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

This study aims to investigate the impact of heat treatment on the microstructure and welding properties of cable-type welding wire gas metal arc welding (GMAW) in shipping steel. In contrast to the untreated weld, the width of the heat-affected zone of the weld after heat treatment decreased. The microstructure of welded joints following heat treatment and air cooling is relatively and finer compared to the grain structure after furnace cooling and without heat treatment. The tensile strength of welded joints decreases compared to that of untreated weld, while it is higher than that of joints after heat treatment and furnace cooling. The impact toughness of heat treatment is higher than that of the weld seam, heat-affected zone, and fusion line without heating treatment, and the impact performance is higher than that of post-weld heat treatment with furnace cooling. [ABSTRACT FROM AUTHOR]

One of the primary challenges in welding aluminum alloys is the formation of porosity in the weld metal, which adversely affects mechanical properties and overall usability. This study aims to evaluate the feasibility of a hybrid welding technique designed to improve weld quality by minimizing porosity. The hybrid process combines gas metal arc welding (GMAW) and gas tungsten arc welding (GTAW). High-speed video analysis was conducted to examine metal transfer, weld pool behavior, and oxide cleaning action. Radiographic testing was employed to assess the porosity in the weld metal. The experiments were carried out using AA5083 plates, with a welding current of 200 A, an arc voltage of 30 V, and travel speeds of 45, 55, and 65 cm/min. The results indicate a substantial reduction in porosity, with a remarkable decrease of up to 93% following the GMAW–GTAW hybrid welding process. Additionally, the appearance of the weld bead was significantly enhanced, featuring a clean, spatter-free surface with smooth ripple patterns. [ABSTRACT FROM AUTHOR]

This paper develops an improved simulation model for the gas metal arc welding process, incorporating the arc root conduction zone, the transistorized power supply, and its PID-controller parameters. The model is applicable to short-circuiting, free-flight, and active control transfer modes. For the short-circuiting transfer mode, the molten metal bridging electrode tip and workpiece is modelled with a parabolic wall profile, dependent on its height. This approach significantly simplifies and accurately addresses numerical issues and singularities in calculating the principal radii. Furthermore, the pressure due to the electromagnetic force is determined, and the average velocity of the transferred liquid metal is estimated using Bernoulli's equation. In the free-flight transfer mode, based on the dynamic force balance model, the arc root zone is considered thanks to the relationship between the arc current and the current emission density. Finally, the proposed model is simulated using MATLAB/SIMULINK, and the simulation results are discussed and compared with those in the specialized literature, showing a great accordance. [ABSTRACT FROM AUTHOR]

Wire arc additive manufacturing (WAAM) is a potential method of producing complicated metal parts directly from computer-aided design (CAD) models. In this experiment, stainless steel 308 L alloy was deposited with a GMAW-interfaced three-axis special purpose Cartesian robot. The major goal was to understand the behaviour of deposited material and, later, its dissolution in specific concentrations of chemical combinations. The deposited samples were investigated for better understanding of the impact of welding current on bead properties, surface roughness, and microstructure. Furthermore, the dissolving behaviour of deposited samples was investigated in various acidic bath mixes to better understand the rate of dissolution. The results reveal that WAAM parameters, particularly current, have a considerable impact on bead properties, roughness, and microstructure. On the other hand, dissolution experiments demonstrated that the faster breakdown of WAAM deposited stainless steel occurs when a 1:1 ratio mixture of acids is used. [ABSTRACT FROM AUTHOR]

The main aim of this research is to investigate the possibilities and challenges involved in the electric arc welding of solid-state-recycled EN AW 6082 aluminum alloy. Lately, solid-state recycling has gained increased attention as a more sustainable and efficient aluminum recycling method, whereby only about 30% of the energy of conventional recycling is used. This method is based on the deformation of small-sized metal waste into solid recycled specimens without a remelting step. For the welding of solid-state-recycled specimens, both metal inert gas welding and tungsten inert gas welding methods are used. To evaluate the weldability of solid-state-recycled material, welded specimens are compared with welded, commercially produced EN AW 6082 aluminum alloy sheets. The welding is performed using the same processes, parameters, and conditions. To evaluate the welding potential of solid-state-recycled alloy, tensile tests, microhardness tests, optical metallography, and scanning electron microscopy, accompanied by energy-dispersive spectroscopy analysis, are performed. [ABSTRACT FROM AUTHOR]

Gas metal arc welding (GMAW) was used to fabricate Zircaloy-2 pipe, producing flawless welds applicable in the nuclear, aerospace, and marine industries. This technique was optimized by testing a great deal and identifying the ideal process parameters (13.6V, 135A, 3mm arc length and welding speed of 170mm/min). Optical microscopy of the welded microstructure of the material demonstrated the presence of columnar and equiaxed dendrites near the weld metal (WM), mostly constituted of α-zirconium and β-zirconium phases. The mechanical properties of welded pipe have been considerably improved by these microstructural changes, which are the result of constitutional supercooling and thermal histories. Tensile strength of weldment increased by 4.3% to 501.9MPa, while base metal (BM) showed 485.2MPa of strength. Results of the tensile test show a simulated error percentage of less than 1%. Notably, the welded pipe showed better mechanical strength than BM, and a 180∘ bend test proved its ductility by revealing no symptoms of cracking. Evaluations of microhardness revealed a decrease in hardness in the BM area (179–186HV), in contrast to maximum values found in the WM (219–243HV). [ABSTRACT FROM AUTHOR]

