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Activating flux is made up of inorganic material mixed with a volatile medium. The objective of this study is to identify and review the literature in activating flux, and different type of welding techniques. For that purpose, a structured review method is adopted and the Scopus database is used as a primary source for the selection of papers. The papers were identified using the string term of "Activating flux" OR "Activated flux" in the title of papers. And a total of 238 papers were identified for the study. Besides the above few other papers were also reviewed and the materials used, the type of flux used, and the findings of different combinations were highlighted in the form of tables. The findings of the study provide a comprehensive understanding of the different type of welding techniques focusing on TIG welding, and the different combination of flux used and their impact was summarized. [ABSTRACT FROM AUTHOR]

The present work reports about the effect of cast scandium doped ER5356 filler rod in Tungsten Inert Gas welding of dissimilar Aluminium Magnesium alloys. The grain refinement effect on weld microstructure by transition metal scandium was investigated with optical and scanning electron microscope. Additionally, XRD analysis, tensile strength (global and component joint) and microhardness were tested on weld samples. The microstructural examination in weld fusion zone observed fine grain size and suppressed dendrite arm spacing. The formation of Al3Sc precipitate in weld fusion zone due to scandium inclusion in filler was identified and resulted in improving the weld strength significantly. The higher joint efficiency of 92.5% was achieved in the global joint of weld samples. The failure location of global joint tensile samples identified the weld fusion zone is stronger than AA5052 base material. Further weld strength was evaluated with component joint by micro tensile test, which results in 70MPa enhancement in UTS values and validating the accurate weld strength. However, the elongation of the tensile test sample reduced marginally for the weld. The fracture mechanism of the weld joint observes decrease in ductility. The significant increase in hardness of the weld fusion zone was evident due to doping of scandium compared to the other zones of the weld. [ABSTRACT FROM AUTHOR]

Hardfacing process is a method used to increase the wear resistance for all kinds of steel. It is known that deformation and residual stress occur in the plates during the hardfacing process made by welding method. In order to minimize these, various welding patterns (welding seams) have been analyzed with a numerical study. TIG welding was chosen as the welding method. Hardfacing weld seams were sparsely applied on the plates. Deformation and residual stress tendencies in patterns can be calculated with sparse weld seams. The numerical model was created using ANSYS finite element software and validated with experimental results. The heat input of the welding process was calculated by using the double ellipsoid moving heat source method. It has been determined that transverse weld seams in rectangular plates cause smaller deformations and residual stresses. [ABSTRACT FROM AUTHOR]

Technological regimes for producing wrought products (2 and 1 mm) from the Al–4.5%Zn–2.5%Mg–2.5%Ca–0.5%Fe–0.2%Zr–0.1%Sc experimental alloy, including thermomechanical processing at temperatures of 400–450°C and a reduction ratio up to 98%, as well as softening annealing of the sheet metal at 350–400°C for 1–2 h, are presented. It is found that the as-cast structure consists of eutectic phases (Al, Zn)4Ca, Al10CaFe2, and a nonequilibrium T-phase Al2Mg3Zn3 with a size from 5 to 25 μm located along the boundaries of dendritic cells (Al). Zirconium and scandium in solid solution out of solidification are observed. After hot rolling, the structure of 2-mm sheets consists of oriented discrete intermetallic particles and their conglomerates up to 40 μm in scale in the (Al) matrix. The structure of 1-mm sheets is characterized by greater fineness and uniformity of structure. An analysis of the fine structure of deformed semifinished products using transmission electron microscopy (TEM) shows that the size of nanoparticles of the Al3(Zr,Sc) phase of the L12 structural type does not exceed 20 nm in cross section. In wrought semifinished products, the following level of mechanical properties is achieved: ultimate strength σu ~ 310–330 MPa and yield strength σ0.2 ~ 250–280 MPa with a relative elongation δ ~ 4.5–7.0%. The possibility of using argon-arc welding with standard AMg5 wire as an additive material is studied. It is shown that the new alloy does not show a tendency to form hot cracks. According to the results of X-ray tomography, the percentage of porosity in the weld is 1.27 vol %. The prevalent pore diameter does not exceed 0.2 mm. In general, the resulting structural and qualitative parameters of welded joints contribute to obtaining a strength of 75% of the strength index of the initial deformed semifinished products (sheets), which is achieved by stabilizing annealing at a temperature of 350°C for 3 h. [ABSTRACT FROM AUTHOR]

