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Welding often induces residual stresses and undesired distortion in components. The negative impacts of these detrimental residual stresses have prompted researchers to explore methods for preventing or mitigating these stresses. Altering the temperature history can influence residual stress, and employing cold or heating techniques during welding has the potential to reduce harmful residual stress. In this study, the dynamically controlled low-stress no-distortion (DC-LSND) method with TIG welding was utilized to reduce the residual stresses in Al alloy 6061-T6. The methodology was simulated using Abaqus software, and the simulation results were validated with experimental data. The Al alloy served as the base metal, alloy (ER-4043) as the filler, and dry ice as the coolant. In the finite element analysis, the longitudinal residual stress at the center of the weld line in TIG welding was calculated to be 77 MPa. In the DC-LSND welding method, this value approached zero. Experimental measurements revealed residual stresses in the center of the welding line to be 183 MPa in conventional welding and 130 MPa in DC-LSND welding. According to the DC-LSND results, a 100% reduction in residual stresses was achieved in the finite element method. In the experimental test, a reduction of approximately 30% in residual stress was observed. The method developed in this research is recommended for application in welding metals and alloys where phase changes do not occur. [ABSTRACT FROM AUTHOR]

This study analyzes the effects of Post Weld Heat Treatment (PWHT) on the mechanical properties and microstructure of Inconel 617 weldments produced by the Activated Tungsten Inert Gas (A-TIG) welding and Tungsten Inert Gas (TIG) welding. The TIG weld joints considered for this study were in an as-welded condition and underwent two different conditions of heat treatment including 1050∘C for 3 and 5 h, respectively. The A-TIG weld joints studied were the as-welded type and the weldment was heat-treated at 1050∘C for 3 h. The microstructure and the characterization of mechanical properties were performed for all weldments and a comparative assessment was made. Tensile strength and the hardness of the heat-treated samples were considerably higher than that of the as-welded samples. Impact toughness was slightly reduced after PWHT. Improvement in tensile strength could be attributed to the precipitation of the carbides and segregation of Chromium (Cr) and molybdenum (Mo). [ABSTRACT FROM AUTHOR]

To meet the rising global demand for copper, advanced and automated welding techniques are crucial in industrial manufacturing. Copper's high electrical conductivity and thermal properties present unique challenges requiring specialized welding. This paper explores various welding techniques, including Tungsten Inert Gas (TIG) Welding, Friction Stir welding (FSW), and Laser Beam Welding (LBW). In TIG welding, automation ensures consistent results, while using fluxes helps prevent oxidation and enhances weld quality, minimizing defects such as cracks and porosity. FSW improves welding quality by monitoring real-time temperatures of the rotating shoulder and weld zone with thermal imaging cameras. LBW, known for its deep penetration and precise control, is well-suited for copper because it can handle high-intensity lasers effectively. High laser power and short pulses are vital for achieving quality welds in copper. This review addresses the technical challenges and essential processes in TIG, FSW and LBW for copper welding, highlighting the importance of accurate parameter control to produce defect-free, robust joints. It also underscores the need to select the appropriate welding technique based on copper's unique properties to maximize efficiency and accuracy in industrial applications. [ABSTRACT FROM AUTHOR]

Most of the conventional welding process induces Welding Residual Stress (WRS), hydrogen embrittlement and distortions to welded components. The post-weld mechanical behaviour has an impact on both structural integrity and operational effectiveness of the welded component. Traditional Post Weld Heat Treatment (PWHT) is capable of relieving WRS to some extent. Based on recent research, Heat Treatment (HT) cycles are comprised of conventional HT and Cryogenic Treatment (CT) gives better fatigue life to welded components by redistributing the residual stress field. There is a need for further research to explore the impact of different parameters of CT affects the mechanical behaviour of welded specimens. In this study, numerical and experimental investigations are conducted to understand the impact of HT cycles comprised of austenitizing, quenching, CT and tempering process, over the TIG welded EN8 plates. Numerical model is developed for predicting the variation in WRS with each stage of HT cycles and observed a considerable redistribution of WRS after the completion of proposed HT cycle. Using the proposed HT cycle, the influence of different soaking periods of CT over the welded components are studied experimentally and shows that 36 hours soaking period have higher impact on the welded component's mechanical behaviour. [ABSTRACT FROM AUTHOR]

The tungsten inert gas (TIG) welding process is widely used in various industries for its ability to produce high-quality welds at a low cost. However, TIG welding struggles with welding thick stainless steel in a single pass, reducing production efficiency. To address this, new TIG variants such as activated TIG (A-TIG), flux bound TIG (FB-TIG), and flux zone TIG (FZ-TIG) have been developed to enhance penetration in austenitic stainless steel. This study investigates the effects of TiO2 and Fe2O3 flux on 304 stainless steels welded using A-TIG, FB-TIG, and FZ-TIG processes. Results show a slight increase in the depth-to-width (d/w) ratio for A-TIG and FB-TIG, while FZ-TIG achieved a 59% higher d/w ratio compared to autogenous TIG welding. The increased penetration is attributed to the reversal Marangoni convection and arc constriction. Microstructural analysis reveals a higher delta ferrite content in A-TIG and FZ-TIG welds due to increased heat input. Additionally, FZ-TIG welds exhibited an 11.5% higher microhardness compared to autogenous TIG welds. FZ-TIG welding enhances penetration and mechanical properties effectively. [ABSTRACT FROM AUTHOR]

