TIG Welding Process Research Articles

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.

WITHDRAWN: Mechanical properties on INCONEL 800H alloy by TIG welding process

Abstract Inconel 800H alloy is widely utilized for high-temperature load-carrying ability in the aerospace and manufacturing sectors of automobiles. This investigation focused on the effect of tungsten inert gas welding on Inconel 800H alloy. The post-weld heat treatment was applied to the Inconel 800H alloy for enhancing the properties. The mechanical strength and characterization of welded and un-welded Inconel alloy were examined with various significant TIG parameters. From the outputs, the TIG welding process parameters were predetermined to acquire the optimum mechanical properties for the material Inconel 800H.

Influence of arc constriction current frequency on tensile properties and microstructural evolution of tungsten inert gas welded thin sheets of aerospace alloy

The main objective of this investigation is to study the influence of arc constriction current frequency (ACCF) on tensile properties and microstructural evolution of aerospace Alloy 718 sheets (2 mm in thickness) joined by constricted arc TIG (CA-TIG) welding process. One variable at a time approach of design of experiments (DOE) was used, in which ACCF was varied from 4 to 20 kHz at an interval of 5 levels while other parameters were kept constant. The joints welded using ACCF of 4 kHz exhibited superior tensile properties extending joint efficiency up to 99.20%. It is attributed to the grain refinement in fusion zone leading to the evolution of finer, discrete Laves phase in interdendritic areas. An increase of ACCF above 12 kHz caused severe grain growth and evolution of coarser Laves phase in fusion zone. Alloy 718 welds showed more obvious tendency for Nb segregation and Laves phase formation at higher levels of ACCF due to the slower cooling rate. The volume fraction of Laves phase was increased by 62.31% at ACCF of 20 kHz compared to that at 4 kHz, thereby reducing the tensile properties of joints. This is mainly due to the stacking of heat input in weld thermal cycles at increased levels of ACCF.

15/15 Ti Stainless Steel Welding Process Optimization for GEN IV Nuclear Application in the GEMMA Project Frame

This paper deals with activities carried out in the frame of GEMMA project on welded samples of 15/15 Ti stainless steel. The focus of GEMMA project has been on the investigation of material properties and associated welded joints for GEN IV nuclear plants. The RCC-MRx code uses the standard Base Metal Grade nomenclature (EN/ISO), but provides also additional specifications. Titanium stabilized “15-15Ti” stainless steel has been the primary choice for fuel cladding of current fast spectrum research reactor projects. The choice of cladding material is based on past experiences and the availability of material databases from similar steel grades proven in past sodium-cooled fast reactors programs [1-4]. On the basis of ENEA past experience, a strict specification has been written to realize a new heat treatment of this special stainless steel (SS). One of the main problems faced with this material is the high tendency to crack after the welding process. Several preliminary welding tests permitted to select TIG and laser welding processes for the 15/15 Ti SS. This fact because the main applications involve small thicknesses without filler material. The welding of the 15/15 Ti was performed using a fully automated TIG work station at ENEA CR-Casaccia. The base materials to evaluate the welding parameters were 15/15 Ti plates 100 X 170 X 3 mm welded under different shielding gas atmospheres and process parameters arrangements that permitted to obtain good quality joints avoiding catastrophic hot-cracking. The welded samples underwent a mechanical and metallographic characterization and the main results are here presented.

Evaluation study of mechanical properties of dissimilar materials through TIG welding process

Abstract In the present work, Titanium grade 5 (Ti-6Al-4 V) and low carbon steel (A516) plates were joint through diffusion bonding using a titanium as interlayer at the temperatures range of 650 °C–700 °C for various diffusion timing of 1hr 5 min under 15KN load in vacuum to examine the strength of the welded materials at the joints. TIG welding was used to join the two different metals at three different temperature ranges. In this investigation, mechanical properties such as tensile strength, elongation, and hardness tests were carried out by using universal testing machine (UTM). Also corrosion resistance test conducted using the salt spray test to examine the corrosion resistance at the welded joints. Thus the result revealed that TIG welding is suitable for joining hard metals at maximum temperature and the welding bond strength is observed better at 700 °C.

