Effect of welding sequence on residual stress and deformation of 6061-T6 aluminium alloy automobile component

Four different welding sequences of double-pulse MIG welding were conducted for 6061-T6 aluminum alloy automobile bumpers by using nonlinear elastoplasticity finite element method based on ABAQUS software.The post-welding residual stress and deformation were definitely different among the four welding sequences.The results showed that the highest temperature in Solution A was approximately 200℃higher than the melting point of base metal.High residual stress was resulted from this large temperature gradient and mainly concentrated on the welding vicinity between beam and crash box.The welding deformation primarily occurred in both of the contraction of two-ends of the beam and the self-contraction of crash box.Compared with other welding sequences,the residual stress in Solution A was the smallest,whereas the welding deformation was the largest.However,the optimal sequence was Solution B because of the effective reduction of residual stress and good assembly requirements.

Numerical simulation of residual stress and deformation for submerged arc welding of Q690D high strength low alloy steel thick plate

The finite element simulation software SYSWELD is used to numerically simulate the temperature field,residual stress field,and welding deformation of Q690D thick plate multi-layer and multi-pass welding under different welding heat input and groove angles.The simulation results show that as the welding heat input increases,the peak temperature during the welding process is higher,and the residual stress increases,they are all between 330–340 MPa,and the residual stress is concentrated in the area near the weld.The hole-drilling method is used to measure the actual welding residual stress,and the measured data is in good agreement with the simulated value.The type of post-welding deformation is angular deformation,and as the welding heat input increases,the maximum deformation also increases.It shows smaller residual stress and deformation when the groove angle is 40°under the same heat input.In engineering applications,under the premise of guaranteeing welding quality,smaller heat input and 40°groove angle should be used.

Sequence optimization of hull structure assembly based on prediction of welding deformation

Optimization of assembly process is significant for ship construction, thus reducing the time and related costs of construction. Welding Structure Deformation Analysis （Weld-sta） was used to predict welding deformation of a hull block. After the reliability of simulation was proved by comparing with measured results, four kinds of welding sequences was determined. By considering welding deformation and assembly process with the e]ficieney of automation, decreasing the overturn times （times of turning the erections upside down during welding） and working hours etc, one of the welding sequences is assumed to be the most reasonable one. The study shows this method is very useful in optimal assembly program determination of practical engineering structures.

Study on welding deformation of the side beam based on numerical simulation method

The welding deformation is a key factor affecting the production quality of the side beam of the subway bogie frame. A major issue is how to control the welding deformation during the manufacturing processes. Based on the ＂Local- Global＂ method, the thermal cycle and the stress of a local model extracted from the global side beam model were simulated. The simulated strain result was mapped into the global model as an initial load to simulate the welding assembly deformation. Then the deformation distribution of the side beam was obtained by elastic finite element method, and compared with the measurement results. Furthermore, the welding deformation under different welding sequences and constraints was simulated. The influence of the welding sequences and constraints on the side beam deformation was analyzed. The results indicate that the deformation is the smallest when the sequence is symmetrical and decreases with the increase in constraints.

Welding deformation control of medium-thickness structures made by advanced high strength steel

In order to investigate the residual angular deformation in fillet welding of T-joint of HG785 high strength steel with a medium thickness plate, both detailed thermo-mechanical finite element simulation and conventional gas metal arc welding experiment were carried out in the present study. In-process deformation control method using backheating method to reduce the residual deformation was discussed.

Numerical simulation of the welding deformation for the side sill of the bogie frame based on local-global method

Considering the limitation of computational capacity, a new finite element solution is used to simulate the welding deformation of the side sill of railroad car＇ s bogie frame based on the local-global method. Firstly, a volumetric heat source defined by a double ellipsoid is adopted to simulate the thermal distributions of the arc welding process. And then, the local models extracted from the global model are computed with refined meshes. On these bases, the global distortions of the subject studied are ascertained by transferring the inner forces of computed local models to the global model. It indicates that the local-global method is feasible for simulating the large welded structures by comparing the computed results with the corresponding actual measured values. The work provides basis for optimizing the welding sequence and clamping conditions, and has theoretical values and engineering significance in the integral design, manufacturing technique selection of the bogie frame, as well as other kinds of large welded structures.

Three dimension simulation analysis of the interpass stress and deformation during multipass welding

It has been widely studied about the final residual stress and deformation in muhipass welding of thick weldments. But there is a lack of a clear understanding of the interrelationship of interpass stress and deformation during multipass welding. In this study, a three dimension numerical model of a sixteen-pass double V-groove welded joint with 50 mm plate is developed to compute the stress field and deformation by using multiple CPU parallel processing technology. The following factors such as the non-linear of temperature, heat radiation, filling of material step by step and so on are considered. Distribution and evolution law of welding stress in the transverse and longitudinal section is analyzed in this paper, and the interpnss stresses are studied also. At the same time the evolution course of angular deformation amount is analyzed, and the experimental results show that the calculated resuhs accord with the measured results of angular deformation.

