Welding Speed Research Articles

Numerical Analysis of Molten Pool Dynamic Behaviors during High-Speed Oscillation Laser Welding with Aluminum Alloy

Increased welding speeds are often used to achieve high welding efficiency. However, welding defects, including pores and humps, can easily be formed under high-speed welding conditions. Therefore, a numerical calculation method is proposed to analyze the molten pool dynamic behaviors during high-speed oscillation laser welding with the aluminum alloy. The experiments on high-speed oscillation laser welding are conducted to confirm the simulated results, and both are found to be in good agreement. The distribution characteristics of the temperature field under the condition of a high welding speed are discussed. With the influence of the stirring process from the oscillation laser beam, the temperature gradient is reduced and fluid flow velocity is decreased. The fluid flow in non-oscillation laser welding is more intense than that in oscillation laser welding. It is found that the proposed method can be used to guide the selection of the optimal process parameters for improving welding efficiency and quality in the practical welding process.

Multi-objective optimization and evolution of dissimilar welding process between Cr-Mo steel and austenitic stainless steel for power plant application

In this study, response surface methodology (RSM) was employed to optimize the welding parameters’ effects on mechanical properties of dissimilar welds between Cr-Mo steel grade (P11) and austenitic stainless steel (AISI 316LN). To determine the best welding parameters, variance analysis (ANOVA), desirability function, and perturbation analysis were used to create regression models and identify the significant parameters influencing tensile strength and hardness gaps in the weld joints. The results indicated that welding speed is the most significant parameter affecting both the austenitic hardness gap and tensile strength, while gas flow has the most significant impact on the hardness gap of Cr-Mo steel. Furthermore, welding speed positively influences the mechanical properties of dissimilar weld, whereas welding current has a slight negative effect on tensile strength. The optimum welding parameters were found to be 130 A for welding current, 70 mm min−1 for welding speed, and 13 l min−1 for welding gas flow, resulting in hardness gap values of 18.10 HV (Stainless steel side), 27.38 HV (Cr-Mo steel side), and a tensile strength of 453.90 MPa. The optimum parameter effect is concentrated at the weld interfaces between the fusion zone and the heat-affected zone. This effect led to limitations in grain coarsening, a reduction in the martensite and delta ferrite phase percentages, a slight increase in the bainite ratio, and a decrease in carbide precipitations. As a result, a homogenization of strain distribution in the optimum weld was achieved, leading to ductile fracture in Cr-Mo steel.

Grey-Taguchi Approach for Optimizing FSW Parameters in Joining AA6262 and AA5083 Alloys

T his study concentrates on the friction stir welding (FSW) joining of dissimilar AA6262 and AA5083 plates. Four input parameters, namely tool rotational speed (TRS), welding speed (WSP), tool tilt angle (TTA), and pin depth (PDP) are chosen to analyze the output responses of tensile strength (UTS), hardness (HBN), and wear rate (WTR) in welding. The primary objective is to optimize the variables of the FSW process for AA6262 and AA5083 alloys using a combination of Taguchi and Grey Relational Analysis (GRA) methods, while also comprehending the correlations among process variables through the application of these two methods. Utilizing the Taguchi approach, L27 orthogonal array is constructed for conducting FSW experiments. After this, the multi-objective optimization challenge is streamlined into a single-objective optimization task by leveraging the grey relational degree. The significance and impact of the distinct variables are elucidated through the application of Analysis of Variance (ANOVA). Confirmation tests and predictive analysis are performed to validate the optimal variables, which are then compared against the acquired outcomes. The results highlight the welding speed as the paramount parameter, exerting substantial influence over the output responses of the welds in contrast to the other variables under examination. The application of the Grey-Taguchi methodology yields enhancements in Tensile Strength (245.23 MPa) and Hardness (99.2 Hv), while concurrently decreasing the Wear Rate (0.00456 m3/Nm). Furthermore, the Grey Relational Grade exhibits an advancement of 0.1312. These findings collectively signify an increased operational efficiency in the welding process, particularly for dissimilar alloys.

