Welding Speed Research Articles

Effect of low frequency vibration-assisted shielded metal arc welding on the properties of mild steel

Vibration-assisted welding (VAW) has emerged to be a feasible alternative to thermal and post-weld vibration treatments for arc welds in order to minimize stress concentrations and distortions thereby improving mechanical characteristics. Limited research is available considering low frequency vibration. The main objective is to develop an experimental setup to analyze the properties of welded connections made with shielded metal arc welding (SMAW) using low-frequency mechanical vibrations. Mild steel (MS) plates with dimensions of 100 mm by 50 mm and thickness of 5 mm are considered in this study. Heat inputs of 80 Amps, 100 Amps and 120 Amps were taken into consideration as input current. Vibration was varied between 0 and 100 Hz at every 20 Hz interval to study the Hardness, Tensile Strength and Impact Strength of welded joints. Microstructure of welded MS plates has been analyzed using SEM analysis. Experimental results revealed improved mechanical properties due to the application of low-frequency vibrations that may tend to increase the welding speed thus reducing time and enabling stronger, durable and reliable welded joints. A fine grain structure is seen for Low-frequency vibration-assisted welded butt joints implying improved mechanical properties due to excitation of weld pool.

Optimization of laser spiral welding using Response surface methodology and genetic algorithms

In the laser spiral welding (LSW) process, the welding parameters have a significant impact on the weld quality. In this paper, experiments were conducted and experimental data were collected on galvanized steel sheets using the LSW process, and mathematical models were developed using response surface methodology (RSM) and genetic algorithm (GA) to verify the specific effects of each process parameter on the weld and to perform process optimization. Laser power, welding speed, gap and focal length were selected as the influencing factors, and melt depth, melt width and concave as the output results. In the RSM model we found that the laser power was positively correlated with the weld depth and width, while the welding speed was inversely correlated with the weld depth and width, the gap was positively correlated with the amount of concave, and the focal length had no significant effect on the weld. In the GA model we use a large amount of experimental data for BP neural network training and iterative optimization using a genetic algorithm. Validation experiments were conducted on two models, and the results indicated that the two models had higher accuracy in predicting the welding depth and width compared to predicting the concave. The GA model had an 8% increase in tensile strength and a 25% increase in plasticity of the weld joint obtained from the optimal process compared to the RSM model. The GA model has higher accuracy in optimizing the LSW process.

A multi-criterion optimization of mechanical properties and sustainability performance in friction stir welding of 6061-T6 AA

Nowadays, the transportation industry is curious about fabricating lightweight vehicles under a sustainable manufacturing process to minimize fuel consumption costs and environmental footprints. Assessing the sustainability performance metrics of the friction stir welding (FSW) process reduces the sawing costs and environmental impacts. However, the evaluation and assessment of the sustainability performance metrics integrated with the mechanical properties of the weld joint have not been sufficiently studied. Thus, this study investigates the multi-criterion process parameter optimization of friction stir welding (FSW) to attain an optimum parameter to enhance the mechanical properties of the weld joint and decrease energy consumption and carbon dioxide emission. Experimentations are conducted using a vertical CNC milling machine on a 5 mm 6061-T6 AA material with a butt joint orientation. Tool rotational speed, traverse speed, and tool profile were used as processing parameters. Response of the study, such as transient temperature and energy consumption, was measured during the joining process, whereas hardness, tensile strength, and CO2 emission were examined post-processing. The multi-criterion optimization was done using the Taguchi-based grey relational analysis method. In addition, the transient temperature was predicted by an auto-regressive moving average (ARIMA) and Ansys simulation. The finding showed that higher rotational and minimum welding speeds had imparted a sound weld. Besides, the analysis of variance results showed that welding speed has a significant parameter at a 95% confidence interval. The proposed ARIMA model's result showed that the transient temperature prediction accuracy reached 99.922%, and the error percentage between the FEA simulation and experimental work reached 2.067%.