Influence of B4C and TiB2 nanoparticles in tungsten inert gas weldment: The development of nanocomposite filler re-melt behaviour for joint strength enhancement

The reinforcement particles present in a metal matrix is a key factor to improve the strength of weld joints. In the present work, in-situ Titanium diboride (TiB2) and ex-situ Boron carbide (B4C) particles were separately reinforced with Al 4043 matrix by ultrasonic cavitation assisted stir casting process. The fabricated composites were cut into composite filler rods to the required size and shape from the reinforced nanocomposites using wire-cut EDM. The TIG welding process was performed on Al 6061 plates using Al 4043 composite filler rod under optimized welding conditions. The tensile strength and microhardness of both type of particle reinforced weldment were compared. Addition of 2 wt% of TiB2 and 2 wt% B4C particles separately produced 59% and 41% higher microhardness compared to base metal weldment respectively. An increase in tensile strength of 201% and 128% respectively was observed when compared to base metal weldment. The High Resolution Transmission Electron Microscopy (HRTEM) and Field Emission Scanning Electron Microscopy (FESEM) were used to characterize the microstructure of B4C and TiB2 reinforced weldments. The re-melting behaviour of TIG welded joints was also investigated for the formulated nanocomposites.

The experiment of ambient wind speed and argon flow rate on tig welding process

Tungsten inert gas (TIG) welding is one of the most popular welding which has high quality welds. TIG welding can be used for all kinds of welding positions and high efficient. During the welding process, the welding specimen and the heat affected zone (HAZ) affected by a series of thermal cycles where the area warms up to a maximum temperature then followed by cooling process. The thermal cycle affects the microstructure of the welding specimen and HAZ. By controlling these parameters to reach the right heat cycle, the mechanical property of the weld metal can be improved and maintain the microstructure of the weld metal. This study is conducted an experiment to determine the effect of different wind velocity around the TIG welding material. Moreover, this study also discuss the effect of shielding gas flow rate on TIG type welding on JIS G 3131 SPHC steel material. The welding area and HAZ the higher the wind speed the hardness value tends to decrease. Because there is a difference in cooling speed and heat input on weld metal and HAZ.

Hardfacing of X2CrNiMoN22-5-3 Duplex stainless steel with Stellite alloy using pulsed TIG welding process

The results presented in this paper demonstrate the ability of the TIG welding process in the pulsed current to produce layers with good functional properties for the engineering surfaces. The Stellite-21 alloy was deposited on a duplex stainless steel substrate, X2CrNiMoN22-5–3, in a range of process parameters that allow control of linear energy and cooling rate. The optimum welding conditions led to the formation of a coating free of pores and cracks, with a good adhesion to the substrate. The morphology and performance of the deposited layers were studied by optical microscopy and hardness measurements.

Comparison between microstructure characteristics and joint performance of AZ31 magnesium alloy welded by TIG and friction stir welding (FSW) processes

Comparison between microstructure characteristics and joint performance of AZ31 magnesium alloy welded by TIG and friction stir welding (FSW) processes

Effects of TIG welding process on microstructure, electrical resistance and mechanical properties of Nichrome 8020

Effects of TIG welding process on microstructure, electrical resistance and mechanical properties of Nichrome 8020

Key manufacturing technologies of the CFETR 1/8 vacuum vessel sector mockup

• Key technology types involved in CFETR 1/8 V V sector model. • Methods and routes of key technologies of CFETR 1/8 V V sector model. • Current manufacturing progress of CFETR 1/8 V V sector model. This paper introduces key technologies and main advances in the development of the 1/8 vacuum vessel (VV) sector mockup of China fusion engineering test reactor (CFETR). The contour accuracy of each VV shell is controlled within ±2 mm through hot forming, solution treatment, and correction of each hyperboloid shell, and cold forming of the single-curved shell. The welding structure between the 1/8 sectors of CFETR VV on site is simulated by using the welding structure between two 1/16 VV sectors as a model. The narrow-gap TIG (NG-TIG) welding process is designed and explored in the sector welding of the 1/32 VV sector. Electron beam (EB) welding of the port stub is completed, and the weld quality meets the design requirement. The results of phased array ultrasonic testing (PAUT) technology reveal that the testing process meets RCC-MR technical requirements and solves the problems of full volume coverage (i.e., missed detection) and signal-to-noise ratio (i.e., misjudgment) of austenitic stainless steel welds. The automatic ray film arrangement trolley can achieve the automatic arrangement of the X-ray film between double shells when the VV is welded on-site. The measurement solution of three-dimensional complex space solves the problem of collimation positioning measurement during the welding, machining, and assembly of the 1/8 VV sector. The results of the study on the virtual assembly and reverse machining technology provide guidance for the actual assembly of the 1/8 VV sector. Finally, measurement and machining of the allowance are realized to solve the problem of numerical control machining of workpieces without a machining datum.

