Optimum Welding Research Articles

The control of fully equiaxed microstructure in laser welding Al-mg-Er-Zr alloy

The Al-Mg-Er-Zr alloy with higher strength and thermal stability was focused on as promising candidate in shipbuilding field. However, when this material was joined and manufactured with high-efficiency laser welding technology, the unmelted strengthening Al3(Er,Zr) particles segregated in weld bead and formed the discontinuous fine equiaxed and column grain zone simultaneously which decreased the joint strength. In order to solve the segregation behavior of precipitates and obtain the fully equiaxed microstructure of weld seam, the transverse scanning adjustable-ring-mode laser technology was employed. The stirring effect in the molten pool pushed the unmolten Al3(Er,Zr) dispersoids from the fusion line to the weld center. At the same time, the temperature distribution of weld seam was more homogeneous as inhibited the growth of column grain. Finally, the homogeneously distributed Al3(Er,Zr) particles as well as higher supercooling degree in the molten pool refined the microstructure. The optimal weld joint was obtained, which displayed remarkable mechanical performance with tensile strength of 389 ± 1 MPa, up to 93.3 % of base metal.

Effect of shielding gas on keyhole stability and pores in laser-CMT hybrid welding of ultra-high strength steel

Laser-CMT hybrid welding (LCHW) is a highly efficient and high-quality welding technique, showing promise for welding ultra-high strength steel (UHSS) in the aerospace industry. However, the presence of pores significantly limits its application in this field. It has been observed that using an argon-rich gas can effectively stabilize the keyhole and prevent the formation of pores. Therefore, this study aims to investigate the effect of different shielding gases on keyhole stability and porosity. The weld profile, pores, electrical signal, droplet transfer, and molten pool internal flow were carefully characterized and compared with various shielding gases. The results show that increasing the CO2 content gradually reduces weld porosity. The optimal weld formation and porosity were achieved at a CO2 content of 25 %. With the CO2 content increases, the droplets shift from off-axis upwards to downwards. This shift increases the distance between the droplet and the keyhole, reducing the time for droplet growth and promoting droplet transfer. Furthermore, the surface tension pressure gradually decreases from 3.86 Kpa to 1.1 Kpa, and at Ar + 25 % CO2, itpromote the opening of keyhole and further suppress the formation of the protrusion on the keyhole rear wall. In addition, when the CO2 content reaches 25 %, the top metal of the molten pool changes from counterclockwise flow to clockwise flow, reducing the likelihood of keyhole collapse. These effects stabilize the keyhole and suppress the formation of pores.

Improving Deposition Quality of Stellite Powder on Valve Seats by Optimized TIG Welding Parameters

The quality of the Stellite powder coated on these valve seats depends on the discharge profile and is crucial to the service length and quality of these seats, especially when called upon to work at their maximum capabilities. This research seeks to work out how to minimize blow holes in the TIG welding process when depositing Stellite powder while maintaining other desirable qualities of the weld. In this respect, the work uses the OVAT technique and Taguchi design approach to analyze the effect of the major welding parameters, such as weld speed, feed rate and welding current, on the formation of blow holes. The research shows that it is possible to gain a remarkable increase in weld quality when the parameters mentioned are strictly controlled. In this systematic experimentation, the optimal welding condition found out was the welding speed of 6.5 rpm, feed rate of 120 mm/min, and welding current of 150A. With this combination, these parameters were determined to reduce the chances of blow-holes forming and increase the welds' quality and durability. With respect to the study objectives, the present investigation offers a clear direction to enhance TIG welding of valve seats with special reference to minimize the defects. Analysis done in the study shows that the welding parameters have the greatest impact in reducing the blow holes; the feed rate is 56.61%, weld speed is 22.28% and welding current is 20.17%. The results enhance weld quality, offering rules for eradicating imperfections in the TIG welding of valve seats, which is crucial for high-performance sectors.