Gas metal arc welding (GMAW) is a widely utilised welding method that forms an electric arc between a consumable wire electrode and a metal workpiece, safeguarded from impurities by a shielding gas. Despite its reputation for being a dependable, fast, and efficient welding method, various defects may arise during welding, potentially compromising the strength of the weld bead. Of these defects, burn-through, porosity, and insufficient penetration are all critical defects that can severely impact the quality of the produced weld bead. Historically, skilled welders have been adept at recognising these flaws by relying on audible and visual cues. However, there is a noticeable lack of research in the available literature concerning the replication of this skill. This paper introduces an innovative automatic approach for detecting faults in GMAW by monitoring the changes in droplet transfer mode during the welding process. The proposed fault detection algorithm exhibits a strong capability to identify and pinpoint burn-through and porosity defects across various natural GMAW droplet transfer modes, accurately detecting 27 out of the 30 burn-through occurrences and all 22 porosity defects presented in this paper. Additionally, it enables the penetration depth to be estimated within 15 % of the values measured from the etched cross-sections, demonstrating its potential as a promising solution for online monitoring in robotic or automated welding applications. These encouraging results highlight the potential of acoustic signal monitoring in automated welding processes to facilitate early detection of significant welding anomalies, thereby reducing dependence on costly non-destructive testing and minimising on-site rework. [ABSTRACT FROM AUTHOR]

The residual stresses at U-rib joints have a significant adverse impact on the structure. Therefore, it is necessary to conduct research and analysis on their residual stresses. Based on experimental testing and thermal elastic-plastic finite element analysis (FEA), this study investigates the residual stress (RS) of a U-rib joint using gas metal arc welding in an orthotropic steel bridge deck (OSBD). X-ray diffraction (XRD) was adopted to measure the RS of the U-rib welds, and the measurement results were utilized to verify the FEA. The effects of the weld root gap, weld penetration, and weld groove angle on the RS of U-rib welds were investigated by using FEA. The weld root gap had minor effect on the RS of the U-rib welds. With an increase in weld penetration, the peak values of the transverse tensile RS at both the deck plate and the U-rib weld toes increased. Additionally, an enlargement of the groove angle also resulted in a notable increase in the transverse tensile RS peak at the deck plate weld toe. [ABSTRACT FROM AUTHOR]

Welding is a widely used manufacturing process for permanently joining components. In fusion welding processes, high temperatures generate residual stresses (RS), which make the welded and thermally affected regions susceptible to failure. These stresses can superimpose on externally applied loads, making it crucial to determine RS to assess the forces borne by the component and prevent failures. Welding parameters, including the shielding gas flow rate (GFR), significantly influence the magnitude of RS. However, GFR has received limited attention in the literature regarding its overall impact. This study investigated the effect of GFR on RS in AWS ER70S-6 weld beads deposited on DIN EN 10025–2 S275JR steel plates using gas metal arc welding (GMAW) and critically refracted longitudinal waves (LCR) for stress measurement. Weld beads were deposited with GFR values of 12, 15, and 20 l/min, while other parameters were kept constant. Longitudinal RS distribution profiles were obtained for each specimen. The results showed a significant impact of GFR on the RS profile, with the highest RS values observed at 15 l/min. These findings can aid the industry in selecting welding parameters that minimize RS, thus improving the prediction of structural integrity and failure of welded components. The study emphasizes the importance of evaluating the influence of welding parameters on RS in welded joints and shows the viability of employing LCR technique to control the stresses in welds. [ABSTRACT FROM AUTHOR]

AbstractIn this study, the influence of repeated thermal cycling during multi-pass welding on the microstructural transformations and mechanical properties of austenitic stainless clad-steel plates (ASCSPs) was investigated, with a particular focus on the clad layer. A novel methodology was employed, involving the complete filling of the groove length and gradually shortening subsequent passes. Microstructural characterization of various zones within the welded joint was conducted using optical microscopy. The results demonstrated that repeated thermal cycles during multi-pass welding caused significant microstructural changes in the weld metal clad layer (WM-CL), including the transformation from columnar to equiaxed grains and the evolution of δ-ferrite morphology from dendritic to skeletal. Additionally, the ferrite number decreased from 8.5 ± 2 in the sixth pass to 2 ± 0.5 in the ninth pass, correlating with increased heat input (HI) from 15.5 kJ/cm to 25.8 kJ/cm and repeated thermal cycling. Furthermore, the heat-affected zone (HAZ) exhibited coarse-grained polygonal austenite near the fusion line, with recrystallization attributed to the high thermal input. Micro-hardness measurements showed a reduction from 320 HV in the sixth pass to 195 HV in the ninth pass, linked to alloying element diffusion and ferrite content reduction. The findings highlight the importance of controlling thermal cycles and HI during multi-pass welding to optimize the microstructural stability and mechanical properties of ASCSP welded joints. These results provide valuable insights for improving the performance of ASCSP in industrial applications. [ABSTRACT FROM AUTHOR]

Investigating ultrasonic frequency pulsed current (UFPC)-assisted welding is crucial owing to its significant advantages over traditional welding methods, including enhanced weld quality, reduced defects, and increased efficiency. This study elucidated the generation mechanism of arc ultrasonic waves influenced by UFPC through theoretical derivation. A microscopic model of arc plasma under the influence of UFPC was developed, and the equations governing the thermophysical properties of the plasma were theoretically derived and calculated. A three-dimensional numerical simulation model was developed to analyze the dynamic behavior of arc plasma and molten metal in UFPC-assisted gas metal arc welding (UFPC-GMAW). The simulation results revealed that the incorporation of UFPC increased both the maximum arc temperature and plasma velocity, resulting in a conical shape of the arc. Additionally, the maximum arc temperature amplitude decreased from 13.6% in conventional GMAW (C-GMAW) to 9.6% in UFPC-GMAW, indicating improved arc stability. The increase in electromagnetic force led to a higher droplet transfer frequency. Moreover, the weld pool in UFPC-GMAW exhibited greater weld penetration than in C-GMAW. Notably, the variations in maximum arc temperature and velocity were synchronized with UFPC, resulting in localized thermal contraction and expansion within the arc. These changes affected the arc volume and shape, leading to the excitation of ultrasonic waves. The calculated droplet size and transfer frequency were consistent with the experimental results, confirming the reliability of the models. These simulation results provide valuable guidance for engineers in designing UFPC-GMAW technology to achieve high-quality welds. [ABSTRACT FROM AUTHOR]

