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ZW61 magnesium alloy has a wide range of application prospects as a lightweight green engineering material. In this paper, the temperature field and microstructure of gas tungsten arc welding (GTAW) for ZW61 magnesium alloy are simulated by the finite element method and the cellular automata (CA) method. The results show that the microstructure in the center of the fusion zone (FZ) is all equiaxed grains affected by compositional supercooling. While at the edge of the molten pool, the crystals produced by associative crystallization evolve into columnar grains after undergoing competitive growth. Furthermore, the temperature field of the molten pool alters as the welding heat input increases. Especially, the temperature gradient behind the molten pool slows down. Thus, the cooling rate during solidification of the molten pool decreases, increasing the size of the weld microstructure. Meanwhile, solute concentration plays an essential role in the weld microstructure evolution. The rise in Zn content both refines the size of the equiaxed grains and inhibits the growth of the columnar crystals. Moreover, the experimental results of the thermal cycling curves and the FZ microstructure exhibit minimal error with the simulation results, verifying the reliability of the model.

In this article, the effects on the weld bead geometry and heat affected zone at observe area explored on Wire Arc Additive Manufacturing Gas Tungsten Arc Welding (WAAM-GTAW). Based on GTAW process, layer by layer WAAM components are produced by deposition welding. Each welding process, the temperature is recorded at one point to determine temperature history. This article explained how specific thermal cycles, from the welding heat input to subsequent cooling phases, dictate the transformation behavior, phase stability, and morphological changes in δ-ferrite, ultimately shaping the material properties and performance of the welded. The factor affecting these properties were explained to identify evolution microstructure in observe area. The paper focuses on the impact of the temperature history to determine macrostructure and microstructure δ-ferrite evolutions of the observe parts deposited in the WAAM process. The thermal cycle experienced during welding lead to the transformation of δ-ferrite into austenite. The δ-ferrite transforms in austenite when the temperature rises above 800 °C–450 °C (T 8/5). Specimens that experienced temperatures above T8/5 exhibited vermicular (V) and eutectic ferrite (EF) modes of delta ferrite. Specimens that had peak temperature prediction records around 750 °C–525 °C in the T8/5 area exhibited ferrite with acicular (Ac) mode. Specimens approaching the lower line of T8/5 around 425 °C showed a transition from acicular to coarse Ac. Specimens with peak temperature records below the T8/5 line generally did not experience changes after the welding process.

This study investigates the effect of a tungsten carbide-nickel coating on the wear resistance of plain carbon steel. The primary phases identified in the coating were Fe3W3C, Fe4W2C, and a eutectic structure containing Fe3W3C and (Fe–Ni)-α. Wear behavior was evaluated through a friction coefficient test and Scanning Electron Microscopy (SEM) analysis. The coated samples exhibited a significantly lower friction coefficient compared to the uncoated sample, indicating superior wear resistance. This improvement is attributed to the presence of a network of (Fe, W)3C carbides and the strong interfacial bonding between the coating and substrate. Coated surfaces displayed parallel scratches and small wear particles, indicative of a scratch-type wear mechanism. Microhardness measurements revealed a distinct profile across the coating thickness. The high hardness near the surface is attributed to the presence of simple carbides. Hardness increased further in the center of the coating due to optimized welding parameters. Hardness decreased towards the interface with the substrate due to a decrease in alloying elements and a shift towards complex carbides.

Recently, a novel Ni–Cr–Co-based superalloy has been developed in China, exhibiting exceptional overall characteristics such as favorable mechanical properties at 800 °C, resistance to corrosion and oxidation, as well as remarkable welding capabilities. In this paper, the welding sample of the novel superalloy was prepared using the gas tungsten arc welding (GTAW) method. The conclusion indicates that the GTAW technique can be utilized to fabricate high-quality weld joints filled with superalloy wire. A segregation phenomenon exists between the core and boundary of the dendrite in the fusion zone. The interface of the joints is effectively fused without any separate area. There is an abundance of co-crystallization occurring between the weld metal and the base metal. Besides, the joint has been tested at room temperature (20 °C) and high temperature (800 °C) for its ultimate tensile strength (UTS). The UTS of the joint is 11780 MPa and 781Mpa at 20 °C and 800 °C, respectively. Moreover, the positions of the fractures in the two cases are different. At 20 °C, the fracture location is in the base metal, while at 800 °C, the fracture location is inside the fusion zone. The SEM analysis of the fracture indicates that at 20 °C, the joint's tensile fracture surface exhibits transparent mixed fracture mode, and there are numerous small dimples; at 800 °C, the dimple on the fracture surface of the joint disappeared, replaced by the feature of smooth fracture along the dendrites.

New systems and methods to access the temperature of the melt pool in welding processes have been developed to study phenomena, monitor behaviours, and even be used in closed-loop control strategies. Concerning arc welding processes, the arc radiation might impose a challenge to measure the temperature. However, heat input is the key point for welding quality. This work aims to evaluate the feasibility and detect potentialities of accessing the thermal field from the rear weld pool in the GTAW process by using in-house developed equipment. The original system was conceptualized based on a previous bichromatic method. Experiments were carried out with and without the wire feed addition, and welding parameters were varied to explore its impacts on the temperature measurement. A strategy to select the regions of interest (ROIs) within the weld pool was created, and the mean temperature was calculated and correlated to the weld bead features. This strategy was able to overcome the challenges imposed by the electrode/nozzle reflection and the arc radiation during the welding. The rear weld pool thermal field was shown to be an important source of data to provide hints of the weld bead features. The mean temperature can indicate geometrical changes in the weld bead. Furthermore, the technique has the potential to be used as a promising real-time process monitoring tool.