• Studied the weldability of 304 CMT additive manufacturing stainless steel successfully. • Welding along the traveling direction can obtain welded joints with better performance. • Welding along the traveling direction, ∂ 1 = 0.919, ∂ 2 = 0.869, and the elongation is 37.7 % after welding. In this study, 304 stainless steel thin-wall component were obtained by wire arc additive manufacturing (WAAM) as one of the methods of additive manufacturing. In view of the limits that the WAAM technology can not produce large and complex components at one time, TIG welding was chosen during secondary processing to achieve the effectively connection. Weldability, microstructure, texture strength and mechanical properties were particularly investigated when welding along the traveling and building direction. The results show that welding along the traveling direction gained better performance weld joints than building direction including higher tensile and yield strength, greater elongation and lower texture strength. Besides, the grain orientation changed from [0 0 1] before welding to [1 1 1] after welding in both traveling and building direction. [ABSTRACT FROM AUTHOR]

This study investigates the feasibility of using two-layer tungsten inert gas (TIG) welding to repair damaged parts made of 3.5NiCrMoV low-alloy steel, which is widely used in various industries for complex and thick components. Experimental and analytical methods are used to determine the optimal heat input for the second layer of welding, which can eliminate the need for post weld heat treatment (PWHT). The first layer is welded with a heat input of 0.42 kJ/mm and the second layer is welded with heat inputs ranging from 0.59 to 0.92 kJ/mm. The effects of the second layer heat input on the microstructure, peak temperature profile, cooling rate, hardness, and impact energy of the welded alloy are evaluated. The optimal heat input for the second layer is found to be 0.76 kJ/mm, which is 1.8 times the heat input of the first layer. This heat input tempers the coarse-grained region in the heat affected zone (HAZ) caused by the first layer, maintains the hardness of the weld metal, and improves the impact energy of the welded alloy. This method is novel and useful because it can save time, money, and energy for repairing the damaged parts made of high strength low alloy steel. This method can also provide useful information for controlling the microstructure and mechanical properties of high strength low alloy steels during welding. Rosenthal's analytical models are used to simulate the temperature and cooling rate profiles of the welded metal and the HAZ, and the results are compared with the experimental data. • Peak temperatures calculated by Rosenthal model are in agreement with experiments. • If HI(2nd Lay.)≤1.4 HI(1st Lay.), temperature in the initial CG-HAZ will be ≤ 600 °C. • If HI(2nd Lay.)≥2 HI(1st Lay.), the refinement of grains occur in initial CG-HAZ. • If HI(2nd Lay.)≈1.8 HI(1st Lay.), peak temperature in CG-HAZ reaches 670–680 °C. • In this condition, tempering of the HAZ microstructure is done well. [ABSTRACT FROM AUTHOR]

Welding processes are widely used in many industries. The determination of welding parameters and the study of their influence on the mechanical and metallurgical behavior of materials require multiple experiments, and the relevant studies are costly in terms of time and resources. Thus, numerical simulations can serve as a solution when it comes to choosing the appropriate welding process and optimizing its parameters while minimizing costs. The present work contributes to the development of a finite element code, using MATLAB software, for the prediction of thermo-mechanical and metallurgical behavior during the Tungsten inert gas (TIG) welding process. Numerical computation is based on the mathematical formulation of physical phenomena and thermal exchanges. In this paper, results dealing with the prediction of the temperature field evolution during the C50 steel TIG-welding process are presented. In this case, the thermal problem is solved numerically using the finite element method. The memory and computation time problems are solved using optimal stocking and resolution algorithms. To validate the developed computation code, numerical results are first compared with other published numerical results, then with our experimental data. A satisfactory concordance between simulated temperature evolutions and those measured with thermocouples implanted in the welded sheets was found.

Titanium and titanium alloys can be welded by gas tungsten arc, gas metal arc, plasma arc and electron beam welding processes. Titanium material is a reactive metal and is sensitive to embrittlement by oxygen, nitrogen, and hydrogen gas at elevated temperatures. Consequently, the metal must be protected from atmospheric contamination. This can be provided by shielding the metal with welding grade inert gas. The present work describes the application of TIG arc welding to titanium and investigated the effect of welding parameters like weld current, weld gap and gas flow rate on mechanical properties of welded joints of unalloyed commercially pure titanium Gr-2 materials. Taguchi optimization method has been used to find out optimal setting of parameters for weld joints characterization. The welded joints showed maximum ultimate tensile strength of about 429MPa with percentage elongation of 23.33%. A significant grain coarsening has noticed in the fusion zone consisting of a-phase in different direction bounded by -phase. The hardness value at fusion zone and base metal are typically observed to be 235HV and 145HV respectively.