In this study, 316L austenitic stainless-steel (ASS) plates fabricated using an additive manufacturing (AM) process were joined using tungsten inert gas (TIG) and laser welding techniques. The 316L ASS plates were manufactured using a laser powder bed fusion (LPBF) technique, with building orientations (BOs) of 0° and 90°, designated as BO-0 and BO-90, respectively. The study examined the relationship between indentation resistance and microstructure evolution within the fusion zone (FZ) of the welded joints considering the effects of different BOs. Microstructural analysis of the weldments was conducted using optical and laser confocal scanning microscopes, while hardness measurements were obtained using a micro-indentation hardness (HIT) technique via the Berkovich approach. The welded joints produced with the TIG technique exhibited FZs with a greater width than those created by laser welding. The microstructure of the FZs in TIG-welded joints was characterized by dendritic austenite and 1–4 wt.% δ-ferrite phases, while the corresponding microstructure in laser-welded joints consisted of a single austenite phase with cellular structures. Additionally, the grain size values of FZs produced using the laser welding technique were lower than those produced using the TIG technique. Therefore, TIG-welded joints showcased hardness values lower than those welded by laser welding. Furthermore, welded joints with the BO-90 orientation displayed the greatest cooling rates following welding processing, leading to FZs with hardness values greater than BO-0. For instance, the FZs of TIG-welded joints with BO-0 and BO-90 had HIT values of 1.75 ± 0.22 and 2.1 ± 0.09 GPa, whereas the corresponding FZs produced by laser welding had values of 1.9 ± 0.16 and 2.35 ± 0.11 GPa, respectively. The results have practical implications for the design and production of high-performance welded components, providing insights that can be applied to improve the efficiency and quality of additive manufacturing and welding processes. [ABSTRACT FROM AUTHOR]

Copyright of Iron Steel Vanadium Titanium is the property of Iron Steel Vanadium Titanium Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Arc welding of Al–Zn–Mg–Cu (7xxx) high-strength Al alloys is an urgent problem to be solved. In this study, tungsten inert gas (TIG) welding of 7075 Al alloy with newly developed 7075 Al alloy wire as filler is successfully carried out and the full-penetration and defect-free joint is formed. The fusion zone (FZ) is consisted of fine and equiaxed α-Al dendrites and a narrow transition zone (TZ) with columnar α-Al grains is formed between the heat-affected zone (HAZ) and FZ. The minimum hardness is obtained in FZ in 7075 Al alloy-welded joints and post-weld heat treatment (PWHT, solid solutioned at 480℃ for 1 h and then aging at 120℃ for 24 h) induces significant hardening in both FZ and HAZ due to the precipitation of GP zones and η' phase. The yield strength, ultimate tensile strength and ductility of as-welded joint are 223 MPa, 374 MPa and 4.6%, and they are improved to 435 MPa, 533 MPa and 7.8%, respectively, after PWHT. The high-strength coefficient for 7075 Al alloy TIG-welded joint can be attributed to the 7075Al alloy wire filler, optimized TIG welding parameters and PWHT. [ABSTRACT FROM AUTHOR]

With its excellent welding quality and high arc stability, tungsten inert gas (TIG) welding occupies a significant proportion in industrial production. However, the low current-carrying capacity of tungsten electrodes results in low welding efficiency, which significantly hampers the industry's development. By compressing the arc and increasing the deposition efficiency, the efficiency of TIG welding can be improved. This study has reviewed three optimization methods, including optimizing process conditions, improving equipment, and external constraints. It has also analyzed the principles and research status of these methods. Further, a magnetic tungsten electrode and a double-torch TIG welding method have been prospected. The former can enhance the magnetic field effect of magnetic control TIG and reduce the volume of welding torch. The latter can increase the parameter adjustability of double tungsten electrode welding. The development of high-efficiency TIG welding promotes the progress of industry and the development of human civilization. [ABSTRACT FROM AUTHOR]

This article presents a study on optimizing Tungsten Inert Gas (TIG) welding on mild steel (SPCC-SD/JIS G3141) with varying thicknesses of 0.6 mm and 0.8 mm. Automobile bodies commonly utilize mild steel with a material thickness ranging from 0.6 to 0.98 mm. The objective of this study was to ascertain the upper limit of tensile-shear strength that can be achieved by utilizing the specific parameters utilized in TIG welding. This study utilizes a three-level experiment and incorporates three input variables in the Taguchi experimental optimization method. The advantage of this approach lies in its ability to yield comprehensive outcomes while minimizing expenses, as it can be adapted to the resources available. An additional benefit is that this approach can be implemented in a multitude of industrial situations.The study's input variables are welding current, argon gas flow rate, and electrode diameter. Utilizing a continuous flow of argon gas of 12 LPM (liter per minute), a welding current of 55 A, and an electrode diameter of 1.6 mm, the maximum mean T-S strength of 3457.13 N was achieved. The ANOVA revealed that the flow rate, welding current, and electrode diameter had a per cent contribution of 50.07%, 26.89%, and 23.04%. The flow rate was the parameter with the most significant impact on the influential variable. The welding current and the electrode diameter do not significantly affect the response. The findings indicate that by adjusting the parameters to the optimal level determined by the Taguchi method, the S-N ratio for T-S strength increases by 9.30%, and T-S strength increases by 12.42%. The findings of this study offer a thorough comprehension of enhancing the TIG welding approach and can be further refined by incorporating additional variables.