Optimizing 3D Laser Foil Printing Parameters for AA 6061: Numerical and Experimental Analysis

Abstract This study utilizes a technology known as 3D laser foil printing (LFP) to create precise structures by layering metal foils using laser welding. Metal foils have the advantages of rapid cooling and efficient heat conduction, allowing for the formation of fine-grained structures. However, when dealing with materials like aluminum alloys in laser processes, defects can arise as a result of their high reflectivity. To address this challenge, laser circular oscillation welding (LCOW) is applied to the LFP process. LCOW's circular motions with higher scanning frequencies widen the keyholes and reduce some defects such as spattering, bubble formation, and microcracks. Simulation predictions with an error margin of approximately 10% in comparison to experimental results demonstrate the reliability of the model. Furthermore, the study integrates circular packing design with artificial neural networks to create comprehensive processing maps tailored to different criteria for extracting optimal welding parameters. As a result, for the optimized processing parameters screened using the above systematic process, no cracks were observed on the upper surface of the 3D LFP parts produced with a laser power of 800 W and a scanning speed of 550 mm/s, and only 0.12% porosity was observed from the cross section of the sample. Future research will focus on incorporating simulation results to model microstructures more precisely and continually refining LCOW parameters as new materials and technologies emerge, ensuring the ongoing enhancement of weld quality in the 3D LFP process.

Optimal Tungsten Inert Gas Welding Parameters of Dissimilar Aluminum Alloys Al 7075 and Al 6061 Using Ultrasonic Vibration and Nanocomposite Filler (Al 5356/ZrB2) to Alleviate Hot Cracking Phenomenon

Abstract In this study, the welding of dissimilar aluminum alloys, Al 7075 and Al 6061, was investigated using Al 5356 filler rods reinforced with ZrB2 particles. The welding process was conducted using tungsten inert gas (TIG) welding, with and without ultrasonic vibration, to enhance weld quality and reduce hot cracking. Optimization of process parameters for dissimilar TIG welding was performed through Response Surface Methodology (RSM), which generated a design matrix to analyze the influence of process parameters on response variables. Numerical and graphical optimization was applied to minimize hot cracking sensitivity and maximize microhardness. The RSM-based models suggested an optimal welding current of 93 A, the use of Al 5356/ZrB2 nanocomposite filler, and the application of ultrasonic vibrations. Experimental validation of the identified solution demonstrated improvements in weld quality, including increased yield strength and ductility. The combination of nano-reinforced fillers and ultrasonic vibrations was found to enhance weldability and mitigate hot cracking in dissimilar aluminum joints. The mechanism of hot cracking reduction involved grain refinement, degassing, and homogenization due to ultrasonic vibrations, as well as the modification of weld pool chemistry and control of dilution by the nanocomposite filler, which collectively minimized solidification shrinkage and stress. Under these optimized conditions, no hot cracking was observed experimentally.

Taguchi, Grey Relational Analysis, and ANOVA Optimization of TIG Welding Parameters to Maximize Mechanical Performance of Al-6061 T6 Alloy

This study presents a comprehensive investigation into optimizing Tungsten Inert Gas (TIG) welding parameters to enhance the mechanical performance of the widely used Al-6061 T6 alloy, specifically in a double V joint configuration with a plate thickness of 6 mm, for aerospace applications. The Taguchi method was employed to design the experiments, providing a robust framework for analyzing the influence of the electrical current, voltage, and gas flow rate on weld quality. Additionally, a Grey Relational Analysis (GRA) and an Analysis of Variance (ANOVA) were used to validate the optimal welding parameters and quantify the significance of each factor. The optimized parameters were determined to be an amperage of 180 A, a voltage of 18 V, and a gas flow rate of 10 L/min, resulting in significant improvements of up to 40% in tensile strength and 23% in hardness, demonstrating the effectiveness of the optimized conditions. The findings provide valuable insights into welding metallurgy, offering practical guidelines for enhancing high-performance welded joints in critical industrial applications. This study underscores the potential of combining Taguchi, GRA, and ANOVA methodologies to achieve superior mechanical properties and reliability in welded structures.