Tungsten inert gas (TIG) welding had been applied to produce four double-V butt welded joints performed on thick plates made from 6082-T6 aluminum alloy. The thicknesses of the plates are 18, 45, 60, and 80 mm. This type of aluminum alloy is very sensitive to heat due to its high conductivity and high thermal expansion coefficient. Heat from TIG welding reduces the strength of the cited welded plates in the welding zone and in the heat affected zone (HAZ) and favorites the formation of porosities and solidification cracks in the welded joints. Porosities and solidification cracks are the most frequent imperfection that appear in this type of welded joints and they are often the reason which prevent them to comply with the requirements of the BS EN ISO 10675-2: 2017 Non destructive testing of welds: Acceptance levels for radiography testing—Aluminium and its alloys, and of the BS EN ISO 23277: 2015 penetrant testing of welds—Acceptance levels. This article represents the type of the filler metal that used and the welding parameters that applied to perform TIG welding of the cited thick plates in order to get welded joints that are free from porosities and solidification cracks as confirmed by X-ray radiography and by red dye penetrant testing of these welded joints. [ABSTRACT FROM AUTHOR]

Automated in-process Non-Destructive Testing (NDT) systems are rapidly gaining traction within the manufacturing industry as they reduce manufacturing time and costs. When considering calibration and verification of such systems, creating defects of known geometry and nature during the deposition of a weld can: (I) help examine the capability of the automated system to detect and characterise defects, (II) be used to form a database of signals associated with different defect types to train intelligent defect classification algorithms, and (III) act as a basis for in-process gain calibration during weld inspection at high temperatures, where the ultrasound beam can be skewed as a result of velocity gradients. In view of this, this paper investigates two unique methodologies for introducing: (a) lack of fusion weld defects by embedding tungsten in the weld and (b) creating artificial weld cracks by quenching to imitate the real cracking scenarios. According to the results of Phased Array Ultrasound Testing (PAUT) inspections, the methodologies used for embedding the artificial defects were successful. The validity of inspections was also verified by extracting micrographs from the defective sections of the welds, and model-based simulations were carried out to gain a better understanding of the wave propagation path and interaction with the generated defects.

This paper investigated the design of a system to monitor the status of the robotic welding process of thin-walled components for an aircraft jet engine. Opportunities to measure and log processing parameters, such as welding speed, current, and voltage, on the existing production cell were taken. The acquired data were processed using elements of descriptive statistics. Obtained indicators were matched with physical inspection results of the weld’s quality. The adopted methodology was used to identify an essential parameter determining the presence of defined weld defects. The developed solution was implemented in the production cell.

Industrial applications often require welded joints of dissimilar metals to perform reliably under adverse working conditions. Such conditions demand high resistance to failure modes, such as fatigue, corrosion, and creep. In applications involving intense vibrational and cyclic loading conditions, high strength-to-weight ratio metals, including aluminum, are more vulnerable to fatigue failure. This study investigates the fatigue strength of base metals and tungsten inert gas welded joints of the two most widely used aluminum alloys, AA7075 and AA2024, under four-point rotating bending. For the comparative study, these dissimilar alloys were joined together by using two different filler rods, AA4047 and AA4043, under similar welding conditions. SN curves for all the samples were generated through the experimental iterations. A comparison of different results shows that welded samples have better fatigue strength than the base metals, while, as a filler, AA4047 has better resistance to fatigue fracture than AA4043.