Al6013 base metals were joined successfully with ER4047 weld metal by using the GTAW method under different welding currents. Post-weld T6 heat treatment effects on corrosion properties were investigated in terms of open circuit potential (OCP), potentiodynamic polarization (PDS), and electrochemical impedance spectroscopy (EIS) tests. It was determined that corrosion resistance of the post-weld samples increased with increasing welding current, while T6 heat-treatment only effective on 110A and 140A welding current samples (3.61 to 2.08, 2.95 to 2.40, and 1.38 to 2.15 µA·cm-2 for 110, 140, and 170A welding current before and after T6 heat-treatment). The characteristics of the oxide films on the surfaces are revealed with EIS analysis by a two-constant equivalent circuit model which observed that while the passive film originating from Al is formed on the surfaces, on the other hand, it contains a pittings on the surface. It was determined that the pitting resistance of the T6 heat-treated 110A samples increased (3075 to 4562 Ω). Post-corrosion SEM surface morphologies showed that low welding currents lead to more damage with increased exposure to corrosion.

An attempt was made to produce graphene reinforced Inconel 718 composite by new combining accumulative roll bonding (ARB) and gas tungsten arc welding (GTAW). The phase composition analysis and wear behavior of the composite were assessed. The microstructure characterization was studied by Raman spectroscopy, scanning and transmission electron microscopy. The results display that integrating ARB with GTAW can be consider as a suitable way to yield superalloy-based composite with enhanced tribological behavior due to carbide and carbonitride formation formed from decomposition of graphene nanoplates (GNPs). The elastic modulus and hardness were initial recorded by nanoindentation and then used to attain the yield stress, and subsequently for characterizing flow behavior parameters like n and K. The obtained results exposed that the load–displacement curve acquired from nanoindentation and Nanoscratching has an excellent potential to investigate microscopic behavior of particle based composites. Evaluation of scratch mechanisms in composite specimens presented that the key failure in specimens are due to tensile state Hertzian cracks. Though, as the applied load rises, the specimen undertakes increasing incremental plastic deformation and failures change to interfacial spallation.

Gas tungsten metal arc welding (GTAW) is used to study the effect of the base metal thickness, welding current and welding speed on the tensile strength and hardness of mild steel welding. The analysis found that base metal thickness had the highest effect and highest means of tensile strength and hardness of the welding. Taguchi’s design (TD) suggested using higher base metal thickness, lower welding current and higher welding speed when welding mild steel in order to obtain maximum tensile strength and hardness. The welding that has higher tensile strength showed higher hardness. However, the hardness increased proportionally with the increased internal stresses of the welding. The welding showed wider heat affected zone (HAZ) with the increase in internal stresses of the welding.

Ultrasonic impact treatment (UIT) is carried out on the Ni-based alloy stainless steel pipe gas tungsten arc welding (GTAW) girth weld, the differences of microstructure, microhardness and shear strength distribution of the joint before and after ultrasonic shock are studied by microhardness test and shear punch test. The results show that after UIT, the plastic deformation layer is formed on the outside surface of the Ni-based alloy overlayer, single-phase austenite and γ type precipitates are formed in the overlayer, and a large number of columnar crystals are formed on the bottom side of the overlayer. The average microhardness of the overlayer increased from 221 H V to 254 H V by 14.9%, the shear strength increased from 696 MPa to 882 MPa with an increase of 26.7% and the transverse average residual stress decreased from 102.71 MPa (tensile stress) to −18.33 MPa (compressive stress), the longitudinal average residual stress decreased from 114.87 MPa (tensile stress) to −84.64 MPa (compressive stress). The fracture surface has been appeared obvious shear lip marks and a few dimples. The element migrates at the fusion boundary between the Ni-based alloy overlayer and the austenitic stainless steel joint, which is leaded to form a local martensite zone and appear hot cracks. The welded joint is cooled by FA solidification mode, which is forming a large number of late and skeleton ferrite phase with an average microhardness of 190 H V and no obvious change in shear strength. The base metal is all austenitic phase with an average microhardness of 206 H V and shear strength of 696 MPa.

Droplet transfer frequency is a decisive factor in welding quality and efficiency in gas tungsten arc welding (GTAW). However, there still needs to be a monitoring method for droplet transfer frequency with high precision and good real-time performance. Therefore, a real-time monitoring method for droplet transfer frequency in wire-filled GTAW using arc sensing is proposed in this paper. An arc signal acquisition system is developed, and the wavelet filtering method filters out noise from the arc signal. An arc signal segmentation method—based on the OTSU algorithm and a feature extraction method for droplet transition based on density-based spatial clustering of applications with noise (DBSCAN)—is proposed to extract the feature signal of the droplet transition. A new conception of droplet transition uniformity is proposed, and it can be used to monitor the weld bead width uniformity. Numerous experiments for monitoring droplet transfer frequency in real time are conducted with typical welding parameters. This method enables the real-time observation of droplet transfer frequency, and the result shows that the average monitoring error is less than 0.05 Hz.

Gas-Shielded Tungsten Arc Welding (GTAW) was modified to a Flux-Cored-Double-Wire GTAW (FCDW-GTAW); in this technique, wires of different compositions are used simultaneously to obtain different microstructures. In the modified GTAW, automatic flux-cored double-wire was used with a combination of four different wires deposited in AISI1020 steel, allowing different microstructures. Pin-on-disk wear tests described by ASTM G99 was used to evaluate the wear coefficients of four hardfacing materials combining Fe–Cr–C, Fe-Cr-C-Nb, Fe-Cr-C-Mo-Nb, and Fe-Cr-C-Mo-Ti alloys. The combination of these wires resulted in a hypoeutectic microstructure with niobium and titanium carbides, with an average hardness of 650 HV0.3, and hypereutectic microstructures formed by different niobium contents, with a microhardness range from 820 to 1020 HV0.3. The wear tests were performed without lubrication at room temperature, using a 6.0 mm diameter polished alumina sphere as a counter-body. The total distance covered was 1000 m with a speed of 0.1 m/s, a track radius of 6.0 cm, and an applied load of 10 N. Hardness, microstructure, wear coefficient, and wear mechanisms were compared. The results showed that wear resistance could be differentiated by the predominant wear mechanism: polishing for the hypoeutectic hardfacing and cracking for the hypereutectic ones.