Effect of Welding Process to the Porosity Formation in Carbon Steel

The effect of the welding process on porosity formation in SPCC carbon steel was studied by comparing MIG, MAG, and TIG welding processes. In this work, the main consideration relates to the welding processes, which are welding current, welding speed, and heat input were investigated. Industrial x-ray observation was performed to study the distribution of porosity within the weld bead. Analysis of bead geometry shows the deepest penetration in TIG welding. The most significant size of porosity was shown in MAG welding compared to MIG and TIG welding. The result indicates that an increase in heat input affects the size of porosity distribution and depth penetration of the weld bead.

Optimization of A-TIG Welding Process Using Simulated Annealing Algorithm

Flux-assisted tungsten inert gas welding process, also known as activated tungsten inert gas (A-TIG) welding, is extensively used in order to improve the performance of the conventional TIG welding process. In this study, the orthogonal array Taguchi (OA-Taguchi) method, regression modeling, analysis of variance (ANOVA) and simulated annealing (SA) algorithm have been used to model and optimize the process responses in A-TIG welding process. Welding current (I), welding speed (S) and welding gap (G) have been considered as process input variables for fabricating AISI316L austenitic stainless steel specimens. Depth of penetration (DOP) and weld bead width (WBW) have been taken into account as the process responses. In this study, SiO2, nano-particle has been considered as an activating flux. To gather required data for modeling, statistical analysis and optimization purposes, OA-Taguchi based on the design of experiments (DOE) has been employed. Then the process responses have been measured and their corresponding signal-to-noise (S/N) ratio values have been calculated. Different regression equations have been applied to model the responses. Based on the ANOVA results, the most fitted models have been selected as an authentic representative of the process responses. Furthermore, the welding current has been determined as the most important variable affecting DOP and WBW with 68% and 88% contributions, respectively. Next, the SA algorithm has been used to optimize the developed models in such a way that WBW is minimized and DOP is maximized. Finally, experimental performance evaluation tests have been carried out, based on which it can be concluded that the proposed procedure is quite efficient (with less than 4% error) in modeling and optimization of the A-TIG welding process.

Experimental investigation on a pulsed TIG welding of Inconel 625

This paper discusses the joining of Inconel 625 plates using A (Activated flux) pulsed TIG welding process. Inconel 625 plates of thickness of 3 mm was welded in butt joint configuration. A pulsed TIG welding was done on plates of INCONEL 625 using three different fluxes namely Al2O3, TiO2 and V205. The quality of the weld was analyzed by measuring the bead geometry (D.O.P. & B.W.) and ultimate tensile strength. A comparison is made between each fluxes effect on the bead geometry and ultimate tensile strength values. Full penetration was not achieved in any of the welding trials. V205 flux resulted in maximum penetration. Depth of penetration was increased by a 0.3 mm when V205 was used as flux material. Maximum tensile strength was obtained when Al203 was used as flux material. Tensile test was increased by 12% when Al203 was used as flux material.

Residual stress analysis, mechanical and metallurgical properties of dissimilar weldments of Monel 400 and AISI 316

Abstract This research manuscript explores the residual stress analysis, mechanical and metallurgical aspects of dissimilar welded joints between AISI 316 and Monel 400 developed by constant, pulse and Interpulse current TIG welding processes. The induced residual stresses have been measured experimentally by employing X-ray diffraction. The mechanical properties of welded joints have been determined by conducting tensile and Vickers hardness testing. The metallurgical properties of weldments have been analyzed by employing optical and scanning electron microscopy. From the experimental results, lower residual stresses have been observed in Interpulse current TIG weldment than the other two weldments. The tensile properties of the Interpulse current TIG weldment were observed to be higher than the other two weldments. In Interpulse TIG weldments, grain refinement and reduced heat affected zone near the fusion zone have been observed.

Residual stress analysis, mechanical and metallurgical properties of dissimilar weldments of Monel 400 and AISI 316

Abstract This research manuscript explores the residual stress analysis, mechanical and metallurgical aspects of dissimilar welded joints between AISI 316 and Monel 400 developed by constant, pulse and Interpulse current TIG welding processes. The induced residual stresses have been measured experimentally by employing X-ray diffraction. The mechanical properties of welded joints have been determined by conducting tensile and Vickers hardness testing. The metallurgical properties of weldments have been analyzed by employing optical and scanning electron microscopy. From the experimental results, lower residual stresses have been observed in Interpulse current TIG weldment than the other two weldments. The tensile properties of the Interpulse current TIG weldment were observed to be higher than the other two weldments. In Interpulse TIG weldments, grain refinement and reduced heat affected zone near the fusion zone have been observed.

