Performance Of Welded Joints Research Articles

Experimental Study on Flexural Performance of Screw Clamping and Welding Joint for Prestressed Concrete Square Piles

To ensure the connection performance of precast concrete square piles, a screw clamping and welding joint connection is applied to the solid square piles. By conducting full-scale bending performance tests on six solid square pile specimens with cross-sectional side lengths of 300, 450, and 600 mm, including pile bodies, screw clamping joints, screw clamping, and welding joints, the bending load-bearing capacity, deformation capacity, and failure characteristics of the screw clamping–welding joint connection are compared and studied. The results show that the bending failure mode of the pile body specimens is shear failure in the flexural shear section and concrete crushing in the compression zone of the pure bending section; the bending failure mode of the screw clamping joint specimens are the pull-out of steel bar heads at the joint end plate; the bending failure mode of the screw clamping and welding joint specimens are concrete crushing in the compression zone of the pure bending section, steel bar breakage in the tension zone of the flexural shear section, and pull-out of steel bar heads at the end plate. It is worth noting that no significant damage occurred at the joints. The cracks in the pure bending section of the bending specimens mainly develop vertically and are evenly distributed, while some cracks in the flexural shear section develop obliquely towards the loading point, with branching. Compared to the pile body specimens, the cracking moment of the joint specimens is up to 16% higher, the ultimate moment is within 15% lower, and the maximum mid-span deflection is within 25% lower, indicating that the provision of anchorage reinforcement can increase the stiffness and cracking moment of the specimens.

A comprehensive review of residual stresses in carbon steel welding: formation mechanisms, mitigation strategies, and advanced post-weld heat treatment techniques

Abstract Residual stresses are critical factors influencing the service performance, reliability, and durability of welded carbon steel joints. These stresses can affect the joint, susceptible to brittle fracture, fatigue failure, and stress corrosion cracking, particularly within the heat-affected zone (HAZ). These stresses result from uneven thermal expansion and contraction during welding, with thicker plates and constrained configurations being more susceptible. Post-weld heat treatment (PWHT) assumes a critical function in mitigating these stresses by tempering martensitic structures, refining microstructures, and enhancing mechanical properties such as toughness and ductility. This review examines the mechanisms driving residual stress formation, evaluates the effectiveness of PWHT techniques, and highlights advanced methodologies like neutron diffraction, computational modeling, and hybrid welding processes. While PWHT significantly alleviates residual stresses, complete stress elimination remains unattainable, emphasizing the need for innovative strategies such as hybrid welding methods, computational modeling, and advanced heat treatments. This work integrates metallurgical principles with experimental findings to provide a strategy for enhancing the performance and reliability of welded joints in critically demanding industrial applications.

Effect of immersion corrosion time on the corrosion performance of welded joints of bimetallic composite pipes

Effect of immersion corrosion time on the corrosion performance of welded joints of bimetallic composite pipes

Fatigue performance analysis of steel joints with high frequency mechanical impact (HFMI) based on the notched stress method

PurposeNotched fatigue life curves of welded joints were established and compared with International Institute of Welding (IIW) standards to verify the metal fatigue performance of welded joints treated with pneumatic impact (PIT).Design/methodology/approachThis paper was based on the notched stress method, and this approach not only allows for the assessment of fatigue failure of welded structures with toes and roots but also for the assessment of fatigue strength of joints with localized post-treatments. The paper summarizes the nominal stress data of weld and pneumatic impact treated (PIT) steel joints of different strengths, fits the nominal stress curves of the joints without the use of strength and obtains the stress concentration factor of the joints through the establishment of the finite element (FE) method. Notched fatigue life curves for welded joints were established and compared with IIW standards.FindingsNotched stress concentration data obtained by the FE method was more reliable. The slope of the fatigue life curve of welded joints treated with pneumatic impact (PIT) increases by at least 2.5%, and the stress concentration factor decreases by 20%.Originality/valueIn the fatigue study of notched systems, there were fewer studies on fatigue life assessment of joints processed by high frequency mechanical impact. The purpose of this paper was to analyze the fatigue test data of typical strength steel welded joints and fit fatigue life curves, and the research content provides an important reference for improving the safety and fatigue failure assessment of heavy steel structures.