Finite element analysis of controlling the TC4 thin plate weldment wave-like deformation by welding with impacting rotation

The new technology of welding with impacting rotation is put forward to decrease the wave-like deformation of the TC4 thin plate weldment. The thermal stress and strain are vital to understand the mechanism of controlling the wave-like deformation. In order to know the development of internal thermal stress and strain, finite element method is utilized for- the stress and strain are difficult to be investigated by experimental methods during the welding process. Temperature field, thermal stress evolution and distortion of thin plate are compared with the test results such as weld thermal cycle, residual stress sectioning measurement, and the deflection of the thin plate respectively. By the finite element analysis and test results verification, the meehaaism of the technology to control the wave-like deformation is brought forward, non-uniform thermal elastic strain between compressive plastic region and elastic extensive region is diminished by a certain amount of extensive plastic deformation by welding with impacting rotation process.

Numerical analysis of joint temperature evolution during friction stir welding based on plastic deformation heat

3D numerical model for friction stir welding （FSW） was developed by using ABAQUS software considering the plastic deformation heat. Effects of the rotation and welding speeds on the temperature field of FSW 2024-73 aluminum alloy were systematicaUy investigated. The temperature measurement was performed to validate the reliability of the model. The simulation results are in good agreement with the experiments. Results show that changing the rotation speed has no influence on the time for reaching the peak temperature at certain point in the workpiece at a constant welding speed. While increasing the welding speed has significant effect on the time for reaching the peak temperature but the value of peak temperature changes little.

A time-dependent measuring system for welding deformation

In this paper the establishment and application of a time dependent measuring system for welding deformation are presented which is established with high quality sensors shielded from strong welding interference. By using this system, vertical and horizontal displacements of the high temperature area are surveyed at the same time. And this system is also used for monitoring and controlling the deformation of real welded structures.

Prediction of Welding Deformation of Underframe

An inherent strain method was applied to the welding deformation analysis of left girder of GM’s Buick’s chassis underframe assembly. Three models are used in the calculation. Model 1 takes into account the longitudinal and transverse inherent strains; model 2 considers only longitudinal inherent strain; model 3 also takes into account the longitudinal and transverse inherent strains, but inherent strains are taken according to the function instead of the constant, for simulating the variation of the girder’s stiffness during welding process. The result shows the deformation of model 2 is less than that of the model 1, the error is less than 10% of the absolute displacement. So the longitudinal inherent strain is the main factor determining boxes-girder’s welding deformation. The deformation of model 3 is also less than that of the model 1, because the inherent strains of the model 3 are less than that of the model 1. At last, the welding deformation of the whole underframe was analyzed. The analysis results can be taken as references not only for the choices of welding sequence, welding parameters and fixture’s location, but also for welding deformation prediction of other car chassis.

Impact Strength Analysis of Plate Panels with Welding-Induced Residual Stress and Deformation

The paper describes the simulation of impact loads applied on plate panels with welding-induced residual stresses and deformation (WSD). Numerical simulations using FEM are carried out to study the influence of welding-induced residual stresses and deformation on the impact strength of plate panels. Welding is simulated using a three dimensional thermal mechanical coupled finite element method. The welding stress and deformation are taken as the initial imperfections in the impact strength analysis and their influence on the behavior of plate panels subjected to impact loadings. The impact loadings from the three directions, the lateral direction and two in-plane directions of the plate panels are studied. Results show a certain reduction in the impact strength due to the existence of welding stress and deformation in the plate panels. It is found that the reduction of impact force is strongly influenced by the welding deformation and the impact directions in the plate panels. This reduction is more significant when the impact force is in the lateral direction.

Numerical simulation of stress and deformation of in-service welding onto gas pipeline

SYSWELD was used to simulate in-service welding process of gas pipeline of X70 pipeline steel. Welding thermal cycle, stress and deformation of in-service welded joint were studied. The results show that peak temperature of coarse grain heat-affected zone （CGHAZ） of in-service welding onto gas pipeline is the same with routine welding, but ts/5, ts/3 and ts/1 decrease at certain degree. For the zone near welded seam, axial stress and hoop stress in the inner pipe wall are compressive stress when welding source passes through the cross-section that is studied, but residual axial stress and residual hoop stress after welded are all tensile stress. Transient deformation and residual deformation are all convex deformation compared with the original pipe diameter size. Deformation achieves maximum when welding thermal source passes through the cross-section that is studied and then decreases during the cooling process after welding.