High-quality thick Ti-6321 titanium alloy welded joints were obtained by tungsten inert gas（TIG）welding， the microstructure changes of fusion zone， heat affected zone and base metal zone of the welded joints before and after annealing were compared.The impact properties， fracture toughness and tensile properties were tested， and which were compared with the base metal. The results show that the microstructure of the fusion zone before annealing is composed of coarse β columnar grains with fully grown intragranular acicular martensite α′ phase， and heat affected zone consists of equiaxed structure with β matrix and primary α phase， martensite α′ phase precipitates in β matrix.After annealing， the martensite α′ phase in β matrix of the fusion zone and heat affected zone completely transforms into secondary α phase. The impact toughness， fracture toughness， tensile strength and elongation of Ti-6321 titanium alloy welded joints are 80.3 J/cm2， 113.00 MPa·m1/2， 873 MPa and 9%， respectively， which are 104.7%， 84.1%， 100% and 67.7% of the base metal，respectively. Compared with the fracture of the base metal， the impact fracture of welded joints has a coarser stepped surface and smaller equiaxed dimples， while the fracture surface of toughness is more flat and the fatigue crack propagation zone is narrower.

Automation in tungsten inert gas (TIG) welding is important to achieve high production rates and quality in manufacturing industries. To improve the welding process and quality inspection methodologies, the intelligent welding robot and vision-based inspection system have been researched and deployed in many engineering fields. Hence to enhance the performance and production, a digital twin-based welding system with the prediction of weld quality based on the consideration of electrode tip angle degradation. The proposed system will capture real-time electrode tip angle and weld pool temperature using a forward looking infrared (FLIR) camera along with welding current and speed correlated with tensile strength as the output parameter. To validate the analysis, support vector machine (SVM) and random forest (RF) algorithms were implemented in which the RF model performs well on the prediction of welding quality by mapping with tensile strength. RF model confirms maximum accuracy of 90% with 0.29 seconds computation time to perform prediction on the next execution of welding operation. It is inferred that if the tip angle degradation increases consecutively welding current decreases drastically impacting the weld quality from good to poor. To forecast the need for immediate or scheduled maintenance to reduce the tip angle degradation, a linear regression algorithm is implemented to enable the inspection engineer to perform maintenance without delay in production. [ABSTRACT FROM AUTHOR]

Copyright of Automobile Technology & Material is the property of Automobile Technology & Material Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Ultrasonic frequency pulse assisted TIG welding (UFP-TIG) experiments were conducted to join Inconel 690 alloy (IN690) by adding Inconel 718 alloy (IN718) as the filler. The effect of the filler on the microstructure, mechanical properties, and ductility dip cracking (DDC) susceptibility of IN690 joints were investigated. The results show that a variety of precipitates, including MC-type carbide and Laves phases, are formed in the weld zone (WZ), which are uniformly dispersed in the interdendritic region and grain boundaries (GBs). The increase in the thickness of the IN718 filler facilitates the precipitation and growth of Laves phases and MC carbides. However, the formation of Laves phases in the WZ exhibits a lower bonding force with the matrix and deteriorates the tensile strength of IN690 joints. Due to the moderate content of Laves phases in the WZ, the IN690 joint with 1.0 mm filler reaches the maximum tensile strength (627 MPa), which is about 96.5% of that of the base metal (BM). The joint with 1.0 mm filler also achieves the highest elongation (35.4%). In addition, the strain-to-fracture tests indicate that the total length of cracks in the joint with the IN718 filler decreases by 66.49% under a 3.8% strain. As a result, the addition of the IN718 filler significantly improves the mechanical properties and DDC resistance of IN690 joints. [ABSTRACT FROM AUTHOR]

This study presents a comprehensive characterization of the microstructure evolution and distribution of interfacial bonding properties in the original rolled plates and a welded AISI 304/Q235B clad plates. The findings reveal that an uneven diffusion layer, rich in chromium (Cr) and nickel alloy elements, is formed at the interface of the heat-affected zone during the welding process. The thickness of the diffusion layer reaches 10 μm in the overheated region. This nonuniformity results from the dilution of alloying elements from stainless steel into carbon steel. The presence of the diffusion layer contributes to the highest microhardness value at the weld metal interface. Tensile-shear experiments indicate a 22% increase in the tensile-shear strength of the overheated zone interface compared to the base metal interface, accompanied by a 30% decrease in elongation. While the diffusion layer enhances the interface shear strength, it reduces the interface plasticity, thereby increasing the risk of fracture. Fracture analysis of the overheated zone interface reveals brittle fracture characteristics, with a small amount of Cr present. In contrast, the interface of original rolled plates displays characteristics of ductile fracture, which emphasizes the intricate interaction between brittle and ductile fracture behaviors at the interface. These observations stem from the nonuniform diffusion layer, distinct microstructure distribution, and varying rates of crack propagation. [ABSTRACT FROM AUTHOR]

This study delves into enhancing tungsten inert gas (TIG) welding using SUS 304 material to support small-scale industries. SUS 304 is a widely used material in household equipment and house fences, where TIG welding techniques are commonly employed, albeit with varying weld quality. The primary objective is to achieve the maximum tensile shear load (TS load) by applying response surface methodology (RSM). The study incorporates three input parameters: welding current, gas flow rate, and electrode diameter. Additionally, the research evaluates the impact of these parameters on hardness values measured across the welding zone, heat-affected zone, and base metal. This research endeavors to significantly advance welding techniques for thin stainless-steel materials, mainly focusing on SUS 304 stainless steel. The selection of SUS 304 (JIS G 4305) material, with a thickness of 1 mm, is based on its corrosion-resistant properties, commonly applied in domestic appliances and food industry applications requiring food-grade materials. The Stahlweld TIG 160 inverter welding machine, operating at a voltage of 220 V/50 Hz, was selected and configured for the study. The maximum TS-load results were achieved during the 12th iteration, registering a magnitude of 1393.00 kgf. Conversely, the highest hardness levels were observed across all welding regions, gradually diminishing in the heat-affected zone (HAZ) and reaching its lowest point in the base metal. The findings of this study align with the attainment of the eighth objective of the Sustainable Development Goals (SDGs), contributing to the advancement of sustainable industrial practices. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Materials Engineering / Cailiao Gongcheng is the property of Journal of Materials Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The tensile properties of 2219-T8 aluminum alloy TIG welding joint were significantly affected by the microstructure, local mechanical properties and weld geometry. This paper proposed a machine learning model to predict and optimize the tensile properties of 2219-T8 aluminum alloy TIG welding joint. The relationship between tensile strength of joint and weld geometry, weld zone and partially melted zone (PMZ) properties was developed by Kriging model combining whale optimization algorithm (WOA). This surrogate model demonstrated a high precision, with R2 = 0.952 and RMSE=3.77 MPa. The surrogate model, which also served as a welding process guide, was utilized to determine the ideal weld geometry corresponding to various weak zone properties. By applying the optimization process based on the surrogate model, the optimized joint strength coefficient reached 70 %, and elongation exceeded 4 %. The collaborative regulation mechanism of geometry and property was also discussed.

