Welding Current Research Articles

Optimization of process parameters of electron beam welded Nimark 300 for weld bead analysis

Electron beam welding (EBW) offers an excellent capability of introducing the desired weld properties in similar and dissimilar welds. The high depth-to-width ratio enables exceedingly concentrated attention to the weld area, resulting in a smaller HAZ, making it one of the finest welding techniques. This study thus optimizes the basic input parameters of the machine based on weld quality, which incorporates weld penetration and geometry. The EBW was performed on Maragine steel (Nimark 300), a given alloy widely utilized in aerospace sensing applications. In analyzing the input variables associated with machining, this research employed the Taguchi optimization tool by zeroing in weld penetration and geometry. Then, variance analysis (ANOVA) was used for further study. Lastly, we conducted a verification test to compare the experimental results with the theoretically predicted values and thoroughly scrutinized the mathematical modelling. The machine parameters as voltage were 40, 50 and 60 KV, and the welding current was selected as 2, 4 and 6 mA. The welding speed for joining was chosen as 300, 600 and 900 mm/min. The maximum penetration was obtained at 50KV, 6mA current and 300 mm/min. The maximum bead width (BW) was obtained at 60 KV, 6 mA and 600 mm/min.

Parameters influence on mechanical properties of resistance spot welding: AISI304L/AISI1005

AbstractWelding dissimilar metals by resistance spot welding offers several advantages, including lighter weight and better mechanical properties for the shipping, aerospace, and automotive industries. The resistance spot welding parameters effects (welding current, squeeze time, welding time, and hold time) on the welding results of AISI 1005 and AISI 304L were investigated in the present research. The joints' tensile shear force, microhardness, and microstructure were examined. The Taguchi design of experiments approach was utilized to analyze the tensile shear force results statistically. A welding current of 7 kA, welding time of 1.4 s, squeeze time of 1.2 s, and hold time of 0.8 s resulted in an optimum tensile shear force of 6.194 kN. Additionally, the nugget zone demonstrated a higher hardness compared to the base metal and heat-affected zones.

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.

Implementation of Manual Metal Arc Welding with Pulsed Current on TIG Modern Inverter Welding Equipment

The TIG welding technique in pulsed current using inverter welding equipment allows the realization of welds at a high technological and qualitative level due to the advantages that the process offers, the control of the welding pool, of the energy introduced in the components, the increase of the arc stability when using low welding currents or when welding at high speeds. Some manufacturers of welding equipment [1, 2] propose the option of using pulsed current on manual metal arc welding sources to increase the technological performance, primarily for the control of the welding pool by using low values of the current frequency below 10Hz, but with limited possibilities to modify the other parameters of the welded joint. The paper proposes the use of TIG welding equipment in pulsed current, in manual metal arc welding using the pulsed welding technique, starting from the advantages that this equipment offers in terms of the much greater possibility of adjusting all the parameters of the pulsed current according to the technological needs. This is possible because the two welding processes use welding equipment with identical external static volt-ampere characteristics.

Comparative Study on the Liquid Metal Embrittlement Susceptibility of the High-Si Advanced High-Strength Steel with EG and GA Zn Coatings

The Zn-coated high-Si advanced high-strength steel (AHSS) tends to suffer Zn-assisted liquid metal embrittlement (LME) during the resistance spot welding (RSW) process. In this study, the LME behaviors of electrogalvanized (EG) and galvannealed (GA) high-Si steels were comparatively investigated. The maximum lengths of the LME cracks at the shoulder and center of the spot weld were approximately 366.6 μm and 1486.5 μm, respectively, for the EG yet 137.0 μm and 1533.3 μm, respectively, for the GA high-Si steels. Additionally, all EG and GA welded joints were etched to measure the nugget size. It was found that the increased welding current could aggravate the formation tendency of the LME cracks for both the EG and GA high-Si steels. Furthermore, the statistical results revealed that the electrogalvanized high-Si AHSS exhibited a relatively higher LME susceptibility than the galvannealed high-Si AHSS. It was deemed that the internal oxidation produced during the annealing before the Zn coating was the crucial factor that led to the difference in the LME susceptibilities for the EG and GA high-Si steels.