Research on the Optimization of Oscillation for the Joint Quality of Laser Welded Joints in Automobile Seat Frames

The increasing adoption of high-strength steel in automotive manufacturing has made laser welding a preferred technique due to its ability to reduce thermal deformation and facilitate single-sided welding. Despite these advantages, challenges persist, particularly in achieving precise welds at the edges of seat frame assemblies. This study explores the application of laser weaving techniques to improve joint strength and penetration depth. The critical variables evaluated include defocusing distance and weaving parameters, which were assessed for their impact on penetration depth, effective joint width, and edge weld quality in a three-sheet stack of dual-phase (DP) steel. Results indicate that increasing the defocusing distance from 5 mm to 20 mm at a fixed oscillation frequency of 20 Hz leads to a corresponding increase in surface bead width. A significant correlation was found between the effective joint width and maximum tensile shear strength, with the highest strength of 34.6 kN observed at an 8 mm defocusing distance. Additionally, the use of oscillation in the welding process improved tensile shear strength by approximately 9 kN compared to line welding without oscillation. Oscillation also enhanced microstructural properties, demonstrating that optimal welding conditions can be achieved even with off-position welding. These improvements are attributed to minimized heat-affected zone (HAZ) effects, which contributed to increased joint strength and hardness.

An Optimization Method for Multi-Robot Automatic Welding Control Based on Particle Swarm Genetic Algorithm

This paper introduces an optimization method for multi-robot automated control welding based on a Particle Swarm Genetic Algorithm (PSGA), aiming to address issues such as high costs, large footprint, and excessive production cycles in multi-robot welding production lines. The method first constructs a multi-axis robotic kinematic model to provide constraint conditions. Then, the PSO (particle swarm optimization) algorithm, which integrates penalty functions into the fitness evaluation, is used to determine the optimal welding path by simulating collective behavior within a group. The GA (genetic algorithm) encodes the position of the welding robot bases into chromosomes to find the optimal layout for coordinated control of multiple robots. The entire process is optimized according to welding standards and requirements. Additionally, a comprehensive production line performance estimation model was used to quantitatively analyze the new scheme. The results show that the optimized production line’s balance rate increased by 10%, the balance loss rate decreased by 10%, the smoothness index increased by 37.8%, the space costs reduced by 44.4%, the equipment demand reduced by 41.1%, the labor demand reduced by 50%, the total costs reduced by 10%, and the average product cycle time was reduced by 5.07 s. Finally, we tested the algorithm in various complex scenarios and compared its performance against mainstream algorithms within the context of this study. The results demonstrated that the optimized production line significantly improved efficiency while maintaining safety standards.

Ultrasonic Welding Parameter Optimization for Electric Component Welding

Industrial requirements to establish metallic joints between dissimilar metals in the electric area. The ultrasonic welding process is an optimal process to joint thin sheets or foils. The goal of the research was to optimize the ultrasonic welding parameters to join thin nickel-coated copper sheets and aluminium sheets. It used a 0.5 mm thick high-purity copper (Cu-OF-R200) sheet coated with a 10 μm pure nickel layer and a 0.5 mm thick aluminium (1050A H24) sheet. The ultrasonic welding is made by a Branson Ultraweld L20 ultrasonic welder equipment. The mechanical properties and exacting geometrical tolerance of the joint were required. The welding parameter optimization is made empirically, with several welding tests. The optimal welding parameters were confirmed by non-destructive and destructive tests of the joints. The non-destructive tests were the visual inspection and geometrical measurements of the joint sizes. The destructive tests were tensile tests and macroscopic and microscopic tests. The completed test results confirmed the process applicability and the quality of the joint.

Impact of Ultrasonic Welding Parameters on Weldability and Sustainability of Solid Copper Wires with and without Varnish.

This article contains an advanced analysis of the properties of solid wire electrical contacts produced by ultrasonic welding, both with and without varnish. The main disadvantage of ultrasonic welding of thin wires is the inability to achieve acceptable peel force and tensile strength, which is mainly due to the deformation and thinning of the wires. This study deals with ultrasonic welding using a ring of thin solid copper wires that minimises the deformation and thinning of the wires. The influence of welding parameters such as energy, pressure and amplitude were systematically analysed. Based on these parameters, the optimum welding programme and control method was determined to weld unvarnished and varnished wires. The investigations included electrical resistance tests, optical microscopy, micro-hardness measurements, peel tests and tensile tests, and the measurement of energy consumption. The results showed no significant differences in microstructure and hardness between varnished and unvarnished joints. Ultrasonic joints of varnished wires achieved lower electrical conductivity (by 38%), lower tensile strength (by 3%) and higher peel strength (by 7%), while the welding process was more sustainable in terms of energy (by 6.6%) and time consumption (without preprocessing).