The fact that the weld geometry is vital in the cooling rate and determining the weld metal quality is obvious to all. So, the Taguchi technique was used to determine the process parameters of gas metal arc welding to access optimal weld bead geometry. In addition, this study investigated the effect of siliconized Zn-graphene oxide complex nanoparticles as one of the input parameters on the weld bead geometry, including the penetration depth, bead height, and bead width of the weld. Hence, the S/N and ANOVA statistical analyses were done to establish the relationship between the gas metal arc welding process's input parameters and output variables to achieve the weld bead with the highest penetration depth and the lowest bead height and width. The results showed that in the L00 sample compared to the L0 sample (sample without nanoparticles), in addition to having a very high penetration depth, the ultimate tensile strength, and yield strength have increased by 58.84% and 28.24%, respectively. [ABSTRACT FROM AUTHOR]

Gas metal arc welding (GMAW) integrated wire arc additive manufacturing (WAAM) depicts non-uniform layers, spatter, thermal distortions, metal overflow, and mechanical anisotropy. The prime cause for these issues is improper thermal energy management due to the current controlled wire feeding mechanism. Here, an autonomous wire feed system (AWFS) has been designed and integrated into the GMAW-WAAM to eliminate such issues. It fine-tunes the wire feed speed (WFS) and maintains a steady flow of arc current. With this developed system, initially, twenty single beads are deposited using ER70S-6 feedstock under different conditions of welding voltage (U), travel speed (TS), and WFS. Later on, an optimum deposit condition has been formulated using response surface methodology-RSM (U ≈ 21.7 V, TS ≈ 8.6%, and WFS ≈ 2.7 m/min). Under this deposit condition, thin-layered parts are manufactured, where inter-layer dwell time (IDT) is only varied (from 2 to 4 min) to illustrate its significance over metallographic and mechanical performances. It is observed that with increasing IDTs, the morphological attributes of the deposit are improved (straight side wall with low surface waviness) with a reduction in grain size that further boosts the hardness and mechanical performances (increased strength and wear resistance). The occurrence of compressive residual stress could additionally support the enhancements in mechanical strength. In addition to the improvements in mechanical performances, the anisotropy in mechanical strength was also reduced (< 5%). Moreover, bulk texture analysis ensures similar fiber texture evolutions along different deposit sections with a least variation in the texture intensity, which point towards isotropicity in the as-fabricated part. [ABSTRACT FROM AUTHOR]

Most published works related to gas metal arc welding processes focus on quality criteria, while energy consumed has not been considered. In this study, key parameters of the gas metal arc welding (GMAW) operation of the AISI 1045 steel, including the current (I), voltage (V), flow rate (F), and nozzle stand-off distance (D) are optimized to minimize energy consumed (EC) and enhance the ultimate tensile strength (TS) as well as elongation (EL). The radial basis function network (RBFN) is employed to propose GMAW responses. The Entropy method, modified grey wolf optimizer (MGWO), and Multi-Attributive Border Approximation Area Comparison (MABAC) were utilized to compute the weights, generate feasible solutions, and determine the best optimality. As a result, the optimal I, V, F, and D were 137 A, 23 V, 12 L/min, and 12 mm, respectively. The EC was reduced by 5.8%, while the TS and EL were improved by 3.3% and 20.7%, respectively, at the optimality. The EC and EL models were primarily affected by the I, V, F, and D, respectively. The TS model was mainly influenced by the I, D, F, and V, respectively. The RBFN-MGWO could be employed to present non-linear data and achieve better optimal results, as compared to the traditional approach. The obtained outcomes could be used to produce high-quality welds with minimizing environmental impacts. [ABSTRACT FROM AUTHOR]

Welding is a crucial technology in modern manufacturing processes, widely applied in automotive, oil refineries, and other industries. This study focuses on two standard welding techniques: Gas Metal Arc Welding (GMAW) and Shielded Metal Arc Welding (SMAW). GMAW uses argon gas as a shielding gas, and the ER70S-6 electrode has a 1.0 mm diameter, while SMAW employs the E7018 electrode with a 2.6 mm diameter. Both methods are tested on ASTM 106 Grade B steel, a commonly used material in various industries. The primary goal of this research is to evaluate the tensile strength of steel specimens welded using MIG and SMAW. The tensi le strength of raw material, as well as the welded materials, is measured to assess the quality of the welds. The results show that the tensile strength of the raw material is 648.26 kgf/mm². After welding, the tensile strength for the MIG-welded material is 540.79 kgf/mm², while the SMAW-welded material achieves a higher tensile strength of 616.17 kgf/mm². These values highlight the significant difference in performance between the two welding techniques. SMAW welding provides the best joint quality among the two methods, with a tensile strength value of 616.17 kgf/mm². This study underscores the importance of selecting the appropriate welding technique based on the desired strength and application, with SMAW proving superior for this particular material. These findings contribute valuable insights into material technology and welding, offering a reference for future industrial applications. [ABSTRACT FROM AUTHOR]

The welding process plays a crucial role in manufacturing and is inseparable from its advancement. Deutsche Industrie Norman (DIN) defines welding as creating a metallurgical bond at the joint of metal or alloy metals in their molten state. This process is essential for constructing strong, durable materials like plates, steel, and pipes. Bending tests, including face bend and root bend, are often conducted to evaluate the quality of welded joints. These tests assess welded materials' toughness, strength, and resistance under specific loading conditions. This study employed two welding techniques: Gas Metal Arc Welding (GMAW) and Shielded Metal Arc Welding (SMAW). GMAW, called Metal Inert Gas (MIG) welding, uses argon or helium as protective gases and a continuously fed electrode wire. On the other hand, SMAW relies on flux-coated electrodes to create the weld seam, with molten metal from both the electrode and parent material filling the joint. The results revealed distinct advantages for each method. The highest bending test value for the root bend was achieved with MIG welding at 982,55 Kgf/mm², demonstrating its effectiveness in creating durable root joints. Conversely, SMAW exhibited superior performance in face bend tests, achieving a bending strength of 104111 Kgf/mm², making it ideal for surface-level joint applications. Both techniques displayed no visible cracks in their welds, ensuring compliance with industry standards and confirming their reliability for various manufacturing needs. These findings highlight the importance of selecting appropriate welding methods based on specific application requirements. [ABSTRACT FROM AUTHOR]

