Conventional Tungsten Inert Gas Welding Research Articles

Particle Swarm Method for Optimization of ATIG Welding Process to Joint Mild Steel to 316L Stainless Steel

316L stainless steel joined to mild steel is widespread in several applications to reach a requested good association of mechanical properties at a lower cost. The activating tungsten inert gas (ATIG) weld was carried out using a modified flux composed of 76.63% SiO2 + 13.37% Cr2O3 + 10% NaF to meet standard recommendations in terms of limiting the root penetration. Modified optimal flux gave a depth of penetration 1.84 times greater than that of conventional tungsten inert gas (TIG) welds and a root penetration of up to 0.8 mm. The microstructure of the dissimilar joints was investigated using a scanning electron microscope and EDS analysis. The mechanical properties of the weld were not affected by the modified flux. The results show that the energy absorbed in the fusion zone in the case of ATIG weld (239 J/cm2) is greater than that of TIG weld (216 J/cm2). It was found that the weld bead obtained with the optimal flux combination in ATIG welding can better withstand sudden loads. The obtained UTS value (377 MPa) for ATIG welding was close to that of TIG welding (376 MPa). The average Vickers hardness readings for ATIG welds in the fusion zone are up to 277 HV, compared to 252 HV for conventional TIG welding.

Welding investigations on mechanical property and microstructure of TIG and A-TIG Weld of Hastelloy C-276

Hastelloy C-276 is a nickel-based alloy with high strength and corrosion resistance at cryogenic to high temperatures. The issue of Hastelloy C-276 shallow penetration by Tungsten Inert Gas (TIG) welding was addressed in the current investigation by applying A-TIG welding with variable oxide flux. In the current investigation, constant welding conditions were used to perform TIG and A-TIG welding using SiO2, TiO2, and a 50% mixture of SiO2 + TiO2 flux. The weld bead width and depth of penetration of the weld bead profile were measured, and the mechanical and metallurgical properties of the weld metal was investigated. SiO2 flux attained the highest D/W ratio and depth of penetration during A-TIG welding when compared to other fluxes used. A-TIG welding using SiO2 flux improved the depth of penetration and the D/W ratio by 118% and 263%, respectively, in comparison with conventional TIG welding. Additionally, the A-TIG welded sample with SiO2 flux had an ultimate tensile strength of 738.295 MPa and a percentage of elongation of 52.75%.

Residual stresses study in butt welded joint of Inconel 617 alloy and effect of post weld heat treatment on residual stresses

Distribution of weld-induced residual stress plays a significant effect on the service life of a welded component. The accumulation of high residual stress accelerates the crack propagation even if the crack is of microscopic level, reducing the service life of the welded component. Prior understanding of residual stress distribution can aid in the design of a component with an adequate factor of safety and reduce the probability of failure. In the present study, two separate circumferential butt welded pipes were fabricated using Alloy 617 and then subjected to post weld heat treatment) at 720°C and 980°C. The deep hole drilling method was used to measure the distribution of residual stress. The fabrication of the welded joint was done using the hot-wire TIG welding process. High welding speeds are possible with hot-wire tungsten inert gas (TIG) welding because it uses less heat than conventional TIG welding. Using hot-wire TIG welding, the welded joint's mechanical properties, such as hardness, are improved in addition to its metallurgical properties. The computational approach is provided to analyze temperature and residual stress fields in multi-pass TIG welds with different passes. Based on ABAQUS FEA software, a coupled thermomechanical computational approach was developed to analyze the residual stress distribution on the welded joint. A 3D finite element model for Alloy 617 tube was created to estimate the welding stress field in two separate multi-pass welded joints. Mixed hardening model (kinematic and isotropic) was used during the numerical analysis. The effectiveness of the computational approach was verified with experimental measurements. The magnitude of hoop and axial residual stresses were observed to be maximum at a depth of 6 mm from the upper surface. The stress gradient in the welded zone and heat-affected zone is dramatically reduced by 70–80% of the as-welded condition during the post weld heat treatment at 980°C.