Dissimilar Weld Joint Performance of Micro Friction Stir Spot Welding with Pin Less Shoulder

Micro Friction Stir Spot Welding is Friction Welding used to joint thin plat less than 1 mm. Each specimen has advantages of properties such as Copper has electrical properties better than aluminium however aluminium has other advantages, these advantages of both could be used in a construction or product. The differences properties and thin of metal as problem of friction welding. This study discussed a tensile test and a fracture analysis of a dissimilar weld joint from a copper with an aluminium sheet welded by Micro Friction Stir Spot welding for 0.5 mm of thickness from both metals. Tensile test represented the mechanical properties and fracture condition show the joining and mixed of both metals. A Copper plate on top from an aluminium plate were forced and swiped with a shoulder without a pin which was revolving with speed and time constant. The rotation speed 3000 rpm and friction time 60 sec were constant. The welding forces were used 40 and 50 kgf and shoulder diameters were applied 4 mm, 6 mm and 8 mm. This study could be concluded than the welding force 50 kgf could resist the tensile load more than 487 N with the longest strain and the fracture condition torn on aluminium side however this weld joint was not release. Friction Stir Spot Welding could join copper and aluminium with thickness less than 0.6 mm, it called Micro Friction Stir Spot Welding. The shoulder diameter specimen 4 mm with welding force 40 kgf and 50 kgf was not strong enough although the fracture weld joint of both metals shown torn of aluminium side and adhere on a copper plate. Bonding in weld joint could be studied by microstructure analysis.

Fatigue reliability assessment of rib-to-deck double-sided welded joints in orthotropic steel decks considering welding residual stress

Fatigue cracking of rib-to-deck conventional single-sided welded joints is a prevalent issue in orthotropic steel decks (OSDs), significantly impacting their structural integrity and durability. Rib-to-deck innovative double-sided welded joints have the potential to enhance the fatigue resistance of OSD. However, Welding Residual Stresses (WRS) significantly influence the fatigue life of these joints, mandating its consideration in fatigue assessments. This study introduces a novel approach for assessing the fatigue reliability of rib-to-deck double-sided welded joints in OSDs, accounting for the effects of traffic vehicle loading and WRS. Initially, a comprehensive fatigue damage equation for welded joints of OSDs was formulated, integrating WRS and dynamic vehicle loads, utilizing fracture mechanics theory. Subsequently, a measurement-based random traffic model was utilized to derive the vehicle-induced stress spectra at the welded joints. The effects of deck thickness, fatigue crack depth and fatigue crack aspect ratio on the stress intensity factor (SIF) of the crack at the weld toe were analyzed. These three variables were considered as feature vectors for the construction of a polynomial model of the shape functions, which was utilized to calculate the SIF. Finally, the fatigue reliability of the rib-to-deck double-sided welded joints in OSDs subject to traffic vehicle loading considering the WRS was estimated using Monte Carlo simulation. The influence of traffic volume growth on fatigue reliability was discussed. This research underscores the critical role of WRS in the fatigue performance of welded joints in OSDs and offers an innovative framework for assessing the fatigue reliability of steel bridge welds.

Atomistic Simulation of Temperature-Dependent Interfacial Diffusion between Solid Nickel and Liquid Aluminum

The performance and durability of welded joints are directly influenced by interfacial diffusion between the metals involved, making it essential to investigate the effect of temperature on these processes. The present research examines temperature-dependent diffusion mechanisms at the interface between solid nickel and liquid aluminum using molecular dynamics simulations. Investigations were conducted at 1200, 1300, 1400, and 1500 K to explore the influence of temperature on atomic mobility and interfacial mixing. Radial distribution function analysis revealed a significant increase in the diffusion of nickel atoms into the aluminum phase with increasing temperature, indicating enhanced atomic interactions at the interface. The mean square displacement analysis supported these findings, showing that aluminum atoms were more mobile than nickel atoms at lower temperatures, while nickel atoms exhibited a faster diffusion rate with increasing temperature, surpassing aluminum in mobility. This trend is reflected in the diffusion coefficients, which exhibit a temperature-dependent increase in the diffusion rate of the nickel atoms. These results emphasize the role of temperature in controlling the diffusion dynamics at the solid–liquid interface. The insights gained from this study are critical for optimizing processes, such as dissimilar metal welding, where precise control over interfacial diffusion is essential for achieving the desired material properties and ensuring the structural integrity of nickel–aluminum joints in high-temperature applications.

