In WELDING process, STRESSES after cooling, which remain in body, are called RESIDUAL STRESSES. Sometimes, the magnitude of STRESSES is high and reduces the strength of welded pieces, moreover, they cause crack in the weld. To predict WELDING RESIDUAL STRESSES, it is necessary to do thermal and mechanical analysis.In this paper, some parameters which influence the WELDING using ANSYS software are investigated. Results show that even by decreasing the travel speed of torch, it makes no differences in the amount of RESIDUAL STRESSES, but preheating causes decreasing the produced STRESSES about 22 percentages. Suitable WELDING sequences also, decreases RESIDUAL STRESSES up to 25 percentages.

In this study, the effect of WELDING parameters on the RESIDUAL STRESSES of resistance spot WELDING of AZ31 magnesium alloy was investigated. Resistance spot WELDING is a complicated multi-regime phenomenon which simulated by a developed electro-thermo-mechanical coupled finite element model. Interactions of parameters were determined using DOE method. The FE model was used to predict temperature changes, nugget growth, and the RESIDUAL STRESSES distribution. The results of the simulation were validated with experimental data, based on the nugget diameter. The results showed that by increasing current and WELDING time the RESIDUAL STRESSES are reduced. Increasing electrode force causes to increase RESIDUAL stress but increasing holding time creates a peak in the amount of RESIDUAL STRESSES. Also, evaluation of current sources revealed, in the same conditions, using direct current creates less RESIDUAL stress than alternating current.

In this investigation, the thermal and RESIDUAL stresess distributions developed during the circumferential butt tungsten arc WELDING (GTAW) of Incoloy 800H pipes were simulated using the finite element method. A coupled thermostructural model was developed in three dimensions using ANSYS software. A subroutine based on the Goldak model was added to the model to simulate the distribution of arc heat source. The plastic behaviour of the material was described by Von-Mises yield function and the bilinear kinematics hardening in the mechanical part of the model, which is sequentially coupled with the thermal one. In order to validate the coupled model, temperature distributions during WELDING and RESIDUAL STRESSES distributions in the welded pipes were both measured using thermocouples and hole drilling method, respectively. Using this model, a process parameter study was performed for the process variables such as WELDING efficiency and the amount of heat input in each pass.The results showed a tension-compression distribution of the axial STRESSES through thickness from inside to outside surface of the pipe and a tensile distribution for the hoop STRESSES. Increasing the heat input by 36% increased the axial RESIDUAL STRESSES along the weld centerline on the inner surface of pipe to 11%. The present simulation model is able to predict distributions of temperature and RESIDUAL STRESSES during the GTAW process with a reasonable precision.

In the present study, temperature fields and RESIDUAL stress states in the weld joint of the stainless steel pipe are computed numerically using a thermo-elastic-plastic analysis. This weld joint is a circumferential butt-weld one and is done in two passes using gas tungsten arc WELDING. WELDING procedure is simulated in two and three dimensions using a subroutine developed in finite element ABAQUS software for applying heat flux. Furthermore, the element birth and death technique is used to simulate weld passes and filler metal deposition into the weld pool. When the simulation is done, the effect of WELDING sequence on WELDING RESIDUAL STRESSES are considered using four different WELDING sequences proposed. Finally, the effect of hydrotest process in decreasing the RESIDUAL STRESSES is evaluated. The results of the simulation show that selecting a suitable WELDING sequence can substantially decrease the amount of tensile RESIDUAL STRESSES and can change them to compressive STRESSES in certain situations. Also the results of this research show that applying a hydrotest pressure after WELDING process can reduce WELDING RESIDUAL STRESSES up to 65%.

The effect of WELDING RESIDUAL STRESSES that was created in thin infill plate of steel plate shear wall system during constructional processes was studied in this research. RESIDUAL STRESSES in a welded structure is the result of the non-uniform expansion and contraction and plastic deformation of the weld and surrounding base metal due to heating and cooling cycle, during WELDING process, this issue could affected SPSW`s behavior. In this research ABAQUS finite element software is utilized to simulation of WELDING process and steel plate shear wall behavior. Sequentially coupled thermo-elastic–plastic finite element computational procedure is developed to calculate temperature field and WELDING RESIDUAL STRESSES in SPSW. The result shows that RESIDUAL STRESSES created in infill plates of three story steel plate shear wall with rigid beam-column connection due to WELDING process makes yielding load, ultimate load, stiffness, ductility and energy absorption, decrease 1.4%, 1.26%, 7.6%, 7.3%, 3.4% respectively in model with RESIDUAL STRESSES in comparison with model without RESIDUAL STRESSES. Thus, the ignore of RESIDUAL STRESSES effect due to WELDING in prospect of thin steel plate shear walls (SPSWs) behavior is negligible.