Suppression of spiking defects in deep penetration electron beam welded ETP copper

The electron beam is an appropriate tool to weld pure copper due to its high absorptivity on the copper surface, a high power density and inert vacuum environment. However, deep penetration electron beam welding of pure copper often produces the spiking defect. In this work bead on plate electron beam welding was done on Cu-ETP. A critical welding speed was determined for the distinction between a conduction-determined (at lower welding speed) and a non-conduction-determined welding speed range (at higher welding speed). The influence of high preheating temperatures was shown. The welds were investigated by light optical microscopy, electron backscatter diffraction measurements, ultrasonic testing, in situ thermal imaging, electrical resistance measurements and tensile tests. It was shown that in the conduction-determined welding speed regime without preheating, full and partial penetration welds exhibited root porosity. This effect was related to the overheating of the weld pool in combination with the phenomena causing spiking. Low defect root formation was achieved by using welding speeds greater than the critical value or by applying high preheating temperatures. The joints reached up to 98% of the international annealed copper standard in terms of specific electrical conductivity. Rupture took place within the joints during tensile tests. The joints exhibited up to 77% of the ultimate tensile strength of the base metal. Welds carried out with preheating exceeded the base metal regarding the fracture strain.

Study of welding deposition performance in changing parameters (welding speed and direction) in hard coating application in sugarcane mills using the FCAW process with a focus on sustainable manufacturing

Being one of the main sources of waste generation from welding processes, filler metal splashes are a source of waste generation that promotes environmental impacts due to their chemical compositions. Actions that converge towards reducing waste, in addition to mitigating environmental impacts, also represent a significant contribution to reducing costs inherent to welding processes. Actions aimed at reducing waste and costs contribute significantly to sustainable production. In this context, a study is proposed that analyzes welding spatter as a contaminating residue and loss of financial resources. Therefore, the objective of this study is to analyze the application of hard coating using the FCAW (Flux-Cored Are Welding) process on shafts in sugar and alcohol plants. The objective is to study the influence of the coating application speed parameter associated with the direction of rotation (welding direction) on the Deposition Yield. As proposed in this study, using welding speeds of 6, 10 and 13.6 m/min with alternating rotation directions (clockwise and counterclockwise), the Deposition Yield was calculated for the 6 situations. The results showed an improvement in performance when 6 m/min and clockwise were combined. This improvement results in savings of approximately R$6.7 million per year and would avoid the generation of 385 tons of hazardous materials in Brazil. These results contribute to more sustainable production.

Enhancing friction stir welding efficiency through rotational speed adjustment: a microstructural and mechanical analysis of Al-Cu alloy

Friction stir welding (FSW) has gained prominence in the aerospace and automotive industries due to its ability to produce high-strength and defect-free welds in aluminum alloys. The present investigation focuses on the impact of different tool rotational speeds (such as 700 rpm, 900 rpm, 1100 rpm and 1300 rpm), on the microstructure and mechanical characteristics of friction stir welded Al-Cu alloys. With the use of optical microscopy, scanning electron microscopy (SEM), x-ray diffraction (XRD), and evaluations of hardness, tensile characteristics, and fracture behavior, a thorough analysis was carried out. The weld nugget zone contained significant changes in grain size and shape as a function of rotational speed, as shown by microstructural analysis. The grain structure gradually became more refined when the rotating speed was raised from 900 to 1500 rpm. According to SEM observations, at faster speeds, the weld zone showed fewer defects per unit area and better bonding properties, which might be attributed to better material flow and plastic deformation. The effect was further clarified by XRD analysis, which showed differences in phase composition with varying rotating speeds. Evaluations of the mechanical properties showed a significant relationship between rotating speed and the mechanical performance of the welds. Hardness measurements showed that as rotating speed increased, hardness levels gradually increased. Welds made at faster rotational speeds had better elongation and tensile qualities, according to tensile tests. Additionally, fracture behavior study revealed that higher rotational speed welds displayed a more ductile fracture mode, indicating increased toughness.