Enhancing weld joint performance of dissimilar aluminium alloy joints through filler rod selection

Enhancing weld joint performance of dissimilar aluminium alloy joints through filler rod selection

Study on the Microstructural and Proficiencies of Heat‐Affected Zone in High‐Slope Mountainous Welded Pipeline Steels

The failure rate of pipelines in mountainous areas is much higher than that in other service areas. To ensure the efficiency and quality of the project, automatic welding has become a development trend. The heat‐affected zone (HAZ) as a weak area, to a large extent, reflects the quality of welded joints. Herein, the microstructure and mechanical properties of HAZ on both sides of welded joints under a 30° large slope are characterized by high‐resolution transmission electron microscopy, electron backscattered diffraction, and Charpy impact. The results show that the properties of HAZ are affected by many strengthening mechanisms such as grain refinement, solid solution, dislocation, and precipitation, among which grain refinement plays a leading role. The slope will affect the NbC phase size and grain size, resulting in differences in HAZ properties on both sides. The grain size of each microzone in the lower side HAZ is coarsened compared to the higher side, and the dislocation density is lower, leading to a decrease in hardness and impact toughness, thus becoming the weakest region in the welded joint. Therefore, for welding under the condition of slope, attention must be paid to the influence of slope on the performance of welded joints.

Achieving microstructural homogeneity in the stir zone across thick AA6061 welds using self-reacting bobbin tool friction stir welding

This study focuses into strategizing the usage of self-reacting bobbin tool friction stir welding (SRBT-FSW) to obtain consistent microstructural homogeneity along the thickness of AA6061 aluminium alloy (AA) thick plates during welding. The SRBT-FSW technology, distinguished by its dual-shoulder design, represents a significant step forward in FSW by eliminating the requirement for a backing anvil and promoting balanced heat distribution. This study seeks to address the issues of maintaining uniform microstructural characteristics throughout the weld zone, which is crucial for the mechanical performance and durability of welded joints in structural applications. The experimental study entails the systematic welding of AA6061 plates of 6 mm thickness using a self-reacting bobbin tool under a fixed processing condition. Electron backscatter diffraction (EBSD) was used to characterize the grain structure and phase distribution over the weld. Mechanical parameters like as tensile strength and hardness were determined to establish correlations between microstructure and mechanical performance. The results demonstrated that SRBT-FSW significantly enhances microstructural homogeneity across the weld zone, leading to improved mechanical properties. In the Bottom Zone (BZ), a refined grain structure with an average grain size (AGS) of 3.53 µm and a random or weak texture was observed, contributing to enhanced hardness and mechanical performance, with an ultimate tensile strength (UTS) of 220 MPa. In contrast, the Top Zone (TZ) exhibited a coarser AGS of 4.33 µm with a pronounced {111} crystallographic texture, resulting in a slightly lower UTS of 205 MPa. The Middle Zone (MZ), influenced by the greater heat input from both the TZ and BZ, showed an intermediate AGS of 3.99 µm, predominantly oriented along the {101} plane, and achieved a UTS of 194 MPa, with a slight reduction in ductility. This study highlights the potential of self-reacting bobbin tool friction stir welding as a reliable method for making high-quality, homogeneous welds in thick aluminium plates and paving way for their wider application in the aerospace, automotive, and shipbuilding industries, where homogeneous microstructural qualities are of significant importance.

