Welding Residual Stress Research Articles

Effect of Residual Stress on the Ultimate Bearing Capacity of Titanium Alloy Pressure Spherical–Cylindrical-Combined Shells

Titanium alloy pressure spherical–cylindrical shells enable the effective utilization of the strength of spherical and cylindrical pressure-resistant shell components. In this study, a numerical simulation of the residual stress of a titanium alloy butt-welding plate was conducted by employing sequential coupling and a temperature heat source model. The results of welding residual stress analysis agreed well with the experimental results reported in the literature. Subsequently, the welding residual stress of a titanium alloy pressure spherical–cylindrical shell was calculated and analyzed using the same method. Finally, the influence of residual stress on the ultimate bearing capacity of the shell was assessed. On the inner surface of the shell, the horizontal welding residual tensile stress, perpendicular to the weld path, exhibited a bimodal distribution. The longitudinal welding residual tensile stresses were higher than the horizontal welding residual stress. Near the weld on the outer shell surface, higher longitudinal welding residual tensile stresses existed, whereas the horizontal welding residual stress was compressive. Both the inner and outer shell surfaces exhibited significant longitudinal residual tensile stresses along the weld path, though residual compressive stresses existed on both surfaces. The influence of welding residual stress on the ultimate load-bearing capacity of the shell was minimal.

Analyzing microstructural, residual stress, and mechanical characteristics in dissimilar welds of Inconel 59 and AISI 904L through double-pulsed gas metal arc welding

In this research, dissimilar welding of the nickel-based superalloy Inconel 59 and austenitic stainless steel AISI 904L steel was successfully done with double-pulsed gas metal arc welding (DP-GMAW) using the filler ERNiCrMo-13. Macroscopic analysis showed a defect-free weld with an aspect ratio of 2.4, attributed to the efficient heat delivery (0.642 kJ/mm) in DP-GMAW. The microstructure of the weld joint was examined through both optical microscopy and scanning electron microscopy. Examination of the microstructure of the weld interface exposed grain coarsening near the heat-affected zone on the AISI 904L side. In contrast, the weld fusion zone contained fine equiaxed dendrites. Microsegregation and alloying element migration across the entire weld area were assessed through energy dispersive X-ray spectroscopy point analysis and line mapping, revealing controlled microsegregation across the region. X-ray diffraction (XRD) analysis was used to ascertain the average grain size (38.41 nm) and secondary phase composition. The XRD-cosα method was used to assess the residual stress of the weld joint, revealing tensile residual stress in the weld zone and compressive residual stress in other regions. Tensile, Charpy impact, and Vickers hardness tests were conducted in the study to evaluate the strength, toughness, and hardness of a dissimilar weld. The impact of two cryogenic treatments, namely shallow and deep, on tensile and toughness characteristics was investigated in this study. The cryogenic treatments significantly enhanced the mechanical properties of weld samples compared to their as-welded condition, leading to an 11.5% increase in tensile strength and a 10% improvement in toughness.

Numerical study on welding residual stress by double-sided submerged arc welding for orthotropic steel deck

The orthotropic steel deck (OSD) is susceptible to fatigue damage under repeated traffic loads, and the welding residual stress (WRS) is an important factor contributing to fatigue damage in OSD. The study on WRS and its distribution is essential for the accurate estimation of the fatigue resistance of U rib-to-deck (RTD) welded joints. A recent emerging double-sided submerged arc welding (DSSAW) technology can generate higher welding temperatures in U rib and deck than traditional arc welding technology, and consequently generate higher welding penetration depth for welding thicker base metal. However, the WRS generated by the DSSAW technology has not yet been investigated. In this study, the finite element (FE) model of OSD with RTD welded joints is established by using a thermo-mechanical sequential coupling calculation method, which is first time to study the WRS generated by DSSAW. Also, the distribution characteristic and generation mechanism of WRS at the RTD welded joints are discussed and analyzed. Moreover, the effects of model length on the WRS simulation results are discussed, and the effects of the deck thickness, the U rib thickness, and the welding sequence on the WRS at RTD joints are analyzed. The findings in this study can help to an in-depth understanding of the WRS generated by the new DSSAW and support further studies on the fatigue resistance of OSD.