Dissimilar weld joints plays a major role in power generation, electronic, nuclear reactors, petrochemical and chemical industries due to environmental concerns, energy saving, high performance, cost saving and so on. However efficient welding of dissimilar metals has posed a major challenge due to difference in thermal, mechanical and chemical properties of the materials to be joined under a common welding condition. In the present work dissimilar joints of AISI 304 and AISI 310 steels are produced using Tungsten Inert Gas (TIG) welding. Welding current, wire feed rate, flow rate of gas and edge included angle are considered as input parameters and tensile strength, Impact strength and Maximum bending load are considered as output responses. Response Surface Method (RSM) is adopted using Central Composite Design (CCD) and 31 experiments were performed for 4 factors and 5 levels. Tensile strength, impact strength and maximum bending load are measured. Analysis of Variance (ANOVA) is carried out at 95% confidence level. Effect of welding parameters on output responses are studied by drawing main effect plots, contour plots and surface plots. Optimal weld parameters are identified using Response optimizer [ABSTRACT FROM AUTHOR]

Aluminium alloys are widely used in the fields of electric module packaging, electronic technology, automotive body structure, wind and solar energy management, due to the advantages of high specific strength, high processability, predominantly anti-erosion, increased conductivity, eco-friendly nature and recoverability. The objective of the study is to review the previous papers on aluminium usages, application, and workability parameters. The methodology adopted for the study is to use the structure literature review technique, and the time period selected for the study is 2008–2019 from the Scopus database. The findings of the study concluded that there are various types of aluminium alloys has been used by the previous researchers, and only 6061 is least explored aluminium alloy among all of them. The future scope of the study is to investigate using distinct activating fluxes for raising penetration & to understand consequences on mechanical components & rust behaviour of TIG-welded aluminium metal welds. [ABSTRACT FROM AUTHOR]

In recent years, microwave welding has received attention for joining of similar and dissimilar metals due to its major advantages like volumetric heating, selective heating of target materials, energy saving and sustainability. In the present work, the microstructural characteristics and mechanical properties of Inconel-625-welded joints developed through microwave hybrid heating and those produced by TIG welding have been compared. Welding through microwave hybrid heating (MHH) was carried out using Inconel-625 interface filler powder of 50 μm size, while TIG welding was carried out using ERNiCrMo-3 filler wire of 2.5 mm diameter which had a composition similar to that of Inconel-625 alloy. The welded samples were characterized in terms of microstructural observations and tensile and microhardness properties. The study reveals that the joining of bulk metals through MHH has potential in manufacturing industries in the near future. TIG-welded joints exhibit superior strength compared to MHH joints because of fine grain structure, lower amount of segregation in the weld zone and also smaller width of the weld zone in joints developed through MHH. The hardness in the weld zone of welded joints in both the cases is observed to be almost the same. Use of a finer interface filler of 20–25 μm particle size may further contribute to improving the mechanical properties of the joints developed through MHH. Furthermore, the use of industrial microwave furnace may improve the strength of MHH-welded joints as the process may be integrated with real-time temperature measurement of the joint zone so as to achieve better control over the process. [ABSTRACT FROM AUTHOR]

The presented study involved mathematical modelling of single pass TIG welding of duplex stainless steel S32205. The temperature fields, the fusion zone and HAZ dimension, the cooling rate fields, residual stresses taking into account kinetics of dissolution of austenite during heating and kinetics of precipitation of austenite during cooling were obtained. The comparative analysis of residual stresses with/without phase transformations showed the difference of residual stresses distribution due to different amounts of austenite and ferrite and due to volumetric changes during phase transformations. 24 Ref, 1 Тabl., 9 Fig. [ABSTRACT FROM AUTHOR]

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

The titanium (Ti) and its alloys are taken into interest for commercial purpose due to its low density, high yield strength and high corrosion resistance properties. The present work deals with microstructural observation and mechanical property analysis of tungsten inert gas (TIG) welded Ti-6Al-4V alloy joints. For the purpose, two different set of plates were welded at same current and voltage, i.e., 190 A and 24 V, by the TIG welding technique. A critical analysis of the microstructure and mechanical properties like tensile strength and hardness of the welded Ti-6Al-4V plates was carried out in this work. It was found that both plates showed different behavior during the tension test. Plate 1 had 464.54 MPa of tensile stress and it broke at the welded joint. Plate 2 was unaffected at the welded zone but was broken at the base metal zone. The second plate had tensile strength of 501.83 MPa. According to the hardness test, both the welded plates possessed the highest hardness at the welded zone. However, plate 2 showed approximately 10% higher hardness than that of plate 2. A proper inter-relationship was observed between the mechanical behavior and microstructural appearance. The microscopic view of the welded joints revealed the presence of α, β and martensitic-α phases. [ABSTRACT FROM AUTHOR]