Effect of keyhole on plasticity-evolved behaviors of thick Ti–6Al–4V laser-arc hybrid welded joint

Revealing plasticity-evolved behaviors of laser-arc hybrid welding welds is indispensable for controlling high-reliability Ti–6Al–4V welded joints used in marine equipment. The relationship between dual heat source coupling and the plasticity of welded joints in thick plate titanium alloy is analyzed in this research. The plasticity-enhancing mechanisms based on the action of the keyhole are also elucidated. The results underscore that due to the faster cooling rate, the keyhole effect weakens the texture strengths of the β and α′ phases by 65.8% and 70.3%, respectively, and improves the ductility of the keyhole-affected region by 20% compared to the keyhole-free region. Furthermore, the keyhole region facilitates the generation of small-sized brittle phase α′, an increase in the number of small-angle grain boundaries, and easily activated pyramidal-slip systems {10 1‾ 1}<112‾ 0>, implying improved grain deformability and plasticity. These results have provided valuable insights into the plasticity-enhancing behaviors of thick Ti–6Al–4V laser-arc hybrid welded joints, offering guidance for subsequently regulating the performance of welded joints to achieve superior plasticity welded joints.

Numerical simulation of molten pool flow behavior in ultrasonic vibration-assisted gas tungsten arc welding of low-alloy high-strength steel

The beneficial effects of ultrasonic vibration-assisted arc welding on the performance of welded joints have been experimentally confirmed. However, the mechanism of the influence of ultrasonic vibration on the temperature and flow fields of the welding pool is still not clear, which also limits further application prospects of this technology. The present study established a three-dimensional molten pool model for ultrasonic vibration-assisted gas tungsten arc (UV-GTA) welding of low-alloy high-strength steel, considering free deformation of the molten pool surface and different ultrasonic vibration amplitudes. The temperature field evolution and the molten pool flow behavior under various ultrasonic vibration amplitudes were systematically analyzed. Compared with GTA welding, the ultrasonic vibration in UV-GTA welding enhanced uniformity of the temperature distribution in molten pool. Moreover, the larger the ultrasonic amplitude in UV-GTA welding, the smaller the depth of the molten pool and the time required for the molten pool to reach a quasi-steady state, but the larger the maximum flow rate at the surface as well as at the center of the molten pool. At an ultrasonic vibration amplitude of 40 µm, the molten pool depth in UV-GTA welding decreased by 34.8 % compared with GTA molten pool depth. The time for this UV-GTA molten pool to reach a quasi-steady state was just 0.57 s, and the maximum velocity at its center increased by 88.1 % over that of the GTA molten pool. Comparative analysis of the UV-GTA molten pool and the GTA molten pool revealed a shorter circulating flow field on the upper surface and periodic variations in the internal flow field motion. The simulation outcomes closely align with the experimental findings, confirming both the validity of the model and the accuracy of the pertinent conclusions. This research may lay a solid theoretical foundation for further systematic exploration of the wider application prospects of ultrasonic vibration-assisted arc welding.

Effect of heat input on the microstructure and performance of dissimilar welded joint between Q345B low-alloy steel and 2205 duplex stainless steel

Q345B/2205 dissimilar steel multi-layer multi-pass welded joints were prepared using gas metal arc welding (GMAW). The effects of heat inputs on the microstructures and properties of welded joints were studied. The morphology and composition distribution of Q345B base metal near the fusion line were investigated. The results showed that the welded joints under different heat inputs were all present “carbon depleted zone” and “carburized zones” on both sides of the Q345B base metal and transition layer interface. The microstructure of the “carburized zones” was composed of martensite phase and granular bainite phase. It was found that only the welded joints with heat inputs of 1.765 kJ/mm and 2.860 kJ/mm met the usage requirements. The corrosion behavior and characteristics of the welded joint with a heat input of 1.765 kJ/mm in a 3.5 wt % NaCl solution were investigated intensively. During the soaked process of 14 days, the total impedance value of the welded joint showed first increasing and then decreasing. The maximum value of 8.7 kΩ cm2 was obtained on the 5th day. As the soaked time increased, the corrosion products of the welded joint underwent the formation, thickening, cracking and detachment, which was the main reason of the change in the corrosion resistance. The research results of this article have significant implications for the application of low-alloy steel and stainless steel welded joints in engineering.