Analysis and Experiment on the Welding Temperature Field of Multi-Layer and Multi-Pass for RHS–RHS Y-Connections

The temperature measuring instrument was utilized to monitor the welding temperature field at designated points along steel rectangular hollow sections (RHSs) during welding. A total of 32 temperature monitoring points were established on the four surfaces of the RHS branch. Additionally, the welding process was simulated using finite element software to calculate the temperature distribution. The calculated temperature results were then compared with the experimental results obtained from the temperature measuring instrument. The relative errors between the numerical simulation and the experimental temperature results remained within 10%, indicating a reasonable agreement between the two. Once the temperature field was determined, it was used as an input load to calculate the welding residual stress. The longitudinal and transverse residual stresses were analyzed for two paths on the four surfaces of the RHS-to-RHS Y-shaped connection branch. By analyzing the residual stresses, it is possible to evaluate the structural integrity and performance of the welded RHS connection. The analysis process in this paper is crucial for ensuring the safety and reliability of tubular steel structure projects.

Digital twin-driven framework for fatigue life prediction of welded structures considering residual stress

The welding of steel generates substantial welding residual stress (WRS), which exerts a significant impact on the fatigue life of steel bridges. In this study, a physical model for calculating the fatigue crack growth (FCG) life of welded specimens in the WRS field is established based on the weight function method. Experimental data validates the reliability and precision of the proposed physical model. The impact of WRS on the fatigue life of structural components is scrutinized and analyzed. On this basis, a digital twin (DT) framework driven by a physical-data model is proposed to consider the inherent parameter uncertainty in FCG behavior within the WRS domain. A dynamic Bayesian network (DBN) is used to characterize the evolution characteristics of fatigue crack states over time in the digital space. Particle filter algorithm is used as DBN inference method. The results show that the calculation of the physical model is in good agreement with the experimental values. Neglecting the influence of WRS distribution may lead to an overestimation of fatigue life in welded structures. The DT framework can update uncertain parameters online and realize the accurate prediction of the FCG life in the WRS field.

Optimization‐improved thermal–mechanical simulation of welding residual stresses in welded connections

AbstractThis paper presents a novel computer‐aided computational framework to determine the optimum shape parameters in a welding heat source model using a coupled supervised Gaussian process regression (GPR) and genetic algorithm (GA) approach in estimating the welding residual stresses. The experimental X‐ray diffraction (XRD) approach validates the optimization‐improved thermal–mechanical simulation method. The validation of the proposed approach includes the welded plates with simple geometry to welded pipe‐to‐plate and the circular hollow section joints with complex topologies. The optimization‐derived shape parameters in a welding heat source model lead to close estimates of the temperature history and the welding residual stresses for these types of welded joints considered in this study.

Residual stresses in linear friction welding of TC17 titanium alloy considering phase fraction

To obtain accurate residual stresses in linear friction welding of TC17 alloy, a numerical relationship between the elastic constants and phase fraction of TC17 alloy was established. The elastic constants with gradient distribution were obtained by combining the phase fraction and introduced into the contour method. The results show that the elastic constants of TC17 alloy are positively correlated with α phase fraction and present a significant gradient distribution in the welding area with a width of about 4 mm. The relative error in calculating the welding residual stresses can be up to 36.06% if the gradient distribution of phase fraction is ignored. The corrected residual stresses in the welding area exhibit a bimodal distribution, with a peak stress of ∼442 MPa located at the edge of the heat-affected zone. The results demonstrate the necessity of considering the phase fraction with gradient distribution.

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.

Ultrasonic Treatment of Welded Joint from External, Internal and Two Sides on Reduction of Residual Welding Stresses

Ultrasonic Treatment of Welded Joint from External, Internal and Two Sides on Reduction of Residual Welding Stresses

Effect of Transformation Plasticity Behavior on the Accuracy of Weld Residual Stress Analysis of Low Alloy Steel

Effect of Transformation Plasticity Behavior on the Accuracy of Weld Residual Stress Analysis of Low Alloy Steel

Influence of post-weld heat treatment on welding residual stress in U-rib-to-deck joint