The demand for improved integrity and reliability of weldment poses a huge challenge to manufacturing industries. In this work, Tungsten Inert Gas (TIG) welding technique was used in the welding of AISI 304 stainless steel, with the aim of investigating the effects of welding parameters (gas flow rate, current, voltage and root gap) on microstructure and mechanical properties. A constant wire feed rate and welding speed of 7 m/min and 15 mm/s, respectively, were utilized throughout the welding process, while experimental design and multi-response optimization were conducted using Taguchi (L934) and grey relational analysis (GRA), respectively. The experimental results revealed that change in welding parameters affects the mechanical properties of the weldment, while analysis of variance results showed that hardness and impact energy are mostly influenced by root gap, current is the most contributing factor on tensile strength. The GRA results revealed that multi-response optimization can be achieved with gas flow rate (5 ml), current (120A), voltage (3 V) and root gap (2.5 mm), while the morphology of the weldment showed heterogeneous microstructure, consisting of finer with few coarse grains of ferrite and pearlite. Also, a percentage error of less than 5% recorded during the validation test represents a good correlation between the experimental and theoretical values. [ABSTRACT FROM AUTHOR]

The current research studies the corrosion behavior of Low Carbon Steel 1020 AISI welded joint by means of TIG welding method using mutable DC current and constant voltage. Before the welding process, shot peening by steel balls for certain welded joints is applied to the sheet metal, and then welding under the same welding conditions without shot peening. A number of corrosion inspection samples have been prepared with the measurements of (15 * 15 * 3 mm), according to ASTM (G71-31). Microstructure, residual stress has been tested and the corrosion test has been conducted electrochemically in 3.5 per cent NaCl solution for all samples. Corrosion rate was computed by means of the Tafel equation. The results show a rise in corrosion rate in some welded joints compared with other welded joints and base metal due to the variation in heat input from the input current for each weld passes. Shot peening process contributed to lower corrosion rate compared to welded joints without shot peening, due to the residual compression stresses produced by shot peening process. The best results obtained when number of welds passes and welding current are decreased to get suitable heat input.

In this research work, Inconel 718 specimens are fabricated by Direct Metal Laser Sintering process in the closed chamber which is filled with argon gas environment from a pre-alloyed powder. The process contains the high intensity of the laser source to melt the powder material, and the segment is placed on the top of the previous layer. Plates were vertically fabricated systematically (i.e., z-axis) and columnar grains are exhibited perpendicular to the build direction (i.e., x-axis). Test specimens are stress-relieved at 980°C for 2 hours and the recrystallized zone are found to be spheroid structure precipitates. The Ni-Cr matrix in the recrystallized interface and grain boundaries is observed in the samples, the micro hardness of the as-fabricated material is found as 340-350 VHN. Also, correspondingly mechanical properties are comparable with the wrought inco-718 alloy material. Further, the as build condition specimens are used for making butt joint configuration using Tungsten Inert Gas (TIG) welding process and Mechanical and microstructural properties are studied. The studies on welding of additive manufactured component will ensure the weldability of the AM material for the research community and industry.

Weld quality mainly depends on the weld bead geometry and mechanical-metallurgical characteristics of the welded joint which has a direct relationship with the type of welding process being used and its input process parameters i.e. welding current, arc voltage, travel speed etc. In the present study, determination of tungsten inert gas (TIG) welding input parameters for achieving maximum tensile strength of 316L austenitic stainless steel is investigated. Box-Behnken design of response surface methodology has been employed to formulate the experimental plan to identify the effect of process parameters on tensile strength. Square butt joint configuration has been made using three factors - three levels of welding input parameters. Joint strength has been evaluated by notch tensile strength (NTS) and Unnotch tensile strength (UTS) method and correlated with microstructure and micro hardness of the weld. The results indicate that gas flow rate has greater influence on both NTS and UTS followed by welding current.