Parametric effect on microstructure evolution, grain size and mechanical behaviour of friction stir butt welding of AA6061-T6 alloy

This study examines how friction stir welding (FSW) changes the microstructure and mechanical properties of an AA6061-T6 alloy joint. Results showed that welding speeds (WSs) affected microstructure evolution, joint impact toughness, tensile strength, and ductility. Frictional heat and deformation rate affect grain size and shape. Additionally, the agitated zone on the advancing side had substantially less precipitates than on the retreating side. Tensile strength and impact toughness increased mostly due to high angle grain boundaries (HABs) and grain refining. X-ray diffraction (XRD) results revealed that intermetallic compounds, such as Mg2Si, MgZn2, and Al2CuMg were formed in various regions of stir zone (SZ), whereas β(Mg2Si) and β″(Mg5Si6) were found in Si-rich zones. Impact test revealed a drop in impact energy at all set of parameters when comparing to ambient temperatures (25 °C), i.e. 23%, 20%, and 22% for sample A1 (rotational speed (RS)/WS-710/40), 15%, 24%, and 30% for sample A2 (RS/WS-710/100), and 12%, 7.5%, and 17% for sample A3 (RS/WS-710/160) at 0 °C, −20 °C, and −40 °C, respectively. The maximum joint efficiency of 74.5% was obtained for sample A3. Hardness value was also found to be higher for sample A3 in SZ due to the increase the precipitates and the dislocation densities walls and substructures.

Modeling and Experimental Investigation of the Impact of the Hemispherical Tool on Heat Generation and Tensile Properties of Dissimilar Friction Stir Welded AA5083 and AA7075 Al Alloys.

This study investigated the effect of a hemispherical friction stir welding (FSW) tool on the heat generation and mechanical properties of dissimilar butt welded AA5083 and AA7075 alloys. FSW was performed on the dissimilar aluminum alloys AA5083-H111 and AA7075-T6 using welding speeds of 25, 50, and 75 mm/min. The tool rotation rate was kept constant at 500 rpm. An analytical model was developed to calculate heat generation and temperature distribution during the FSW process utilizing a hemispherical tool. The experimental results were compared to the calculated data. The latter confirms the accuracy of the analytical model, demonstrating a high degree of agreement. Sound FSW dissimilar joints were achieved at welding speeds of 50 and 25 mm/min. Meanwhile, joints created at a welding speed of 75 mm/min exhibited a tunnel-like defect, which can be attributed to the minimal heat generated at this particular welding speed. At a lower welding speed of 25 mm/min, a higher tensile strength of the dissimilar FSWed joints AA5083 and AA7075 was achieved with a joint efficiency of over 97%.

Multi-objective optimization of FSW variables on joint properties of AA5754 aluminum alloy using Taguchi approach and grey relational analysis

Friction stir welding (FSW) processing of the joint is a technique to improve the quality of the weld. The present research employed the friction stir welding technique to butt-weld AA5754 plates, whereby the joints of every weld case were identified based on their tensile strength, hardness, and impact toughness. The plates were joined by varying the rotational speeds, welding speeds, and tool tilt angles. A multi-objective optimization Taguchi’s design of experiments approach and grey relational analysis (GRA) were used in this study to assess the combined effects of the process variables. The developed models are evaluated for sufficiency, and then the most significant parameters are determined using the analysis of variance (ANOVA). The results of the ANOVA showed that the rotational speed has a maximum contribution of 55.24%, 59%, and 46.27% in obtaining the optimal values of tensile strength, hardness, and impact toughness, respectively. It was found that formability and mechanical behaviors increased with increasing tilt angle for the tilt angle range examined in the current study. The two methods provide the same results, and the optimal conditions are a rotational speed of 1000 rpm, a welding speed of 60 mm/min, and a tilt angle of 2.5°. The optimal values for tensile strength, hardness, and impact toughness, respectively, were found to be 136 MPa, 85.25 HV, and 13 J. Significant implications for the welding industry may arise from the highly favorable outcomes in terms of microstructure and mechanical attributes.