X80 pipeline steel is widely used in oil and gas pipelines because of its excellent strength, toughness, and corrosion resistance. It is welded via gas metal arc welding (GMAW), risking high cold crack sensitivities. There is a certain relationship between the joint hardness and cold crack sensitivity of welded joints; thus, predicting the joint hardness is necessary. Considering the inefficiency of welding experiments and the complexity of welding parameters, we designed a set of processes from temperature field analysis to microstructure prediction and finally hardness prediction. Firstly, we calculated the thermal cycle curve during welding through multi-layer welding numerical simulation using the finite element method (FEM). Afterwards, BP neural networks were used to predict the cooling rates in the temperature interval that ferrite nuclears and grows. Introducing the cooling rates to the Leblond function, the ferrite fraction of the joint was given. Based on the predicted ferrite fraction, mapping relationships between joint hardness and the joint ferrite fraction were built using BP neural networks. The results shows that the error during phase fraction prediction is less than 8%, and during joint hardness prediction, it is less than 5%. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to investigate the manufacturing of a steel wall using gas metal arc welding (GMAW) process and to study its dimensional features, mechanical properties, and the microstructure. The selected parameters were the interpass dwell time, the welding speed, and the wire feeding speed. Based on the results, the average wall height and thickness decreases with increasing welding speed due to less weld deposition in the layer. A relationship between the wall thickness and height in terms of the welding speed and wire feeding speed was proposed. A longer interpass dwell time increased the wall height. The effective area percentage also increased with increasing welding speed. Tensile strength and elongation (%) were investigated based on the presence or absence of voids and microstructure. In high welding speed and long interpass dwell time, the microstructure included columnar grains with fine widmanstätten ferrite and intergranular pearlite. At low welding speed and short interpass dwell time, the microstructure consisted mostly of blocky ferrite and coarse pearlite. Both of these structures showed satisfactory strength and elongation. But in the other conditions, where the possibility of brittle phases in the heat-affected zone was higher, the strength and elongation decreased. [ABSTRACT FROM AUTHOR]

The grain growth in the fusion zone (FZ) and heat-affected zone (HAZ) of metal inert gas (MIG) welding processes negatively affect the mechanical properties of aluminum alloy MIG welds used in automotive components. Although the addition of Sc- and Zr-based filler wires can refine weld microstructures and enhance the mechanical properties, conditions resembling actual automotive component joints have not been sufficiently investigated. In this study, 5083-O aluminum alloy base material was welded into butt and lap joints using conventional 5000-series aluminum alloy filler wires (Al-5.0Mg) and wires containing Sc and Zr (Al-4.8Mg-0.7Sc-0.3Zr) under various heat input conditions. The mechanical properties of the welds were evaluated via tensile tests, and the microstructures in the FZ and HAZ were analyzed. In butt joints, Al-4.8Mg-0.7Sc-0.3Zr exhibited a finer and more uniform grain structure with increased tensile strength compared with those welded using Al-5.0Mg. The microstructure became coarser with the increased heat input, and the tensile strength tended to decrease. In lap joints, the tensile-shear strength of Al-4.8Mg-0.7Sc-0.3Zr was higher than that of Al-5.0Mg; it further increased with the increase in the amount of deposited metal. The coarsening of the microstructure with the increased heat input was disadvantageous for the tensile-shear strength, and the increased weld size offset the adverse effects of the coarse microstructure. These results indicate that the heat input and the amount of deposited metal must be optimized to ensure stiffness in various joints of automotive components. [ABSTRACT FROM AUTHOR]

In this research, fillet welding was conducted on 8-mm thick Miilux OY Protection 600 (MIL-A-46100) armor steel using AWS A5.9 GeKa ER307 austenitic filler wire. The welding process involved robotic MIG/MAG with five different heat inputs ranging from 0.3 to 1.2 kJ/mm. The study focused on examining the influence of heat input on the microstructure, elemental changes, microhardness, and dimensions of the weld metal and the heat-affected zone (HAZ). These investigations were conducted to determine the welding parameters that they satisfy the quality requirements of the MIL-STD-1185 standard for this steel grade and weld consumable. Through analysis of macrostructure, microstructure, and microhardness, it was observed that increasing the heat input led to a decrease in hardness for both the weld metal and the HAZ, while expanding the HAZ width. The weld metal exhibited a homogenous hardness distribution at lower and higher heat inputs, but hardness increased from the root to the face for both heat inputs of 0.5 and 0.7 kJ/mm welds. Notably, a significant decrease in hardness occurred in the transition of partial transformation region (intercritical HAZ) and tempering region (subcritical HAZ) for heat inputs above 0.7 kJ/mm, indicating softening. Moreover, the width of the subcritical heat-affected zone substantially increased. Evaluation of the distance required to reach base metal hardness from the welding toe revealed that a heat input of 1.2 kJ/mm exceeded the maximum requirement of 15.9 mm according to the MIL-STD-1185 standard. However, the requirements of the military standard were satisfied for other heat input values. These findings were associated with microstructural changes in grain size, martensite, bainite, martensite/austenite morphology and their fractions, as well as delta ferrite morphology. The results successfully demonstrated that robotic GMAW welding can be applied using lower strength (undermatched) filler metal to satisfy the requirements of the respective standard of MIL-STD-1185. [ABSTRACT FROM AUTHOR]