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Effect of inter-pass temperature on the microstructure evolution and mechanical properties of AISI 430 ferritic stainless steel welded by autogenous tungsten inert gas (TIG) technique was investigated. The relationship between the structure and the property of the weldments with inter-pass temperature and without inter-pass temperature is elaborated in this study. Microstructure studies depicted the presence of martensite in the weld metal and some parts of the heat affected zone (HAZ). Increasing inter-pass temperature resulted in higher amount of martensite both in the weld metal and in the HAZ. In addition, high inter-pass temperatures resulted in large HAZ width and grain growth which in turn led to poor tensile strength and ductility of the weldments. An optimum inter-pass temperature of 150 °C provided the best mechanical properties. However, it was inferred that when it is not possible to have a precise control on inter-pass temperature during manufacturing AISI 430 joints, it is better to complete welding without applying inter-pass temperature in order to at least keep tensile strength and ductility of the weldments. [ABSTRACT FROM AUTHOR]

Experimental values are derived for the tribological characteristics of EN-GJV-400 cast iron, as well as its surfaces modified by melting, alloying with copper and nickel, and tungsten inert gas (TIG) welding in a high-frequency magnetic field. The latter process considerably improves the wear resistance. [ABSTRACT FROM AUTHOR]

In this paper the influence of tack welds distribution and welding sequence on angular distortion of the Tungsten Inert Gas (TIG) welded joint was tested. Additionally, the effect of welding current on angular distortion was assessed. For research X2CrTiNb18 (AISI 441) stainless steel (2.5 mm thick) was chosen. During research specimens were prepared with different distributions of tack welds. Then they were welded by different welding sequences with the use of different welding current values. After welding the angular distortion of each specimen was measured by using the coordinate measuring machine. In the next step specimens were cut. Cross-sections were polished and the metallographic macroscopic testing was conducted to check the geometry of performed welds. Performed experiments allowed determining the optimal tack weld sequence and welding parameters for welding thin stainless steel sheets. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Engineering & Architectural Faculty of Eskisehir Osmangazi University / Eskişehir Osmangazi Üniversitesi Mühendislik ve Mimarlık Fakültesi Dergisi is the property of Eskisehir Osmangazi University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Duplex stainless steel has the inimitable arrangement of two phase microstructure of 50% d-ferrite and 50% austenite. TIG welding on DSS is more easy, comfortable and useful, if the process is precisely understood and controlled through development of the science & technology of the process in the context of DSS welding by extensive research. In present work, influence of welding current, speed of TIG welding and gas flow rate on quality of DSS weld has been examined through valuable experiments. After experiment its analysis has been done. A design of experimentations has been used which is constructed upon the Taguchi technique. Experimental data has been analyzed by Principal Component Method. Investigation of present-day experiments is scheduled to have various perceptions of Butt joints of TIG welding between UNS2205 duplex stainless steel (DSS) plates. The sole aim of the current investigation is to use the Taguchi analysis, in order to create the optimum combination of controllable factors for Tungsten Inert Gas (TIG) Welding on 2205 DSS. The Taguchi analysis is used to define the optimum design set indices like welding current, shielding gas flow rate and speed of the welding. The experimental readings have been studied; inferred and evaluated with the help of ultimate tensile strength, yield strength, percentage of elongation integrated with the help of Principal Component Analysis (PCA) technique. Butt welding joints of 2205 duplex stainless steel plates have been made. Recently, DSS weld has made sufficient responsiveness in many avenues, such as in oil and gas industries, water purification plants etc. The Principal Component Analysis technique is used to find the optimum set. [ABSTRACT FROM AUTHOR]

Various preheating treatment and cooling rates conditions were carried out in Tungsten Inert Gas welding to study mechanical behavior and microstructural evolution of AA5083-H321 aluminum alloy welded joints. The microstructural analysis illustrated the diverse grain size during welding at different preheating and cooling rate. The highest preheat temperature caused to enlarge dendritic grains and during the fastest cooling rate formed the smaller grains. Also, the texture and grain size impressed on tensile behavior and hardness welds. Grain structure of the heat-affected zone, partially melted zone, and weld metal appeared to have a tangible relationship with preheating and cooling rate conditions. The microhardness of these regions increased by increasing the cooling rate and decreasing the preheating temperature. The high preheating had a negative effect on the hardness and width of different zones of welded joints. The results showed that the cooling rate has remarkable effects on the mechanical properties of the welded specimen. [ABSTRACT FROM AUTHOR]