Assessment of intelligent CMT with TIG welding on stacked thin sheets of CRNGO electrical steel

TIG (Tungsten Inert Gas) is the widely utilized welding process in industrial operations till date. TIG welding is commonly adopted for ease of use and economic reasons. The industries are recently dealing with the issues associated with higher losses in equipments occurred due to the welding process. Stators, which are utilized in electric motors (EM) and hybrid electric vehicles (HEV), are one among such industrial products. The advanced pulse operated cold metal transfer welding technology offers a workable substitute for traditional and pulsed TIG welding, because of its characteristic features. The study's primary objective is to combine stacks of CRNGO (Cold rolled non-oriented) electrical steel, which are prime materials for stators of HEV and EM and join them using welding process. After choosing the GMAW CMT technique over the conventional TIG welding procedure, which was predominantly employed to join the electrical steel sheets, a systematic strategy is used to emphasize the studied investigations. The GMAW CMT welding samples revealed improved performance with around 15 HV reductions in micro-hardness variations (mechanical property), about 25% reduced geometry (D/W ratio) of weld seam (macroscopic features), and around 50 µm reduced grain sizes (microscopic characteristics) of the weld CRNGO thin sheet samples compared to conventional TIG welding. The research work can be considered as a reference to utilize GMAW CMT technology for joining stacks of CRNGO sheets.

Effect of fluxes on weld penetration during TIG welding – A review

Tungsten Inert Gas (TIG) welding, also known as Gas Tungsten Arc Welding (GTAW), is a common welding procedure which produce high quality weld with composition as close to that of parent metal. Wide range of materials like, ferrous alloys, magnesium alloys, Aluminum alloys and Titanium alloys can be welded using TIG welding process. Conventional TIG welding can only produce a maximum penetration of 3 mm in a single pass. Alloys with higher thickness require multi-pass TIG welding which involves preparation of joint and additional filler. This leads to the increase in production cost and higher heat input which leads to increased thermal stress and distortion of weld. This paper reviews recent novel developments to improve the penetration depth in TIG welding of various materials. The application of Activated Flux induced TIG welding (A-TIG), Flux Bounded TIG welding (FBTIG) and Flux cored wire TIG of A-TIG on Ferrous alloys, Titanium alloys, Magnesium alloys and Aluminum alloys are discussed. The paper also discusses about the mechanism involved in improving the penetration of weld in these three processes. It also discusses the future scope of application of these processes.

Performance of weld bead profile during A-TIG welding on nitrogen alloyed stainless steel

Austenitic stainless steel (ASS) is widely fabricated by tungsten inert gas (TIG) welding for aesthetic look and superior mechanical properties while compared to other arc welding process. Hitherto, the limitation of this process is low depth of penetration and less productivity. To overcome this problem activated tungsten inert gas (A-TIG) welding process is employed as an alternative. In this investigation the welding performance of conventional TIG welding is compared with A-TIG process using TiO2 and SiO2 flux with respect to weld bead geometry. The experimental investigation on A-TIG welding of ASS-201 grade shows TiO2 flux helps in achieve higher penetration as compared to SiO2 flux. While welding with SiO2 the hardness in HAZ and weld region higher than that of TIG welding process.

Study of Mechanical and Metallurgical Properties of Cold and Hot Reciprocating Wire TIG Welding on AISI 1035 Carbon Steel

A novel Tungsten inert gas (TIG) welding variant is introduced in this research. The authors studied the tungsten inert gas welding with different wire feeding system such as cold wire, hot wire, cold wire reciprocating, and hot wire reciprocating. Microstructural and mechanical properties of AISI 1035 carbon steel joints using different feeding system have been studied. The reciprocating filler wire system stirs the molten metal of the weld pool before it solidifies during the welding operation. The hot wire reciprocating tungsten inert gas welding has given the best results in terms of tensile properties and hardness of the joint. It also instigated the grain refinement in the weld zone which is attributed not mainly to dendrite fragmentation but impeding of the dendritic growth . The microstructure study of reciprocating wire feeding tungsten inert gas welded joints has shown the small size as well as uniform grains as compared to the conventional TIG welded joints. The reciprocating hot wire feeding tungsten inert gas welding gives a phenomenal improvement in the mechanical properties when compared with conventional TIG welding.