Many diverse components are deployed for contemporary applications, ranging from the production of cars and other vehicles using sheet metal to heavy engineering using thick sections. These components are fabricated by welding high-strength micro-alloyed steels. The current study characterizes the microstructure of the controlled-rolled, 25 mm-thick micro-alloyed steel plate's tight gap weld joints. A controlled-rolled, micro-alloyed steel plate with dimensions of 250 × 100 mm is used for the welding process. By properly milling the plates, conventional gaps with width of 25 and 20 mm (CG-25 & CG-20) and narrow gaps with width of 13 mm (NG-13) are created as per the desired design. The root pass is created by gas tungsten arc welding (GTAW) process with autogenous technique, further filling passes are created by GTAW, and successive filling passes are made by pulsed current gas metal arc welding technique. It is found that increasing mean current (Im) from 160 to 230A reduces the dendrite fraction while increasing the reheat refined region in the matrix. However, at a particular Im, an increase in dimensionless factor (ϕ) and heat input (Ω) from 0.15 to 0.23 and 5.28-7.61 kJ/cm, respectively, has no effect on the matrix. [ABSTRACT FROM AUTHOR]

This study investigates the feasibility of using friction stir extrusion (FSE) recycled aluminum wires as filler metals for gas tungsten arc welding (GTAW) and additive manufacturing applications. A NC-controlled GTAW feeding system was developed to enable the deposition of these recycled wires. The effect of cleaning the machining chips before the FSE process on the quality of the manufactured wires and the resulting welded beads was evaluated. Wires produced from uncleaned chips and cleaned chips were compared in terms of their external appearance, ductility, and the presence of porosity after the weld deposition. The results showed that cleaning the chips before the FSE process is crucial for obtaining more uniform wires with better ductility. Automatic GTAW deposition using cleaned wires resulted in significantly improved bead geometry, reduced external porosity, and overall better quality compared to uncleaned wires. However, both wire types exhibited internal porosity, with uncleaned wires showing the worst performance. The findings demonstrate the potential of using FSE recycled aluminum wires for welding and additive manufacturing while highlighting the importance of chip cleaning and the need for further optimization to minimize porosity in the deposited material. [ABSTRACT FROM AUTHOR]

In this work, an attempt is made to find out the optimized weld parameters in double‐pulse metal inert gas‐welded 15CDV6 high‐strength low‐alloy steel. Three parameters namely wire feed speed, pulse frequency, and amplitude were varied and the weld quality was assessed based on bead width, depth of penetration, and tensile strength. Best and worst weld parameter combinations were identified using Technique for Order of Preference by similarity to ideal solution optimisation technique. Weld obtained through optimised parameter combination had a tensile strength of 867.28 MPa and the weld obtained through worst weld parameter combination had a tensile strength of 212.21 MPa. Compared to the base metal, the best weld had 21% higher tensile strength, and the worst weld had 65% lower tensile strength. A higher percentage of martensite in the microstructure of the best weld played a major role in achieving a high value of tensile strength. The best weld also had lower percentage of ferrite in both the heat‐affected zone and the weld zone compared to the worst weld. Best weld also had a lower percentage of high strain regions than the worst weld as indicated by electron backscatter diffraction results. [ABSTRACT FROM AUTHOR]

This study investigates the effect of welding parameters on the microstructural evolution and mechanical properties, such as tensile strength and hardness, in mild steel plates welded using gas metal arc welding (GMAW). The welding parameters examined include welding current, arc voltage, and gas flow rate, with ER K-71 T filler wire as the consumable material. Results indicate that a higher welding current and reduced gas flow rate result in a maximum tensile strength of approximately 533 MPa. However, discrepancies were noted in the microhardness data across different zones, with the heat-affected zone (HAZ) exhibiting a hardness of 115.8 HV, while the weld zone and base metal showed values of 76.7 HV and 112.9 HV, respectively. Microstructural analysis revealed the presence of bainite and ferrite with a tempered martensitic structure in the welded area, demonstrating that the combination of welding parameters plays a critical role in controlling phase transformations and mechanical behavior. It is essential to reconcile the observed hardness values with the conclusions drawn to ensure accurate interpretation of the data. Highlights: The study investigates how different welding process parameters, including current, voltage, and gas flow, affect the internal structure and mechanical characteristics of weld metal. It was found that the highest tensile strength is achieved with a combination of high welding current and low gas flow rate. The welded joint shows greater hardness in the heat-affected zone compared to the original metal, with the fusion zone being less hard. Analysis of the weld area reveals the presence of bainite, ferrite, and tempered martensite, which are responsible for the mechanical properties observed. [ABSTRACT FROM AUTHOR]

Narrow-gap arc welding is an efficient method that significantly enhances industrial production efficiency and reduces costs. This study investigates the application of low-alloy steel wire EG70-G in narrow-gap gas metal arc welding (GMAW) on thick plates. Experimental observations were made to examine the arc behavior, droplet transition behavior, and weld formation characteristics of double-wire welding under various process parameters. Additionally, the temperature field of the welding process was simulated using finite element software (ABAQUS 2020). Finally, the microstructure and microhardness of the fusion zone in a double-wire, single-pass filled joint under the different welding speeds were compared and analyzed. The results demonstrate that the use of double-wire GMAW in narrow-gap welding yielded positive outcomes. Optimal settings for wire feeding speed, welding speed, and double-wire lateral spacing significantly enhanced welding quality, effectively preventing side wall non-fusion and poor weld profiles in the welded joints. The microstructure of the fusion zone produced at a higher welding speed (11 mm/s) was finer, resulting in increased microhardness compared to welds obtained at a lower speed (8 mm/s). This is attributed to the shorter duration of the liquid molten pool and the faster cooling rate associated with higher welding speed. This research provides a reference for the practical application of double-wire narrow-gap gas metal arc welding technology. [ABSTRACT FROM AUTHOR]