Welding residual stress (WRS) significantly influences the fatigue life and safety of welded steel structures. Post-weld heat treatment (PWHT) is a common method employed to mitigate WRS. In present study, the WRS evolution law and relaxation mechanism of U-rib-to-deck joints was investigated during PWHT. High-temperature heat treatment tests with varying holding times were conducted on U-rib-to-deck joints to reduce WRS. The WRS distributions were measured using the hole-drilling method before and after PWHT. ABAQUS software, incorporating the Norton-Bailey creep constitutive model, was employed to simulate the WRS evaluation during both welding and PWHT processes. The simulated values were validated against the measured data, and the effects of different holding times, holding temperatures, and heating and cooling rates during PWHT on WRS relaxation were discussed. The results demonstrate that PWHT effectively reduces WRS and leads to a more uniform distribution. Extending the PWHT holding time from 0.5 h to 1 h and 2 h results in a gradual decrease in WRS relaxation at 600 °C, primarily occurring in the high-value stress region of the weld zone with a small amplitude. Elevating the PWHT temperature from 500 °C to 550 °C and subsequently to 600 °C amplifies the significance of WRS relaxation. Variations in heating and cooling rates (200 °C/h and 80 °C/h, 100 °C/h and 40 °C/h, 50 °C/h and 20 °C/h) lead to a gradual decrease in WRS relaxation across the entire model. Furthermore, considering the creep effect, the stress relaxation rate in the weld is approximately 70 %–80 %, which found to be about 2–3 times higher than that without considering the creep effect. By understanding the evolution law and relaxation mechanism, this study provides valuable insights for designing PWHT processes and assessing their impact on structural safety and fatigue life.

Numerical and experimental study of residual stress in multi-pass laser welded 5A06 alloy ultra-thick plate

The laser welding technology of ultra-thick plates has been widely applied in many crucial engineering structures, where its safety and stability still suffer from the residual stress brought by the welding temperature. In this work, experimental and numerical studies are carried out to reveal the evolution and distribution of the residual stress. A 5A06 aluminum alloy plate with 30 mm thickness is used to conduct the laser welding experiment, and the short-wavelength X-ray diffractometer (SWXRD) is employed to measure the residual stress. Furthermore, a multi-pass laser welding numerical model is developed to predict the residual stress during the welding process. The simulation results of the weld pool geometry and residual stress agree well with the experimental data, which gives a good validation of the numerical model. Based on the proposed numerical model, the influence of the welding parameters, including inter-pass cooling time and welding rate are also investigated. It is discovered that the reduction of the inter-pass cooling time results in weakness effect of the temperature gradient, which hinders the generation of plastic deformation and leads to a lower residual stress value. Meanwhile, the simulation results also show that the increase in welding rate promotes the generation of thermal stress, which brings a higher residual stress value appeared in the structure.

Prediction of Residual Stresses in 316 Stainless Steel Pipes Welded Joint

Due to the extremely complicated thermal cycle for the welding process, the fusion zone and heat-affected zone (HAZ) produce irreversible elastic-plastic deformation and residual stresses. The differential heating of the pipes caused by the weld heat source causes residual stress as a result of the welding process. However, the strength and lifetime of the component are also decreased as a result of residual stresses in and around the weld zone. The objective of this research is to analyze the residual stresses created during the welding process and select the best welding parameters that give the lowest residual stresses in 316SS pipes with 50 mm diameter and 4 mm thickness that were manually welded by used (316) welding wire and using shielded metal arc welding (SMAW) in a single-pass butt joint with the various values for each of current (58, 68, 78, 88) amperes and voltage (22, 23, 24, 25, 26) volts. The shielded metal arc welding process involves heating, melting, and solidifying the parent metals and filler material in a localized fusion zone by a transient heat source to create a junction between the parent metals. The welding process free from preheating and heat treatment will be obtained. ANSYS Finite Element methods are used to calculate the welding residual stress distribution. The mechanical and thermal models were used to carry out the theoretical analysis. In general, the numerical study found that the residual stress distribution at the weld zone’s center is continuous, rising, and has a value of about (1738 MPa). Additionally, the residual stress at the boundary between the heat-affected zone and the weld zone climbs to a maximum value of around (3799.6 MPa). On the other hand, the magnitude of the residual stress in the heat-affected zone of the weld reduces significantly and achieves a minimum value at a position of (20 mm) with a value near zero.