Effect of hydrogen additions to shielding gas on activated TIG austenitic stainless steel weld

In tungsten inert gas (TIG) welding, less penetration depth is achieved in a single pass which adversely affects productivity, Activated TIG (A-TIG) welding techniques achieve better performances and higher penetration depths compared to conventional TIG welding. Pure argon does not have the potential to provide adequate penetration in austenitic stainless steel. Argon–hydrogen shielding gas mixture provides high heat flux, thereby influencing the arc voltage and penetration. In the present study, hydrogen is added to base shielding gas argon to study the effect on weld geometry during TIG and A-TIG of 310S stainless steel. The result shows a higher weld depth to width ratio and a significant reduction in the angular distortion. Also, higher tensile strength is obtained in A-TIG weld metal with 1% hydrogen addition, due to more efficient cooling of the weldment. However, increasing the hydrogen concentration in shielding gas resulted in defect formations in the weldment due to the interaction between activated flux and the hydrogen.

“Effects of using oxide fluxes as activating flux on Activated flux Tungsten Inert Gas welding” – A review

Tungsten Inert Gas welding (TIG) is preferred in the Aerospace Industry where thin sections have to be welded with quality and precision. But, when thick sections are to be welded, conventional TIG welding is not usually preferred due to low penetration depth necessitating more passes. Activated flux Tungsten Inert Gas (A-TIG) welding was invented to improve productivity when welding thick sections. This study reviews the effects of using oxide fluxes in the A-TIG welding.

Effects of ATIG Welding on Weld Shape, Mechanical Properties, and Corrosion Resistance of 430 Ferritic Stainless Steel Alloy

Flux activated tungsten inert gas (ATIG) welding is a variant of tungsten inert gas (TIG) welding process with high production efficiency, high quality, low energy consumption, and low cost. The study of activating flux mechanism by increasing weld penetration has direct significance in developing flux and welding process. This study has been conducted on 430 ferritic stainless steel alloy. Design of experiment is used to get the best formulation of flux. Based on Minitab17 software, nineteen compositions of flux were prepared using the mixing method. Fluxes are combinations of three oxides (MoO3-TiO2-SiO2). Using the optimizer module available in Minitab 17 software, the best formulation was obtained to achieve the best weld depth. Hence, the obtained depth is twice greater than that achieved by conventional TIG welding. Moreover, mechanical properties and corrosion resistance have been investigated for TIG and ATIG welds respectively in tensile, impact, and hardness tests, and in potentiodynamic polarization measurement test.

Analysis and Characterization of the Weld Pool and Bead Geometry of Inconel 625 Super-TIG Welds

The welding market is changing globally, becoming eco-friendly, robotized and automated. The tungsten inert gas welding (TIG) process is indispensable in industries that require high-quality welds with the absence of spatter and fumes. However, the production rate of TIG welding is very low, which limits its many applications. The present study introduces a novel TIG welding method called super-TIG welding. Super-TIG welding is able to produce a high production rate of welds compared to other fusion welding methods. In super-TIG welding, the novel C-type filler is used, which is different from the conventional TIG welding of circular wire. The relations of the heat input ratio in super-TIG welding to weld pool length and weld bead geometry were measured using the Inconel 625 C-filler. Two types of deposition techniques were used for a bead-on-plate welds, such as stringer beads and oscillation beads. The weld pool and bead geometry measurements are found to be different between stringer beads and oscillation bead techniques. The length of the molten pool and bead size were higher for oscillation beads over the stringer beads. These changes were associated with the difference in heat transfer contact area and bead height.

Applying the ultrasonic vibration during TIG welding as a promising approach for the development of nanoparticle dispersion strengthened aluminum weldments

Abstract In the present work, an innovative approach by adding the filler materials containing ZrO2/TiO2 hybrid nanoparticles to the weld pool during tungsten inert gas (TIG) welding under ultrasonic vibration (UV) was developed to fabricate nanostructured welds. Nanocomposite filler materials were manufactured from Al–Si alloy strips and ZrO2/TiO2 hybrid nanoparticles using accumulative roll bonding. After TIG welding, the influence of UV on the nanoparticle dispersion as well as the microstructure of welds was assessed using electron microscopes (SEM and TEM). When UV treatment was applied, the morphology of α-Al grains was changed from a coarse dendritic structure to a fine and globular shape and Al–Si eutectic phase was significantly refined. The results depict that the addition of nanoparticles together with application of UV can improve the grain refinement and as a result increases the mechanical properties than that of conventional TIG welding.

