Welding Distortion Research Articles

Experimental and Numerical Study of Maximum Welding Joint Temperature Impacts in Alloy Steel Pipe Welding Microstructure, Distortion, Corrosion Resistance, and Mechanical Properties

Experimental and Numerical Study of Maximum Welding Joint Temperature Impacts in Alloy Steel Pipe Welding Microstructure, Distortion, Corrosion Resistance, and Mechanical Properties

Enhancing Welding Productivity and Mitigation of Distortion in Dissimilar Welding of Ferritic-Martensitic Steel and Austenitic Stainless Steel Using Robotic A-TIG Welding Process

The P91 martensitic steel and 304L austenitic stainless steels are two mainly used structural steels in power plants. The major problem in conventional multipass tungsten inert gas (TIG) welding of P91/304L steel is high heat input and joint distortion, increased cost and time associated with V groove preparation, filler rod requirement, preheating and welding in multiple passes, and labor efforts. Hence, in this study, a novel approach of robotically operated activated flux TIG (A-TIG) welding process and thin AlCoCrFeNi2.1 eutectic high entropy alloy (EHEA) sheet as the interlayer was used to weld 6.14 mm thick P91 and 304L steel plates with 02 passes in butt joint configuration. The joints were qualified using visual examination, macro-etching, X-ray radiography testing and angular distortion measurement. The angular distortion of the joints was measured using a coordinate measuring machine (CMM) integrated with Samiso 7.5 software. The quality of the A-TIG welded joints was compared to the joints made employing multipass-TIG welding process and Inconel 82 filler rod in 07 passes. The A-TIG welded joints showed significant reduction in angular distortion and higher productivity. It showed a 55% reduction in angular distortion and 80% reduction in welding cost and time compared to the multipass-TIG welded joints.

A new welding distortion analysis method considering inherent deformation-based tendon force estimation

A new welding distortion analysis method considering inherent deformation-based tendon force estimation

Influence of the Pulse Mode of Manual Metal Arc Welding on Weldment Distortions.

As a result of the thermo-mechanical impact during welding, distortions are generated in welded structures. These distortions significantly influence the geometric and dimensional accuracy of welded structures, in many cases lowering their working characteristics and reliability. An optimal design for welded structures is a prerequisite for increased reliability and reduction in manufacturing cost, and such an optimal design can be achieved knowing the distortions in weldments. Despite the fact that pulsed metal inert gas welding and metal active gas welding have been broadly applied in the last few decades, nowadays, few manufacturers, for instance, Fronius, EWM, Redco, and Perfect Power Welders, offer such an option for manual arc welding. This work aims to determine the influence of the parameters of pulsed welding modes on distortions that are generated during manual arc welding. Two different inverter welding power sources were used, and the welding distortions were measured by 3D scanning. The results showed that the pulsed mode during manual arc welding led to a reduction in distortions compared to the conventional welding mode. The crucial part of the manual welding system proved to be the qualification and performance of the welder.

Numerical and experimental studies on the effect of cryogenic treatment on welding residual stress of TIG welded EN8 steel plate

Most of the conventional welding process induces Welding Residual Stress (WRS), hydrogen embrittlement and distortions to welded components. The post-weld mechanical behaviour has an impact on both structural integrity and operational effectiveness of the welded component. Traditional Post Weld Heat Treatment (PWHT) is capable of relieving WRS to some extent. Based on recent research, Heat Treatment (HT) cycles are comprised of conventional HT and Cryogenic Treatment (CT) gives better fatigue life to welded components by redistributing the residual stress field. There is a need for further research to explore the impact of different parameters of CT affects the mechanical behaviour of welded specimens. In this study, numerical and experimental investigations are conducted to understand the impact of HT cycles comprised of austenitizing, quenching, CT and tempering process, over the TIG welded EN8 plates. Numerical model is developed for predicting the variation in WRS with each stage of HT cycles and observed a considerable redistribution of WRS after the completion of proposed HT cycle. Using the proposed HT cycle, the influence of different soaking periods of CT over the welded components are studied experimentally and shows that 36 hours soaking period have higher impact on the welded component’s mechanical behaviour.