Efficient optimization of friction stir welding parameters for AA7075 and AA6082 alloys: A Hungarian method approach

Friction stir welding (FSW) is a key technique for welding high-strength aluminium alloys without melting, making it indispensable in industries where maintaining material integrity is of utmost importance. The current study presents a novel application of the Hungarian method, a combinatorial optimization technique, to determine the optimal FSW parameters for AA7075 and AA6082 alloys. The weldments were produced by applying different feed rates (40, 50 and 60 mm/min) and rotational speeds (1000, 1100 and 1200 rpm) in accordance with a L9 orthogonal array. The optimal combination was, a feed rate of 40 mm/min and a rotational speed of 1200 rpm, yielding an ultimate tensile strength of 162.26 MPa, a percentage elongation of 2.56 and an impact energy of 2.5 J/mm². The microstructural investigation showed substantial improvement in the grain refinement of the weld nugget, which significantly contributed to improved mechanical properties. However, under optimal welding conditions, the weld nugget exhibited a significant negative corrosion potential compared to the base metals, indicating a higher susceptibility to corrosion. These results show that the Hungarian method provides a systematic approach to optimizing FSW parameters, but it might be necessary to adapt post-weld treatment to lower propensity to corrode. This study illustrates not only the application of the Hungarian method in the optimization of operating parameters of FSW but also establishes a base for further studies dealing with combinatorial optimization problems in welding and other manufacturing processes.

Prediction of wall geometry forcold-metal-transfer-based wire-arc additive manufacturing

Wire-arc additive manufacturing (WAAM) is an advanced technique for fabricating large metal components through layer-by-layer material deposition using arc welding methods. This study focused on optimizing the WAAM process by employing machine learning models to predict and control bead geometries, specifically bead height (BH) and bead width (BW), while ensuring consistent height increments in multibead walls. Based on CMT technology in cold metal transfer experiments, linear regression models achieved high accuracy in predicting BH and BW. Analysis of variance results highlighted the considerable influence of voltage (V) and travel speed (TS) on bead geometries. For multibead wall characteristics, polynomial regression models incorporating non-linear terms, such as travel speed (TS²) and dwell time (Dt²), were developed to predict height (H) and waviness (W). Various optimization metrics were employed to balance the trade-offs between H and W for identifying optimal welding conditions that achieved the target H while minimizing W. A notable innovation of this research is the optimization of dwell time (Dt) for each layer to achieve a linear incremental H profile, minimizing W and ensuring consistent layer quality.

Experimental study under thermal shock environment to investigate effect of welding width on properties of ultrasonically welded joints of multiple copper cables

Based on the ultrasonic welding technology, this study uses three different welding widths to weld copper cables with different specifications. The influence of welding width on the mechanical properties and microstructure of each group of welded joints was systematically studied for the first time. The thermal shock test was carried out for each group of welded joints under optimum welding width to simulate the influence of severe temperature change environment on joint performance. It is found that the cross-sectional area of joint is 20 mm2 and optimal welding width of joint composed of two and three cables is 7 mm. The optimal welding temperature of the joint composed of four cables is 5 mm. Under the optimal welding width, the average shear strength of two-cable joint reaches 309.4 N. The four-cable joint is only 232.2 N. Moreover, the welding strength weakens significantly as the number of cables and the peak temperature decreases. The high temperature of bonding interface is the key factor to form a good weld. The peak temperature during welding is negatively correlated with the porosity of joint and positively correlated with peeling strength of joint. In addition, the morphology of ultrasonically welded joints has changed obviously after thermal shock test. With the participation of oxygen, the surface of welded joint is gray and bright brass, while the interior of joint is purple due to lack of oxygen. Moreover, the phenomenon of atomic diffusion and thermal expansion generates joints which were initially in a mechanically interlocked form and welding interface of the metallurgical bond under the action of high temperature. So the maximum joint peel strength is slightly improved.

