Optimization of CA-TIG welding parameters to predict and maximize tensile properties of super alloy 718 sheets for gas turbine applications

2022 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Tushar Sonar ◽  
Visvalingam Balasubramanian ◽  
Sudersanan Malarvizhi ◽  
Thiruvenkatam Venkateswaran ◽  
Dhenuvakonda Sivakumar

Purpose The primary objective of this investigation is to optimize the constricted arc tungsten inert gas (CA-TIG) welding parameters specifically welding current (WC), arc constriction current (ACC), ACC frequency (ACCF) and CA traverse speed to maximize the tensile properties of thin Inconel 718 sheets (2 mm thick) using a statistical technique of response surface methodology and desirability function for gas turbine engine applications. Design/methodology/approach The four factor – five level central composite design (4 × 5 – CCD) matrix pertaining to the minimum number of experiments was chosen in this investigation for designing the experimental matrix. The techniques of numerical and graphical optimization were used to find the optimal conditions of CA-TIG welding parameters. Findings The thin sheets of Inconel 718 (2 mm thick) can be welded successfully using CA-TIG welding process without any defects. The joints welded using optimized conditions of CA-TIG welding parameters showed maximum of 99.20%, 94.45% and 73.5% of base metal tensile strength, yield strength and elongation. Originality/value The joints made using optimized CA-TIG welding parameters disclosed 99.20% joint efficiency which is comparatively 20%–30% superior than conventional TIG welding process and comparable to costly electron beam welding and laser beam welding processes. The parametric mathematical equations were designed to predict the tensile properties of Inconel 718 joints accurately with a confidence level of 95% and less than 4.5% error. The mathematical relationships were also developed to predict the tensile properties of joints from the grain size (secondary dendritic arm spacing-SDAS) of fusion zone microstructure.

2018 ◽  
Vol 7 (3.6) ◽  
pp. 206
Author(s):  
P Jerold Jose ◽  
M Dev Anand

In this research, the effects of heat input on tensile properties and microstructure were investigated for super alloy Inconel-718 sheets weld by Tungsten Inert Gas (TIG) welding process. The tensile properties and microstructure of weld joints were evaluated. The experiment was conducted with six different combinations of welding parameters like welding current, voltage and welding speed, which were give in six different welding heat input combinations of welding parameters. The experimental results shows that the welding joints weld with low welding heat input was yield higher tensile properties. From the experimentation it was understand that the tensile properties increases when the welding heat input decrease. Drastic grain coarsening was evidenced when the heat input was increases. For the weld joints experimented in this research it was also observed that amount of laves phase was increased with increase in the welding heat input which is the major fact for noticeable variation in the ultimate tensile strength of the weld joints welded by TIG welding process with different welding heat input. 


Metals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1327 ◽  
Author(s):  
Zhenyu Fei ◽  
Zengxi Pan ◽  
Dominic Cuiuri ◽  
Huijun Li ◽  
Bintao Wu ◽  
...  

Keyhole mode Tungsten Inert Gas (K-TIG) welding is a novel advanced deep penetration welding technology which provides an alternative to high power density welding in terms of achieving keyhole mode welding. In order to facilitate welding procedure optimisation in this newly developed welding technology, the relationship among welding parameters, weld formation and tensile properties during the K-TIG welding was investigated in detail. Results show that except for travel speed, the heat input level also plays an important role in forming undercut defect by changing the plasma jet trajectory inside keyhole channel, leading to the formation of hump in the weld centre and exacerbation of undercut formation. Both undercut defect and root side fusion boundary can act as a stress concentration point, which affects the fracture mode and tensile properties considerably. The research results provide a practical guidance of process parameter optimisation and quality assurance for the K-TIG welding process.