A study on cracks and IMCs in laser welding of Al and Cu

Aluminum-copper laser welding has become a crucial joining technology for battery manufacturing. However, dissimilar material mixing in welding often causes the formation of intermetallic compounds (IMCs) and cracks, which reduce weld quality. In this study, the effects of laser power and welding speed on material mixing, IMCs formations, and crack formation were investigated by 3D micro-X-ray computed tomography imaging, computational fluid dynamics, and chemical/elemental analyses. Of crack formation during Al-Cu laser welding, transverse cracking was found to be the major type. The crack formation is associated with the IMC distributions generated throughout the weld fusion zone when high laser energy input caused more extensive Al/Cu material mixing.

Microstructure and fracture analysis on MIG welding of Nimonic alloys

Advanced alloy has an essential role in welding process to enhance the performance characteristics. Nimonic alloy has outstanding welding characteristics. The purpose of this work is to analyze the microstructure and fracture analysis of the welded Nimonic alloy joints by employing metal inert gas welding (MIG) welding. In this work, Taguchi analyze was effectively utilized to anticipate the ideal parameters of the input variables such as voltage, welding speed, welding current towards the maximized optimal value of the welded specimen's ultimate tensile strength. In this study, a L9 orthogonal array was employed, and the ultimate tensile strength for the specimen were estimated. The findings reveal that at maximum welding speed and voltage, the specimen has a satisfactory strength bonded joint. Microstructure and fracture analysis were also discussed. The objective of the work is to enhance the ultimate tensile strength of the nimonic welded joints. The optimal welding strength was attained at welding current of 110A, speed of 20 m/s and voltage of 155 V.

A Contribution to the Analysis of the Effects of Pulsed Current in GTAW Welding of 1-mm-Thick AISI 304 Sheets

GTAW welding with pulsed current has been misinterpreted in some of the classic literature and scientific articles. General conclusions are presented, stating that its use provides greater penetration compared to the use of constant current and that the simple pulsation of the current promotes beneficial metallurgical effects. Therefore, this manuscript presents a critical analysis of this topic and adopts the terminology of thermal pulsation for the situation where the weld undergoes sensitive effects, regarding grain orientation during solidification. For comparison purposes, an index called the form factor (ratio between the root width and the face width of the weld bead) is adopted. It is shown that the penetration of a welding with pulsed current can be worse than constant current depending on the formulation of the adopted procedure. Moreover, metallurgical effects on solidification, such as grain orientation breakage, only occur when there is adequate concatenation between the pulsation frequency and the welding speed. Finally, a thermal simulation of the process showed that the pulsation frequency limits the welding speed so that there is an overlap of the molten pool in each current pulse, and continuity of the bead is obtained at the root. For frequencies of 1 Hz and 2.5 Hz, the limit welding speed was 3.3 mm/s and 4.1 mm/s, respectively.

Varying rotational speeds and their effect on the mechanical properties of friction stir welded 6082-T651 aluminium alloy plates

The need to understand the effects of varying rotational speeds on the mechanical properties of Friction Stir Welded 6082-T6 aluminium alloy plates motivated this study. The rotational speeds used were influenced by the capabilities of the Friction Stir Welding machine used. The lowest rotational speed used on the machine was 680 rpm followed by 780 rpm and 900 rpm respectively. The rotational speed is the rate at which the welding tool rotates around its axis and is one of the most important parameters in Friction Stir Welding. Speeds are related to processing temperature which influences the underlying physical conditions of the material. The changes in rotational speeds had an influence on the resulting mechanical properties. The change in rotational speed affected heat distribution in the weld area causing changes in the ductility of the Heat Affected Zone (HAZ) which affected weld behavior during mechanical testing and how these failed during testing. The optimal welding rotational speed was obtained during the welding of 6082-T6 aluminium alloy plates used in this study. This observation is also backed by mechanical evaluation done on friction stir welded plates used and results compares to work of other researchers in the field. In terms of hardness, in the weld area, the optimum speed had a higher average hardness distribution in the weld area. Heat distribution in the weld area caused changes in the ductility of the Heat Affected Zone (HAZ) and this was proven during tensile testing. Vickers hardness across the weld area revealed changes in the hardness of the base metal and the weld area. Changes in tensile strength due to changes in rotational speed are also documented and reported on. The plunge depth, tilt angle and welding speed were kept constant throughout the duration of the welding procedure. This made it easier to analyze and compare the resulting changes in the properties of Friction Stir Welded 6082-T651 aluminum alloy plates.