Optimization of Joining Parameters in Pulsed Tungsten Inert Gas Weld Brazing of Aluminum and Stainless Steel Based on Response Surface Methodology

Combining aluminum and steel offers a promising solution for reducing structural weight and fuel consumption across various industries. Pulse in tungsten inert gas (TIG) weld brazing effectively suppresses interfacial brittle intermetallics and enhances joint strength by influencing pool stirring and heat input during aluminum-to-steel joining. However, optimizing the pulsed TIG weld brazing process is challenging due to its numerous welding parameters. This study established statistical models for Al/steel joint strength without reinforcement using response surface methodology (RSM) based on central composite design (CCD). The models’ adequacy and significance were verified through analysis of variance (ANOVA). The four welding parameters influence weld strength in the following descending order: pulse on time > base current > pulse current > pulse frequency. Additionally, interactions between pulse current and pulse frequency, and between pulse on time and base current, were observed. Numerical optimization using RSM determined the optimal pulsed GTA weld brazing parameters for aluminum and stainless steel. With these optimized parameters, the joint strength reached 155.73 MPa, and the intermetallic compound (IMC) thickness was reduced to 3.4 μm.

Corrosion Rate Optimization and Prediction for Enhanced Strength and Structural Integrity of Pipeline Weldments Using RSM and ANN

This study investigates the optimization and prediction of non-elastic performance factors required to augment the pipeline weldments' structural integrity and strength. The study's main focus is on the components of the operation, like the welding current, voltage, and gas flow rate to optimize and predict the corrosion rate of the pipeline weldment. Utilizing Design Expert software for experimental design and data analysis, the study employs the Central Composite Design (CCD) methodology to generate a quadratic model that predicts the responses effectively. The research also integrates Artificial Neural Networks (ANN) to further enhance the prediction accuracy. Experimental results indicate that the optimal welding parameters 160 amps current, 21.28 volts voltage, and 14.67 liters/min gas flow rate—yield a corrosion rate of 0.018 mm/yr. The study concludes that both RSM and ANN can be effectively used for optimization and prediction in welding processes, with RSM showing slightly better predictive capabilities.

Investigation on the Effect of Projection Types on Stud Weld Strength by Taguchi Method

In this study, the effect of different weld projections on the mechanical properties of stud welds was analyzed using the Taguchi experiment planning method, using a projection welding machine with a capacity of 100 kVA with MFDC transformer. The samples were subjected to the tensile rupture force test with a destructive test device. The aim of this study was to ensure product safety by capturing the spot-welding quality, which is determined by the specifications of the automotive main industry, using a bolt with a lower weight. In this study, 1.5 mm WSS-M1A365-A11 uncoated steel sheet and 8.8 quality M6x1.00x25 triple projection uncoated welding bolts and 8.8 quality M6x1.00x18.5 ring shaped weld bolts were used as stud welding bolts. Different welding times, different welding currents and different welding clamping forces were used on the WSS-M1A365-A11 steel sheet samples in the stud welding operation with bolts. Taguchi analysis showed that ring shaped stud weld bolts required welding parameters of 32 ms welding time, 27 kA welding current and 500 daN welding force, while triple projection stud welding was found to perform the best optimum weld with 23 ms welding time, 18 kA welding current and 350 daN force.

Characterization and optimization of TIG welding parameters for AISI 304 and AISI 316 stainless steel dissimilar joints

This study explores the impact of tungsten inert gas (TIG) welding parameters on the mechanical properties and microstructure of dissimilar welds between AISI 304 and AISI 316 austenitic stainless steels. Given the growing industrial demand for these materials, the research focuses on optimizing welding current, shielding gas flow rate, and voltage to enhance tensile strength, hardness, and impact toughness. Using the L9 orthogonal array based on Taguchi’s methodology, the experiments revealed that Relatively highs currents and voltages significantly improved the ultimate tensile strength (up to 673.67 MPa) and impact energy absorption (up to 36.5 J). Microstructural analysis indicated refined grain structures in the heat-affected zones, with pronounced grain growth in AISI 316 due to its thermal sensitivity. The micro-hardness analysis revealed that the highest hardness occurred in the HAZ of AISI 304, with samples 5 and 6 exhibiting the optimal hardness profile, reflecting the most favorable welding parameters. The study concludes that a current range of 80-90 A and a voltage range of 10-11 V and a shielding gas flow rate of 12-16 L/min provide optimal welding conditions, offering robust guidelines for industrial applications requiring high-performance dissimilar welds.