Author(s):  
Soo-sung Kim ◽  
Geun-il Park ◽  
Jung-won Lee ◽  
Jin-hyun Koh

A remote welding machine for a DUPIC (Direct Use of spent PWR fuel In CANDU reactors) bundle fabrication was designed to establish the optimum welding processes in a hot cell environment. An initial investigation for hands-on fabrication outside the hot cell was performed in the consideration of the constraints of welding machine in the hot cell conditions. Gas tungsten arc welding (GTAW), laser beam welding (LBW), friction welding (FW), and resistance welding (RW) process were assessed as candidates for this application. A preliminary welding investigation to improve the RW process was also performed. The RW process was determined to be the most suitable process in a hot cell environment for joining an endplate to an endcap. An advantage of RW would be a qualified process for overlapped plates welding for which there is extensive production experience were available. A preliminary investigation for a hands-on fuel fabrication outside the hot cell was conducted in the consideration of the constraints caused by a welding in a hot cell. The optimum resistance welding parameters for the endplate welding process were obtained in terms of the current, electrode pressure and welding cycle. This paper presents an outline of the developed RW machine for a DUPIC bundle fabrication and reviews the conceptual design of a remote RW welder by using a master-slave manipulator. The design of RW machine by using the 3D modeling method was also designed. Furthermore the integrity of the welds by the resistance welding was confirmed by the results of the torque test, an examination of the microstructure and the fracture surfaces of the welds.


Author(s):  
Elisan dos Santos Magalhaes ◽  
Cristiano Pedro da Silva ◽  
Ana Lúcia Fernandes Lima e Silva ◽  
Sandro Metrevelle Marcondes Lima e Silva

Purpose The purpose of this article is the determination of the temperature fields in a weld region has always been an obstacle to the improvement of welding processes. As an alternative, the use of inverse problems to determine the heat flux during the welding process allows an analysis of these processes. Design/methodology/approach This paper studies an alternative for the thermal analysis of the tungsten inert gas welding process on a 6,060 T5 aluminum alloy. For this purpose, a C++ code was developed, based on a transient three-dimensional heat transfer model. To estimate the amount of heat delivered to the plate, the specification function technique was used. Lab experiments were carried out to validate the methodology. A different experimental methodology is proposed to estimate the emissivity (radiation coefficient). Findings The maximum difference between experimental and numerical temperatures is lower than 5 per cent. The determined emissivity value for the aluminum 6,060 T5 presented a good agreement with literature values. The thermal fields were analyzed as function of the positive polarity. The specification function method proved to be an adequate tool for heat input estimation in welding analysis. Originality/value The proposed methodology proves to be a cheaper way to estimate the heat flux on the sample. The estimated power curves for the welding process are presented. The methodology to calculate the emissivity (radiation coefficient) was validated.


Author(s):  
Iñigo Hernando ◽  
Jon Iñaki Arrizubieta ◽  
Aitzol Lamikiz ◽  
Eneko Ukar

A numerical model was developed for predicting the bead geometry and microstructure in Laser Beam Welding of 2 mm thickness Inconel 718 sheets. The experiments were carried out with a 1 kW maximum power fiber laser coupled with a galvanometric scanner. Wobble strategy was employed for sweeping 1 mm wide circular areas for creating the weld seams and a specific tooling was manufactured for supplying protective Argon gas during the welding process. The numerical model takes into account both the laser beam absorption and the melt-pool fluid movement along the bead section, resulting in a weld geometry that depends on the process input parameters, such as feed rate and laser power. The microstructure of the beads was also estimated based on the cooling rate of the material. Features as bead upper and bottom final shapes, weld penetration and dendritic arm spacing were numerically and experimentally analyzed and discussed. The results given by the numerical analysis agree with the tests, making the model a robust predictive tool.