The metallurgical changes and micro defects after welding can influence the mechanical property, corrosion resistance and dimensional stability of the stainless steel wielding joints. It is necessary to explore an effective post-welded method to improve the service performance for stainless steel welding joints. Furthermore, the essential mechanism between microstructure changes and macro-property variation during this process needs deep reveal. Therefore, this paper aims at investigating the effects of different post-weld treatments including naturally aging, artificial aging and cryogenic treatment on the residual stress and mechanical properties of 304 stainless steel weldments. The microstructure evolution was also studied to reveal and establish the microstructure-performance relationship. The results showed that the distribution of residual stress was most uniform with lowest magnitude (decreased by up to 49%) after cryogenic treatment. At room temperature, weldments subjected to the three post treatments showed similar mechanical properties. At cryogenic temperature, cryogenic treatment exhibited an outstanding role on maintaining the mechanical properties of weldments. By contrast, the mechanical properties were obviously reduced by artificial aging. The transformation of δ-ferrite and the carbide precipitation in grain boundaries are the main reasons for the decrease of mechanical properties after artificially aging. Welding process was able to cause the transfer of the alloying elements and decrease the stability of austenite. Consequently, martensitic transformation can be induced during cryogenic treatment. The new formed martensite resulted in the refined microstructure and high mechanical properties of weldments, and also the release of residual stress after welding.

The Ti-4Al-2V (wt. %) titanium alloy has garnered widespread applications across diverse fields due to its exceptional strength-to-weight ratio, high toughness, specific strength, and corrosion resistance. The welding of Ti-4Al-2V titanium alloy components is often necessary in manufacturing processes, where the reliability of a welded joint critically influences the overall service life of these components. Consequently, a comprehensive understanding of the welded joint's microstructure and mechanical properties is imperative. In this study, Ti-4Al-2V titanium alloy was welded using multi-layer and multi-pass TIG welding techniques, and a detailed examination was conducted to analyze the microstructure and grain morphology of each microzone of the welded joint. The results revealed the presence of an initial α phase and a secondary lamellar α phase in the heat affected zone (HAZ). Meanwhile, the fusion zone (FZ) primarily comprised a coarse secondary α phase and a small amount of an acicular martensitic α' phase. Both the recrystallization zone and the superheated zone exhibited a distinct preferred orientation, with grains smaller than 10 μm accounting for 65.9% and 55.1%, respectively. To assess the mechanical properties of the various microzones and the typical microstructure within the welded joint, nanoindentation tests were performed. The results indicated that the recrystallization zone possessed a higher nanohardness (3.753 GPa) than the incomplete recrystallization zone (3.563 GPa) and the superheated zone (3.48 GPa). Among all the microzones, the FZ exhibited the lowest average nanohardness (3.058 GPa). Notably, the basket-weave microstructure demonstrated the highest average nanohardness, reaching 3.93 GPa. This was followed by the fine-grain microstructure, which possessed a slightly lower nanohardness. The Widmanstätten microstructure, on the other hand, exhibited the lowest nanohardness among the three microstructures within the HAZ. Therefore, the basket-weave microstructure stands out as the most desirable microstructure to achieve in the welded joint. In summary, this study provides a comprehensive characterization and analysis of the microstructure and properties of Ti-4Al-2V titanium alloy TIG welds, aiming to contribute to the optimization of the TIG welding process for Ti-4Al-2V titanium alloy. [ABSTRACT FROM AUTHOR]

This research aims to investigate the impact of different welding sequences in the circumferential direction on the welding process of 304 stainless steel pipes. A fully coupled transient thermo-mechanical simulation technique used to numerically replicate welding behaviour on a single-pass butt-welded cylinder joint with a nominal diameter of 300 mm and a thickness of 8.38 mm. Five distinct welding sequences are considered, and temperature profiles are measured at four circumferential positions. The findings reveal that the residual stresses within and near the weld deposit are indeed influenced by the chosen welding sequence. In case 1, the value of maximum temperature reached 1840 Degree K at point T4, achieving equilibrium between the flux input and heat losses during welding. In case 3, the maximum temperature value (1530 Degree K) is lower than all other cases due to better heat distribution. Respective to the temperature distribution the maximum stress values in case-1 to 5 are 211, 201, 138, 146, and 147 Mpa. Based on a comprehensive analysis of these factors, case 3 emerges as the preferable welding sequences for pipes falling in the NPS 10 to NPS 24 size category. [ABSTRACT FROM AUTHOR]