Influence of activating flux tungsten inert gas welding on mechanical and metallurgical properties of the mild steel

Mild steels have versatile application in various structural design like in steel frame buildings, pipelines, railway wagons etc. Tungsten inert gas (TIG) welding is common to use this kind of materials. However, less depth of penetration in single weld pass make it time consuming and less productive during fabrication of thick sections (usually >3 mm). Activating flux tungsten inert gas (A-TIG) welding is growing as solution for less penetration. Successful implementation of the A-TIG welding process on mild steel could reduce the fabrication cost drastically. Therefore, in the current work, efforts are made to develop the weld joint using suitable processes/approaches. In view of above, weld joints of mild steel were developed using conventional TIG welding process and activating flux tungsten inert gas welding process. The weld joints were characterized in respect of weld bead geometry, angular distortion, microstructure, hardness distribution, tensile properties, and the impact toughness. Results have been discussed in light of microstructure study and mechanical behaviour of the weld joints.

A Computational approach in optimizing process parameters influencing the heat input and Depth of Penetration of Tungsten Inert Gas welding of Austenitic Stainless Steel(AISI 316L) using Response Surface Methodology

Austenitic stainless steel (AISI 316L) possesses high strength, and corrosion resistance finds application as a major base material for the manufacturing of boilers, chemical reactors, etc. Tungsten Inert Gas Welding (TIG) is a common process used for making joints in the fabrication industries like chemical, railway coaches, and automobile parts. In this work, Austenitic Stainless steel plates of Size 200 x 100 x 5 mm undergoes conventional TIG process. The input parameters set for the study was Welding Current, Welding Speed and Gas flow rate and the output response chosen for the study was Depth of Penetration (DOP) and Heat Input. Central Composite design, a common response surface methodology of Design Experimentation was used to conduct the welding trials. ANOVA was conducted to find a relation between the input and the output with a certainty level of 95%. A full quadratic response surface regression model was developed between Depth of Penetration (DOP), Heat Input and welding current, Welding Speed, and gas flow rate. It was found DOP there exists a linear relation for the input parameters. The Heat input model shows a quadratic relation exists between welding current, welding speed, and output response. The model accuracy was 95.29% for DOP and 99.43% for Heat input. The difference between R-sq. and R-sq. (adj) was less than 2% for both the cases which indicates the model accurately resembles the experimental parameters chosen for the study. Desired depth & heat were accomplished at an optimum current of 185 A, welding speed of 50.11 mm/min and gas flow rate of 13.1 l/min.

Dissimilar welding of Al0.1CoCrFeNi high-entropy alloy and AISI304 stainless steel

Abstract

Activated flux TIG welding of Inconel 718 super alloy in presence of tri-component flux

ABSTRACTIn this study, we have explored the influence of newly developed tri-component oxide flux (Cr2O3, FeO, and MoO3) on weldability, bead geometry, weld pool temperature variation, and mechanical strength of Inconel 718 welded joints. Moreover, the influence of used flux on weld pool, the surface morphology of electrode and penetration capability of tungsten inert gas (TIG) welding on Inconel 718 plates have been well elucidated. Results indicate that the flux mixture significantly increases the penetration depth as well as aspect ratio almost 200% as compared to conventional TIG welding. The arc constriction caused by newly developed oxide flux upsurges the heat density and the weld pool temperature of joints. The alloying effect caused by entrapped oxide particles greatly improves the hardness as well as the tensile strength of joints. The reported reinforcement in the welding performance may increase potential utility of the developed methods for real-world applications.