Accurately predicting WELDING RESIDUAL STRESSES and developing a convenient WELDING sequence for a weld system is an appropriate task since WELDING RESIDUAL stress is inevitably produced in a welded structure. In this work, the effect of layered, block and cascade WELDING sequences on the thermo-mechanical response of shell weldments is studied by use of a 3-D thermo-viscoplastic model. An Anand model is used to simulate the rate dependent plastic deformation of welded materials. At the same time, modeling of the welded region in the present study has been done on the basis of the "isothermal melting pool" approach. The temperature dependency of the thermal and mechanical properties of materials is considered in the analysis and the effect of the WELDING speed and WELDING lag, and the inter-pass temperature is introduced into the model as well. Thus, the model presented here has provided a convenient WELDING sequence to enhance the fabrication process of a circular weld.

In electric arc WELDING, the heat generated by the arc causes non-uniform expansion and contraction in the weld and surrounding areas. Uneven expansion and contraction and the resulting plastic deformation are the main sources of RESIDUAL distortion and stress in welded structures. The distribution of RESIDUAL STRESSES in a welded joint depends on factors such as heat input, arc WELDING speed, material properties, preheating, part thickness, groove geometry and WELDING execution schedule. In this research, a head to head joint is investigated by penetration WELDING with experimental methods and finite element simulation. RESIDUAL STRESSES are measured by the central hole drilling method and by converting the obtained data into RESIDUAL STRESSES, the obtained results are used to verify the developed finite element model. In the finite element model, the non-coupled thermal-mechanical mode is used and the method of birth and death of the elements is used in the simulation of filler materials. In the simulation, the phase transformation process is considered and with the help of LTT filler introduced, the RESIDUAL STRESSES in the single-pass WELDING show a 15% reduction and in the two-pass WELDING show a 17% reduction in the tensile RESIDUAL STRESSES. By examining the effect of the arrangement and composition of the passes and the type of WELDING fillers, it was found that the combination of LTT electrode with 6010 electrode provides more favorable results for RESIDUAL STRESSES. Regarding the effect of thickness change in the cross section of the samples, the output of the results of both numerical analysis software does not show significant changes.

In this paper, two API X70 steel pipes (with spiral seam weld) of 56 inch outside diameter and 0.780 inch wall thickness were girth welded first. Next, hole drilling tests were conducted for strain measurement on the surfaces of the pipes. The values of RESIDUAL STRESSES on the internal and external surfaces of the pipe were determined, from strain data using ASTM 837 standard. The experimental data showed that the maximum tensile RESIDUAL stress (318MPa) was located on the centre line of the weld gap on the pipe outer surface alongside with the pipe hoop direction. Moreover, the maximum compressive (hoop and axial) RESIDUAL STRESSES (137MPa) occurred on the pipe inner surface at 30mm from the centre line of the weld gap.

In this research, opening WELDING on an aluminum shell and investigating the effect of WELDING sequence on RESIDUAL STRESSES and distortion after WELDING by finite element simulation have been investigated. Then, the results are compared in ABAQUS and SYSWELD. Using experimental data, simulation and experimental results are compared. The temperature distribution is not uniform in different area of the WELDING zone, the most important factor in this incident is the non-uniform WELDING geometry. Thermal retransmission and the difference between thermal pick in different situations increases with increase of WELDING steps, which will affect the development of RESIDUAL STRESSES as well as distortion after WELDING. The peak of the RESIDUAL STRESSES is reduced and more uniform distribution occurs as the number of WELDING sequences increases. Also, the amount of elongation will be greater, with the higher the distortion in the weld area.

The article presents a study on the effects of ultrasonic treatment on RESIDUAL WELDING STRESSES (RWS). Ultrasonic treatment was administered from three orientations: external, internal, and bilateral. Six samples, each with a thickness of 8 mm and composed of steel grade 09G2S, were prepared. The WELDING of these samples was executed using semi-automatic equipment and adhered to regulatory and technical guidelines. The magneto anisotropic technique, foundational to the operation of the Stress Vision Lab device, was employed to measure RESIDUAL STRESSES. Given that this device quantifies RESIDUAL stress values in arbitrary units, a calibration table was devised to translate these measurements into megapascals (MPA). This calibration was established by correlating values obtained from the ZW-100 testing machine with those measured by the Stress Vision Lab, necessitating the preparation of three additional samples of the same steel grade. Experimental investigations revealed that ultrasonic treatment applied internally to the samples facilitated the most significant reduction in RESIDUAL (tensile) STRESSES, with reductions of 37.5% from external application and 27% from internal application. Leveraging the data acquired, a device has been developed to mitigate RESIDUAL WELDING STRESSES within the inner wall of the near-seam zone of pipelines.