Discussion on Construction Technology and Welding Deformation of High-Rise Steel Frame Structure

Because of urbanization,land resources in China’s cities has become increasingly scarce.Therefore,modern buildings are becoming taller,making high-rise steel frame structures the new favorite of the construction industry.However,the construction of high-rise steel frame structures requires advanced technology.If the construction technology is effectively implemented and the welding techniques of the construction personnel align with the requirements for high-rise steel frame structures,it can help mitigate deformations in the steel structure,thus preserving the overall construction quality of high-rise steel frame structures.To enhance the applicability of steel frame structures in high-rise buildings,this paper focuses on analyzing the optimization path for the construction process of high-rise steel frame structures.It introduces a tailored approach to control welding-induced deformations in steel frame structures,aiming to make a valuable contribution to the advancement of China’s construction industry.

PREDICTION OF WELDING DEFORMATIONS BY FEM BASED ON INHERENT STRAINS

Welding deformations can be predicted by inherent strains that are assumed to be distributed in the welds and nearby area. This method is more convenient compared with the thermo elasto plastic finite element method because only elastic analysis is necessary. The problem is how to know the inherent strains in advance during deformation analysis. The relations between inherent strains and welding parameters based on some experimental curves and a 3 D FEM model were introduced. According to this study, the longitudinal and transverse inherent strains that are the most important factors on welding deformations can be determined. The effectiveness of the proposed methods is demonstrated through the deformation analysis of a large welded cylinder with multipass welds as an example.

A new type of wear resistant overlay welding rod

By adopting the alloy wire of Ni 80 Cr 20 as the welding core and adding the alloy elements of B, Si, Mo and W into the outer plating covering, a new type of wear resistant overlay welding rod of Ni Cr B Si was developed. This overlay welding rod has several properties such as low melting point and good fluidity. With low content of W and Mo, the wearability and crack resistance of the overlay welding rod can be increased, and the hardness can be increased to about HRC64. This kind of overlay rod has been applied to the overlay of wearable workpieces, such as the valves of high temperature, high pressure and the side plates of floor boarding brick die.

Study on deformation and microstructure characterizations of mild steel joints by continuous drive friction welding

Macro-deformation characteristics of continuous drive friction welded mild steel joints were examined by using one deformable workpiece （objective） and the other undeformable one （rigid）. The microstructure evolution and hardness change across the joint were studied. The results show that the axial shortening and radial increment of joints increase with increasing the frictiou time at l 200 rpm. The cementite particles of pearlites in the weld center are uniformly distributed on the ferrite matrix, while the cementites of the pearlite in the thermal-mechanically affected zone are broken and discontinuously dispersed in the pearlite. The hardness decreases rapidly from the weld center to the parent metal under the coupled effects of heat and deformation during the rapid heating and cooling processes.

Numerical Simulation of Welding Deformation for Hull Superstructure Steel Based on the Finite Element Analysis

Using finite analysis element software, the transient displacement field of automatic submerged arc welding is established. It was also considered that the thermal physical properties changes were depended on the temperatureand the heat loss on the surface. At the same time, it analyzed the influence of the deformation and stress, whichgenerated in the plate butt-welding process, to the superstructure steel welding deformation. The result showedthat the deformation and stress generated in the steel plate butt-welding process are considered to be the mainfactors to influence the welding deformation of superstructure steel. It found the effective ways to reduce the weldingdeformation of the hull superstructure steel is to relieve the butt-welding deformation and release butt-welding stressbefore welding the hull superstructure steel.

Computational analysis of linear friction welding process and micromechanical modeling of deformation behavior for medium carbon steel

Finite element simulation of linear friction welding(LFW) medium carbon steel was carried out using the ABAQUS software. A two-dimensional(2D) coupled thermo-mechanical model was established. First, the temperature fields of medium carbon steel during LFW process were investigated. And then, the Mises stress and the 1st, 2nd and 3rd principal stresses fields' evolution of the steel during LFW process were studied. The deformation behavior of LFW carbon steel was analyzed by using micromechanics model based on ABAQUS with Python code. The Lode parameter was expressed using the Mohr stress circle and it was investigated in detail.

High Effective FE Simulation Methods for Deformation and Residual Stress by Butt Welding of Thin Steel Plates

In order to propose high effective simulation using finite element method (FEM) for predicting deformation and residual stress generated by one pass butt welding, a series of numerical analyses were carried out. By idealizing the movement of heat source (the instantaneous heat input method), the tendency of welding out-of-plane deformation and the residual stress distribution could be predicted. The computing time was around 9% of that by the precise model with considering the movement of heat source. On the other hand, applicability of two dimensional shell elements instead of generally used three dimensional solid elements was examined. The heat input model with considering the temperature distribution in the thickness direction was proposed for the simulation by using the shell elements. It was confirmed that the welding out-of-plane deformation and residual stress could be predicted with high accuracy by the model with shell elements and the distributed heat input methods. The computing time was around 8% of that by the precise model with solid elements.