Weld overlay coating of Inconel 617 M on type 316 L stainless steel by cold metal transfer process

A study of microstructure and volumetric dilution of Cold Metal Transfer (CMT) clad of Nickel based super alloy, Inconel 617M on type 316L stainless steel (SS) substrate was carried out. Overlay coatings were deposited at three different current inputs (80, 90 and 100 A) to synergetic CMT welding set while the wire feed rate and pulse frequency were pre-programmed. The ability of CMT to produce very low dilution and low heat input with the minimal heat affected zone (HAZ), when compared to conventional Tungsten Inert Gas welding (TIG) process was successfully demonstrated. Detailed microstructural evaluation of the cross sections revealed porosity and crack free Inconel 617M overlay with complete fusion, making a metallurgical bonding at the interface. Transverse micro Vickers hardness evaluation from clad to substrate showed the absence of significant HAZ for overlay produced by CMT. Calculation of percentage volumetric dilution, based on elemental Energy Dispersive Spectroscopy (EDS) of Fe-K counts, revealed that the cladding deposited at 100 A current exhibited low dilution value of 6.3% at 100 μm away from the interface while clad produced by TIG show significantly higher dilution value of ~50% at 100 μm from interface. Electron Backscattered Diffraction (EBSD) studies revealed morphology similar to epitaxial growth, with same crystallographic orientation of grains across the interface for CMT overlaid coatings.

TIG spot weld bonding of 409 L ferritic stainless steel

Tungsten inert gas (TIG) spot weld bonding is a hybrid joining process, which combines the conventional tungsten inert gas welding with adhesive bonding to achieve a better quality joint with superior joint performance than any single technique. The present research aims to study the effect of input process parameters i.e. welding current, weld time and gas flow rate on weld penetration, bead width and tensile shear strength of the weld bonds using design of experiment (DOE) approach. Further, some selected samples were characterized by optical microscopy and hardness testing. It was observed that weld time most significantly affect the weld performance followed by welding current and gas flow rate. The tensile results showed failure of weld bond in two ways namely interfacial failure and button pull out failure.

Investigation on the Effect of Activating Flux on Tungsten Inert Gas Welding of Austenitic Stainless Steel Using AC Polarity

Tungsten Inert Gas (TIG) welding is a popular joining process due to its inherent capability in producing superior quality welding in a wide range of materials. However, lower productivity of it paves the way for introduction of a number of variants of TIG welding, including Flux Bounded TIG (FB-TIG) welding and Activated TIG (A-TIG) welding. In this paper, variations of weld morphology and characteristics with heat input in AC A-TIG welding of both bead-on-plate and butt joining of 6mm thick 316L stainless steel plates using TiO 2 , Cr 2 O 3 and Fe 2 O 3 as activating flux and a stainless steel filler material are investigated. Results are also compared with that obtained in conventional TIG welding. Variations of various weld characteristics viz. depth of penetration, width of weld bead, reinforcement, Reinforcement Form Factor (RFF), and Penetration Shape Factor (PSF) against change in heat input are analyzed and compared. It is observed that TiO2 and Fe 2 O 3 fluxes effectively enhance the penetration due to increase in fluidity and wettability of molten metal and, at the same time, reduce the width of weld bead; whereas, Cr 2 O 3 flux gives inferior results as it reduces penetration instead of increasing it as compared to conventional TIG welding.

Application of Automatic TIG Welding for Yamal LNG Process Piping Fabrication

The representative materials, used in Russian Yamal LNG project, are ASTM A333 Gr.6 (low temperature carbon steel, designed temperature of –50°C) and ASTM A312/A358 TP304/304L (austenitic stainless steel, designed temperature of –196°C). The welding technical specification demands TIG (Tungsten Inert Gas) welding for root welding of piping. This project adopts the construction way of prefabrication in Qingdao and assembly in Russian. Therefore, high construction accuracy is required. This article introduces the LNG process piping welding by automatic TIG welding which contains welding process design, welding process parameters, test and analysis of weld mechanical property and advantage analysis of TIG welding as well. In this project, the automatic and high efficient TIG welding is used for the root welding and hot welding of low temperature carbon steel and austenitic stainless steel piping. The result shows that the mechanical properties of weld metals meet the requirements of LNG project technical specification and code ASME B31.3. The efficiency of automatic TIG welding increases 2 times compared with conventional manual TIG welding. The automatic TIG welding improves and optimizes the quality and construction progress of the LNG project process piping.