The petroleum industry is essential for supplying crude oil, which is vital for fuel and chemicals and drives substantial investments in technologies, especially in regard to increasing the durability of the drill strings used in wellbore construction. This study aims to establish and to validate a hardbanding technology for reconditioning NC50 tool joints subjected to wear, thereby increasing drill pipe durability and reducing the risk of failure during drilling, which can lead to ecological pollution, human safety issues, and financial costs. The hardbanding of the tool joints was carried out using the gas metal arc welding process (GMAW) with two different wear-resistant wires, ARNCO 100XT and FLUXOFIL M58. The equipment designed for this research allowed for the application of high-quality hardbanding layers in very good condition, according to the favorable results obtained by macroscopic analyses, metallographic studies and hardness measurements. The hardbanding procedure of the tool joint drill pipe was documented in a welding procedure specification (WPS), which validates the process and is useful for operators, drilling companies and other oilfield service companies who wish to apply under the same conditions and at the same high-quality level, in a repetitive mode, the reconditioning process to minimize the risk of drill-string failures. [ABSTRACT FROM AUTHOR]

This study examines the dependent relationship between microstructure, mechanical properties, and corrosion performance on the wire arc additive manufactured (WAAM) ER2209 duplex stainless steel (DSS). DSS is renowned for its corrosion resistance and mechanical strength, making it favorable for various applications. This study uses the gas metal arc welding (GMAW)‐ based WAAM technique to fabricate the wall structure using ER2209 DSS filler wire. Fine, equiaxed dendrites are formed along the build direction, with the austenite phase exceeding 70% due to the repeated heating and slow cooling inherent to WAAM process. X‐ray diffraction (XRD) confirms no brittle intermetallic phases. The results shows that varying austenite‐ferrite fractions significantly influences the anisotropy in mechanical properties between build and deposit directions. Along the build direction, the varying phase fraction causes difference in hardness of 19.59 HV0.3 and tensile strength of 20 MPa. The maximum tensile strength (787.08 MPa) is observed in the deposit direction, with a 52 MPa difference between the build and deposit directions. Tafel and EIS measurements indicated that WAAM samples corrosion resistance was almost close to wrought 2205 DSS. This study highlights WAAM's potential for defect‐free DSS parts and suggests post‐heat treatment to optimize microstructure and mechanical properties. [ABSTRACT FROM AUTHOR]

This paper compares the microstructure and corrosion performance of Alloy 625 weld cladding deposited using Top Wire Feeding GTAW (TWF-GTAW) and Plasma Transferred Arc with Powder (PTA-P). The analysis indicated higher dilution values for TWF-GTAW, with 27.5% for a single layer, whereas in PTA-P, the dilution was 5.1% for a single layer. Both single and double layers presented similar dilution for the different welding conditions because the second deposited layer only partially melted the first layer. The Fe content was higher in TWF-GTAW compared with PTA-P welding. Micrographic characterization showed the formation of micropores in welding using the PTA-P process, with a predominance of Laves phase formation as an interdendritic precipitate. In contrast, TWF-GTAW welding showed the formation of Laves phases and carbide without the presence of micropores. Corrosion resistance was superior for TWF-GTAW weld cladding, with slightly better performance observed for the double layer. In the PTA-P process, interdendritic corrosion was observed, which can be associated with the presence of micropores. [ABSTRACT FROM AUTHOR]

Directed energy deposition-arc (DED-arc) is a viable method of metal 3D printing for manufacturing in-space under microgravity conditions. This study investigates the effect of reduced gravity on the droplet transfer in a gas metal arc welding (GMAW)-based DED-arc process. Single bead deposited using GMAW welding process under microgravity and standard terrestrial gravity (1 g) are compared. Microgravity was simulated in a drop tower where the experimental capsule was subjected to 2.5 s of free-fall. The experimental setup for GMAW welding process, including high-speed cameras and sensors, was present within the experimental capsule. Droplet frequency and diameter were measured and compared between microgravity and 1 g using the images obtained. Further, the impact of reduced gravity on weld bead geometry and the distribution of gas porosity was investigated. Microhardness analysis was also conducted on both 1 g and reduced gravity samples to assess variations in material hardness. A statistically significant difference in droplet diameter and frequency was found. This difference is attributed to the reduction in gravitational force. Upon analyzing the weld bead geometry, noticeable variations are detected in the contact angles and the reinforcement of beads formed under different gravity conditions. These differences are attributed to alterations in convection within the molten weld pool. The blowhole analysis revealed a noticeable trend, wherein reduced gravity facilitated the coalescence of gas porosity, resulting in larger diameters due to alterations in weld pool convection. There were no statistically significant changes observed in both microhardness and surface finish. [ABSTRACT FROM AUTHOR]

The possibility of producing multilayer billets by wire arc additive manufacturing (WAAM) technology with layer-by-layer forging using Cr20Mn5Ni4Mo2.5Cu3N0.3 flux-cored wire of 1.6 mm diameter as electrode material is investigated. The applied method resulted in the production of a weld metal with austenitic-ferritic structure (δF ≈ 1.5 vol %) without defects, which demonstrates a good combination of strength and plastic properties (σB = 960 MPa, σ0.2 = 670 MPa, δ = 35%). [ABSTRACT FROM AUTHOR]

The Gas Metal Arc Welding (GMAW) process is leading the way in arc welding process growth because it is more efficient, economical, and of high quality. The effects of ER70s filler metal on mechanical properties and corrosion behaviour in low carbon steel with a base metal thickness of 12 mm are investigated in this study using robotic gas metal arc welding (GMAW). After the welding process, the quality, microstructure, and micro-hardness of each specimen were measured and the effect was studied. The immersion test was studied using weight loss and corrosion rate measurements for 1, 2, 4, 6, and 8 weeks in the absence and presence of 3.5wt. % NaCl. As a result, the microstructure displayed the different grain boundaries of each parameter that affected the welding parameters. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) are used to characterise the surface morphology and pitting areas on the welded substrate. The corrosion rate of the welded sample immersed in 3.5wt. % medium was higher than in the absence of NaCl. The SEM results revealed that NaCl played an aggressive role in inducing the corrosion process and producing significant pits on the welded joint, particularly in the HAZ area. This research may provide a significant understanding of how the welding process, filler metal, and low carbon steel metal caused corrosion behaviour in the marine environment, particularly for oil and gas applications. [ABSTRACT FROM AUTHOR]