In this paper, the combination of shielded metal arc welding (SMAW) and gas tungsten arc welding (GTAW) welding methods are used in a double V groove SS304 10 mm thick plate. Welding current variation of 110A SMAW/120A GTAW, 100A SMAW/130A GTAW, and 90A SMAW/140A GTAW was used to observe the effect of the welding current variation on the tensile strength and microstructure. Tensile test and metallography test were performed to observe the phenomenon. ImageJ software was used for microstructure analysis. The welding current variation resulted in higher tensile strength with the highest current on GTAW method, while a more dispersed and lathy ferrite structure was observed on the microstructure.

If filler metal AH36 steel is used in bimetallic welding, it has the disadvantage of oxidation in the weld area. Also, the weld crack is encountered if filler metal J4 stainless steel is used in bimetallic welding. In this research, welding methods include the preparation of two types of base metal and a twisted combined filler of AH34 steel and J4 stainless steel as a filler rod applied. The welding of 5 mm thick bimetallic material uses the GTAW (Gas Tungsten Arc Welding) or TIG (Tungsten Inert Gas) process with a current electric welding 60 A, 70 A, and 80 A, one layer and two layers, and angle position 90o to 75o. Preparation of tensile test specimens, provision of shallow notches in the weld where the cross-sectional area of the same as the two-parent metals that have been welded together, tensile testing, and analysis of research data are conducted. The welding results using a current of 60 A with one layer showed a tensile strength of 402 MPa. However, welding with two layers decreased to 200 MPa with a difference of 50 % that means there is a significant difference. In the current of 70 A with one layer, the tensile strength is 433 MPa and with two layers, the value decreases very little at 426 MPa with a difference of 2 %, which means there is a minimal difference and makes the best current selection. For current 80 A with one layer produces tensile strength of 412 MPa. Yet, with two layers, the value decreases slightly to 380 MPa with a difference of 8 %, which means there is a relatively small difference.

In this study, three welding methods are used. The purpose to investigation the effects of SMAW, SAW, and gas tungsten arc welding (GTAW) on the tensile stress of low carbon steel conforming to ASTM 283 c. 8mm thick plates are used as base material for butt welded joints. The tensile properties of the welded joints were evaluated and the results were compared by experts using the Taguchi method to design three levels of each parameter (current, voltage and displacement speed). From this research, it is found that compared to metal shielded arc welding and submerged arc welding, the pulling effect of the gas shielded welding joint of the tungsten electrode is the best. This is mainly due to the presence of The results of using analysis of variance (ANOVA) to estimate important parameters show that welding current and speed of the weld have a significant effect on tensile stress .the experimental results are in agreement with predicted results, and the maximum error is 3%..

Abstract This study investigated the pitting and crevice corrosion behavior of the gas tungsten arc welding (GTAW) process in the UNS S32205 according to industrial parameters. Results revealed that the welding process presented a weld metal chemical composition similar to the base metal and an adequate balance of the austenite and ferrite phases. No relevant variation in the hardness was observed and XRD spectra did not identify the presence of deleterious phases in the weld bead. Cyclic polarization tests revealed similarities between welded and base metal samples (20±2°C, NaCl 3.5% wt.). When comparing the behavior obtained in the crevice, and pitting tests, a decrease in the corrosion resistance was observed in the presence of a crevice former. The SEM-EDS proved that the attack occurred mainly in secondary austenites. Profilometry measurements revealed that the crevice corrosion in the weld region was deeper than in the base metal. However, considering the welded samples as a unit, making no difference between regions: weld metal, HAZ, and base metal, the average crevice corrosion depth was comparable to that of the base metal samples. Finally, it was concluded that the welding process used for the UNS S32205 steel did not harm its corrosion resistance.

A comparative study was carried out on GTAW AISI 316 welds fabricated by three different filler metals including ER-317M, ER-316 and ER-308. Filler metals were selected in a way to induce varying Molybdenum (Mo) concentrations in the weld metal, so that the effect of Mo on the microstructural, mechanical and corrosion behavior of the welds was investigated. Microstructural studies revealed that as Mo concentration increased in the weld metal, the dendritic morphology of this zone gradually was changed from cellular dendritic to columnar dendritic and a noticeable amount of austenitic phase and precipitations were formed. Mo-containing ER-316 and ER-317M welds showed appreciable amount of Mo- and Cr-rich carbides such as (Fe,Cr)23C6 which formed at the grain boundaries of δ-ferrite phase resulting in increased the hardness and strength of welded samples. The highest microhardness value of 188 HV and yield strength of 330 MPa belonged to ER-317M welds containing the highest Mo concentration. Also, corrosion resistance of the welds significantly improved by increasing Mo concentration and a minimum corrosion rate of 4.178 mm/year was accounted for ER-317M welds in which, the formation of passive film was more facilitated due to the higher concentration of Mo.

The welding use correct process parameters will produce joint with optimum in mechanical properties. The current is a very important process parameter in welding. Gas Tungsten Arc Welding process carbon steel A53 Gr B uses current variations can be an option to get the best quality joints. The purpose of this research is to get optimum mechanical properties and microstructure by varying the current. The experimental method uses GTAW process by varying current in welding A 53 Gr B using a single V butt joint and a 5G welding position, the Argon protective gas flow rate of 15 liters per minute with filler rod ER 70 S-6. This process also uses 11-13 Volt voltage with DCEN polarity and current 70, 90, and 110A. Based on ASME Section IX, the test results show that the specimen with a current of 90A gives optimum results with a tensile strength of 480 MPa and a hardness value of 190 HV, whereas specimens with welding current of 70A bring incomplete penetration defects in the weld area. The use of welding current 90A in this research provides welding results with better mechanical properties and microstructure compared to the use of currents of 70 and 110A

The gas tungsten arc weldability of micro-alloyed hot-rolled ferritic XPF800 steel, which is newly produced by Tata Steel, has been studied. The weld geometry profile, mechanical properties and microstructure affected by heat input have been investigated. The micro examination of the welded joint has been characterized utilizing optical microscope and scanning electron microscope. Atomic concentrations of metallic elements in carbides have been determined by energy dispersive X-ray spectrometry. The optimum parameters for current, welding speed and heat input have been found to be 140 A, 100 mm/min and 0.62 kJ/mm in the GTAW of XPF800 plates, respectively.

