Activated Flux Tungsten Inert Gas Research Articles

Metallurgical and mechanical properties evaluation of the activated flux tungsten inert gas weldments

The activated flux tungsten inert gas welding process is an attractive joining technique to increase the depth of penetration in a single pass. In the last two decades, the research on activated flux tungsten inert gas welding increased drastically. Despite enhanced weld penetration, activated flux tungsten inert gas is not frequently implemented in industries because of a lack of information about the process. However, research on activated flux tungsten inert gas welding has significantly increased in the last decade due to the widespread information related to the advancements in weld penetration and mechanical properties of the activated flux tungsten inert gas process. The activated flux tungsten inert gas welding process provides a high single pass depth of penetration along with good mechanical properties compared to the tungsten inert gas welding process. The current work offers an in-depth analysis of the activated flux tungsten inert gas welding process mechanism, advancement in activated flux tungsten inert gas methodology to improve weld bead geometry, and mechanical and corrosion behaviour of the weldments. The current work also highlights recent progress made in the field of dissimilar metal joining using the activated flux tungsten inert gas welding process.

AUGMENTATION OF DEPTH OF PENETRATION AND PRODUCTIVITY BENEFITS OF ATIG WELDS USING THE AHP

Weldability is an important issue in the fabrication of different grades of stainless steel used in industry. Tungsten inert gas (TIG) welding is widely used in industry for accurate and precision work, but lack of penetration is observed in this process even though current and welding speed can be varied considerably to increase heat input to obtain deeper penetration. Increased heat input adversely affects mechanical properties of the weldment. To overcome this, activated flux TIG welding is often used in industry to achieve higher depth of penetration with relatively less heat input. In this study, activated flux TIG welding is used with input variables such as heat input, welding speed and pulse frequency. The chosen base metal is SS 304L stainless steel, and a hybrid flux mixture containing fluxes of SiO2, MnO2 and MoO3 in a ratio of 1:1:2 is used to obtain the desired depth of penetration. Nine experimental runs are conducted to obtain the optimum depth of penetration. Heat input values are 2.767 kJ/mm, 1.470 kJ/mm and 1.281 kJ/mm and pulse frequency is 160 Hz, 120 Hz and 80 Hz. Welding speed varies from 0.5 mm/s to 1.18 mm/s. A maximum depth of penetration of 4.42 mm is achieved with a heat input of 2.767 kJ/mm, welding speed of 0.5 mm/s and pulse frequency of 160 Hz. The reversed Marangoni effect and arc constriction effect are the mechanisms responsible for the deeper penetration in ATIG welding. In this research, a multi criteria decision making tool, the Analytical Hierarchy Process (AHP), is used to validate the optimum value obtained. The optimal values obtained in the research are in good accordance with those obtained using the AHP. The outcome of the present investigation indicates the applicability of ATIG welding for joining large thickness of stainless steel flats to give enhanced productivity by reducing the number of weld passes.

Influential Behavior Study of Fluxes during Activated Flux Tungsten Inert Gas Welding of IRSM 41 Steel

Influential Behavior Study of Fluxes during Activated Flux Tungsten Inert Gas Welding of IRSM 41 Steel

Investigation of Weld Geometry, Mechanical Properties, and Metallurgical observations of Activated Flux Tungsten Inert Gas (A-TIG) Welding on 304 Austenitic Stainless Steel

Investigation of Weld Geometry, Mechanical Properties, and Metallurgical observations of Activated Flux Tungsten Inert Gas (A-TIG) Welding on 304 Austenitic Stainless Steel

Corrosion behaviour study of Inconel 617 TIG and A-TIG weldments using potentiodynamic polarisation test and intergranular corrosion test

Inconel 617 alloy is known for its impressive resistance to numerous corrosive environments and is widely used in high-temperature applications. This study analyses the microstructure and corrosion behaviour of the Inconel 617 weldments fabricated by activated flux tungsten inert gas (A-TIG) welding and TIG welding. Potentiodynamic polarisation (PDP) test in a 3.5% NaCl solution and intergranular corrosion (IGC) test was conducted to analyse the corrosion behaviour of the base metal (BM) and weldments. In accordance with the PDP test evaluation, the BM, TIG weld and A-TIG weld samples had corrosion rates of 0.0028, 0.0156 and 0.0043 mpy, respectively. PDP test results showed that all three samples had outstanding corrosion resistance. According to IGC test findings, the A-TIG weld sample had a greater corrosion resistance of 15.1 mpy when compared to BM and the TIG weld sample, which had corrosion resistances of 19.78 and 23.2 mpy, respectively. Chromium depletion at the grain boundaries caused by carbide formation was the reason for the TIG weld sample's poor corrosion resistance.