Fatigue Life Comparison of Tubular Joints in Tripod and Jacket Offshore Support Substructures Using 3D Fatigue FE Analysis

In a wind energy system, the safety and stability of substructures plays an important role during the in service of offshore structure. Offshore structures are continuously subjected to high cyclic fatigue loads and may experience fatigue cracks due to the continuous accumulation of plastic strain and stress concentrations at welded joints. The fatigue life of welded tubular joints is one of the most important factors determining the life of offshore structures. In this study, the fatigue analysis of tubular joints of the tripod and jacket support structure was performed using 3D fatigue FEM to estimate the fatigue life and predict the positions of crack initiation. The 3D fatigue FE is based on constitutive equations and continuum damage mechanics. The welding state of tubular joints were reproduced to calculate the welding residual stresses and welding deformation. The residual stresses and weld deformation were used as input together with cyclic loading in the 3D fatigue FE to calculate the fatigue life and predict the crack initiation positions. The S-N curve calculated by the 3D fatigue FE analysis were compared with the SN curves of Eurocode 3. The results show that 3D fatigue FE analysis is an effective tool to analyze large and complex structures before installation to ensure the safety and stability of the structure.

Stress Measurement of Stainless Steel Piping Welds by Complementary Use of High-Energy Synchrotron X-rays and Neutrons

Probabilistic fracture mechanics (PFM) is increasingly recognized as a viable approach for evaluating the structural integrity of nuclear components, such as piping, primarily affected by stress corrosion cracking (SCC). PFM analysis requires several input parameters, among which welding residual stress is critically important due to its significant influence on SCC initiation and propagation. Recently, a novel technique involving a double-exposure method (DEM) utilizing synchrotron X-rays was introduced as an effective means for measuring welding residual stress with high spatial resolution. In this paper, we applied DEM to assess the residual stress of a plate specimen, which was extracted from a welded pipe through electrical discharge machining. Consequently, detailed stress maps under a plane stress state were generated. Additionally, the residual stress distributions in the welded pipe under a triaxial stress state were evaluated using neutron diffraction. Based on these findings, we proposed a methodology to acquire detailed stress maps of welded pipes by combining high-energy synchrotron X-rays and neutron diffraction.

Component test for the assessment of delayed hydrogen-assisted cracking in thick-walled SAW joints for offshore applications

Offshore wind turbines continuously increase in size and weight and demand adequate offshore foundations concepts like monopiles, tripods, or jackets. These components are typically constructed using submerged arc welding (SAW) with high-strength thick steel plates like the S420ML. During welding, the occurrence of delayed hydrogen-assisted cracking (HAC) must be anticipated. HAC is a critical combination of the local hydrogen concentration within a susceptible microstructure under certain mechanical load, i.e., the occurring (welding) residual stresses. The welding sequence of the thick-walled plates complicates the residual stress distribution due to the necessary repeated thermal cycling, i.e., welding seam/layer deposition to fill the joint. For that purpose, SAW with two-wire-technique was used to weld a specially designed and prototype-like mock-up of a real component with a thickness of 50 mm, filled with over 20 passes and a seam length of 1000 mm. Additional welded stiffeners simulated the effect of a high restraint, to achieve critical HAC conditions. The necessity of a minimum waiting time (MWT) before the NDT can be conducted (to exclude HAC) was critically verified by the application of ultrasonic testing of the welded joint at different time-steps of the NDT of up to 48 h after the completion welding. The residual stresses were determined by a robot XRD goniometer. Tensile residual stresses up to the yield limit are found both in the weld metal and in the heat-affected zone. Numerical modeling allowed the qualitative estimation of the hydrogen diffusion in the weld. No noticeable HAC occurrence was identified and confirms the high cracking resistance of the investigated material. Finally, the applicability of the MWT concept should be critically discussed.

Re-Distribution of Welding Residual Stress in Fatigue Crack Propagation Considering Elastic–Plastic Behavior

The welding residual stress re-distribution behavior during fatigue crack propagation in butt-welded high-strength steel plates for ship construction is investigated based on experimental test results and numerical analyses. The specimens’ initial welding residual stresses are obtained from X-ray for middle tensile (MT) specimens cut from butt-welded high-strength steel plates. Then, fatigue crack propagation experiments on MT specimens are conducted, and a strain gauge is used to measure the residual stress re-distribution field around cracks. A practical fatigue crack propagation simulation procedure is developed with a dynamic update of in-situ welding residual stress, where the residual stress intensity factor Kres of the MT specimen is deduced. The stress ratio effect on Kres during fatigue crack propagation is analyzed and a good agreement between experimental and numerical results is achieved.