Pitting corrosion would pose difficulty for the cleaning of equipment used in food processing, even when using the Cleaning in Place (CIP) process. It tends to occur at a location requiring welding. In general, Gas Tungsten Arc Welding (GTAW) is the most applicable process for food and drug equipment. To improve the properties of the weldment, filler metals are commonly used. However, the use of thin-sheet stainless steel in the application of filler metals would be difficult in food processing. In this research, the weld metal properties would be improved only by using N2 mixing to the backing gas during welding. Experiments were conducted using various mixtures of N2 on 1.5, 2.0, and 3.0 mm thicknesses of 304 stainless steel. The roots of weld metal taken from the samples were evaluated for corrosion properties in 3.5%NaCl from the polarization curves. The results showed the improvement of pitting corrosion from 379 mV to 757 mV, while the general corrosion rate decreased from 0.00477 mm/y to 0.00099 mm/y with 100%Ar and 100%N2, respectively. Both Nitrogen content and solidification rate together affected the solidification modes and ferrite contents that would affect the corrosion properties. At least 15%N2 mixing would be sufficient for weld metal property improvement. Due to the decrease of ferrite content from N2 addition, solidification cracking susceptibility test by fishbone test was acceptable with no cracking observed, showing the potential to recommend N2 mixtures for actual production.

Use of the powder metallurgy (PM) in production of various components has been growing in the automotive industry, including production of sintered stainless steels (SSSs). This study aims to improve the functional properties of SSSs by formation of the Cr3C2-NiCr coating by APS method. The next stage involved alloying of the surface of SSSs using the gas tungsten arc welding (GTAW). Analysis of microstructures was carried out using microscopy (metallographic microscope and scanning electron microscope). Furthermore, the study presents XRD (X-ray powder diffraction) examinations, mechanical properties and surface roughness measurements. The presented modification improved properties of the surface layers examined in the study and enabled a reduction in the wall thickness of the detail, which is important factor in the automotive and transport industry.

This study presents an appropriate filler metal or welding electrode to join aluminum alloy (AA2024-T3) sheet of 3.2 mm thickness with a square butt joint using Gas Tungsten Arc Welding (GTAW) process. This process was carried out at three different welding currents with three various filler metals: ER4047 (12% Si), ER4043 (5% Si), and ER5356 (5% Mg). Experiments were conducted to investigate the microstructure and the mechanical properties. The effect of various filler metals upon the weld joints quality were analyzed via an X-ray radiographic and tensile test. Hardness test, microstructures, SEM, and XRD also conducted to the welded specimens. It was found that the best result was at 100 Ampere with using filler metal (ER5356) which produced the highest strength of 240 MPa in comparison with welded joints with utilizing fillers (ER4043) and (ER4047) having values of 235 MPa and 225 MPa, correspondingly. The hardness results showed that the highest hardness values were at the weld metal for ER4047 and ER4043, then decreased to HAZ and increased in the base metal. While in the case of ER5356, the highest hardness was in HAZ and decreased in the weld metal. The fractography of the fracture surface of the welded joints after the tensile test was analyzed using SEM

In present work, two nuclear grade steel (P91, P92) are joined using the arc welding process. The welded joints were subjected to the heat treatment in order to restore the mechanical properties and overcome the heterogeneity across the joints. The weldments were studied for microstructure evolution and mechanical behavior under different condition of heat treatment. The variation in mechanical behavior obtained for the welded joints were tried to relate the microstructural evolution. After the normalizing based heat treatment, homogeneity with negligible δ ferrite across the welded joints was observed.

The present article discusses the simulation and mathematical modelling of GTAW for various parameters of single and double V-groove butt joint welds. The chosen materials are EN 10025steel(grade S295) and D36 ship building steel, owing to their wide industrial applications and corrosion resistive nature. The simulation modelling was carried out at 90°, 60°, 45° and 30° groove angles for both similar and dissimilar base metals to predict the deformation, residual stress distribution, heat flux, and nodal temperature using ABAQUS software package. A subsequent mathematical model was developed using MATLAB tool to further predict the temperature distribution and total stress concentration at any localized nodal point. The model can be used to obtain optimal weld parameters such as weld, speed torch temperature, current and voltage. The obtained results were plotted to attain the clear conclusion over the results. The results under simulation showed 45° to be the most effective angle for both Single-V and Double-V grooved butt joints.

Welding of ferritic steel tube material T91 (9Cr-1Mo), was used because of high temperature withstanding, mechanical properties, compatibility with chemicals and adequate weldability. The main objective of this project is to find out near optimum welding parameters with appropriate shielding gas in gas tungsten inert gas welding (GTAW) of T91 tube. The quality and productivity of the weld joint strongly depends on welding parameters. The perfect arc during welding is produced when the welder uses the optimum welding parameters. The composition of shielding gas plays an important role ensuring sound quality of welds. The composition of shielding gas with the molten pool has a marginal influence in the depth of penetration. The optimized parameters with three samples were prepared with different purging gases Viz. 100% helium, 100% Argon, Argon 50% plus Helium 50% for welding of 2.9 mm thick T91 tube with ER 505 filler wire.

In this study, three welding methods are used. The purpose to investigation the effects of SMAW, SAW, and gas tungsten arc welding (GTAW) on the tensile stress of low carbon steel conforming to ASTM 283 c. 8mm thick plates are used as base material for butt welded joints. The tensile properties of the welded joints were evaluated and the results were compared by experts using the Taguchi method to design three levels of each parameter (current, voltage and displacement speed). From this research, it is found that compared to metal shielded arc welding and submerged arc welding, the pulling effect of the gas shielded welding joint of the tungsten electrode is the best. This is mainly due to the presence of The results of using analysis of variance (ANOVA) to estimate important parameters show that welding current and speed of the weld have a significant effect on tensile stress. The experimental results are in agreement with predicted results, and the maximum error is 3%.