Effect of welding speed on microstructure, nano-mechanical and nano-tribological characteristics of dissimilar friction stir welded AA6061-T6 and AZ31 alloy

The microstructural, tribological, and mechanical performance of friction-stir welded AA6061-T6 and AZ31 alloys were investigated using electron back scattered diffraction, scanning electron microscope, X-ray diffraction, and electron dispersed spectroscopy methods. The non-destructive X-ray microcomputed tomography test was used to analyse weld porosity. The distribution of volumetric and surface flaws (pores) was found to be confined across the weldment. Using a novel atomic force microscopy method, the nano-tribological characteristics of the base metal and localized regions of welded sample were studied for the first time. The significant difference in wear and friction behaviour was observed in all weld zones and base metal of magnesium side, which was correlated with the hardness of these regions. AFM results showed strong variation in tribological properties in correlation with the hardness trends of different weld zones, i.e. higher hardness leads to low wear. In weldments, intermetallic compounds such as Al12Mg17 and Al3Mg2 were produced, resulting in nanohardness differences as measured by the nanoindentation test. The joint efficiency of 65%, 84%, and 91% were obtained at welding speeds of 16 mm/min, 20 mm/min, and 25 mm/min, respectively.

Effects of welding parameters on Inconel 625 coating synthesised by tungsten inert gas cladding

Inconel 625 coatings were synthesised on AISI 4130 steel substrates by tungsten inert gas welding. Optimisation of process parameters was conducted through a combination of numerical simulations and technological experiments. The welding speed has a significant effect on the width and height of the cladding layer and the welding current mainly affected the penetration. A proper decrease of welding speed with raising heat input was conductive to the decrease of coating residual stress levels and dilution rates, which promoted the solid solution of corrosion resistant elements (Mo and Nb) and favoured the improvement of coating corrosion resistance. The cladding quality and efficiency could be improved by parameter optimisations through the combination of numerical and technological methods.

Welding investigation of Hastelloy C-276 and parametric optimization using integrated MRA-TLBO algorithm during A-TIG process

A-TIG welding is a modified form of GTAW process that has become popular due to its ability to create high-quality welded joints with minimal cracks and distortion. This technique is commonly used to join various metals, including stainless steel, aluminum, titanium, and nickel alloys like Hastelloy C-276, which is used in fabrication of complex components across marine, nuclear, aerospace, and chemical industries. In this investigation, A-TIG welding of Hastelloy C-276 was studied using three parameters - welding current, welding speed, and gas flow rate - at three distinct levels. The impact of these parameters were analyzed on two responses, namely penetration depth and width of weld. Macrostructural investigation, sensitivity analysis, and parametric studies revealed that welding current (I) had the most influence, followed by speed of welding (S) and flow rate of gas(G). Full quadratic multiple regression analysis-based models were developed for both responses, which were found to be suitable with a higher coefficient of determination and an average percentage error of 2.165% and 2.624%, respectively. Additionally, a teaching learning based optimization algorithm was integrated with these models to identify the most effective A-TIG parameter combination for higher penetration depth and lower weld width. The MRA-TLBO integrated approach resulted in an optimal parametric combination of I (170A), S (180 mm min−1), and G (11.37 l min−1) that resulted in a penetration depth and weld width of 4.503 mm and 4.684 mm, respectively. Validation at this optimal setting showed an improvement of 3.365% and 1.284% for weld width and penetration depth, respectively, suggesting the robustness of the developed methodology.

Welding between confinements as a new approach for high deposition rate additive manufacturing with laser-assisted double wire welding with nontransferred arc

Laser-assisted double wire welding with nontransferred arc uses an electric arc to melt two welding wires fed toward each other. The molten material drips onto the substrate, where it is joined to the substrate without undercuts by means of oscillated laser radiation. The process offers possibility of creating structures with high deposition rates (8.4 kg/h), but faces challenges in fulfilling the requirements for surface properties and geometric accuracy. One approach to meet the requirements is to confine the final seam geometry by applying the melt into a mold. Such a confinement can be a wall previously applied by a process with higher geometric accuracy. An investigation of this approach was carried out by studying the deposition of mild steel weld beads within two confining structures, in this case, a groove. A particular interest in the evaluation is connection of the weld bead to the base material in the corners, the bottom surface, and the side surface of the groove. In the first step, weld beads are deposited in 12 mm wide grooves in a mild steel substrate with variable laser beam oscillation amplitudes of 10–13 mm. In the second step, several layers are deposited with variable welding speeds. The oscillation amplitude that generates the best connection in the corners is 13 mm. Bonding on the bottom and side surfaces could be achieved with all parameter sets. When applying several layers, the best lateral connection in the groove was produced with a welding speed of 200 mm/min.