Analysis of variables in finite element analysis for multi-pass welding in nuclear power plant components, part 1: Comprehensive study with experimental validation using scientific weld specimen

The influence of various parameters in welding simulations using finite element analysis (FEA) was investigated in this study. Welding experiments and finite element simulations were conducted to analyze residual stress and post-welding distortion. It was a specially designed V-groove specimen, filled with bead passes using Gas Tungsten Arc Welding (GTAW), that facilitated the measurement of distorted shapes and residual stress. Advanced measurement techniques, including three-dimensional laser scanning and the contour method, were used to capture detailed data on the welded specimen. Three different heat source models (body heat flux, temperature boundary, and Goldak's double-ellipsoidal model) were employed in the simulations, and their effect on residual stress distributions was analyzed. Additionally, the effects of hardening models, bead deposition methods, bead shape modeling, welding sequences, and lumping of weld passes on simulation were systematically analyzed. The findings suggest that a combined approach using different modeling techniques and careful calibration of parameters can enhance the reliability of simulations in predicting weld residual stress and distortions.

Prediction of the keyhole TIG welding-induced distortions on Inconel 718 industrial gas turbine component by numerical-experimental approach

Welding technologies represent a paramount joining process for ensuring the quality and reliability of critical industrial components; therefore, their innovation constitutes a driving force in realizing increasingly competitive products. A recently developed technology is the keyhole TIG welding, a new high energy–density alternative to the conventional TIG process. A key role in improving innovative manufacturing processes such as the keyhole TIG is covered by numerical simulation; indeed, it allows the development of a process digital twin able to support decisions and work as a predictive tool. Within this framework, the paper deals with the numerical-experimental investigation of the keyhole TIG technology, successfully employed on a simplified mock-up of an industrial gas turbine component consisting of two 6.5-mm-thick Inconel 718 rings. Numerical analysis aimed at predicting welding-induced distortions was performed employing two different computational approaches, namely the moving heat source and the simplified imposed thermal cycle methods. The numerical-experimental comparison of the results demonstrates an innovative approach in the field of the current keyhole TIG numerical simulation since, besides verification of numerical thermal analysis, further substantial validation of the post-weld distortion predictions is provided through comprehensive three-dimensional experimental data. Moreover, the comparative assessment of the two computational approaches and experimental evidence revealed that the imposed thermal cycle method implementation does not compromise the accuracy of welding distortion forecasting in industrial applications such as that investigated. Therefore, it can be regarded as a valuable tool for supporting the process engineer in designing the ideal set-up to comply with a variety of industrial requirements, among them strict design tolerances.

Correction to “Use of a low transformation temperature effect for the targeted reduction of welding distortion in stainless chromium‐nickel steel for an application in rail vehicle construction”

Correction to “Use of a low transformation temperature effect for the targeted reduction of welding distortion in stainless chromium‐nickel steel for an application in rail vehicle construction”

The influence of welding-induced 3D residual stress and distortion on the ultimate strength of multi-stiffened thin plate structures under cyclic load

Stiffened thin plates made of high-strength steel are widely employed in ship hull structures. Their strength capacity is highly sensitive to the welding imperfections and potential extreme cyclic loading from harsh sea state. In this work, a thermal elasto-plastic finite element analysis is conducted to simulate the 3D distribution of welding-induced residual stress and distortion of stiffened thin plate structures with triple spans and triple bays varying the plate thickness and heat input. Experimental results provided by other scholars are used to validate the welding simulation. Afterwards, the ultimate strength and collapse behaviour of the welded structures under different load patterns are dealt with, including monotonic compression load, cyclic compression-tension load and cyclic compression load. Observation from numerical results indicates that, in general, the compressive strength is reduced in each considered cycle by the residual stress as the amplitude of cyclic compression-tension load approximates to the ultimate compressive strain. When this parameter is much greater than the ultimate compressive strain or the stiffened plate is subjected to cyclic compression load, the reduction in ultimate strength is significant in the first cycle, whereas the reduction is ignorable in the later cycles. Besides, if the buckling mode of initial deflection with antisymmetric configuration is superposed to the symmetric out-of-plane welding distortion, impact of the residual stress will be diminished as the asymmetry becomes notable.

Use of a low transformation temperature effect for the targeted reduction of welding distortion in stainless chromium‐nickel steel for an application in rail vehicle construction

Use of a low transformation temperature effect for the targeted reduction of welding distortion in stainless chromium‐nickel steel for an application in rail vehicle construction

Experimentally validated numerical prediction of laser welding induced distortions of Al alloy parts for railcar body by inherent strain method combined with thermo-elastic-plastic FE model

A laser welding with wire filler feeding was developed to replace traditional arc welding process for joining aluminium alloy railcar body components. A three-dimensional (3D) thermo-elastic-plastic finite element (FE) model was applied to compute the plastic strains of weld zone in a downsized aluminium alloy plate with butt-joint, T-joint and fillet-joint configurations, respectively, combined with corresponding experimental validations. The achieved plastic strains at the weld zone were then input as inherent strain loadings into elastic structural FE model of fully sized aluminium alloy railcar body components to predict the welding induced distortion with the experimentally measured out-of-plane distortions. The experimentally validated FE model was then further applied for optimizing the inverse pre-deformation of plates to counteract the welding induced deformation, finally to mitigate the welding distortion issues.