A dissimilar welded joint of Inconel 718 and 304L austenitic stainless steel was prepared using a combined procedure with the gas tungsten arc welding and shielded metal arc welding processes by employing the Ni-based fillers: ERNiCr-3 and ENiCrFe-3. The welded joints were investigated for metallographic testing and mechanical properties, and a relationship was established between the microstructure and the resultant mechanical properties. Microstructural observation revealed the formation of the unmixed zone on the 304L SS side. The weld metal showed that the fully austenitic microstructure consisted of the Nb- and Ti-rich carbide phases along the inter-dendritic spaces. The tensile test results at room temperature showed the failure from the weld metal which might be due to alloying element segregation along the inter-dendritic spaces. However, a tensile test at 600 °C showed the failure from the 304L SS base metal with a tensile strength and % elongation value of 377 MPa and 24%, respectively. The hardness plot showed the average hardness value of the weld metal of 236 ± 5 HV, which was higher than the 304L SS BM (204 ± 4 HV) but lower than the IN718 BM (243 ± 5 HV). The impact toughness of the weld metal was 109 J, which was significantly lower than the base metals. The poor impact strength of the weld metal might be due to the evolution of the NbC phase along inter-dendritic spaces.

This study focuses on the results of the welding process when the Taguchi method is added to the design of experimental welding parameters when creating the welding procedure for gas tungsten arc welding (GTAW) by ASME Code for duplex stainless steel (UNS31803). A Vickers hardness tester is employed to collect and convert the tensile strength data for each test piece (weld bead, base material, and heat-affected area). A ferritic rate meter can quickly determine the ferric contents, which affect corrosion resistance and susceptibility to cracking. The test data are entered into the Taguchi technique to analyze the influence of each component on the welding quality. The L9 (34) orthogonal table is used to design the parameters for the experiment. We fixed the same shielding gas and flow rate. Backing gas at root, workpiece clamping angle, heat input, and interlayer temperature are employed as control factors for the four essential variables of the GTAW process. The ideal set of quality analysis and optimization parameters can be found. The welding parameters could be used to improve the welding quality of thin and short duplex stainless steel pipe fittings during argon welding.

Abstract Supermartensitic steels represent a new sub-class of martensitic stainless steels with higher toughness and corrosion resistance than conventional grades. These properties were improved by the drastic reduction of carbon content, and the addition of nickel and molybdenum. These chemical composition changes also increased the weldability of these steels, since the soft and ductile martensite formed is not susceptible to cold cracking during welding. However, post weld heat treatment may be necessary for uses in sour, aggressive and embrittlement environments. This work investigates the mechanical properties of a weld produced by gas tungsten arc welding (GTAW) of a pipe of 12%Cr supermartensitic stainless steel with 625 nickel alloy as filler metal. The response of the weld metal to post weld heat treatments at 650oC was also evaluated.

در این تحقیق خواص اتصال غیر مشابه مس خالص به فولاد زنگ نزن 304 توسط جوشکاری قوسی با الکترود تنگستن و گاز محافظ مورد بررسی قرار گرفت. بدین منظور از قطعات جوشکاری شده با فلزات پرکننده اینکونل 625 و فولاد زنگ نزن 309L، دو نمونه تهیه گردید. ریزساختار و خواص مکانیکی هر دو نمونه توسط آزمون های متالوگرافی، کشش و ریزسختی سنجی مشخصه یابی شد. در جوشکاری با فلز پر کننده ERNiCrMo3 ترک انجمادی در فلز جوش مشاهده گردید در حالی که با فلز پر کننده ER309L، ساختار جوش کاملاً آستنیتی و بدون ترک بود. همچنین در نمونه جوشکاری شده با فلز پرکننده ER309L شکست در منطقه متاثر از حرارت فلز مس اتفاق افتاد. با توجه به نتایج آزمون های صورت گرفته فولاد زنگ نزن 309L، به‌عنوان فیلر مناسب برای این اتصال پیشنهاد شد.

Ferrite number (FN) is a crucial parameter for austenite steel-welding products, since it has a specific relationship with crack sensitivity and other important properties. In this paper, artificial neural network (ANN) models were built to predict FN, based on the GTAW tests of 304L plates produced by two different steelworks, Dongfang Special Steel hot-rolled sheet (DFSS) and Anshan Iron and Steel cold-rolled sheet (ASIS). The results show that a high performance, of more than 98% accuracy, can be achieved when the models of DFSS and ASIS are modeled separately, and that accuracy is also above 96% when an integrated model is built. The influences of nitrogen content and multiwelding parameters, such as travel speed, wire-feed rate, welding current and arc length, on FN are also analyzed through the FN-prediction model for DFSS. The results show that FN increases monotonously with the increase of nitrogen content, but the influences of either of the other two parameters on FN are nonlinear.

Austenitic stainless steels are high corrosion resistant alloys widely used in many industrial fields. Among this family of steels, AISI 317L stands out due to its higher localized corrosion resistance when compared to the traditional grades AISI 304L and AISI 316L. In some applications in oil refineries, the AISI 317L is being specified for services at moderately high temperatures. At the same time as it is sought to use new stainless steels, is also desirable to apply and develop emerging welding processes, replacing conventional ones, in order to achieve better behavior in service. In this respect, this work studied the effects of thermal aging on the toughness and resistance to pitting corrosion of AISI 317L steel weld metals produced by the Gas Tungsten Arc Welding (GTAW) and Friction Stir Welding (FSW) joining processes. After prolonged exposures at 450°C, for 200h, 300h and 400h, the microstructural characterization by scanning electron microscopy (SEM), toughness evaluation and anodic polarization tests in 3.5% NaCl solution were performed. The results showed that the increase of the exposure time in both weld metals caused a toughness decrease. The pitting potentials measured in the polarization tests also decreased with the aging at 450ºC.