Innovative D-process MIG welding for enhanced performance of thick sections of MDN 250 in aerospace applications

Maraging steel, known for its exceptional strength, toughness and ductility, is widely used in aerospace and hypersonic missile manufacturing. The present study investigates the feasibility of joining 12 mm thick sections of maraging steel using advanced D-Process MIG welding technology. The D-Process integrates different welding modes such as MIG, Single Pulse-MIG and Double Pulse-MIG to optimize welding parameters, minimizing heat input. Additionally, the research investigates the influence of various post-weld heat treatments (PWHTs) on the performance of welded joints. The PWHTs included in the study are Ageing Treatment (AT), Solution Treatment + Ageing Treatment (SAT) and Homogenizing Treatment + Solution Treatment + Ageing Treatment (HSAT). Metallographic and mechanical tests were conducted on as-welded (AW) and PWHT conditions. Results showed the HSAT condition yielded superior properties with an average UTS of 1771 MPa, YS of 1734 MPa, and an average fracture toughness (FT) of 88 MPa√m. This underscores the efficacy of D-Process welding in meeting stringent requirements for maraging steel in aerospace and high-performance applications.

Corrosion performance of super duplex stainless steel and pipeline steel dissimilar welded joints: a comprehensive investigation for marine structures

This study investigates the corrosion behavior of dissimilar gas tungsten arc (GTA) welded joints between super duplex stainless steel (sDSS 2507) and pipeline steel (X-70) using electrochemical and immersion corrosion tests. The GTA welds were fabricated using ER2594 and ER309L filler metals. The study examined the electrochemical characteristics and continuous corrosion behavior of samples extracted from various zones of the weldments in a 3.5 wt.% NaCl solution, employing electrochemical impedance spectroscopy, potentiodynamic polarization methods, and an immersion corrosion test. EIS and immersion investigations revealed pitting corrosion in the X-70 base metal/X-70 heat-affected zone, indicating inferior overall corrosion resistance due to galvanic coupling. The corrosion byproducts identified in complete immersion comprised α-FeOOH, γ-FeOOH, Fe3O4, and Fe2O3, whereas γ-FeOOH and Fe3O4 were predominant in dry/wet cyclic conditions. Corrosion escalated with dry/wet cycle conditions while maintaining a lower level in complete immersion. The corrosion mechanism involves three wet surface stages in dry/wet cycles and typical oxygen absorption during complete immersion. Proposed corrosion models highlight the influence of Cl−, O2, and rust layers.

Effects of water cooling of friction stir welding of magnesium alloy stiffness joint

This study presents a comparative analysis of friction stir welding (FSW) and underwater friction stir welding (UFSW) of AZ31 magnesium alloy in T-configuration, emphasizing the effects on heat distribution, material properties, and mechanical performance. Simulation results revealed a more uniform heat distribution in both welding techniques, with the hottest area on the advancing side. The maximum temperatures recorded at the shoulder-workpiece contact were 404 °C for FSW and 349 °C for UFSW, a 13.6 % reduction in UFSW. Material velocity at the trailing edge was 63 mm/s for FSW and 42 mm/s for UFSW, showing a 34 % decrease due to lower heat generation in UFSW. Strain rates were 450 s⁻¹ for FSW and 420 s⁻¹ for UFSW. Grain size in the stir zone was 26 micrometers for FSW and 21 micrometers for UFSW, a 19 % reduction. Ultimate tensile strength (UTS) increased by 6 % in the skin direction and 12.8 % in the flange direction for UFSW compared to FSW. SEM analysis indicated enhanced ductility in UFSW fractures. These results demonstrate UFSW's superiority in improving thermal management, microstructural properties, and mechanical performance of welded joints.

Resistance Welding of Thermoplastic Composites, Including Welding to Thermosets and Metals: A Review.

This review paper presents the current progress in the development of resistance welding techniques for thermoplastic composites, with a particular emphasis on their application in hybrid joints, such as those involving thermosetting composites and metals. Resistance welding, a fusion bonding method, offers significant advantages over adhesive bonding and mechanical joining by eliminating the need for additional adhesive materials and enabling integration into automated manufacturing processes. The study highlights the unique benefits of resistance welding, including lower energy consumption compared to other methods and its compatibility with automated manufacturing, which can reduce production costs by up to 40%. Key findings from the literature indicate that resistance welding is particularly effective in achieving strong, durable joints for complex and large structures, such as those used in the aerospace industry. The review also identifies the main challenges associated with resistance welding, including temperature control, current leakage in carbon-fiber-reinforced polymers, and potential corrosion when using metal meshes. To address these challenges, various strategies are discussed, including surface treatments, the use of nanocomposites, and the integration of carbon nanotubes. The review concludes by emphasizing the need for further research to optimize welding parameters and to develop non-destructive testing methods for industrial applications, ensuring the reliability and long-term performance of welded joints.