Robotic MAG welding defects and quality assessment with a defect threshold decision model-driven method

The use of machine vision and deep learning methods for online monitoring and evaluation of welding quality during the welding process and timely detection and correction of welding defects is essential for intelligent welding manufacturing. In this paper, with the goal of online monitoring of the welding quality of the robotic arc welding for the excavator boom, we established a multi-source sensing system for robotic arc welding processes. We have developed various feature extraction algorithms for extracting information about welding pools, arc sounds, currents, voltages, and other features. We proposed to extract welding pool image features using Res2-MobileNetV3 to obtain a 12-dimensional welding pool feature, which enabled good inter-class discrimination among different welding defects. We designed a welding defect threshold decision (DD) strategy model using the responsive machine learning and lightweight network Res2-MobileNetV3 method, achieving a welding defect recognition accuracy of 96.59%. Finally, we tested the accuracy and reliability of the welding defect recognition model on an actual welding scene for the robotic welding of the excavator boom. It provided valuable scientific methods and technological approaches for intelligent welding in complex scenes.

Hardfacing of GX40CrNiSi25-20 cast stainless steel with an austenitic manganese steel electrode

Abstract To enhance the wear and corrosion resistance of engineering components, various surface modification techniques have been devised. Among these, arc welding processes employing specialized electrodes offer relatively straightforward methods with low production costs for hardfacing applications. This paper focuses on the hardfacing process using pulsed current arc welding to reinforce cast austenitic steel structural components, aiming to prolong their lifespan. Typically, hardfacing coatings utilize Fe, Ni, and Co-based alloys. Among these, Fe-based alloys, such as manganese austenitic alloys employed in our experiments, are favored for their robust mechanical work hardening capacity, resulting in significant hardness enhancements (from 186–219 HV5 in the as-deposited layer to 468–492 HV5 after mechanical work hardening) under intense wear and impact conditions. The innovation of the hardfacing process developed in this study lies in utilizing a universal TIG source adapted for manual welding with a covered electrode in pulsed current mode. This hardfacing technique can be applied to both worn components in operation and new ones before being put into service, thereby ensuring long-term durability and reducing maintenance costs.

Influence of Printing Parameters on the Morphological Characteristics of Plasma Directed Energy-Deposited Stainless Steel

This study investigated the influence of printing parameters and strategies on the morphological characteristics of austenitic stainless steel beads deposited on carbon steel substrates, using plasma directed energy deposition (DED). The experimental setup varied the welding current, wire feed speed, and torch travel speed, and we analyzed three printing strategies: simple-linear, overlapping, and oscillating. Moreover, advanced 3D scanning and computational analysis were used to assess the key morphological features, including bead width and height. The results showed that the computational model developed by using parabolic assumptions accurately predicted the geometric outcomes of the overlapping beads. The oscillating printing strategy was the one that showed improved morphological uniformity and bead substrate wettability, so these features were used for multi-layer component manufacturing. The use of equivalent wavelength–amplitude values resulted in maximum combinations of bead height and width. Moreover, cost-effective carbon steel substrates were feasibly used in microstructural and elemental analyses, with the latter ones confirming the alignment of the bead composition with the wire-fed material. Overall, this study provides practical insights for optimizing plasma DED processes, thus enhancing the efficiency and quality of metal component manufacturing.

Effect of slag recycling on bead geometry, dilution and microstructure in submerged arc cladding of stainless steels

The submerged arc welding (SAW) process generates a large quantity of slag, which, when disposed-of, harms the environment and wastes valuable ingredients. A technology was developed to recycle the SAW slag generated in stainless steel cladding, enabling its reuse as flux. Bead geometry and dilution play crucial roles in weld cladding. Dilution determines the minimum number of layers needed to achieve the desired chemistry, while bead width dictates the fewest passes required to cover the entire surface area. Additionally, bead geometry influences the mechanical strength of the clad layers. The microstructure and solidification mode also significantly affect clad quality. Therefore, understanding the impact of recycled slag on bead geometry, dilution, and microstructure is essential. This paper presents a systematic investigation into the effects of process variables and recycled slag on bead geometry and dilution in clad welding. It includes a comparison of microstructures obtained using fresh flux versus recycled slag. The results indicate that increasing the welding current (I) by 37.5% enhances weld penetration (p), bead width (w), reinforcement (r), and dilution (d) by 50.9%, 14.4%, 69.5%, and 5.5%, respectively. Conversely, increasing the travel speed (V) by 90%, decreases p, w, and r by 19.29%, 11.9%, and 25.3%, respectively; however, dilution (d) increases by 17.6%. On the other hand, increasing the open-circuit voltage (V) by 26.7% increases bead width (w) and dilution (d) by 10.4% and 5.4%, respectively, while reinforcement (r) decreases by 7.5%. Both single and multilayer claddings prepared with fresh flux and recycled slag exhibit similar microstructures.