Proses pengelasan yang di lakukan pada material aluminium 5083 yang banyak di gunakan pada industri perkapalan yang khususnya digunakan pada bagian konstruksi. Penelitian ini bertujuan untuk membandingkan antara pengelasan TIG (Tungsten Inert Gas) dan MIG (Metal Iert Gas). Pengelasan ini dilakukan pada aluminium 5083 dengan jenis pengelasan TIG dan MIG dan jenis sambungan pengelasan single v butt joint 60o, dengan kekuatan arus sama yakni 200 A. Dari hasil penelitian menunjukan bahwa pada pengujian tarik tingkat kekuatan pengelasan TIG lebih baik dan lebih optimal dibandingkan dengan pengelasan MIG. Pada pengujian bending jenis pengelasan MIG lebih baik dibandingkan dengan jenis pengelasan TIG. Pada arus yang sama yaitu 200 A memberikan kekuatan tarik yang lebih optimal dan lebih baik pada jenis pengelasan TIG. Sedangkan untuk pengujian bending dengan perlakuan yang sama menghasilkan tegangan lentur yang lebih tinggi pada pengelasan MIG dibandingkan dengan pengelasan TIG.

The automotive industry is constantly under several challenges in many aspects, such as development of new materials and improvement their manufacturability. In order to achieve light weight, reduced emissions and ensure conductor safety, advanced high strength steels (AHSS) are able to fulfill these requirements. Dual phase steels (DP) are well suited for light weighing car body constructions. The gas tungsten arc welding (GTAW) process is focused in literature as an alternative choice for joining AHSS steels; this study is held to disclose the exhibited microstructural constituents. In addition, quantitative determinations of the volume % of phases in the various weld regions were made. The relative amounts of lower bainite (LB), upper bainite (UB), and polygonal ferrite (PF) in the heat affected zone (HAZ) were determined by image analysis from optical microscopy (OM) and scanning electron microscopy (SEM). It was found that GTAW promoted the development of significant amounts of LB in the HAZ (50.89 %). In contrast atomic force microscopy (AFM) leads to quantify the different phases by the morphology, height and roughness, it was found that martensite (M) dropped down to 7.5% in the intercritical zone (IZ) although PF increases to 92.5% compared with the base metal (BM).

The effect of the nitrogen content in the shielding gas and its effect on temperature distributions at the welded zone of thin sheets of duplex stainless steel have been evaluated. The duplex stainless steels have many features due to unique microstructural combination of austenite and ferrite grains. The phase balance can be easily shifted depending on the welding parameters. Two sheets were welded using pure argon and pure argon plus 2% of nitrogen as shielding gas. The thermal profile had shown that N2-supplemented shielding gas lead to higher peaks of temperature using similar welding parameters. Microstructural examination showed that the austenite phase in the weld increased with the presence of nitrogen in the shielding gas. The added nitrogen promoted primary austenite formation and slightly increases the microhardness at the solidified zone. Microhardness mapping and metallographic imaging presented information about microstructures, confirming the formation of secondary phases during thermal cycle in the temperature range 850 °C and 950 °C. Control of ferrite amounts in the welds is essential mainly to improve mechanical properties and corrosion resistance of welding zones.

Progress in sustainable manufacturing is a crucial element to minimise negative environmental impacts. The conventional fusion weld process used to join aluminium alloys resulted in coarse grain structure, inevitable defects, and severe joint softening. Friction stir processing (FSP) has the potential to modify the microstructure of materials in joint structure and improve the mechanical properties. In this investigation, the effect of friction stir post–processing was evaluated to study the microstructural characteristics and mechanical properties of GTAW (gas tungsten arc welding) welds in the aluminium 5052 alloy. During FSP, the grains’ dendritic microstructure was destroyed, and the dynamic recrystallisation resulted in a very fine and equiaxed grains structure in the fusion zone. The hardness of the friction-stir-processed welds significantly improved because of microstructure grain refinement. The processed joint demonstrated higher ultimate tensile and yield strength (~275 MPa and 221 MPa, respectively) and superior elongation (31.1%) compared to the unprocessed weld; at the same time, the mechanical strength (yield and ultimate tensile) is similar to that of the base metal.

Gas Tungsten Arc Welding (GTAW) is one of the most used methods to weld aluminum. This work investigates the influence of welding parameters on the microstructure and mechanical properties of GTAW welded AA6105 aluminum alloy joints. AA6105 alloy plates with different percent values of cold work were joined by GTAW, using various combinations of welding current and speed. The fusion zone, in which the effects of cold work have disappeared, and the heat affected zone of the welded samples were examined under optical and scanning electron microscopes, additionally, mechanical tests and measures of Vickers microhardness were performed. Results showed dendritic morphology with solute micro- and macrosegregation in the fusion zone, which is favored by the constitutional supercooling when heat input increases. When heat input increased and welding speed increased or remained constant, greater segregation was obtained, whereas welding speed decrease produced a coarser microstructure. In the heat affected zone recrystallization, dissolution, and coarsening of precipitates occurred, which led to variations in hardness and strength.

This work focuses on the effect of welding parameters on corrosion behavior of welded duplex stainless steel (DSS) and super duplex stainless steel (SDSS). The effect of welding parameters, such as heat input, inter-pass temperature, cooling rate, shielding/back purging gas, on corrosion behavior was studied. DSS and SDSS pipes were welded with Gas Tungsten Arc Welding (GTAW) process. After welding, the test samples were non-destructively tested to ensure no defects and test samples were prepared for microstructural examinations and ferrite content measurements. The root region had complex microstructure because of the repetitive heating of the zone during different weld layers. It was observed that at low heat input desirable microstructure was formed. The test samples were subjected to corrosion tests, i.e. ASTM G48 test for the determination of pitting corrosion rate, potentiodynamic polarization tests, and potentiostatic tests to verify susceptibility of the alloys to corrosion attack. DSS weldments had CPT in between 23 °C to 27 °C and SDSS weldments had CPT between 37 °C to 41 °C in potentiostatic measurements. The corrosion test results were correlated to the microstructures of the weldments. The pitting resistance of individual phases was studied and the effect of secondary austenite on corrosion attack was also observed.