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

In this study, the tungsten inert gas (TIG) welding process was applied to high-carbon steel plates in order to simulate hot cracking in welds. A customised acoustic emission (AE) system was used to capture the AE waveforms generated during welding and cooling of the sample plates. The AE signals were analysed using fast Fourier transform (FFT) and short-time Fourier transform (STFT) algorithms. Comparison of the features arising from different sources observed in the frequency spectra of the acquired AE signals was carried out. The results demonstrate the possibility of applying the AE technique for monitoring and detecting signals generated from cracking activities using frequency domain analysis. [ABSTRACT FROM AUTHOR]

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

The dissimilar lap joint was investigated among Inconel 718 and high-strength steel using tungsten inert gas welding. The weld zone has an austenitic microstructure with the existence of secondary phases. The distribution of secondary phases is observed in the weld zone and the fusion line of the Inconel 718. The elemental mapping from the electron probe microanalyzer has analyzed the development of secondary phases along the grain boundaries and interdendritic regions. The hardness of the weld zone varies due to the presence of secondary phases. The hardness mapping-confirms secondary phases causing the higher hardness in the weld zone. The selected filler metal has good compatibility with the Inconel 718 and the high-strength steel base metal to obtain a high-quality weld. The X-ray diffraction analysis confirms the presence of secondary phases in the weld zone. [ABSTRACT FROM AUTHOR]

The combination of Inconel 718 with AISI 4140 steel joint is in continuous demand for various applications. The difference in the physical and metallurgical properties between the two materials lead to difficulty in joining with conventional fusion welding methods. TIG welding is a suitable welding method to join such materials without any major issues. Therefore, the welding parameter effects on mechanical properties were studied experimentally and using the response surface methodology model. The microstructural characteristics and fracture surfaces of the welds were analyzed using the optical and scanning electron microscope. The reactions between the filler metal and substrates were evaluated by the electron probe microanalyzer for the presence of secondary phases. The formation of equiaxed and cellular dendritic growth of microstructure was observed from the welds. The fractography analysis investigated the ductile mode of failure after lap shear and fatigue tests. [ABSTRACT FROM AUTHOR]

The effects of three activating fluxes, SiO2, TiO2, and MoO3, in tungsten inert gas (TIG) welding process on penetration, morphology, and mechanical properties of weld joint were investigated by bead on plate welding on 2219 aluminum alloy. Experimental results showed that a noticeable increase in the weld penetration and depth to with ratio was obtained by using activating fluxes. Among all the activating fluxes used in this study, the maximum penetration was achieved in case of SiO2 flux. The microstructure analysis demonstrated that oxide fluxes can promote transition from columnar to equiaxed grain growth in the fusion zone. It is also found that A–TIG weldments exhibit superior mechanical properties including tensile strength and hardness than those of TIG welding without flux. [ABSTRACT FROM AUTHOR]

The present paper deals with the numerical simulation of weld pool development in Tungsten Inert Gas (TIG) process. A mathematical model is developed in order to solve the Navier–Stokes equations expressed in the stream–vorticity formulation coupled with heat equation taking into account the liquid solid phase change. Using the stream–vorticity formulation in incompressible fluid flow, the same problem is solved with reducing the number of transport equations. Therefore, only one transport equation (vorticity) and one Poisson equation (stream) are considered in this model. The FORTRAN programming and the numerical simulation are then achieved using appropriate discretization that ensures the convergence of the numerical methods to solve a large and sparse linear algebraic systems. Furthermore, to solve the radiation phenomena during welding described by the Stefen law, another method is proposed. The obtained numerical results are discussed and validate with experimental. [ABSTRACT FROM AUTHOR]

Welding-based additive manufacturing can potentially produce a cost-effective process for the production of dense metallic parts. Tungsten inert gas (TIG) welding-based additive manufacturing process uses wire as a filler material and offers a high deposition rate with low spattering. In this study, different orientations of wire feeding nozzle and TIG welding torch, such as front wire feeding (FWF), back wire feeding (BWF), and side wire feeding (SWF), were investigated for thin-walled metal deposition with enhanced dimensional accuracy and mechanical properties. The dimensional accuracy of thin-walls deposited at four different orientations were investigated in terms of deposition height and deposition width. The FWF orientation with higher wire feeding angle and SWF orientation produced poor dimensional accuracy in the deposition. FWF orientation with normal wire feeding angle and BWF orientation provided a decent dimensional accuracy and surface appearance. The deposited samples exhibited a similar trend for Vickers microhardness, residual stress, and microstructure for the four different wire feeding orientations. [ABSTRACT FROM AUTHOR]