Welding process optimization for blast furnace shell by numerical simulation and experimental study

At cold temperatures, the stress after welding a blast furnace shell is not completely released because of the fast cooling speed, which results in cracks. To solve this problem, an integrated method combining gray relational analysis, back propagation (BP) neural network, and genetic algorithm-BP (GA-BP) was proposed in this study. Its aim was to analyze the dominant mechanism of residual stress in multi-layer and multi-pass welding process under the heating of ceramic sheet and achieve super-objective collaborative optimization of residual stress. GRA indicated that through the correlation analysis of welding parameters, residual stress, maximum temperature of characteristic point, and deformation, welding speed was determined to be an all-important factor affecting welding quality. A BP prediction model of residual stress was established. The predicted value was in good agreement with the experimental value, and the maximum error was 8.75%. The influence of each factor on the quality of welding seam is not a single, but a complex mechanism of mutual influence. GA-BP determined the combination of low level welding speed 28 mm/min, medium level welding current 210A and medium and low level welding voltage 21V as the optimal solution of low residual stress. The maximum prediction error of residual stress was 13.76%. The experimental results show that the maximum prediction error of residual stress is 4.4%, and the optimized weld has better macro and micro structure, which proves the feasibility of the multi-objective optimization method. Most importantly, the proposed method can effectively identify the optimal welding parameters, which can provide a reliable theoretical basis for engineering practice.

Strengthening of Al/Cu dissimilar joint due to complicated interface produced by pulsed TIG welding with a constricted nozzle

Al/Cu dissimilar welding is a key technology for weight reduction in fabricating high-functional products, however, conventional tungsten inert gas (TIG) welding is difficult to be applied due to a large fusion area. The constricted nozzle equipped inside the conventional TIG torch has been developed and can improve the position accuracy of tungsten electrode and arc plasma characteristics, moreover increase the heat input density. In this study, 0.5 mm-thick Al and Cu dissimilar sheets were butt welded using pulsed TIG welding with the constricted nozzle under two welding speed-current combinations of 50 mm/s-85 A and 100 mm/s-105 A. The 50 mm/s-85 A joint exhibited that Al and Cu mixed each other in the entire weld metal, containing two intermetallic compounds (IMC) of Al2Cu and Al4Cu9 mainly in the Al side. In contrast, both elements hardly mixed each other in the 100 mm/s-105 A weld metal and the interface exhibited hook-like shape at a nearly constant pitch, depending on the welding speed and pulse frequency. Consequently, the formation of IMC layers was limited. Based on the three-dimensional images reconstructed using a serial sectioning technique, the hook-shaped Al/Cu interface was also formed inside the weld metal. The mixed-zone volume per unit weld length of the 100 mm/s-105 A joint was estimated to be about 0.12 mm3/mm, and is much smaller than that of the 50 mm/s-85 A joint (0.97 mm3/mm). The average tensile strength of the 100 mm/s-105 A joint were higher than those of the 50 mm/s-85 A joint, suggesting that the hook-shaped Al/Cu interface together with the reduced mixed zone seems to increase the joint strength.

The Correlation of Kissing Bond, Microstructure and Mechanical Properties of the 2195 Al-Li Alloy Friction Stir Welding Joints at Different Welding Speeds

Reasonable welding speeds are a prerequisite for obtaining high-quality joints by friction stir welding (FSW). In this paper, 2195-T8 Al-Li alloy FSW joints were successfully fabricated at different welding speeds (100–600 mm/min) with a constant rotation speed. The effect of welding speed on the microstructure and mechanical properties was analyzed under different experimental methods. Microstructural characterization was conducted using optical microscopy (OM), scanning electron microscopy (SEM), electron backscattered diffraction (EBSD) and transmission electron microscopy (TEM). Mechanical properties were measured by a hardness test and a tensile test. The results showed that the original T1 precipitates disappeared in the nugget zone (NZ), generating many dislocations. With welding speeds increasing, joints obtained at lower welding speeds developed coarser T1 precipitates in the heat-affected zone. Also, the equiaxed grains with a bigger size and a higher fraction of high angle boundaries (HABs) were detected in the NZ of these joints. As the welding speed increased, the area of hardness value changes gradually shrunk, which was consistent with the trend of the cross-section morphology. A kissing bond and macroscopic cracking were observed in the joints that were fabricated at the higher welding speeds. The appearance of those defects significantly reduced the ultimate tensile strength and elongation of the joints at high welding speeds. Fracture morphologies of the different joints were all characterized in quasi-cleavage fractures.