Analysis of Electrode Tip Angle Variation on Weld Geometry, Distortion, and Hardness in Commercially Pure Titanium Welded Using Pulsed-Gas Tungsten Arc Welding

Analysis of Electrode Tip Angle Variation on Weld Geometry, Distortion, and Hardness in Commercially Pure Titanium Welded Using Pulsed-Gas Tungsten Arc Welding

Prediction of Laser Welding Distortion in Cylindrical Shell Structures Using Direct Application of Inherent Strain

In this study, a simplified analysis method by directly applying inherent strain (DIS) at integration points to predict welding distortion of cylindrical shell structures was suggested. The 3D thermo-elastoplastic method demands substantial computational time. The strain as direct boundary (SDB) simplified method using virtual temperature encounters challenges in consecutive thermal structural analysis including welding distortion. The suggested method (that is, DIS) offers the advantage of enabling continuous thermal structural analysis after welding distortion analysis, with computational efficiency. To calculate inherent strain, lap laser welding with 2 mm and 2.6 mm SUS304 plates was performed, measuring fusion and heat-affected zone sizes via cross-sectional observations. Using the calculated inherent strain and our suggested direct input method, we conducted welding analysis and welding test on cylindrical shell structures. Comparison of welding distortion under same conditions revealed radial distortion difference within approximately 10%, corresponding with the experimental result and confirming a computational time reduction by over 2,000 times than those of thermo-elastoplastic analysis. Therefore, an efficient and accurate prediction of welding distortion was achievable through the suggested method.

Fatigue performance analysis of stainless steel cruciform joint with angular misalignment

AbstractWelding distortion causes the change of stress distribution of load‐carrying cruciform stainless steel welded joints, and the weld with angle less than 90° between steel plates became the fatigue performance control weld because of stress magnification. The effect of angular misalignment on fatigue performance of stainless steel cruciform welded joint was experimentally and numerically studied. The fatigue damage evolution equations, under different stress amplitudes, were derived using relative deformation increment as damage variable based on continuum damage mechanics to explain the process of damage transformation from micro to macro crack and finally rapid fracture. The hot spot stress magnification factor was positively correlated with the welding distortion angle and exhibited two discernible stages of rise and fall with increasing nominal stress taking the proportional limit as boundary. A proposed formula considering both misalignment angle and applied stress aimed to enhance accuracy in fatigue performance evaluation compared to current methods.

Reduction of distortion during laser beam welding by applying an in situ alloyed LTT effect and considering influencing factors

In rail vehicle construction, austenitic stainless steels are used to achieve lightweight design concepts, as the higher specific strength of the material allows the thickness of parts to be reduced. However, when these are welded to create complex structures, increased welding distortion occurs even with low-heat joining processes such as laser beam welding.In order to reduce distortion, an in situ low transformation temperature (LTT) effect has been achieved using commercially available materials rather than specially manufactured LTT alloys. The LTT effect introduces compressive stresses into the weld seam, which counteract the formation of welding distortion due to tensile stresses. However, in the case of complex structures, several other factors influence the formation of distortion. The influence of the LTT effect and other factors such as tack welding, clamping and cooling conditions were analysed by distortion measurements and a maximum distortion reduction was determined.

Experimental and numerical investigation of a gouging heat source model and gouging/welding residual stress and deformation

Gouging is generally used for groove preparation of multi-pass welding and repair welding. Arc gouging is one of the most efficient gouging methods which utilizes an arc heat source and a trailing air blower. To date, the heat effects from the arc gouging are not clear especially when it is coupled with subsequent welding. In this study, a new heat source model considering the blown molten metal as well as the increased heat transfer by the blowing air was proposed. A 3D finite element model for gouging and welding was employed to analyze the thermal behavior, welding distortion and residual stresses. The transient temperature predicted by the proposed heat source model has good agreement with thermocouple measurements, both featuring multiple peaks in the thermal profile. The predicted distortion and residual stress due to gouging show similar trends as those in experiment. The proposed analysis approach can provide necessary insights, with high accuracy, in the evaluation of welding distortion and residual stresses in practical manufacturing.