Finite element modeling and optimization of hybrid laser–TIG welding of type 316L(N) austenitic stainless steel

An integrated approach was followed for determining the optimized process parameters for hybrid laser-tungsten inert gas (TIG) welding of 316L(N) stainless steel which involve FEM followed by optimization. FEM-based model was developed to predict the thermal distribution for a various combination of welding process parameters. The hybrid heat source combining conical and double-ellipsoidal heat sources was used for generating the temperature distribution during welding. The penetration depth produced by welding was estimated from the thermal model for various set of process parameters by running the model several times. The generated dataset consisting of process parameters and the depth of penetration (DOP) was used for developing adaptive neuro-fuzzy information system (ANFIS) model for correlating the set of input process parameters with the output DOP. This ANFIS model was then used in the objective function of a genetic algorithm (GA) for identifying the optimum process parameters to achieve the maximum DOP during autogenous hybrid laser–TIG welding. The optimized solutions were validated by performing bead-on-plate experiments on 5.6-mm-thick type 316L(N) stainless steel plates. The above-integrated approach was found to accurately determine the optimum hybrid laser–TIG welding process parameters for achieving the maximum DOP with minimum experimentation.

Study of metallurgical changes and mechanical properties of dissimilar weldments developed by interpulse current TIG welding technique

This research manuscript compares the metallurgical changes and mechanical behavior of AISI 316 and Monel 400 dissimilar weldments developed by Interpulse TIG welding process with ERNiCrMo-3 and ER316 filler wires. Metallurgical aspects are envisioned by using optical and scanning electron microscopes. Mechanical behavior of welded joints were studied by conducting tensile and microhardness tests. Metallurgical study has shown that the ERNiCrMo-3 filler weldment divulged completely with austenitic phase structure at the weld zone. Also, at the HAZ of Monel 400 clear grain boundaries with fine grains were observed. The mechanical properties corroborated that the weld strength of ERNiCrMo-3 weldment was found better than the ER316 weldment. Microhardness on the weldment made of ERNiCrMo-3 filler has shown higher values than that of base metals. Weldment made by ER316 was observed to fail near the interface of Monel 400 under tensile test due to the existence of micro-pores and partially melted zones. Further, the metallurgical and mechanical properties are compared with that of the weldment developed by TIG welding process.

Effect of welding parameter on mechanical properties of TIG welded AA6061

Aluminum alloys are currently used in aircraft and automotive parts such as chassis because of its strength and lightweight structure. This work studies the outcomes of welding parameters on 5 mm thick AA6061 sample welded by using the gas tungsten arc welding. TIG welding process is chosen because of its superior technique and better economy. For the selected parameters, the welding was carried on the sample as per the standard American Welding Society (AWS) in four passes by using MGS 525/409 as the filler metal using argon as the shielding gas. Microstructure, hardness and tensile strength were determined to analyze the properties and various parameters of the welded joint. The yield and tensile strength of the sample welded at 160A was found to be 245 MPa and 105 MPa which represents 20% reduction in the ultimate tensile strength and reduction of 61% in yield stress. The hardness was found to be highest for the sample welded at 190A at the metal surface, heat-affected zone and weld zone measured was 103 HRC, 90 HRC and 87 HRC respectively. The Sample welded with 190A showed good bending strength and represented a low included angle. Microstructure showed fine and equiaxed grains uniformly distributed in the welding region.

Optimization of TIG welding parameter in dissimilar joints of low nickel stainless steel AISI 205 and AISI 216

Abstract Low nickel 200 series grade austenitic stainless steels are popular due to their low price and the welding of these materials is of interest to engineers and fabricators. Therefore, the dissimilar joining of AISI 205 and AISI 216 stainless steels are examined in this paper. The study used a TIG welding process with an ER307 filler metal and stepped up welding speeds with varying mixtures of H2 in the argon shielding gas. The weldments on the weld bead (shape and size), solidification mode (predicted on WRC-1992) and the delta-ferrite content (compared between the predicted and calculated lath ferrite with vermicular ferrite) were examined. The microstructure (volume and formation of delta-ferrite in the austenite matrix), mechanical properties (hardness and tensile strength tests) and pitting corrosion resistance (pitting potential and pitted initial) are also studied. The results indicate that the welding speed can be stepped up from a minimum of 1 to a maximum of 3.5 mm/sec. This parameter affected to an increase weld bead size, delta-ferrite, hardness, tensile strength and pitting corrosion resistance of the weld metals. The role of H2 can help heat collection in the weld pool during welding allowing the welding speed to increase up to a maximum 5.2 mm/sec. This was achieved with a 6 vol.% of H2 in the argon shielding gas. These results can help increase productivity and thus be considered a successful outcome for this work.