In order to address the irregularity of the welding path in aluminum alloy frame joints, this study conducted a numerical simulation of free-path welding. It focuses on the application of the TIG (tungsten inert gas) welding process in aluminum alloy welding, specifically at the intersecting line nodes of welded bicycle frames. The welding simulation was performed on a 6061-T6 aluminum alloy frame. Using a custom heat source subroutine written in Fortran language and integrated into the ABAQUS environment, a detailed numerical simulation study was conducted. The distribution of key fields during the welding process, such as temperature, equivalent stress, and post-weld deformation, were carefully analyzed. Building upon this analysis, the thin-walled TIG welding process was optimized using the response surface method, resulting in the identification of the best welding parameters: a welding current of 240 A, a welding voltage of 20 V, and a welding speed of 11 mm/s. These optimal parameters were successfully implemented in actual welding production, yielding excellent welding results in terms of forming quality. Through experimentation, it was confirmed that the welded parts were completely formed under the optimized process parameters and met the required product standards. Consequently, this research provides valuable theoretical and technical guidance for aluminum alloy bicycle frame welding. [ABSTRACT FROM AUTHOR]

The paper presents a detailed theoretical analysis of the electromagnetic forces in the arc plasma and the weld pool metal in Tungsten Inert Gas (TIG) welding at direct current (DC) and high-frequency pulse current (HFPC) modulation with a frequency of 10 kHz. The electromagnetic (Lorentz) force, acting on arc plasma and metal is presented via potential (magnetic pressure) and rotational (equivalent electromagnetic force) force components. This approach allows us to substantially simplify the analysis of the Lorentz force effect on the arc plasma and weld pool metal under different arc burning modes. It was shown that in HFPC TIG welding with a given frequency, the effect of modulated current on the arc plasma is inherently non-stationary, whereas the effect on the weld pool metal is determined by the time-averaged magnitude of electromagnetic force throughout the period of current modulation. The proposed approach serves as a basis for numerical analysis of the electromagnetic forces in arc plasma and weld pool metal during DC and HFPC modes of the welding process. We established that the application of HFPC modulation promotes a greater intensity of both the gas-dynamic processes in the welding arc, thereby significantly increasing the pressure on the weld pool surface, and convective heat transfer from the most heated central region near the weld pool surface towards the weld pool bottom. Both these factors lead to an increase of the arc penetrability in the case of the HFPC mode compared with the DC mode, all other conditions being equal. • Only rotational part of the Lorentz force initiates vortical flow. • Square-wave pulse is used as a welding current wave form. • Non-stationary magnetic field diffusion equation is solved numerically. • In-house Wolfram Language code is used for FEM-analysis. • HFPC modulation increases the effective driving force in the weld pool. [ABSTRACT FROM AUTHOR]

This study focuses on examining the variation in mechanical characteristics of low-carbon sheet steels when they are subjected to heat input from Tungsten Inert Gas (TIG) welding. The weld heat input parameters, such as welding speed and current, were controlled through the TIG welding process. A finite element analysis was performed to evaluate the couple field thermomechanical effects of the weld heat line, using the Gauss heat flux approach for thermal heat variation across the weld heat-affected zone. The numerical study yielded results for weld heat-affected deflection, residual stress, and modal analysis through the finite element model. It was found that the ductility decreased and hardness increased in the fusion zone, as a function of weld current and speed. The residual stresses and their zone of influence, as determined by weld line parameters, were found to be key factors affecting deflection and natural frequencies in structural aspects of low carbon sheet steels. [ABSTRACT FROM AUTHOR]

Products of thin-sheet copper are widely used in radio electronics, instrumentation, power engineering, etc. This article considers micro-plasma and TIG welding of copper with a thickness of 0.2 mm in argon and helium. As a result of the conducted research, it was established that in case of using helium as a shielding gas, the welding speed increases by more than 2 times compared to the microplasma process and by almost 5 times compared to TIG welding in argon. At the same time, the width of the weld and heat-affected zone (HAZ) decreases to 1.4…1.6 mm and 1.0…1.5 mm, respectively. Metallographic examinations of the welds did not reveal defects such as pores, cracks or lack of fusion. The weld microstructure consists of a set of equiaxed crystallites with a grain size of 4…8 μm without clearly expressed crystallization direction and with a smooth transition of the fusion line. The mechanical properties of the welded joints such as temporary resistance and microhardness were determined. Ref. 8, Fig. 7, Tab. 2 [ABSTRACT FROM AUTHOR]

The finite volume method (FVM) was used to model a tungsten inert gas (TIG) arc welding process. A two-dimensional axisymmetric model of arc plasma integrating fluid–solid coupling was developed by solving electromagnetic and thermal equations in both the gas domain and the solid cathode. In addition, two additional coupling equations were considered in the gaseous domain where the arc is generated. This model also included the actual geometry of torch components such as the gas diffuser, the nozzle, and the electrode. The model was assessed using numerous numerical examples related to the prediction of the argon plasma mass fraction, temperature distribution, velocity fields, pressure, and electric potential in the plasma. A new linearization method was developed for the source term in the energy conservation equation, allowing for the prediction of Joule effects without artificial conductibility. This new method enhances the efficiency of the classical approach used in the literature. [ABSTRACT FROM AUTHOR]

This work aimed to compare the quality and properties of the welded joints of AMg6 aluminium alloy produced via conventional TIG welding with the properties of those produced with flux backing tape. This study focussed on the relative length of oxide inclusions (Δoi) and the amount of the excess root penetration (hroot) of the AMg6 alloy weld beads. The results show the influence of the thickness of the flux layer of the backing tape on the formation and quality on the AMg6 alloy welds, along with the effect of flux backing tape and edge preparation on the mechanical properties of the 6 and 8 mm thick welded plates. In accordance with the results obtained, the joints produced by means of TIG welding with flux back backing tape and without edge preparation have higher mechanical properties. Moreover, the TIG welding of AMg6 alloy using flux backing tape reduces the total welding time by 55%, reduces filler wire consumption by 35%, reduces shielding gas consumption by 43% and electricity consumption by 60% per 1 linear meter of the weld line. [ABSTRACT FROM AUTHOR]

