering the tool rotation direction in the second pass resulted in symmetrical heat distribution on both the advancing and retreating sides compared to the first pass. Moreover, increasing the number of welding passes from one to two at a rotational speed of 1100 rpm and a traverse speed of 25 mm/min resulted in a reduction of the average grain size across all microstructural regions and a 21% increase in hardness.

A study on annealing temperature in FEM simulation of residual stress in SUS316 weld

To accurately assess the residual stress distribution on the superficial layer of the weld for a pure copper butt-welded joint after laser shock peening (LSP), a coupled model was established by integrating experimental measurements with numerical simulations. This model simulates both the tungsten inert gas (TIG) welding process of pure copper and the subsequent LSP treatment applied to the weld. On this basis, the effects of the spot overlapping rate, number of impact layers, and pulse width on the weld residual stress profile were evaluated via multi-point LSP simulations. The findings imply that LSP converts the weld's superficial residual stress from tensile to compressive, which verifies the accuracy of the simulations through the experimental data. Multi-point LSP numerical simulations demonstrate that elevating the spot overlapping rate and number of impact layers enhances the amplitude and affected depth of the surface compressive residual stress (CRS). A slight decrease in the CRS on the superficial layer of the weld was observed with an increase in pulse width. Compared with increasing the overlapping rate and pulse width, increasing the number of impact layers has a more significant strengthening effect. When the impact layer reached 3 times, the surface CRS reached -219.4 MPa, and the influence depth was 1.3 mm.

Effect of strain hardening and martensite phase transformation on residual stress in 30MnCrNiMo high-strength steel laser-MAG hybrid welding

Investigation of microstructure, mechanical properties, residual stress, and distortion in multi-pass gas metal arc welding of ZGMn13Mo/A514 dissimilar joints

A force-data-constrained approach for simulation of temperature field and residual stress in friction stir welding

To reflect the influence of material property changes caused by temperature history on welding residual stresses, this paper conducts a study on residual stress calculation using a combination of molecular dynamics (MD) and finite element (FEM) methods. Firstly, a multi-scale material property calculation method is established using the theory of MD-FEM to calculate the problem of material property transformation under high-temperature history. Then, a residual stress calculation model that considers the effect of material recrystallization (RE-Model) is established using finite element method (FEM), and the study of residual stress calculation is conducted. Furthermore, the fatigue lifespan of a T-joint welding structure is calculated using the multi-axis fatigue lifespan method. The results show that the fatigue lifespan calculated by the RE-Model is reduced by more than 20% compared with the traditional residual stress calculation model, proving the importance of considering recrystallization effects in the calculation of welding structure strength.

Numerical analysis of residual stress and deformation in friction stir welding of large 2219 aluminum alloy cone components

Free vibration analysis of double-layer thin-walled cylindrical shell–ring stiffened plate coupled structure considering welding residual stress

MIG welding microstructure, residual stress and mechanical properties of powder metallurgy 7A52 aluminum alloys

Abstract Ship hull girder fabricated by welding is inevitably subjected to cyclic loading induced by wave over its lifespan. It is of great significance to investigate the characteristics of residual stress shakedown and progressive collapse of hull girder under such loading condition. In the present article, ISSC container ship is taken as a typical example to clarify the relaxation behavior of welding residual stress (WRS) in the hull girder under different patterns of cyclic loading. Then, parametric nonlinear finite element analysis is conducted to deal with the ultimate strength characteristics of hull girder under monotonic or extreme cyclic bending moments considering the ratcheting effect and the Bauschinger effect. The influence of material property, WRS, initial deflection shape, bottom lateral pressure, and model extension on the ultimate strength is involved. The failure mechanisms of hull girder under bidirectional/unidirectional cyclic bending moments are elaborated. It is found that the progressive collapse behavior is governed by the coupling effect of several key factors. The developed insights are useful to improve the safety assessment of ship structures.