Optimization of process parameters for shielded metal arc welding for ASTM A 572 grade 50

The quality of a weld significantly depends on the mechanical characteristics of the welded joint, the welding process, and its associated input parameters. Insufficient parameter values can lead to welding defects and distortion that adversely affect mechanical properties. Consequently, carefully selecting appropriate parameters at an optimal level becomes crucial to mitigate defects, enhance productivity, and achieve desirable mechanical attributes in shielded metal arc welding (SMAW). This study explores optimizing SMAW parameters for ASTM A572 Grade 50 steel joints, vital in heavy machinery. Using Taguchi L16 array, parameters were varied across four levels. Grey relational and principal component analysis guided optimization. Results reveal groove angle's impact on tensile strength, electrode diameter on impact strength, and welding current on hardness and angular distortion. Optimal parameters were: 160 A welding current, 60° groove angle, 3.25 electrode diameter, 3 mm root gap, and 3 mm root face. Implementation of optimal parameters led to significant improvements: 10.53% higher tensile strength, 14.28% increased impact toughness, 8.55% reduced hardness, and a remarkable 33.33% decrease in angular distortion.

Influence of Initial Structural Dimensions of Plates on Welding Distortion

Aiming at the complex full-field deformation problem that easily occurs when welding plates, this paper adopts the elastic–plastic finite element method with heat-force coupling to study the deformation law of plates in different initial states. First, a rectangular plate finite element model with an initial radius and Gaussian heat source model was established to obtain the welding temperature field and deformation field of the plate; then, the method based on digital image correlation technology was used to detect the full-field dynamic deformation of the plate to verify the accuracy of the finite element model; finally, the influence of the initial structural dimensions of the plate on the weld deformation was investigated. The study shows the following: the thermoelastic–plastic finite element model proposed in this paper has high accuracy in both static and dynamic deformation; plates with the same curvature, and different lengths and widths of the initial structure of the plate welding deformation are saddle-shaped, and the edge effect of the welding of the plate is evident, independent of the length of the plate; and the maximum out-of-face deformation of the welding of the plate is linearly related to the length and the closer the aspect ratio of the plate is to 1, the smaller the out-of-face deformation is.

The effect of welding deformation on the equivalent structural stress of dissimilar girth welded joint

Weld distortion refers to the phenomenon of shrinkage around the weld seam and warping of the outer weldment edges. This leads to a deviation from the original straight force transfer path in the joint, resulting in higher stress concentration. The weld root's stress concentrations can cause significant fatigue issues in dissimilar girth welded joints. However, previous evaluation methods have generally overlooked the impact of the welding process on fatigue assessment. To address this gap, this paper proposes integrating welding deformation into the fatigue life calculation process for welded joints made of G20Mn5 cast steel. In this study, a welding calculation program was developed to accurately simulate joint deformation using a two-curvature conical heat source model. Subsequently, high-frequency fatigue test data from scaled specimens of four types of joints were analyzed. The original equivalent structural stress fatigue data were corrected by taking into account the initial condition of weld deformation. This correction resulted in a reduction in the scatter of the fatigue data. Furthermore, the study also analyzed the welding deformation differences and the dispersion of stress concentration in scaled specimens caused by welding inhomogeneity.

Analysis of the effect of welding sequence and speed on the distortion of ASTM A36 joints by MIG method

The welding process with the Metal Inert Gas (MIG) method often produces distortions that are detrimental to product quality, one of the factors that affect the characteristics of the welding results is heat input. The heat input provided in the welding process is influenced by arc current, arc voltage, and welding speed, besides that the welding sequence can also affect the distortion of thin plates due to welding on materials such as ASTM A36 plates. The welding process uses welding wire/electrode type AWS ER 70S-6 with a diameter of 1.0 mm, the welding parameters applied are: voltage of 22 Volts, current of 150 Amperes, DC + Current type (DCEP), the shielding gas used is 100% Argon with a flow rate of 15 liters per minute, horizontal welding position (1G), the amount of heat input is differentiated by changing the welding speed and the welding sequence used is the stepping stone method. The results of the study using ANOVA indicate that welding distortion increases with an increase in input heat, the repetition of welding sequences leads to greater distortion due to thermal stress, and the welding sequence and input heat have an influence of 80.4% in reducing distortion.