The attractive mechanical properties of 7075 alloy, such as its high strength-to-weight ratio and fracture toughness, have received special attention in the automotive and aerospace industries. However, welding as a fabrication process has a detrimental effect on this alloy’s properties which affects its mechanical performance. In this work, to compensate for the loss in mechanical properties caused by welding, proper heat treatment operations are adopted. To this end, 1.5 mm AA7075 sheets were first preheated and butt welded using the gas tungsten arc welding process. The welded sample was solution heat treated, quenched, and then artificially aged. Microhardness tests showed an increase of hardness in all zones of the aged specimen compared to those of the original welded blank before heat treatment. A maximum microhardness value of 180 HV was recorded in the heat-affected zone of the aged specimen. In addition, elongation at break, and strength (yield, tensile, and fracture) of the original welded blank increased by about 50% after the artificial aging operation.

The finite volume method (FVM) was used to model a tungsten inert gas (TIG) arc welding process. A two-dimensional axisymmetric model of arc plasma integrating fluid–solid coupling was developed by solving electromagnetic and thermal equations in both the gas domain and the solid cathode. In addition, two additional coupling equations were considered in the gaseous domain where the arc is generated. This model also included the actual geometry of torch components such as the gas diffuser, the nozzle, and the electrode. The model was assessed using numerous numerical examples related to the prediction of the argon plasma mass fraction, temperature distribution, velocity fields, pressure, and electric potential in the plasma. A new linearization method was developed for the source term in the energy conservation equation, allowing for the prediction of Joule effects without artificial conductibility. This new method enhances the efficiency of the classical approach used in the literature.

Abstract An important goal in a number of optimization studies is a high-quality weld joint. Thermal analysis of AISI 1020 low carbon steel plate agglutinated by gas tungsten arc welding technique was carried out using S 2021 version. With SOLIDWORKS Premium, the simulation was run. The simulation was performed using the Thermal Simulation programme with 20 weld runs. With the findings of the initial study serving as a sensor, a design study was conducted. A total of 15 runs were completed, and the weld dilution and thermal conductivity responses were available. A range of welding temperatures including 3397 to 3688 °C were experimentally applied in the joining process of AISI 1020 low carbon steel plate of 10 mm thickness, and a strain gauge indicator was used to measure the thermal stresses induced in the steel plate. However, minimum and maximum weld dilution values of 73.1 and 46.8% were obtained with FEM at an input of arc heat of 66.4 and 37.2 J/mm, while the minimum and maximum weld dilution values of 71.55 and 45.5% were computed using experimental approach at the same heat input. On the other hand, maximum and minimum weld dilution of 71.55 and 44.5% were computed from experimental process at minimum and maximum welding current of 199.77 and 250.23 A, while 73.1 and 46.8% were obtained for the maximum and minimum weld dilution through FEM procedure at the same welding input variables. Hence, gas tungsten arc welding input parameters should be properly selected and controlled during welding operation, in order to minimize thermal effects and welding flaws such as high dilution rate.

Nd: YAG Laser and Tungsten Inert Gas (TIG) welding processes are the most promising joining techniques used for stainless steel (SS) alloys due to their significant weld characteristics. In this study, the effect of two process parameters (weld power and travel speed) on the mechanical properties (ultimate tensile strength and microhardness) of the weldment is investigated. Two different machine learning techniques, namely Adaptive Neuro-Fuzzy Inference System (ANFIS) and Unified Convolutional Neural Network (UCNN) are also evaluated for prediction of mechanical properties and defect detection through the image processing technique, respectively. A correlation has been performed between these two machine learning approaches with the experimental values. The training data sets are developed for the machine learning techniques, and the obtained results of (ANFIS) and (UCNN) models are related to the actual experimental values. The output of both developed models (ANFIS & UCNN) showed a good agreement with the actual experimental test results. The predicted tensile and microhardness values from the (ANFIS) model were found to greatly agree with the Peak Signal-to-Noise Ratio (PSNR) values from the (UCNN) model. However, owing to the increase in the applications of welding processes in industries, the utilization of machine learning techniques would be more efficient when compared with the other traditional methods that are being adopted.

An important goal in a number of optimization studies is a high-quality weld joint. Thermal analysis of AISI 1020 low carbon steel plate agglutinated by gas tungsten arc welding technique was carried out using S 2021 version. With SOLIDWORKS Premium, the simulation was run. The simulation was performed using the Thermal Simulation programme with 20 weld runs. With the findings of the initial study serving as a sensor, a design study was conducted. A total of 15 runs were completed, and the weld dilution and thermal conductivity responses were available. A range of welding temperatures including 3397 to 3688 °C were experimentally applied in the joining process of AISI 1020 low carbon steel plate of 10 mm thickness, and a strain gauge indicator was used to measure the thermal stresses induced in the steel plate. However, minimum and maximum weld dilution values of 73.1 and 46.8% were obtained with FEM at an input of arc heat of 66.4 and 37.2 J/mm, while the minimum and maximum weld dilution values of 71.55 and 45.5% were computed using experimental approach at the same heat input. On the other hand, maximum and minimum weld dilution of 71.55 and 44.5% were computed from experimental process at minimum and maximum welding current of 199.77 and 250.23 A, while 73.1 and 46.8% were obtained for the maximum and minimum weld dilution through FEM procedure at the same welding input variables. Hence, gas tungsten arc welding input parameters should be properly selected and controlled during welding operation, in order to minimize thermal effects and welding flaws such as high dilution rate. [ABSTRACT FROM AUTHOR]