Optimization of TIG welding process parameters using Taguchi technique for the joining of dissimilar metals of AA5083 and AA7075

This research paper aims to optimize the TIG welding parameters to join dissimilar metals of AA5083 and AA7075 using the Taguchi technique. The TIG welding current and root gap of butt geometry configuration are considered input parameters, and welding characteristics such as tensile strength, 0.2% of yield strength, hardness, and impact energy are output responses. The base metals are joined according to the Taguchi L-09 design of experiments. The welded samples were inspected using the X-ray radiography method for internal defects. Tensile properties, hardness number, and impact energy of different welding coupons were evaluated by conducting the uni-axial testing, a Brinell hardness test, and an Izod impact test, respectively. A better weld strength of 224 MPa was observed at 210 A welding current, and the root gap of 1.5 mm was maintained. Better hardness and impact energy values were observed when the root gap of 1.5 mm and welding current of 220 A were maintained. The root gap is the primary factor influencing tensile strength enhancement, which accounts for 44.78% of the effect, followed by 40.5% welding current. Root gap is the parameter that affects the tensile properties, hardness number, and impact toughness the most. The findings of this paper suggest the optimal parameters for welding AA5083 and AA7075 dissimilar base metals, which are suitable for complex structures requiring both durability and resistance to harsh environments.

Thermodynamic Insights into the Influence of Welding Current on Oxygen Levels in the Submerged Arc Welding Process

Welding current is an essential parameter for submerged arc welding process. In submerged arc welding, the enormous heat generated by the current promotes the decomposition of the oxides in the flux, releasing oxygen and increasing the oxygen level in the metal, which further affects the microstructure and mechanical properties of the weld joint. Although previous studies have developed various models to evaluate oxygen content, the thermodynamic mechanism by which current influences oxygen levels in metal remains inadequately understood. This study integrates CALPHAD technology with welding thermodynamics to predict and simulate the impact of the welding current on oxygen content in metals. By combining experimental data with thermodynamic modeling, the research investigates how different current settings affect oxygen content in the metal across various welding zones, specifically when using CaO-Al2O3 fluxes with low and high basicity indices for the welding of typical carbon steel. This study selected two current values, 300 A and 600 A, for modeling analyses of the welding process, along with two typical fluxes with basicity indices of 1.6 and 0.4. The results indicate that the proposed method outperforms the BI model and can predict the metallurgical effects of current on oxygen content in the droplet and molten pool zones. The thermodynamic mechanisms that govern the metal oxygen level are also evaluated. These findings aim to enhance the understanding of the thermodynamic mechanism that governs oxygen behavior under different current conditions, thereby contributing to the optimization of submerged arc welding process.

Dissimilar MIG Welding Optimization of C20 and SUS201 by Taguchi Method

This study looks at how welding intensity, speed, voltage, and stick-out affect the structural and mechanical characteristics of metal inert gas (MIG) welding on SUS 201 stainless steel and C20 steel. The Taguchi method is used to optimize the study’s experiment findings. The results show that the welding current has a more significant effect on the tensile test than the welding voltage, stick-out, and welding speed. Welding voltage has the lowest influence. In addition to the base metals’ ferrite, pearlite, and austenite phases, the weld bead area contains martensite and bainite microstructures. The optimal parameters for the ultimate tensile strength (UTS), yield strength, and elongation values are a 110 amp welding current, 15 V of voltage, a 500 mm.min−1 welding speed, and a 10 mm stick-out. The confirmed UTS, yield strength, and elongation values are 452.78 MPa, 374.65 MPa, and 38.55%, respectively, comparable with the expected value derived using the Taguchi method. In the flexural test, the welding current is the most critical element affecting flexural strength. A welding current of 110 amp, an arc voltage of 15 V, a welding speed of 500 mm.min−1, and a stick-out of 12 mm are the ideal values for flexural strength. The flexural strength, confirmed at 1756.78 MPa, is more than that of the other samples. The study’s conclusions can offer more details regarding the dissimilar welding industry.

Study of GTA-Welded Joints of ZW61 Magnesium Alloy — Effect of Welding Current on the Microstructure and Mechanical Properties

An attempt has been made to weld ZW61 magnesium alloy extruded plates by gas tungsten arc welding (GTAW). In this paper, the zone with the largest average grain size in the welded joint was the fusion zone (FZ) rather than the heat-affected zone (HAZ). The grains of the FZ were nearly equiaxed, and their average size increased gradually with the increase of welding current. Simultaneously, the mechanical properties of the joints decreased with the increase of welding current under the set conditions of this experiment. The optimum mechanical properties of the joints were obtained at a welding current of 100 A. Their ultimate tensile strength (UTS), yield strength (YS), and elongation (EL) were 230 MPa, 103 MPa, and 19.2%, respectively, while the joint efficiency (σb / σb BM) was only 77.7%. The fracture locations of all the joints were found in the FZ. Excessive grain size was one of the significant factors contributing to the weakness of this zone. In addition, the semicontinuous second phase on the grain boundary induced high-stress concentrations, contributing to the fracture of the welded joint. The tensile properties of the joints can be improved by limiting heat input.