Electron Beam Welding Process for Ti6Al-4V Titanium Alloy.

The electron beam welding process of titanium alloys induces a series of physicochemical changes in the material that remain a relevant and necessary area of investigation. A necessary step performed after the electron beam welding process of titanium alloys in the Ti6Al-4V grade to mitigate the resulting thermal stresses is the post-weld heat-treatment process conducted through stress relieving. This study presents the comparative analysis results of the mechanical properties and structure of the Ti6Al-4V titanium alloy after electron beam welding and subsequent stress-relieving heat treatment at a temperature of 590 °C for 2 h. The analysis focused on the levels of mechanical properties such as microhardness in the heat-affected zone and weld, tensile strength, and microstructure analysis in the heat-affected zone and weld. The aim of the research was to answer the questions regarding whether the post-weld heat treatment through stress relieving after electron beam welding of the Ti6Al-4V titanium alloy would significantly affect the changes in mechanical properties and microstructure of the alloy and whether the applied welding speed in the study would cause a significant depletion of alloying elements in the material. During the course of the study, it was found that conducting the electron beam welding process at a speed of 8 mm/s resulted in a depletion of one of the alloying elements (aluminum) in the face area. However, the decrease in aluminum content was not significant and did not exceed the critical value of 6% specified in the material standards, which determined the material's application based on its strength properties.

Crystallization of Zr-Based Amorphous Alloys in Laser Welding

Crystallization often occurs in the laser welding of amorphous alloys, reducing the properties of amorphous alloys. Therefore, the research in this thesis focuses on the experimental selection of suitable welding parameters to prevent crystallization of Zr-based amorphous alloys during the laser welding process. As such, it is necessary to simulate the temperature field curve of the welding area by computer and then determine the power and laser moving speed of laser welding. In this paper, the temperature field curve of the Zr41.2Ti13.8Cu12.5Ni10Be22.5 (Vit1) amorphous alloy in laser welding is obtained by finite element analysis. The continuous heating curve (CHT) of Vit1 is fitted by the Vogel–Fulcher–Tammann (VFT) equation and the Kissinger equation. If the temperature field curve intersects with the CHT curve, crystallization occurs. The experiment results show that the VFT equation can be used to predict the crystallization of Vit1 better in laser welding. The temperature and welding time are increased by using a low welding speed. Therefore, the temperature of the weld zone cannot fall in time, resulting in the intersection of the temperature field curve and the CHT curve. Thus, crystallization can be avoided if the welding speed is controlled within a reasonable range, and the highest temperature is kept under the CHT curve. The combination of the CHT curve and the temperature field curve shows that the samples at 300 W-3 mm/s and 300 W-6 mm/s welding parameters all undergo crystallization, while the samples at 300 W-9 mm/s and 300 W-12 mm/s welding parameters do not undergo crystallization. Through the flexural test, it is found that the flexural strength of the welded interface is at its the maximum under 300 W-9 mm/s.

Investigations on the formation of pores during laser beam welding of hairpin windings using a high-speed x-ray imaging system

Electric drives continue to grow in importance for future mobility. In recent years, hairpin winding has become established for stator production. For connecting rectangular hairpin ends, a laser beam welding process is usually implemented. For sufficient vibration resistance and current carrying capacity, pores must be avoided. This work investigates the pore formation by using a high-speed x-ray imaging system during the welding process of hairpins. This allows us to observe the formation of pores during the welding process using x-ray videos. Specifically, the use of different intensity distributions with static beam shaping (ring and core shape) is analyzed. In addition, the welding speed and the use of a protective gas (argon and helium) are taken into account. The welding results are evaluated with an x-ray CT-analysis. It is found that the formation of pores most likely occurs at the transition area of one pin end to the other. The results also show that with different intensity profiles of the laser beam, the number of process pores occurred can be influenced and reduced. An optimum welding speed and the use of a protective gas also have positive effects on pore formation.