Structural pseudo-β-titanium alloys attract a lot of interest in fabrication of critical structures. This alloy class includes alloys with the structure represented by one β-phase after hardening or normalizing in the β-region. The alloy weldability is an important factor at application of pseudo-β-titanium alloys in aircraft and rocket engineering. By their mechanical characteristics, the welded joints of modern pseudo-β-titanium alloys should match the level of base metal mechanical properties. In this work, the impact of argon arc welding, as well as further heat treatment on the phase composition, structure and mechanical properties of welded joints of pseudo-β-titanium alloy was studied. It was established that as a result of the impact of thermal cycle of welding predominantly β-phase in the amount of 77% is recorded in the weld metal of joints of pseudo-β-alloy V19. Application of VT1-00sv filler wire enhances the quantity of dispersed α-phase particles and reduces the quantity of β-phase in the weld metal to 60%, respectively. Annealing results in formation of a uniform, homogeneous finely-dispersed two-phase (α+β)-structure with ultimate tensile strength values of welded joints on the level of σt = 1010 MPa, that exceed the respective base metal values by 12%. [ABSTRACT FROM AUTHOR]

Structural pseudo-β-titanium alloys attract a lot of interest in fabrication of complex constructions for critical purposes. This alloy class includes alloys with the structure represented by one β-phase after hardening or normalizing from the β-region. The alloy weldability is an important factor at application of pseudo-β-titanium alloys in aircraft and rocket engineering. By their mechanical characteristics, the welded joints of modern pseudo-β titanium alloys should match the level of base metal mechanical properties. In this work, the impact of argon arc welding, as well as further heat treatment on the phase composition, structure and mechanical properties of welded joints of pseudo-β-titanium alloy was studied. It was established that as a result of the impact of thermal cycle of welding predominantly β-phase in the quantity of 77% is recorded in the weld metal of joints of pseudo-β alloy VT19. Application of VT1-00sv filler wire enhances the quantity of dispersed α-phase particles and reduces the quantity of β-phase in the weld metal to 60%, respectively. Annealing results in formation of a uniform, homogeneous finely-dispersed two-phase (α+β)-structure with tensile strength values of welded joints on the level of σt = 1010 MPa, that exceed the respective base metal values by 12%. 16 Ref., 5 Tables, 8 Figures. [ABSTRACT FROM AUTHOR]

A review of investigations devoted to the processes of inert-gas nonconsumable electrode welding with welding current modulation was performed. The third part of the review is devoted to analysis of the works, dealing with theoretical study and mathematical modeling of the processes of heat-, mass- and electric transfer in arc plasma and welded metal in TIG welding by modulated current. Different approaches to theoretical study of the above-mentioned processes are described, as well as respective mathematical models, allowing for the conditions of nonconsumable electrode welding with low-frequency (up to 10 Hz) and high-frequency (above 10 kHz) pulsed modulation of welding current. Results of numerical analysis of the distributed and integral characteristics of an argon arc with refractory cathode at pulse variation of current are given. It was performed on the base of models of a non-stationary arc with distributed and concentrated parameters. Results of computer modeling of thermal, hydrodynamic and electromagnetic processes in the welded metal (also at self-consistent accounting of the processes that proceed in arc plasma) were analyzed for the case of spot TIG welding with low-frequency pulse modulation of current. Presented are the analytical dependencies that describe the impact of the shape and parameters of welding current pulses on the characteristics of dynamic action of an arc with a refractory cathode on weld pool metal. [ABSTRACT FROM AUTHOR]

The purpose of the current work is to investigate the combined effect of thickness and the mechanical properties of dissimilar aluminum alloys annealed AA6061-O and heat-treated AA7075-T6 on the tensile strength of the joint. The joint is made by Tungsten Inert Gas (TIG) welding using suitable fillers Al 4047 and Al 5356. Different samples i.e. Welded Over-Nugget Sample (WOS), Welded Ground Sample (WGS) and Base Material (BM) were investigated under tensile loading. In order to avoid failure, the thickness of weak strength AA6061-O must be greater as compared to the thickness of AA7075 comprising high strength in order to balance stresses on both sides. In addition to, the effect of grounded and as-welded bead on the joint properties of the weld is explained in this research. The joint is also characterized by microstructural attributes using electron microscopy and the grain size is observed as well. [ABSTRACT FROM AUTHOR]