EVALUATION OF THE MECHANICAL PROPERTIES AND MICROSTRUCTURE OF A-TIG AND TIG WELDMENTS OF INCONEL 617

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[Formula: see text]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.

Effect of post weld heat treatments on microstructure and mechanical properties of dissimilar P92 steel-AISI 304H ASS A-TIG weld joint

In present work, the efficacy of post weld heat treatment (PWHT) on microstructure and mechanical properties of dissimilar P92 steel-AISI 304H austenitic stainless steel (ASS) activated flux-tungsten inert gas (A-TIG) weld joint was studied. Based on the time temperature cycle, the post weld heat treatment was performed in two ways: (a) PWHT-1 (760 °C, 2 h) and (b) PWHT-2 (1160 °C, 2 h and 760 °C, 2 h). After PWHTs, the microstructure and mechanical properties (micro-hardness, tensile behavior and impact toughness) of weld joint were tested and compared with as-welded condition. PWHT-1 resulted in coarsening of existing precipitates and formation of new precipitates in weld zone. The average size of precipitates along the PAGB and inside the grain matrix was measured to be 294 ± 50 nm and 153 ± 50 nm, respectively. After PWHT-2, the microstructure of P92 FGHAZ, P92 CGHAZ and weld zone were observed to be quite similar due to the re- austenitisation during this PWHT regime. The hardness distribution shows the non-uniformity even after PWHT-1 however; PWHT-2 shows negligible variation in hardness of P92 side HAZs and weld zone. In tensile testing, the failure location has been changed to P92 steel base metal from AISI 304H ASS which suggests that P92 steel becomes weak after the post weld heat treatments. An increase in elongation % (PWHT-1: 37% and PWHT-2: 45%) was also obtained after PWHTs. Upon PWHTs the weld zone impact toughness also improved (PWHT-1: 59 ± 2 J and PWHT-2: 132 ± 2 J) and satisfy the minimum average impact toughness as per standard EN 1559:1999.

Effect of TIG and activated flux TIG welding processes on weld bead geometry, microstructure, and hardness of SAF 2507 grade super duplex stainless steel joints

Tungsten inert gas (TIG) welding is frequently used to fabricate super duplex stainless steel weldments due to its superior mechanical qualities and attractive appearance in contrast with other arc welding techniques. The broad use of TIG welding remains constrained despite all of its advantages. Thus, the process of activated flux tungsten inert gas (A-TIG) welding is created. In the current study, ATIG welding with different oxide fluxes is used to execute bead-on-plate welding on 6 mm thick super duplex (SS) SAF 2507 grade. The TIG and ATIG processes are used for bead-on-plate welding, and the macrostructure, microstructure, and mechanical features of super DSS weld beads are analysed. When different oxide fluxes are used, the A-TIG technique achieves a greater depth of penetration and a narrower weld bead width than the standard TIG process. SiO2 flux with ATIG welding gives the highest depth of penetration (5.42 mm) among all other fluxes used. Also, A-TIG welding using SiO2 flux has a finer grain structure and a higher hardness value than other fluxes. The primary microstructure in the A-TIG weld zone was austenitic, but delta ferrite was still present.

Experiment analysis of A-TIG welding and comparison between TIG, Double-TIG, and A-TIG of Hastelloy C-276

The present study Hastelloy C276 welding performs using tungsten inert gas (TIG) and activated flux-TIG (A-TIG) welding technique. A nickel (57%), molybdenum (15 to 17%), chromium (14.5 to 16.5%), Iron (4 to 7%) and tungsten (3 to 4.5%) alloy called Hastelloy C-276 has outstanding all-around corrosion resistance and is easy to work with. Reverse marangoni and the arc concentration effect both considerably increased the depth of penetration during ATIG welding with SiO2 flux. The Macro structural analysis and hardness survey of weld bead profile of TIG, Double TIG and ATIG performed and find out that ATIG welding have greater depth of penetration and high hardness value than normal TIG welding. A TIG welding produced better hardness; the difference in hardness values was about 8.45%.