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.

Monitoring the gas metal arc additive manufacturing process using unsupervised machine learning

The study aimed to assess the performance of several unsupervised machine learning (ML) techniques in online anomaly (The term “anomaly” is used here to indicate a departure from expected process behavior which may indicate a quality issue which requires further investigation. The term “defect detection” has often been used previously but the specific imperfection is often indirectly inferred.) detection during surface tension transfer (STT)-based wire arc additive manufacturing. Recent advancements in quality monitoring for wire arc manufacturing were reviewed, followed by a comparison of unsupervised ML techniques using welding current and welding voltage data collected during a defect-free deposition process. Both time domain and frequency domain feature extraction techniques were applied and compared. Three analysis methodologies were adopted: ML algorithms such as isolation forest, local outlier factor, and one-class support vector machine. The results highlight that incorporating frequency analysis, such as fast Fourier transform (FFT) and discrete wavelet transform (DWT), for feature extraction based on general frequency response and defined bandwidth frequency response, significantly improves performance, reflected in a 14% increase in F2 score, compared with time-domain features extraction. Additionally, a deep learning approach employing a convolutional autoencoder (CAE) demonstrated superior performance by processing time-frequency domain data stored as spectrograms obtained through short-time Fourier transform (STFT) analysis. The CAE method outperformed frequency domain analysis and traditional ML approaches, achieving an additional 5% improvement in F2-score. Notably, the F2-score (The F2 score is the weighted harmonic mean of the precision and recall (given a threshold value). Unlike the F1 score, which gives equal weight to precision and recall, the F2 score gives more weight to recall than to precision.) increased significantly from 0.78 in time domain analysis to 0.895 in time-frequency analysis. The study emphasizes the potential of utilizing low-cost sensors to develop anomaly detection modules with enhanced accuracy. These findings underscore the importance of incorporating advanced data processing techniques in wire arc additive manufacturing for improved quality control and process optimization.

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.

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.

Microstructure and properties of Mg/Ti joint welded by resistance spot welding with an aluminum interlayer

Magnesium alloy AZ31B and titanium TA2 were welded by resistance spot welding technology employing an interlayer of aluminum foil and asymmetric electrodes. The microstructure of the joint was observed, with an analysis conducted on the impact of welding current and welding time on the tensile shear load of the joint. During the welding process, the aluminum interlayer melted and blended with the molten magnesium alloy, leading to the formation of a eutectic layer consisting of Mg17Al12 and (Mg) in close proximity to the welding interface. As the increasing of welding current or the extending of welding time, there was an initial increase followed by a slight decrease in the tensile shear load of the AZ31B/TA2 joint. At a welding current of 16 kA, the tensile shear load of the joint achieved the maximum, which was approximately 6.48 kN. The findings suggest that it is effective to use an aluminum foil as an intermediary to regulate the metallurgical reaction at the interface and utilize nonsymmetrical electrodes for thermal compensation in the resistance spot welding between titanium and a magnesium alloy.

Improving Dissimilar Metal Joining Quality Through Shielded Metal Arc Welding: A Taguchi Optimization Strategy

The results of an experiment that used an orthogonal Taguchi method to improve shielded metal arc welding (SMAW) were given. The SMAW method was used to join dissimilar metal of SPHC and St. 30. SPHC material has a low carbon steel content, while St. 30C steels contain a medium amount of carbon steel, which is used for tractor shaft axles. Carbon percentages vary slightly between the two substances. This study aimed to achieve the highest possible quality of tensile strength by utilizing the specified SMAW parameters. SPHC material has a low carbon content, whereas St. 30 steel has a moderate carbon content. This study used the Taguchi experimental method with three input variables and three experimental levels. The SNR ratio is used to evaluate the most optimal SMAW performance. ANOVA analysis is used to evaluate the most crucial parameters in determining the response variable. This research has successfully provided input on the combination of SPHC and St. 30C for SMEs. It operates effectively with a welding current of 133 A, a welding voltage of 9 V, and a filler diameter of 2.0 mm. The S/N ratio analysis found that the welding current, voltage, and filler diameter all had a significant impact on the outcome.