High-strength aluminum alloy fabricated using spray deposition technology possesses many advantages, such as fine crystal grains, low component segregation, uniform microstructure, and small internal stress. In this study, spray-deposited 2195 Al-Cu-Li alloy in forged state was used and welded using the gas tungsten arc welding (GTAW) process to test and verify the features of the fusion joint. Quantitative analysis was carried out to evaluate the relationship between the local microstructures and performances of the fusion joint, which was composed of four zones: weld metal, fusion zone, heat-affected zone, and base metal. The characteristic quantities of each zone, including recrystallized grain fraction, grain sizes, grain misorientation angle, and Vickers hardness, and their distributions were considered as the key factors affecting the performance of the joint because of welding thermal cycle impact on the fusion joint. To recognize the metallurgical characteristics of spray-deposited alloy 2195, a statistical algorithm based on the concept of the Hall–Petch relationship was proposed to validate the actual test results, which include the correlation effects of both the filler wire and welding process. The correlation between the microstructures and performances of several characteristic quantities were evaluated by integrating the above characteristic information of the fusion joint under the strong coupling of multiple factors. Thus, the advantages of weldability of spray-deposited alloy 2195 using GTAW could be understood in detail.

7075 aluminum alloy in the T6 state was subjected to surface remelting treatment using Gas Tungsten Arc Welding (GTAW). The changes in the material microstructure were examined by means of light microscopy, scanning electron microscopy and EDS. Moreover, profilometric tests and comparative measurements of material hardness in the state before and after the treatment were conducted. In the remelted layer strong microstructure refinement and the disappearance of microstructure banding were found. A fine dendritic microstructure was dominant in the remelted zone. Use of the GTAW method reduced the number of intermetallic precipitates in the surface layer. A consequence of dissolving the precipitates was a decrease in the hardness of the material in relation to the hardness before the modification. All the samples were characterized by the presence of a remelted zone, a narrow partially remelted zone and a wide heat affected zone. With an increase in the heat source travel speed, and consequently less heat entering the remelted material, the dimensions of the individual zones decreased. The conducted research showed that GTAW technology can be used in the surface remelting treatment of aluminum alloys and can be a competitive solution in comparison to other technologies.

This work aims to investigate the effects of two welding techniques (gas tungsten arc welding (GTAW) with filler metal ER70S-3 and flux cored arc welding (FCAW) with filler metal E71T1C) on the microstructure and mechanical properties (including softening due to the conversion of martensite into tempered martensite) of DP steels with different martensite volume fractions ranging from 9 to 20%. Microstructure features and the constituents of base metals and heat affected zones of all weldments were examined and analyzed using an optical microscope and a scanning electron microscope integrated with energy-dispersive x-ray spectroscopy. Hardness, tensile, and v-notch impact toughness measurements were also carried out. Visual and radiographic inspection showed that both the FCAW and GTAW techniques produced sound weldments. However, DP steel weldments exhibited softening effects, which led to a decrease in joint efficiency. This decrease were related to transformation of the original martensite into tempered martensite. The results also revealed that the DP steel joints efficiencies are ranged from 85.9 to 87.7% using the FCAW process and ranged from 83.3 to 86% using the GTAW process. The impact toughness of the samples welded by FCAW is higher than the impact toughness of those welded by GTAW due to a higher percentage of acicular ferrite. This information should be valuable in the automotive and other industries, where DP steels are valued for their combination of high strength and ductility, which leads to weight savings and thus to reduced fuel consumption.

The objective of the present work was to evaluate welding of thin sheets (thickness < 1 mm) of similar and dissimilar NiTi alloys with AISI 304 stainless steel using the Gas Tungsten Arc Welding (GTAW) process and to study the mechanical and metallurgical properties of the joints with and without post-welding heat treatment (PWHT). The GTAW process was chosen because it is more economical than the usual welding processes for NiTi alloys, such as the Laser Beam Welding (LBW). The welded joints were characterized by the techniques of SEM, OM, electrical resistance in temperature (ERT), tensile test and Vickers microhardness. It was observed that the dissimilar joints presented a brittle behavior due to the formation of brittle elements along the weld metal by the excessive increase of the hardness in this region with peaks of hardness higher than 900HV. Similar joints presented superior mechanical behavior, with extensive plastic deformation before rupture and fracture surface with ductile appearance. The PWHT in the similar joints promoted a decrease in the rigidity of the material by minimizing the thermal stresses from the welding process, the PWHT did not influence the dissimilar joints mechanical behavior.

Este artículo estudia el efecto de la soldadura de raíz (GTAW) con ERNiCrMo-3 sobre la microestructura y propiedades mecánicas de una unión de fundición nodular cuando las pasadas de la cubierta se realizan con la técnica SMAW con electrodos de Ni. Para tener una mejor comprensión de los resultados, se comparan con las características de una soldadura completa de Ni SMAW. Esto se hizo antes y después de un recocido a 900 °C con el fin de evaluar las influencias y los posibles beneficios de este tratamiento térmico. Los resultados muestran que la presencia de una soldadura de raíz de GTAW ERNiCrMo-3, a pesar de la mejora de la penetración, conduce a una pérdida de propiedades mecánicas en la soldadura de raíz que, incluso con un recocido, no es posible eliminar.

The purpose of the present work is to understand the evolution of residual stresses in weldments. The study made to weld the multipass dissimilar of Nickel-based superalloy Inconel 625 and stainless steel 316L using Continuous Current Gas Tungsten Arc Welding (CCGTAW) and Pulsed Current Gas Tungsten Arc Welding (PCGTAW) process employing ERNiCrMo-3 and ERNiCr-3 fillers. The L4 orthogonal array was used in the present experimentation process. Analysis of Variance (ANOVA) is applied for the optimization and to identify the critical parameters. In welding process, the size of the lattice size will be stressed due to welding parameters; the lattice dimension is measured by non-destructive technique X-Ray diffraction to investigate residual stress in the weldment in the lateral surface of the plate. X-Ray Radiography test has evaluated the quality of welds. The results show that root gap is a critical parameter and filler wire and weld processes are not critical.