Investigation of the Mechanism of Powder Pool Coupled Activating TIG Welding

As a highly effective welding method, PPCA-TIG (Powder Pool Coupled Activating Flux–Tungsten Inert Gas) welding aims to achieve automated activation of TIG welding through the use of suitable activating fluxes. However, due to the unique transitional behavior of activating elements, the mechanism of PPCA-TIG is a little bit different from common activating TIG welding. In this research, a two-dimensional model is established to investigate the effect of four activating fluxes (TiO2, SiO2, MnO2, CaF2) on arc morphology and force. A series of welding experiments is performed to study the impact of the different activating elements on the molten pool. The results show that the increase in the penetration of TiO2 is related to the high arc temperature and great arc force and electromagnetic force in the molten pool. The problem of the softening of 3003 aluminum alloy welded joints is solved. Other activating fluxes are less effective than TiO2. The addition of calcium fluoride significantly affects penetration. The use of TiO2, SiO2 and MnO2 changes the molten pool viscosity and affects the molten pool oscillation, thus affecting the weld quality.

OPTIMIZATION OF PROCESS PARAMETERS FOR THE A-TIG WELDING OF INCONEL 617 USING PARTICLE SWARM OPTIMIZATION AND GENETIC ALGORITHM

Inconel 617 alloy has been included in the boiler and pressure vessel (BPV) code of the American society of mechanical engineers (ASME) for its effectiveness in nuclear applications due to its ability to maintain strength at elevated temperatures. This study is based on the optimization of process parameters for activated flux tungsten inert gas (A-TIG) welding of 10-mm thick Inconel 617 material. Process parameters considered in this study include weld current (A), weld torch travel speed (mm/min), arc gap (mm) and flux powder (silicon dioxide (SiO[Formula: see text] and titanium dioxide (TiO[Formula: see text] combination. The bead on plate welding experiment was carried out by varying the combination of process parameters in each experimental trial. The Taguchi L16 orthogonal array was the design matrix used for the design of experiments (DOE). In the bead on plate welding experiment, a total of 16 experimental trials, each having a different set of process parameters was conducted. The weld bead samples corresponding to each trial were prepared for measurement of the responses which were measured from each of the 16 weld bead samples and included depth of penetration (DOP), bead width (BW), depth to width ratio (DWR), weld cross-sectional area (WA), and bead height (BH). The objective of this work was to maximize DOP, DWR, WA, BH and minimize BW. Analysis of variance (ANOVA) was used to identify the significance of process parameters. Optimization techniques including particle swarm optimization (PSO) and genetic algorithm (GA) were used in the study. The optimized process parameters and optimal solutions attained from each optimization technique were compared. It was found from the study that weld current was the most significant process parameter for all responses followed by weld torch travel speed, flux powder combination and arc gap. Optimal process parameters to achieve maximum DOP, DWR and WA were found to be weld current of 290 A, weld torch travel speed of 50[Formula: see text]mm/min along with an arc gap of 1[Formula: see text]mm and 100% TiO2 as flux. The optimal solution for DOP, DWR and WA was found to be 7.04[Formula: see text]mm, 0.437 and 7.619[Formula: see text]mm2 respectively. The optimal solution for BW and BH was 6.302 and 0.677[Formula: see text]mm, respectively. A confirmation test was conducted to validate the optimal solution obtained from this study. The results from the confirmation test agreed with the solution obtained by optimization techniques.

Parameter optimization and experimental validation of A-TIG welding of super austenitic stainless steel AISI 904L using response surface methodology

Super austenitic stainless steel (SASS) is a premium stainless steel (SS) variant which finds applications in challenging environments. One of the premium grades of SS that falls under the said category is AISI 904L. Autogenous activated flux tungsten inert gas (A-TIG) welding is an established technique for fabricating sound steel joints which offers various advantages. In this context, this research aims to identify an optimum set of input process parameters to effectively employ A-TIG welding to fabricate 10 mm thick joints of SASS AISI 904L plates by employing bead on plate welding trials. The input parameters varied for the trials are welding current, torch travel speed, and percentage of Argon gas present in a mixture of Argon and Helium – which is the shielding gas used, while the responses were the depth of weld penetration (DOP) and weld bead width (BW). For finalizing the combinations of input parameters and the run order of the welding trials, the design of experiments (DOE) was performed using central composite design (CCD) of response surface methodology (RSM). After performing the trials, the DOP and BW attained were measured and the data thus generated were analyzed to study the influence of varying input parameters on the two responses. Analysis of variance (ANOVA) was then performed to check the input parameter's level of significance. RSM's desirability approach was used for numerical optimization to attain maximum DOP and a moderate BW. A linear regression equation generated can be used to precisely predict DOP and BW for any random values of input parameters. The bead on plate trial's validation study displayed root mean squared error (RMSE) values of 0.328 and 0.653 for DOP and BW respectively, The RMSE values of DOP and BW of the joint fabricated with optimized parameters was 0 and 0.311 respectively.