This study focuses on the tensile strength properties and microstructural development of A588 Grade K high strength low alloy (HSLA) steel. The research involves welding of 4 mm thick HSLA using E308L filler wire in the MIG welding process. The correlation between microstructure and tensile strength is explored with a welding current ranging from 120–150 A and a welding speed between 2–6 mm/s, rest of the parameters are consider as a constant. Results indicate that, the combination of 130 A and 2 mm/s reveals the better mechanical properties, exhibiting enhanced tensile strength with fewer defects compared to other parameters. Notably, the improved tensile strength at 130 A is 1.07 times higher and at 120 A is 1.05 times higher than that of the friction stir welding (FSW) process. However, there is a noteworthy improvement compared to laser welding, with 1.034 times at 130 A and 1.06 % at 120 A. The microstructure evolution in various zones are studied, no major defects are found, and confirming a transformation of ferrite morphology in the heat affected zone (HAZ), particularly with an increased amount of acicular ferrite in the fusion zone under the 130 A input current. The paper further details the tensile behavior and fracture morphology analysis under the specified experimental conditions. [ABSTRACT FROM AUTHOR]

In the welding of materials, metal inert gas (MIG), gas tungsten arc welding (GTAW), and tungsten inert gas (TIG), are typical welding technologies. Welding titanium alloys involves several challenges due to their susceptibility to oxidation phenomena. Shielding arrangements of a relatively new type are tested to overcome this contamination. A proposed design and configurations are used to join commercially pure titanium sheets with variations in ARC, GMAW, and GTAW process parameters along with travel speed and welding current. Variations were made to process parameters toward full penetration butt joints in experimental bead-on plate (BoP) trials with a sheet thickness of 5 mm. Macrostructure images were subsequently captured. Analysing the microstructure of the heat-affected zone, base metal, and fusion zone is done using optical microscopy. TIG welding is 7.39% harder than MIG welding and 2.72% harder than Arc welding. A TIG welding joint exhibited 11% greater tensile strength than a GTAW joint, while a MIG welding joint possessed 6.7% greater tensile strength than a TIG joint. A TIG welding process elongates 15.5% more than a MIG welding process, and 3.31% more than an arc welding process. Titanium alloy plates are best joined by TIG welding because of its microstructure and mechanical properties. For aerospace and high-performance engineering parts, TIG welding offers excellent results due to the precise control of welding parameters. [ABSTRACT FROM AUTHOR]

Purpose: The main novelty of the paper is to present the Ti alloy welding for automotive application. Welding titanium is a difficult task. The aim of the article is to develop the MIG (Metal Inert Gas) welding process for titanium alloys and to indicate the correct process parameters. Design/methodology/approach: Various parameters of the titanium alloy welding process were tested and then the quality of the obtained joint was checked by the mechanical tests. Findings: The correct process parameters were determined and the properties of the joint were compared with the properties of the base material. Research limitations/implications: In the future, it can be suggested to investigate the effect of modified shielding gas mixtures (Ar-He) for the MIG welding. Practical implications: The proposed process innovation will result in savings of production cost, because titanium and its alloys are suggested to be welded in a vacuum, which is a much more expensive process. Social implications: By modifying the process, environmental protection is not impaired, EU directives on reducing CO2 emissions (carbon footprint) are fulfilled. Originality/value: It is to propose a new solution in automotive industry. The article is especially addressed to manufacturers of titanium alloys for means of transport. [ABSTRACT FROM AUTHOR]

A large number of MIG welding tests were carried out on a 3 mm thick 7075 aluminum alloy plate prepared by the self-developed jet forming–extrusion–drawing process of 7075 high-strength aluminum alloy welding wire, and the welding process of the welding wire and the change in the performance of the welded joint after T6 heat treatment were studied. The results show that the self-developed wire has a good forming joint and a wide welding process window: the welding speed is 5–7 mm/s, and the welding current is 100–150 A. The main precipitated phases in the joint were η(MgZn2), S(CuMgAl2), Mg2Si, and Al13Fe4, which were continuously distributed at the grain boundaries in the form of coarse networks or long strips, which was an important reason for the weak performance of the joints. After the heat treatment of T6, the precipitated phase in the joint was greatly reduced, the element segregation phenomenon was improved, and the residual precipitated phase was mainly Al13Fe4 and a small amount of insoluble phase Fe and Si, and the recrystallization size of the heat-affected zone was refined. Through heat treatment, the average microhardness of the joint was increased from 110 HV to 150.24 HV, and the tensile strength was increased from 326 MPa to 536 MPa, reaching 97.5% of the strength of the base metal, indicating that the softening phenomenon was significantly improved after heat treatment, and the joint had excellent performance. [ABSTRACT FROM AUTHOR]

The effects of heat treatment on the microstructure and corrosion behavior of chromium carbide-based hardfacing alloys deposited via gas metal arc welding were investigated. The hardfacing alloy, high chromium white iron (HCWI), containing 27 wt% Cr and 4.8 wt% C, was heat treated at 650 °C and 950 °C for six hours followed by natural cooling to room temperature. Microstructural characterization revealed that heat treatment promoted the transformation of austenite to ferrite and increased carbide precipitation. X-ray diffraction analysis identified the primary carbides as Cr7C3, which remained stable during heat treatment. Electrochemical corrosion testing in artificial seawater, including potentiodynamic polarization and electrochemical impedance spectroscopy (EIS), demonstrated progressively improved corrosion resistance with heat treatment temperature. Both techniques confirmed that the specimen treated at 950 °C exhibited superior corrosion resistance compared to the 650 °C treatment and as-deposited condition, with the specimen treated at 950 °C exhibiting the highest charge transfer resistance (4711 Ω·cm2) compared to the 650 °C treatment (2608 Ω·cm2) and as-deposited condition (374.6 Ω·cm2). The enhanced corrosion resistance was attributed to the increased carbide precipitation and optimization of the matrix composition. While heat treatment at both temperatures improved corrosion performance, the 950 °C treatment yielded superior results, suggesting this could be an optimal temperature for enhancing the corrosion resistance of chromium carbide-based hardfacing alloys. [ABSTRACT FROM AUTHOR]