Evaluating the TIG welding process mechanically and microstructurally in relation to welding parameters

The exceptional mechanical qualities of super martensitic stainless steel have led to its widespread use in structural components subjected to cyclic loadings. The Tungsten Inert Gas (TIG) welding process, an essential technology for modern industrial fabrication, offers potential improvements in weld quality through precise parameter adjustments. This study investigates the effects of varying TIG welding parameters, specifically welding speed (S), welding current (I), voltage (V), and gas flow rate (GFR). Parameters were explored within the ranges of 50–150 mm/min for welding speed, 10–20 volts for voltage, 90–160 amperes for welding current, and 8–20 l/min for gas flow rate. Using response surface methodology (RSM), we identified optimized values of 120 mm/min for welding speed, 15 volts, 140 amperes, and 15 l/min for gas flow rate, which significantly enhance the strength and quality of welds. Mechanical testing such as tensile and hardness tests along with bead profiles and microstructural characterization were conducted to validate the strength and integrity of the welds under these optimized conditions. The findings suggest that, compared to baseline settings, optimizing both energy use and welding quality not only conserves resources but also improves the durability and performance of welded joints. SEM analysis of AISI 410 S SMSS weldment reveals grain boundaries, 42% ferrite in elongated bands, 44% delta ferrite phase of martensite, and scattered globular Cr2C3, indicating a complex microstructure with mixed phases.

Multiscale modelling strategy for predicting fatigue performance of welded joints

This study predicts the fatigue performance of welded joints through a multiscale modelling strategy accounting for material and structural inhomogeneities. An S-N curve and detailed fracture surfaces with distinct beach marks were first derived by uniaxial fatigue tests utilising the designed cruciform welded joints. Considering the intrinsic features of welded joints, a multiscale modelling strategy was proposed to integrate multiple factors, including microstructural variations, strength distributions within the heat-affected zone (HAZ), and the diversity of three-dimensional weld toe shapes. Significantly, a modelling strategy was presented for the first time to simulate the simultaneous initiation, growth, and coalescence of multiple cracks, and was validated against experimental evidence. The results indicate that the proposed strategy can accurately predict both the fatigue strength and the overall crack growth process. Additionally, comparative assessments of single-crack and multiple-crack modelling strategies revealed notably shorter predicted fatigue lives when considering crack coalescence. Overall, this work establishes a multiscale framework for assessing the fatigue performance of welded joints considering both microscopic and macroscopic factors, offering substantial practical implications for engineering applications.

Optimising the quality of several welds in a metal-inert gas arc joining of AA6082 and AA7075 using the grey-based Taguchi technique

In recent times, welding procedures have become increasingly crucial for fabrication and manufacturing businesses. Gas metal arc welding, also known as metal inert gas (MIG) welding, has attracted much attention because of its versatility. Its benefits include low capital needs, high deposition rates, high productivity, and simplicity in adjusting to automation. It has drawn much interest because of its versatility in welding metallic materials and ease of automation. This work's objective is to maximise the multi-performance properties of the aluminium alloys AA6082 and AA7075's MIG-welded butt junction by using a hybrid grey-based Taguchi technique. During MIG welding, With the L9 Taguchi orthogonal array, the welding speed, gas flow rate, and current were optimised. Weld joint integrity has been evaluated using the fusion zone's Vickers microhardness, per cent elongation, tensile strength, and yield strength. The ideal welding current for the MIG process is 140 A, the perfect welding speed is 10 mm/min, and the excellent gas flow rate is 18 lit/min. The material showed 159.68 MPa of tensile strength, 112.79 MPa of yield strength, 16.79% of percentage elongation, and 70.95 HV of hardness under optimal conditions. With a 63.99% contribution to the process, welding speed greatly affected the weldments' overall performance. The confirmatory test confirmed the optimisation procedure also demonstrated that optimising numerous welded joint performance factors may be achieved effectively with the grey-based Taguchi approach.