Spectroscopic analysis of the arc plasma during activating flux tungsten inert gas welding process

A-TIG welding has been widely used in the manufacturing fields of aerospace, pressure vessels and ships as a highly efficient welding method. However, the mechanism of the effect of the activating flux on the arc behavior is still controversial. In this work, the spatial distribution of A-TIG welding arc spectra under the action of three types of active agents (fluorides, oxides and chloride) was studied using a spectral diagnostic method. The distribution characteristics of active agent particles, argon and iron particles in the arc were analyzed as well as the arc electron temperature was calculated using Boltzmann plot method. The experimental results shown that the distribution state of different active particles in the spatial of the arc is different. The influence of different active agents on the arc electron temperature in the spatial area of the arc is inconsistent. Chloride can cause a significant increase in the whole arc temperature. Fluoride can increase the arc electron temperature near the anode area. Oxide has less effect on the overall arc temperature.

A New Perception of Activated Flux Tungsten Inert Gas (A-TIG) Welding Techniques for Various Materials

Tungsten inert gas welding (TIG) is more stable and allows for more precise control than most other arc welding processes. TIG welding is desired in the aerospace sector when thin parts have been welded with accuracy. However, when welding thick sections, autogenous TIG welding is not commonly recommended due to the limited depth of penetration required. It is in effective for joining the thick parts in a particular pass. Welding with activated flux tungsten inert gas (A-TIG) enhances weld penetration by four times in a single pass. This process will improve penetration depth, depth/width ratio and also, minimize angular distortion and residual stresses. A-TIG is the topic of investigation among researchers due to its deep penetration capacity. Properties of A-TIG welding in diverse materials was investigated in this study which also discusses the mechanisms, varied forces like lorentz force, buoyancy force, shear stress prompted by plasma jet, shear stress prompted by surface tension gradient, reverse marangoni force and aerodynamic drag force induced in the weld pool. The impact of activated fluxes on various materials of A-TIG weld was also investigated in this study. Recent advancements in TIG welding methods were also explored. According to the findings, A-TIG welding improves weld penetration significantly, but there is a lot of slug on the weld surface. This constraint can be addressed by using new versions of the A-TIG welding progression, such as flux bounded and the flux zone.

Analysis of Mechanical, Microstructural Properties and Weld Morphology of A-TIG Welded AH-36 Marine-Grade Steels with Oxide and Duplex Flux Coating

The current study investigates the metallurgical, mechanical properties and weld morphology of AH36 marine grade steel (with a thickness of 8 mm) by activated-tungsten inert gas (A-TIG) butt joints, with the application of different fluxes (MoO3, V2O5, and duplex of MoO3 and V2O5) at various process parameters. The welding speed was kept constant at 120 mm/min, and current varied from 160 A to 220 A uniformly to optimise process parameters to achieve desired mechanical properties, weld morphology, and lowest possible heat input. The study also focused on comparing tensile strength, impact strength, and microhardness, heat input during welding, weld bead depth and width between conventional TIG welding and activated flux TIG welding processes at various operation parameters. Tensile results reported that fracture occurs at the base region in ordinary TIG welding and the activated tungsten inert gas welding process. It was noticed that a higher depth to width ratio attained MoO3 and V2O5 duplex flux coated weldments. There is evidence that the depth of weld joints is enhanced because of stable arc, Marangoni effect, and arc constriction. Microhardness results reported that the fusion zone has a higher microhardness in the activated tungsten inert gas welding than the ordinary TIG welding. It was concluded that out of all fluxes, MoO3 and V2O5 duplex flux coating produce better butt welds of AH36 steel.