Estimation of the size and location of an artificial weld seam defect based on the actual ultrasonic welding phenomenon for online inspection

A series of research has been conducted to analyze the quality of weld seams by non-destructive testing methods. Research on defect analysis using the actual ultrasonic welding phenomenon has not been addressed yet. To ensure a comprehensive quality evaluation, this research estimates the size and location of artificial weld seam defects by the actual ultrasonic welding phenomenon without conventional inspection systems. The welding parameters (power, pressure force, and speed) were carefully selected to ensure optimal bond strength. A superimposed type of seam was produced longitudinally by PVC-coated hybrid textiles in rough to smooth surface contact for two welding groups, using a welding width of 10 mm with an activated cooling air effect. Artificial defects were introduced across the weld seam at five different locations spaced 50 mm apart using Teflon films of 3 and 5 mm width. The actual weld phenomenon of ultrasonic welding process parameters was determined after the recorded machine parameters were converted. The effect of welding process parameters on the seam quality was also analyzed, comparing the weld seam quality between different welding groups and Teflon widths. Based on the discovered graph of the actual welding phenomenon, the location and extent of artificial weld seam defects were estimated. The artificial weld seam defect with a thickness of 0.059 mm at a width of 3.85 mm was estimated at an interval of 50.77 mm using 275 N welding pressure force and 120 W welding power at 2 m min−1 welding speed for 3 mm Teflon width. The results showed that the estimated values closely align with the actual size and position of defects. Overall, this research contributes to the development of a non-destructive testing approach for detecting weld seam defects in ultrasonic welding, emphasizing the importance of these techniques for online inspection and control of weld seam quality.

Tensile Test on Friction Stir Welded AZ31B and AZ91B Magnesium Alloys

Rare earth materials containing magnesium alloy AZ91B and AZ31B is finding widespread use in the automotive, aerospace and military industries due to its greater strength-to-weight ratio and formability. Magnesium is typically regarded as difficult to fuse together through material fusion procedures due to flaws found in welding inclusions, porosity and welded junction distortions. Friction stir welding solid state joining procedure is used for Mg joining alloys successfully. The process variables influencing the combined characteristics of weldments include tool pin geometry, downward axial force, tool welding speed (rpm). In the current research, five distinct tool types were used to create friction stir weldment geometries. There were 18 trials overall with 3 components and 8 stages run in accordance with the primary composite design matrix. The information produced by a mathematical model through response surface approach was sufficient for the developed ANOVA was used to verify the model. Large interaction between welding parameters and tensile strength graphs are utilised to depict its behaviour. It was discovered that the cylindrical straight pin has the greatest tensile qualities. The mathematical model is beneficial for adjusting the tensile strength forecast to enhance the weld quality by choosing suitable process parameters for AZ31B and AZ91B welded magnesium alloys.

Uncovering the peel strength performance of multi-layer ultrasonic weld seams in PVC-coated hybrid textiles for weather protection

Ultrasonic welding is a fast and efficient solid-state welding process widely used in various industries. This study focuses on optimizing seam quality and peel strength in multi-layered hybrid textile materials using continuous ultrasonic welding. The influence of welding process parameters (pressure force, power, and speed) on multi-layered peel strength is examined. Three-by-three experimental designs for two and three-layer weld seams with 6 and 12 mm welding widths were developed and applied using superimposed seam type. The impact of varied factors on multi-layered peel strength was analyzed statistically and explored their corresponding tendencies in the relationships. Numerical optimization and analytical models were used to determine parametric levels for achieving desired peel strength. The results show that peel strength is affected by welding parameters, with variations observed based on layer, width, and speed. Increasing speed reduces peel strength, while higher power and pressure force enhance peel strength up to a certain point. However, excessive power and pressure forces can cause material deformation and reduce peel strength. The study also found a strong correlation between power and peel strength, emphasizing the importance of energy input during welding. Power and speed are identified as significant determinants of peel strength, with their combined influence playing a crucial role. The optimal peel strength (34.86 N/12 mm) is achieved at a welding speed of 2.11 m/min, power of 118.18 W, and pressure force of 343.94 N for a three-layer weld seam with a 12 mm welding width. Nonlinear quadratic analytical models are developed to predict multi-layered peel strength, and their results align closely with the actual points. Overall, this research provides valuable insights into optimizing seam quality and peel strength for multi-layered hybrid textile materials, benefiting weather protection applications and advancing bonding techniques in ultrasonic welding.