Gas metal arc welding (GMAW) is widely used for its productivity and ease of automation across various industries. However, certain tasks in shipbuilding and heavy industry still require manual welding, where quality depends heavily on operator skill. Defects in manual welding often necessitate costly rework, reducing productivity. Vision sensing has become essential in automated welding, capturing dynamic changes in the molten pool and arc length for real-time defect insights. Laser vision sensors are particularly valuable for their high-precision bead profile data; however, most current models require offline inspection, limiting real-time application. This study proposes a deep learning-based system for the real-time monitoring of both the molten pool and weld-bead profile during GMAW. The system integrates an optimized optical design to reduce arc light interference, enabling the continuous acquisition of both molten pool images and 3D bead profiles. Experimental results demonstrate that the molten pool classification models achieved accuracies of 99.76% with ResNet50 and 99.02% with MobileNetV4, fulfilling real-time requirements with inference times of 6.53 ms and 9.06 ms, respectively. By combining 2D and 3D data through a semantic segmentation algorithm, the system enables the accurate, real-time extraction of weld-bead geometry, offering comprehensive weld quality monitoring that satisfies the performance demands of real-time industrial applications. [ABSTRACT FROM AUTHOR]

In the present work, CMT-based robotic MIG welding is carried out for wire arc additive manufacturing of SS308L part. Commercially available SS308L-T1 wire is used as feedstock material. Studies of direction-specific microstructure evolution and mechanical property characterization of as-built specimens are carried out. WAAMed SS308L exhibits a typical microstructure consisting of grain boundary δ ferrite with varied morphologies (vermicular/skeletal and lathy) within γ austenite dendrites. The amount of δ ferrite along with its morphology is observed to be varied from location to location, within the as-deposited specimen. Such variation diminishes after the heat treatment. The average ultimate tensile strength of horizontally cut specimens supersedes than that of vertically cut specimens. Heat treatment causes reduction in microhardness value of WAAMed SS308L. Additionally, temperature data as recorded by the thermocouple (tacked with the substrate plate) are utilized to understand various heat interaction phenomena during the WAAM process. Effect of post-deposition heat treatment is also studied. [ABSTRACT FROM AUTHOR]

Wire arc additive manufacturing (WAAM) is a rapidly growing technology that offers several advantages over traditional manufacturing methods, such as high deposition rates and the ability to build large components in a cost-effective manner. However, WAAM is also prone to the generation of defects, so the timely identification of anomalies is important to reduce the waste and get components of high quality. To develop anomaly detection application, the feature extraction process represents a key ingredient which allows machine learning systems to analyze big data. Waveform GMAW welding processes are typically used in WAAM to reduce the heat input supplied to the material and avoid defects such as excessive bending of parts and residual stress. These processes are based on the controlled dip transfer principle, so the waveforms should repeat themselves during deposition. This suggests that the frequency content of the voltage and current welding signals acquired during the process can provide important information about the process state. In this research, an experimental campaign was conducted to collect data for pulsed welding and surface tension transfer (STT) processes during the deposition of mild steel ER70S6, stainless steel 316L, Aluminum 4043, and Inconel 718 alloys. Welding voltage and current signals were acquired during the building processes, and a frequency domain analysis was conducted using the Fast Fourier transform (FFT) and discrete wavelet transform (DWT) with the aim to extract features from signals aiming to better separate the feature space, which means improve anomaly detection performance in detecting defects like arc instability, porosity, geometrical defect due to arc blow and humping. Furthermore, a methodology based on time-frequency analysis enhanced by Gabor filter for texture anomaly detection of scalograms obtained by Morlet Continuous Wavelet Transform is proposed, which showed an improvement of performance in separation between normal and anomalous deposition of several materials under different welding technologies. [ABSTRACT FROM AUTHOR]

The paper describes a high-current Gas Metal Arc Welding (GMAW) process using wire electrodes with diameters up to 4.0 mm for single-pass full penetration butt joint welding of 20 mm thick steel plates. Fundamental research aims to develop thick-wire GMAW into a high-efficiency method by identifying the limits of welding performance and achievable deposition rates. Current gaps in understanding include equipment requirements, process properties, application fields, and weld quality. The research project addresses these gaps through systematic investigations of basic technological analyses, application sample welding, and quality evaluations. The objective was to create a robust, cost-efficient gas-shielded high-performance welding technology with deposition rates comparable to Submerged Arc Welding. The fully mechanized, automatic welding setup included two parallel-connected welding power sources, one wire feeder and one high-power welding torch. Welding parameters and conditions were evaluated with the aim of achieving a high-quality weld. Optimal parameters were identified for one-sided single-pass welding on 20 mm thick plates. Validation of thick-wire GMAW for 20 mm thick high-strength steels was conducted via two-sided single-pass welding on S690Q grade plates. Testing of the weld joint included static tensile strength test (3x tensile specimen), a Charpy impact test at −40 °C (6x Charpy V-notch specimens respectively with notch position in weld metal, base material and heat-affected zone (HAZ)), microstructure examination and a hardness test. The lowest recorded impact energy was observed to be 50 J within the weld metal, in combination with hardness peaks in the HAZ reaching 415 HV1, and all tensile specimens failing outside the HAZ within the base material. The process achieved reliable, reproducible, and economical joint welding, meeting necessary mechanical-technological quality standards. The paper enhances the understanding of selected welding techniques tor thick plate joining and offers valuable industrial insights, demonstrating the technique's applicability and feasibility for high-strength applications. [ABSTRACT FROM AUTHOR]