Dissimilar joining of aluminum alloy and low-alloy carbon steel by resistance spot welding

In this work, the resistance spot welding (RSW) process was performed to join aluminum alloy and low-alloy carbon steel plates. The macro characteristics including nugget diameters and indentation rates, microstructure and tensile-shear strength of RSW joints were investigated. The results showed that the nugget of the RSW joints comprises a ‘bowl’ shape nugget on the aluminum side and an elliptical shape nugget on the steel side. Also, the intermetallic compound (IMC) layers containing Fe4Al13 and Fe2Al5 were formed around the aluminum/steel interface with the steel side having a tongue-shape and the aluminum side having a needle-shape. According to metallurgical evaluation and temperature distribution of RSW joints analyzed by the finite element method, the nugget on the aluminum side contained the dendritic grains and equiaxed dendritic grains. The nugget on the steel side consisted of a large amount of bainite and a small amount of coarse lath martensite. The nugget diameters and the indentations rates of RSW joints increased when increasing either welding current or welding time, and decreased when increasing the electrode pressure. The maximum values of nugget diameter and indentation rate of RSW joints were 9.076 mm and 4.144% when using the welding current of 16 kA, welding time of 450 ms and electrode force of 3 kN. In tensile-shear tests, the RSW joints showed a shear-off fracture mode. When increasing the welding current, welding time or electrode force, the tensile-shear strength of RSW joints increased first, and then reached a maximum, and finally decreased. The welding current of 16 kA, the welding time of 300 ms, and the electrode pressure of 3 kN were considered as the optimal welding parameters in the present study which resulted in the maximum tensile-shear strength of 2.24 kN. In addition, the IMC layers of the RSW joints exhibited a uniform and continuous appearance with a thickness of approximately 1.9 μm, and the IMC layer in the central area was thicker than that in the edge area.

The effect of welding speed on the microstructure, mechanical properties, and fatigue failure of Q690D high-strength steel

This study analyzes the effect of welding speed on the microstructure and mechanical properties of CO2 gas-shielded welded joints of 4 mm thick Q690D high-strength steel. The results show that the weld zone is mainly composed of acicular ferrite. The coarse-grained zone and fine-grained zone contain lath bainite and lath martensite. As the welding speed increases, the degree of recrystallization in the weld zone initially increases and then decreases. At the optimal welding speed of 38 cm/min, the tensile strength of the welded joint reached 692.1 MPa, with an elongation of 9.63 %. The maximum microhardness of the welded joint was 303 HV, and the residual stress was a tensile stress of 167 MPa. After fitting the S-N curve, the ultimate fatigue strength of the welded joint was 210 MPa. Both fatigue and tensile fracture surfaces displayed second-phase precipitate particles, impacting the mechanical properties.

Impact Analysis of Welding Sequence to Reduce Weld Deformation in Aluminum Hulls

Aluminum hulls, which are preferred in the marine industry due to their durability, corrosion resistance, and lightweight properties, face serious challenges due to thermal deformation during welding. This study aims to predict and minimize transverse deformations due to welding sequences for a transverse model in the lower part of an aluminum hull. To predict deformations, heat source dimensions obtained from actual weld beads were used as simulation conditions, and various welding sequence conditions were simulated through the developed finite element method (FEM). The simulation results were compared with actual deformation measurements to verify their reliability, and the optimal welding sequence which minimized deformation was derived. The simulation results show that by changing the welding sequence conditions, the maximum displacement can be reduced from a maximum of 52.1% to a minimum of 39.1%, and the effective plastic strain can be reduced from a maximum of 19.6% to a minimum of 4.8%. These results show that adjusting the welding sequence conditions can significantly improve structural integrity by minimizing deformation. The results of this study suggest that the control of the welding sequence can be used to reduce the deformation of aluminum hulls and promote a more sustainable marine industry with improved quality.