Fundamental study of blue wavelength laser for welding low thickness dissimilar Cu and steel materials

The present study reports on the application of blue wavelength (450 nm), continuous wave laser welding of Ni-coated copper to mild steel in lap joint configuration. The laser power was varied from 1 kW to 1.5 kW in incremental steps of 0.1 kW whilst the welding speed was kept constant at 6 m/min. Metallographic examination of the weld samples revealed that the weld penetration and width strongly correlated to the laser power, the characteristic of a stable welding process due to the high absorption of the blue wavelength laser. No substantial cracks or a large number of porosities were observed in the welds. The mechanical properties of the weld samples were characterized through tensile testing and microhardness measurements to establish the microstructure property relationship. The maximum tensile strength measured for specified weld geometries was 649 N with corresponding weld efficiency of 91%. The higher-strength welds showed a tensile fracture in the heat-affected zone (HAZ) of Cu, at the periphery of weld nuggets while lower-strength welds showed interfacial fracture due to the lack of fusion. In samples made with sufficient penetration the joint strength was controlled by the HAZ rather than the joint microstructure. A significant increase in the microhardness was measured inside the weld nugget compared to the parent materials, attributed to the formation of Cu-Fe composite microstructure owing to the inter-mixing of Cu and Fe during welding. The highest microhardness was observed in the HAZ of the mild steel due to martensitic microstructure formation in this region.

Design performance optimization of laser beam welded joints made for vehicle chassis application using deep neural network-based Krill Herd method

The welding to be performed must be defect free, offer lower residual stress and strain, be compact in size and withstand different load conditions. However, the existing investigations in this scenario are still not modernized. Therefore, in this study, a specific welding method called laser beam welding (LBW) is performed and different weld parameters have been inspected and analysed. Advanced instruments based on the non-destructive (ND) are implemented to find the variable LBW responses such as weld bead defects, residuals and strain. The experimentation has been designed using Design Expert software, response surface methodology (RSM) and Box Behnken design (BBD) and verified by analysis of variance (ANOVA) analysis and FIT statistics. Moreover, a hybrid deep neural network-based Krill Herd optimization (DNN-KHO) is implemented to predict the output parameters like, undercut (µm), overlap (µm), total strain (mm/mm) and residual stress (MPa) during welding. The proposed DNN-KHO was also used to optimize LBW input parameters such as, peak power (W), weld speed (mm/s), gas flow rate (l/min) and beam diameter (µm) simultaneously. Predictions show that the proposed DNN-KHO algorithm outperformed by 21.53%, 45.428% and 41.31% higher in accuracy compared to respective hybrid random forest based grey wolf method (RF-GWO), RF and DNN predictions.

X-ray analysis of welding parameters influence on pressure vessel steel P355 N

The paper presents a study on the influence of welding parameters that is done by radiographic interpretation of the X-ray analysis results collected from welded joins that had been realized by varying the welding current intensity, tension and welding speed. The base material of the experiment is a pressure vessel steel P355 N used for constructing railway tanks for transporting liquids by train. The welding method used is flux-cored arc welding, done by a semi-automatic welding machine using welding wire as joining material. The research aims to find connections between different material welding defects and the welding parameters involved in the process of flux-cored arc welding.

Feasibility of orbital friction stir welding on clad pipes of API X65 steel and Inconel 625

Orbital friction stir welding (FSW) has been applied to clad pipes, which is certainly of interest to the oil and gas industry. In this context, an FSW system capable of performing sound joints in one pass with full tool penetration was developed. Orbital FSW was executed in 6 mm thick API X65 PSL2 steel clad pipes with 3 mm thick Inconel 625 using a polycrystalline cubic boron nitride (pcBN) tool. The metallurgical and mechanical properties of the joints were investigated. Sound joints with axial forces of 45–50 kN, tool rotational speeds of 400–500 rpm, and a welding speed of 2 mm/s were obtained, illustrating that the developed system can perform FSW joints without volumetric defects.