The non-consumable tungsten electrode plays a key-role in the tungsten inert gas (TIG) welding process, governing the behavior of the electrical arc that is essential for generating the necessary heat in welding. This study is focused on varying of electric parameters in the purpose to identify the appropriate conditions that promote electrode integrity. The post weld cathode analysis revealed that both the input current intensity and its frequency affect the overall morphology and microstructural and mechanical performance of the refractory electrode. Noticeable physical alterations occur with increased current, leading to larger grains and a reduction in microhardness values. In addition, it causes apparent defects such as perforation and superficial deformation. However, applying higher frequencies mitigates these defects significantly. Based on these findings, it seems crucial to take into consideration the interactive effect of current applied and its frequency to ensure better electrode conservation, thereby enhancing the efficiency of the welding process. [ABSTRACT FROM AUTHOR]

The main direction of improving the operational characteristics of titanium alloys is creation of heat-resistant and high-temperature titanium alloys. The high specific strength and corrosion resistance of this type of alloys at temperatures up to 500-600 °C, enables making them the main structural material for aircraft and rocket engineering. However, their widespread use is associated with the problem of precipitation of brittle phases during welding, which requires additional technological operations, such as local heat treatment or preheating. In this paper, the finite element modeling method was applied to study the influence of the TIG welding thermal cycle of high-temperature titanium alloy of Ti-6.5Al-5.3Zr-2.2Sn-0.6Mo-0.5Nb-0.75Si system with and without the use of preheating and to plot the cooling rate diagrams of the produced welded joints. [ABSTRACT FROM AUTHOR]

This study aims to reduce the number of weld passes and total heat input to 316LN stainless steel during hot-wire tungsten inert gas (HW-TIG) welding process by optimizing process parameters. Therefore, the response surface methodology (RSM) of design of experiments (DOE) approach has been adopted to optimize HW-TIG welding parameters and study the interaction between the parameters and responses. In order to minimize the total number of experimental runs, a design matrix was generated with 30 sets of process parameters. The bead-on plate welding experiments were carried out based on the above generated process parameters. Using the RSM, a quadratic model was developed based on a central composite design to establish the regression equations between input variables (welding current, wire feed current, welding speed, and wire feed rate) and responses (bead width, depth of penetration, and weld cross sectional area). The input process parameters and their responses were correlated with the regression model. Further, parameter values were optimized using the desirability approach and the optimized solutions were generated. Using the optimized process parameters, 316LN stainless steel weld joints were fabricated. Tensile testing and metallography samples were extracted from the fabricated weld joints. The results reveal that the optimization of process parameters by RSM based approach reduced the number of weld passes and improved the weld quality with lower heat input to 316LN stainless steel. In addition, the fabricated weld joint of 316LN stainless steel using the optimized process parameters exhibited better microstructure and strength properties. [ABSTRACT FROM AUTHOR]

The present research work focuses on the investigation of hot cracking susceptibility of TIG-welded AA5052 aluminum alloy with two filler materials ER4043 and ER5356, respectively. Welded samples were undergone Houldcroft testing to estimate the solidification cracking susceptibility in the weldment. Microstructural characterization, microhardness testing, X-ray diffraction analysis and scanning electron microscope examination were performed on the weldments. The solidification cracking is not identified while using ER4043 since it has relatively narrow freezing range. High crack sensitivity of 29% is found when welding was performed using ER5356. Hardness for the specimens welded with ER4043 filler material showed 106 ± 3 HV and 116 ± 2 HV in heat affected zone (HAZ) and fusion zone (FZ), respectively, but the specimens welded with ER5356 filler material showed higher hardness of 160 ± 2 HV and 150 ± 4 HV in HAZ and FZ, respectively. The specimens welded by ER4043 and ER5356 showed the formation of Mg2Si at FZ. [ABSTRACT FROM AUTHOR]

This work is based on a comparative study of the weldments fabricated by Activated Flux Tungsten Inert Gas (A-TIG) welding and autogenous Tungsten Inert Gas (TIG) welding of 10 mm thick Inconel 617 plates. Flux powders used for A-TIG welding were Titanium dioxide (TiO2) and Silicon dioxide (SiO2). Macrostructure and microstructure analyses and characterization of mechanical properties of both A-TIG and TIG weldments were investigated. The microstructure of Inconel 617 was made up of several secondary phases and fine austenitic grains. Mechanical testing carried out in this study included Bend Test, Tensile Test, Vicker's Micro-Hardness Test and Charpy Impact Test at room temperature (RT) and a sub-zero temperature (SZT) of −50 ∘ C. The Bend test was found satisfactory for both A-TIG and TIG weldments. TIG weldments' tensile strength and microhardness were determined to be 782 MPa and 265.44 HV, respectively. However, it was determined that the base metal had a tensile strength of 756 MPa and that the tensile strength and microhardness of the A-TIG weldment were 707 MPa and 252.73 HV, respectively. The TIG weldment was proved to have the highest tensile strength and microhardness due to the availability of strengthening elements like Molybdenum (Mo) and Chromium (Cr), as carbides in the fusion zone. Impact toughness of the A-TIG weldment was higher than that of the TIG weldment both at room and sub-zero temperatures due to the application of TiO2 as flux and the high heat input during A-TIG welding. The ductile mode of fracture was observed in all weldments. [ABSTRACT FROM AUTHOR]