Experimental investigation on microstructure and mechanical properties of joining stainless steel 316LN to Low Activation Ferritic Martensitic steel (LAFM) using activated flux TIG welding

ABSTRACT One of the most significant requirements for joining dissimilar materials is to produce a minimum number of deeper-penetration welds and thereby avoid flaws. The Activated Flux TIG welding process improves penetration depth in a single pass, reducing the number of weldments. The dissimilar weld between LAFM – Stainless Steel 316LN also possesses the same requirement for a particular application. The present study aims to investigate the structure-property relationship and mechanical properties of dissimilar weldments of LAFM – SS 316LN using conventional TIG and Activated TIG welding using TiO2 and Co3O4 oxide fluxes. The microstructure study of conventional TIG weld reveals the fine lath martensitic structure as compared to weld prepared with A-TIG using TiO2 flux due to difference in the cooling rate. Also, the carbide formation in conventional TIG and A-TIG using TiO2 confirms the presence of delta ferrite But, the same observation was not confirmed with A-TIG weldments prepared using Co3O4. Similarly, the hardness results also support the microstructure study. The higher transverse tensile strength of weld indicates that it is stronger than base metal. The lower impact energy in case of Activated Flux TIG welding process was reported due to presence of oxide flux.

Comparison of feasibility, microstructure and performance of hybrid laser arc, activated flux tungsten inert gas and friction stir welding for thick plate of innovative ultra-pure ferritic stainless steel

Comparison of feasibility, microstructure and performance of hybrid laser arc, activated flux tungsten inert gas and friction stir welding for thick plate of innovative ultra-pure ferritic stainless steel

Improvement in Depth of Weld Penetration During TIG, Activated-TIG, and Pulsed TIG Welding

Joining of dissimilar materials has gained a lot of interest in the recent years due to the increased demand of high strength and light weight designs. Fusion welding plays a vital role in repairing and manufacturing industries like automobile, construction, ship building, and energy sector. Tungsten inert gas (TIG) welding is more advantageous over other welding processes as it produces high precision welds with aesthetic appearance. The limitation of the process is shallow penetration, distorted and weaker joint formation, and low productivity. In the present work, a critical review and analysis has been done on weld penetration and its enhancement during TIG, activated flux TIG, and pulsed current TIG welding of steels. The purpose of this review is to raise an insight about using the variants of TIG, minimising the energy consumption and heat affected zone while increasing the weld penetration and productivity. Proper selection of welding parameters along with welding speed, electrode diameter, shielding gas, electrode tip angle, arc gap, and flux greatly increase the weld penetration.

Effect of activated flux tungsten inert gas (A-TIG) welding on the mechanical properties and the metallurgical and corrosion assessment of Inconel 625

This article makes an attempt to investigate the outcome of activated flux and filler wire in addition to A-TIG welding and TIG welding of Inconel 625 respectively. Ni-Cr-Mo enriched filler namely ERNiCrMo-3 was used to join 6.5-mm-thick plates. Microstructure characterization, mechanical properties evaluation and secondary dendritic arm spacing measurements were carried out to find the cause of the perceived differences. Tensile test failures were observed at the weld zone in both welding processes. Charpy impact studies showed that weldment using A-TIG revealed a low toughness value compared to the TIG weldment. Root bend test showed no discontinuity in both fusion zones and hence, the weldment was produced without defect. The deleterious laves phase was reduced when activated flux and fillers were used. Corrosion performance was undertaken in a 3.5 wt% NaCl solution, to illustrate the outstanding corrosion resistance in Inconel 625’s fusion zone using A-TIG and TIG welding processes.

Dissimilar Metal Welds used in AUSC Power Plant, Fabrication and Structural Integrity Issues

ABSTRACTIn the current era, the Advanced Ultra Super-Critical (AUSC) plants have been used to substantially increased efficiency with environmental protection. AUSC components boiler header, re-heater and super-heater tube etc. are fabricated by using advanced materials to join by the welding process. Any failure of the power plant can lead to grave consequences, not only of substantial financial losses but additionally immensely treasured and irreparable human life loss. In this review, the dissimilar metal welds (DMWs) have many issues such as metallurgical issue, cracking, carbon migration, welding electrode selection, creep properties, suitable welding process and structure integrity issues which enhanced the failure of weldments. The results of our review showed that DMWs of AUSC power plant are joined by activated flux Tungsten Inert Gas (A-TIG) and Pulse A-TIG process to increase the productivity and cut the significant fraction of cost. However, A-TIG process with Post Weld Heat Treatment (PWHT) improved the mechanical properties and high-temperature creep resistance properties of DMWs. This state of the art is encouraged the researchers about the enormous future scope.