Evolutions of temperature field and stress field in narrow gap oscillating laser welding process based on equivalent heat source

With the increased demand for high-performance thick high-strength steel structures in high-end offshore equipment, narrow gap oscillating laser welding with the advantage of high power density and satisfied penetration depth has attracted considerable attention. A thermal-elastic-plastic finite element model was established to calculate the narrow gap oscillating laser welding process of 30-mm-thick high-strength steel, which requires a large amount of computational time cost. To increase the computational efficiency, two equivalent heat source models were founded to replace the laser oscillation. The temperature field and stress-strain field were analyzed. The accuracy of the equivalent heat source model was verified from the weld seam profile and residual stress distribution curves. Results showed that the simulated results were in good agreement with the actual results. With the number of welding passes increasing, the cross-section shape of the molten pool changed from an elongated shape to an arc shape, and the groove gap on the top surface was reduced from 4.82 mm before welding to 3.18 mm after welding. The maximum equivalent residual stress, with the value of 669 MPa, was distributed in the middle and upper parts of the weld seam as well as the root. The longitudinal residual stresses exhibited tensile stresses in the weld seam zone. Due to the upward bending of the workpiece, the transverse residual stresses showed compressive stresses on the top surface of the weld seam and maximum tensile stresses with the value of 806 MPa at the bottom of the weld seam.

Stress Distribution of EH40 with Defects Considering Solid-State Phase Transformation

Residual stress of laser-welded marine steel EH40 was experimentally and numerically analyzed considering weld defects (collapse, hump, and unfitness) and solid-state phase transformation (SSPT). A double-cylindrical source model was used to simulate the temperature distribution. The mean prediction errors of the model without and with weld defects along the plate thickness were 9.2 and 3.5%. Based on the thermodynamics of SSPT, microstructure fractions were computed and verified by weld hardness test results. Under the effect of SSPT, residual stress changed from compressive stress to tensile stress with the increase of the distance from the weld center. Weld defects have an influence on the value of residual stress, and this effect was greater when SSPT was considered. The affected zone extended from the vicinity of weld defects to the whole weld. The variations of longitudinal residual stress (LRS) and transverse residual stress (TRS) caused by weld defects and SSPT both exceeded 150 MPa. LRS was mainly affected by the loss and increase of metal, while TRS was affected by the stress concentration caused by shape geometry changes. Thus, the influence of weld defects on TRS was greater than that on LRS. The proposed finite element model considering weld defects and SSPT can be used to accurately predict residual stress in laser welding of marine steel EH40 and provide a theoretical basis to reduce welding stress.

Application of local fatigue approaches on corroded welded joints with consideration of weld geometry and residual stresses

Corrosion can significantly affect the fatigue strength of steel structures. On the one hand, it can cause stress concentrations by changing the surface geometry, and on the other hand, it can lead to embrittlement of the material. In welded steel components, sharp notches are already present due to the weld geometry, which may interact with the notches from corrosion. In addition, residual stresses exist in the fatigue-relevant area, which can also be partially modified by surface preparation methods such as clean blasting. In the current standards, all the mentioned effects are considered by reducing the design stress-life (SN) curves, in which all aforementioned effects are superimposed. One possibility to consider the effects separately is the application of local concepts, with which the influence of the geometry, here obtained from 3D-scans, the influence of measured residual stresses, and the influence of material can be considered individually. For butt and fillet welds investigated in this study, it could be shown that by considering the real geometry via a reverse engineered 3D-solid model, the locations of crack initiation in the fatigue tests, measured by digital image correlation (DIC), matched with the numerically predicted locations in most cases. Moreover, it was shown that by taking into account the real geometry and residual stresses, the use of local approaches can result in a substantially reduction of the scatter in SN-curves from Tσ = 2.17 to Tσ = 1.26, demonstrating the great reliability of the applied method.