Characteristics of welding laser beam and its influence on weld forming coefficient

Laser welding is a very complicated process. At present, there is no systematic research on the relationship between welding parameters and forming coefficient. By studying the internal relationship between laser parameters and the characteristics of welding laser, laser beam indexes, such as focusing index, are defined. They are simplified to a few laser parameters so as to facilitate the study of the influence of welding parameters on the forming coefficient. The results show that material, assembly gap, laser power and welding speed have great influence on weld penetration. When the laser power density reaches 106J/cm2, the characteristics of deep penetration welding appear. Under the condition of constant clearance, the weld depth increases with the increase of t/b. The weld penetration increases with the increase of laser power and tends to be stable when the welding speed is 12mm/s. Different materials also have a certain influence on the weld penetration depth. Under the same conditions, X6CrNiTi1810 obtains greater penetration depth, indicating that physical and chemical properties of materials are also one of the factors affecting the penetration depth. The mechanism and condition of laser welding were analysed. The relationship between laser absorptivity of sheet surface and physical properties of the materials is also studied and then obtained. The study will provide theoretical guidance for laser welding process design and welding parameter selection of steel plate.

Numerical analysis of thermal differential distribution in Bobbin tool friction stir welding of 7075-AZ31B dissimilar alloy

The theoretical model of bobbin tool friction stir welding (BT-FSW) structure and dynamic process is established. Because of the great differences in properties of different materials, the mathematical relationship between material stress and deformation will be expressed based on 3D transient heat conduction equation and J-C constitutive model. The BT-FSW process of 7075 and AZ31B was analyzed by finite element method, and the field distribution, thermal cycle curve and stress distribution characteristics of different welding areas of the welded material were simulated. To predict and control the non-equilibrium distribution of welding temperature and stress field, the influences of different Rotating speed, welding speed, offset and other variables on the BT-FSW process of 7075/AZ31B aluminum magnesium dissimilar alloy were studied comprehensively. Finally, the reliability of the model is proved by fitting the experimental and numerical analysis results. The research results show that the temperature of BT-FSW presents an “hourglass” symmetrical distribution, and the stress distribution on both sides of the plate is uniform when the aluminum alloy is placed on the advancing side, the stirring tool is offset to the aluminum alloy by 2mm, and the rotating speed and welding speed are 700r/min and 180mm/min, respectively.

Optimization of process parameter of FS-welding of aluminum-lithium alloy (AA8090) by using desirability analysis

This study explores the potential of Friction Stir Welding (FSW) for Aluminum Lithium (AA8090) Alloys, emphasizing the crucial role of experimental investigations in optimizing the FSW process. Using a vertical machine center (VMC) with a customized fixture and tool for FSW, factors like Rotational speed (RS), Tilt angle (TA), and Welding Speed (WS) are considered to enhance ultimate tensile strength (UTS) and % elongation (EL). A regression model based on Response Surface Methodology's Central Composite Design (CCD) is used to analyze UTS and % EL. The effectiveness of welded joints is comparable to the parent metal, with optimal UTS and EL achieved at 1428 rpm rotational speed, 36.4 mm/min welding speed, and 1.5° tilt angle. While significant interaction effects are observed in UTS, none are noted in EL. FSW joint performance is evaluated through microstructural analysis, microhardness distribution and fractography analysis.