There is an increasing demand for welding of steel pipes meant for pressure purposes. P355NH (1.0473) steel became an important construction material used for structuring and restructuring of a medium-pressure gas pipeline due to its properties, such as significant tensile strength at the level of 600 MPa and increased yield point. These properties ensure appropriate service life of the principal pipeline structures. When welding P355NH steel, processes that enable high-quality welds without significant changes in the chemical composition of the base material, are applied. It is recommended to use the TIG welding process to produce joints, although P355NH steel joints are considered as difficult to weld. During welding, various welding defects might appear, which mainly include sticking and lack of fusion. Creation of joints with the desired properties, including those used in the construction of medium pressure gas pipelines, with the required class B quality, requires selection of appropriate parameters and compliance with the welding process practice. This is very important for the service life of the structure. Therefore, the article aims to select the most appropriate parameters and thermodynamic conditions for welding P355NH steel in order to obtain the best mechanical properties. The most important of the tested welding parameters of P355NH steel is welding speed, welding current, preheating temperature, interpass temperature and, above all, the role of various shielding gases. (Three different shielding gases containing argon and helium additives were tested.) The obtained joints were tested by: non-destructive tests, such as VT—visual examination; MT—magnetic particle testing, PT—penetration tests, UT—ultrasonic testing and by the destructive methods, such as tensile strength, impact toughness, bending test, light microscopy and scanning electron microscopy. The cause-and-effect relationships between the obtained joint structure and its mechanical properties were determined. The considerations were supported by the nucleation model and the mechanisms of formation of the acicular ferrite phase in the joint material. The chosen parameters of TIG process allow to obtain joint with adequate strength for the production of the gases pipeline, without welding defects. The results have a practical implication, the developed production technology for the obtaining the joints. The presented solution gives the possibility of producing correct welded joints, which can be used in the responsible steel construction. The originality of manuscript is the presentation the newly, uncomplicated solution of obtaining joint with good mechanical properties included the thin-walled tubular structure with a thickness of 3.6 mm. A novelty in the article is a clear indication of the importance of detailed thermodynamic welding conditions and obtained weld structure on the mechanical properties of the P355NH steel joint, which lead to the formation of various non-metallic titanium inclusions, which have a decisive impact on the mechanical properties of the joint, especially its strength and impact strength. [ABSTRACT FROM AUTHOR]

In the present day, the joining of dissimilar metals used in the same industry applications is of great interest. MIG and TIG welding processes are among the most common methods used to join dissimilar metals with high strength and reliability. Due to the different mechanical properties of dissimilar metals to be joined by these welding methods and welding parameters, they must be carefully selected. In this study, the effects of Total Accumulated Weld Volumes (TAWV) and different groove angles (45°, 60°, 75° and 90°) on the mechanical properties of AISI 1040 and AISI 8620 cylindrical steel joints were investigated experimentally. In addition, the fracture surfaces of the samples were examined by scanning electron microscopy (SEM) and energy dispersive X-ray (EDAX). In the process with MIG and TIG welding, only current and voltage changes were made in order to measure the effects of parameters on the mechanical properties of the joints more clearly. As a result of the studies, the highest average Ultimate Tensile Strength (UTS) was 579.611 MPa and the lowest average UTS value was 424.611 MPa. Based on TAWVs, the highest average UTS value was obtained in TIG welded joints, and the lowest average UTS value was obtained in MIG welded joints. It was observed that the UTS values of the joints were positively affected by the increase in TAWV. The UTS value of the 90° groove angled joint was found to be 40.25% higher than the UTS value of the 45° groove angled joint. [ABSTRACT FROM AUTHOR]

Welding of two dissimilar metals is a very difficult process. However, in today's industry, it has become very important to use different metals in the same structure and therefore combine them in order to reduce the weight of parts and structures. In this study, (6061-T6) aluminum alloy and (St-37) low carbon steel were joined by TIG and brazing welding methods, and their mechanical and microstructural properties were examined. Welding applications were carried out with samples with thicknesses of 2 mm, 5 mm and 10 mm. Hardness tests and tensile tests were applied to determine the characteristics of the weld areas of the samples we obtained and to examine their strength. In addition, changes in the microstructure were observed by SEM image analysis. According to the results, it was found appropriate to join 2 mm and 5 mm sheets by brazing, and to join 10 mm and thicker materials by TIG welding. [ABSTRACT FROM AUTHOR]

The article presents the method of preparing the tube sheet of a heat exchanger made of B265 Grade 1 titaniumclad steel with B338 grade 2 titanium tubes allowing for the qualification of the TIG (Tungsten Inert Gas) orbital welding technology. A test plate was made of A516M Grade 485 unalloyed steel clad with B265 Grade 1 titanium using the explosive method. The 300 x 300 mm plate consisted of a layer of 60 mm thick non alloy steel and 5 mm titanium clad. It had 20 holes drilled in a triangular arrangement, into tubes with a diameter of 34.93 mm made of B338 Grade 2 titanium with a thickness of 0.7 mm were welded. In order to obtain mechanical restraint inside the holes in the test plates, the titanium tubes were rolled out. For rolling, a five-roller was used, equipped with a retaining collar which allows the tube to move freely during rolling. The tests carried out showed that the proposed technology for preparing tube -- sieve bottom elements allow for the preparation of a test plate for the qualification of welding technology. The test plate made in accordance with the technological assumptions met all the requirements necessary to qualify the technology for welding tubes with tube plates. Both in the case of non-destructive testing and macrographic testing, there were no problems with compliance with the PN-EN ISO 15614-8:2005 standard. [ABSTRACT FROM AUTHOR]

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