Automatic joint detection is of vital importance for the teaching of robots before welding and the seam tracking during welding. For narrow butt joints, the traditional structured light method may be ineffective, and many existing detection methods designed for narrow butt joints can only detect their 2D position. However, for butt joints with narrow gaps and 3D trajectories, their 3D position and orientation of the workpiece surface are required. In this paper, a vision based detection method for narrow butt joints is proposed. A crosshair laser is projected onto the workpiece surface and an auxiliary light source is used to illuminate the workpiece surface continuously. Then, images with an appropriate grayscale distribution are grabbed with the auto exposure function of the camera. The 3D position of the joint and the normal vector of the workpiece surface are calculated by the combination of the 2D and 3D information in the images. In addition, the detection method is applied in a robotic seam tracking system for GTAW (gas tungsten arc welding). Different filtering methods are used to smooth the detection results, and compared with the moving average method, the Kalman filter can reduce the dithering of the robot and improve the tracking accuracy significantly.

Celem pracy była ocena wpływ u metody napawania Inconelem 625 rur kotłowych ze stali P235GH i 16Mo3 na mikrostruk- turę i własności podłoża i napoiny. Badania prowadzono na odcinkach rur kotłowych napawanych stopem niklu Inconel 625. Rury zostały dostarczone do Fabryki Kotłów SEFAKO S.A. przez czterech dostawców, stosujących różne metody napawania, a mianowicie CMT, GMAW i GTAW. Badania wykazały, że mikrostruktura i własności mechaniczne rur napawanych istotnie zależą od zastosowanej metody napawania oraz od składu chemicznego materiału podłoża.

En este trabajo se determinó la influencia de la corriente continua, la corriente pulsada con 20 y 50 Hz de frecuencia en las propiedades mecánicas, microestructura así como ancho del cordón del proceso de soldadura GTAW en titanio 6Al4V de 1,6 mm de espesor. Se realizó un diseño de experimentos factorial completo con tres réplicas. En el diseño de experimentos fueron analizados los factores, como el uso de aporte y frecuencia. Se consideraron dos niveles para el factor metal de aporte cuyo nivel máximo es el uso de aporte y el mínimo sin uso de aporte. Para el caso de la frecuencia se consideraron tres niveles, siendo el mínimo, corriente continua, 20 Hz como nivel medio y 50 Hz como nivel máximo. Se realizaron ensayos mecánicos de tensión, microdureza Vickers 500 g, así como macro y micrografías de las uniones soldadas. Se encontró que las propiedades mecánicas de la unión son afectadas significativamente (valor P < 0,05) con respecto a la frecuencia, tanto utilizando metal de aporte, o sin el uso de este. El ancho de cara y raíz disminuyó cuando ocurrió un cambio de corriente continua a 20 Hz, mientras que de 20 a 50 Hz no presentó un cambio significativo.

Se llevaron a cabo soldaduras sin material de aporte y empleando un electrodo convencional (ER308L) para unir un acero inoxidable ferrítico, empleando el proceso de soldadura de arco con electrodo de tungsteno (GTAW). Los parámetros de soldadura fueron ajustados para obtener tres valores diferentes de calor de aporte. La microestructura revela la presencia de una matriz ferrítica gruesa y placas de martensita en la Zona Afectada por el Calor (ZAC). La dilución entre el metal base y de aporte fue correlacionada con la presencia de austenita, martensita y ferrita en el metal de soldadura. Los ciclos térmicos de la soldadura fueron medidos para correlacionar la transformación microestrutural en la ZAC. Mediciones de microdureza (mapas y perfiles), permitieron identificar las diferentes zonas de las uniones soldadas (metal base, ZAC y metal de soldadura). Se observó un incremento de dureza en el metal de soldadura (~350 HV0,5) y en la ZAC (~310 HV0,5), en relación al metal base (~172 HV0,5), que se ha atribuido a la formación de martensita. La resistencia a la tensión de las uniones soldadas sin metal de aporte aumentó ligeramente con respecto al metal base. En cambio, la ductilidad se incrementó aproximadamente un 25% en relación al material base, lo cual mejoró la tenacidad de las uniones.

The paper presents the analysis of solidification mode at gas tungsten arc welding (GTAW) of AISI 430 ferritic stainless steel. Two solidification modes (epitaxial and equiaxial) were discovered, which have a major influence on a weld tensile strength. The optimal welding parameters for ferritic stainless steels were found in a narrow range. They should be selected according to mechanical strength of the welded joints and not only according to their visual appearance.

This paper presents the use of two welding processes for the refurbishment of damaged industrial tools. In the first part the problem is presented followed by the comparison of GTAW and laser welding in terms of repair welding of damaged tools. The macrosections of the welds show the difference between both welding processes in repairing of damaged tools. At the conclusion the main findings are presented. In many cases it is useful to use both welding processes in order to achieve better weld quality and to make welding more economical. The order of the technology used depends on the tool material, the use of the tool and the tool damage.

Gas tungsten arc welding (GTAW) with three different heat inputs controlled by the weaving width was performed to understand their effects on the microstructural changes during bead-on-pipe welding of super duplex stainless steel. The microstructure of the weld metals was categorized into three different types of zones: non-reheated, reheated type, and reheating-free zone. Even though single-pass welding with different weaving widths was employed, a reheated microstructure was detected, which has been previously observed with multiple pass welding. This phenomenon was called “dynamic reheating”, because it was produced by the weaving operation during welding regardless of the weaving width. The categorized area fraction varied with the weaving width change. Electron backscatter diffraction (EBSD) results at the edge (the area near the fusion line) of the low-heat-input condition indicated a higher austenite volume fraction and a lower Cr2N fraction than that of the medium heat input condition. Thus, it described an inverse relationship, because higher heat input provided a lower austenite fraction. In addition, it was observed clearly that the austenite fraction at the medium heat input condition was dramatically increased by reheating, while the Cr2N fraction was reduced. Regardless of the weaving width, reheating contributed to the increase of the austenite fraction, further reducing the Cr2N quantity. The edge areas in the map showed an inverse relationship in the reheated area fraction between low heat input and medium heat input. For this reason, the austenite fraction on the weld metal was determined not only by the heat input, but also by the amount of reheating.