Investigating parametric effects during TIG welding of dissimilar metals

This paper explores the optimization of Tungsten-Inert-Gas (TIG) welding process parameters for creating a hybrid structure of Aluminium 6061 and Stainless Steel 304 using a copper filler rod (ER-Cu). The Welding of these two materials has industrial relevance owing to its weight reduction capabilities and environmental benefits. However, Aluminium and Stainless-Steel have different melting points and thermal properties. Aluminium has twice coefficient of thermal expansion and six times coefficient of thermal conductance as compared to Stainless-Steel. This difference often results in residual stresses and brittle intermetallic compounds in the weld region. We have chosen the Welding Current, Welding Speed, and Gas Flow Rate as input parameters, and Ultimate Tensile Strength (UTS) and Micro-hardness as response parameters. We have employed the Response Surface Methodology (RSM) using a Box-Behnken design to evaluate the influence of input parameters on UTS and Micro-hardness. Furthermore, an Analysis of Variance (ANOVA) is conducted to determine the input parameters' significance on the response parameters. Our surface plots demonstrate that UTS improves with increased Welding Current and reduced Welding Speed. Simultaneously, Micro-hardness increases with elevated Welding Speed and decreased current, up to a specific limit. The peak value of UTS (79 MPa) was observed with a Current range of 85-90 A, Speed range of 95-100 mm/min, and Gas Flow Rate of 14.5-15 l/min. On the other hand, maximum Micro-hardness (260HV) was obtained with a Current range of 80-85 A, Speed range of 105-110 mm/min, and Gas Flow Rate of 14.5-15 l/min. This research contributes to improving the manufacturing process of hybrid structures, specifically by optimizing the advantages of both Aluminium and Stainless Steel while addressing the challenges that arise during their combination. The study's conclusions have major consequences for sectors looking to take advantage on the mutually beneficial characteristics of different metals in welding applications.

Microstructural and corrosion behaviours of dissimilar friction stir welded aluminium alloys

In this study, the friction stir welding (FSW) process was employed to investigate the effect of tool geometry on the corrosion behaviour and microstructure of friction stir welded AA7075-7651 and AA1200-H19 using Central Composite Design. The workpieces were machined and welded, and the interfaces were milled. A 2-level full factorial experimental design was deployed using Response Surface Methodology (RSM). A rotational speed of 1500 rpm, welding speed of 30, 60, and 90 mm/min, and a 2° tilt angle of the tool with a plunge force of 7 kN were utilized. The results show that regardless of the tool geometry, multi-response optimum weldment can be achieved at 60 mm/min welding speed and a tilt angle. The microstructure of the optimal weldments presents an ‘onion ring’ pattern, indicating proper mixing of the alloys during FSW. Analysis of the corrosion behaviour revealed a decrease in the polarization resistance when the transverse speed increased from 30 to 90 mm/min, as polarization resistance has a direct relationship with corrosion rate. It can be concluded that FSW ensures excellent weldment, as evident in the microstructural evolution of the resulting weldments, and that tool geometry plays a significant role in the corrosion inhibition efficiency of the alloys.

Improving the weld seam quality in laser welding processes by means of Bayesian optimization

The determination of appropriate process parameters is crucial for the development of laser welding processes. This usually requires extensive and time-consuming experimentation combined with expert knowledge. To reduce the number of experiments required to determine appropriate process parameters, Bayesian optimization was used in this work. Bead on plate laser welding of AA5754 samples was performed while optimizing the laser power, the welding speed, the focus position and the power distribution in the core-ring fiber laser system with the objective of achieving welds with a specific weld depth and low number of defects at high welding speeds. The welds were evaluated using X-ray imaging and height measurements. A cost function was developed to quantify the overall weld quality based on the weld properties. It is demonstrated that the Bayesian optimizer can determine appropriate process parameters for the given objective, based on a cost function, within a comparatively small number of 29 experiments.

Optimization of laser welded ASTM A36 mild steel with different laser beam oscillation patterns utilizing experimental and simulation data

Recently, there has been an increase in the use of laser beam welding of mild steel in various industries, including petroleum refineries, power plants, pharmaceuticals, and even residential areas. This research paper focuses on studying the effects of laser welding process parameters, such as laser power and welding speed, on the tensile strength of welds. To do this, three types of laser beam oscillations (sinusoidal path, triangular path, and square path) were performed to weld 125mm x 60 and 1.8 thick sheets of ASTM A36 mild steel alloy. The researchers used statistical tools such as ANOVA to generate mathematical models and experimental designs using the Taguchi method. The results indicate that the optimal welded joint has good mechanical properties after laser welding. For ASTM A36 mild steel, the optimal parameters for laser welding are a laser power of 1800 W, a welding speed of 50 mm/s, and triangular welding mode.