2021 ◽  
pp. 85-91
Author(s):  
А.С. Угловский ◽  
И.М. Соцкая ◽  
Е.В. Шешунова

Цель рассмотрения численного метода заключалась в получении подробных данных, позволяющих оценить проведение сварочного процесса: изменение объёма сварного шва, радиуса сварного шва, радиуса зоны термического влияния. При проведении моделирования авторами выведены зависимости параметров точечной сварки низкоуглеродистой стали толщиной до 3,2 мм. Данные зависимости будут определять качество сварных швов. Соответствующее сочетание параметров точечной сварки обеспечит прочное соединение и хорошее качество сварки. The purpose of the numerical method consideration was to obtain detailed data allowing evaluating the performance of the welding process: changing the volume of the weld, the radius of the weld, the radius of the weld-affected zone. During the simulation the authors have derived dependencies of the parameters of spot welding of low-carbon steel up to 3.2 mm thick. These dependencies will determine the quality of the welds. The correct combination of spot welding parameters will ensure a firm joint and good welding quality.


2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
T. Sathish ◽  
S. Tharmalingam ◽  
V. Mohanavel ◽  
K. S. Ashraff Ali ◽  
Alagar Karthick ◽  
...  

Aluminium and its alloys play a significant role in engineering material applications due to its low weight ratio and superior corrosion resistance. The welding of aluminium alloy is challenging for the normal conventional arc welding processes. This research tries to resolve those issues by the Tungsten Inert Gas welding process. The TIG welding method is an easy, friendly process to perform welding. The widely applicable wrought aluminium AA8006 alloy, which was not considered for TIG welding in earlier studies, is considered in this investigation. For optimizing the number of experiments, the Taguchi experimental design of L9 orthogonal array type experimental design/plan was employed by considering major influencing process parameters like welding speed, base current, and peak current at three levels. The welded samples are included to investigate mechanical characterizations like surface hardness and strengths for standing tensile and impact loading. The results of the investigation on mechanical characterization of permanent joint of aluminium AA8006 alloy TIG welding were statistically analyzed and discussed. The 3D profilometric images of tensile-tested specimens were investigated, and they suggested optimized process parameters based on the result investigations.


Author(s):  
Nick Bagshaw ◽  
Chris Punshon ◽  
John Rothwell

Boiler and steam piping components in power plants are fabricated using creep strength enhanced ferritic (CSEF) steels, which often operate at temperatures above 550°C. Modification of alloy content within these steels has produced better creep performance and higher operating temperatures, which increases the process efficiency of power plants. The improved materials, however, are susceptible to type IV cracking at the welded regions. A better understanding of type IV cracking in these materials is required and is the basis of the Technology Strategy Board (TSB) UK funded VALID (Verified Approaches to Life Management & Improved Design of High Temperature Steels for Advanced Steam Plants) project. In order to study the relationship between creep performance and heat input during welding, several welds with varying amounts of heat input and resultant HAZ widths were produced using the electron beam welding process. The welding parameters were developed with the aid of weld process modeling using the finite element (FE) method, in which the welding parameters were optimized to produce low, medium and high heat input welds. In this paper, the modeling approach and the development of electron beam welds in ASTM A387 grade P92 pipe material are presented. Creep specimens were extracted from the welded pipes and testing is ongoing. The authors acknowledge the VALID project partners, contributors and funding body: Air Liquide, Metrode, Polysoude, E.ON New Build & Technology Ltd, UKE.ON, Doosan, Centrica Energy, SSE, Tenaris, TU Chemnitz, The University of Nottingham, The Open University and UK TSB. Paper published with permission.


2019 ◽  
Vol 66 (4) ◽  
pp. 412-417 ◽  
Author(s):  
Naiyan Zhang ◽  
Dezhi Zeng

Purpose Bimetallic composite pipe consists of a corrosion resistance alloy (CRA) layer for corrosion resistance and carbon steel for mechanical properties, which shows a promising prospect of gathering pipeline with its effective-cost and reliable corrosion resistance. However, the corrosion resistance of composite pipe is determined by the quality of its welding gap. This paper aims to investigate the TIG welding gap corrosion resistance of X52/825 metallurgical clad pipe in H2S/CO2 environment. Design/methodology/approach Corrosion tests of X52/825 welding gap were performed in a stimulated gas field solution containing both 1 MPa CO2 and 1.5 MPa H2S at 70°C for 720 h in a self-designed high temperature and high pressure autoclave. The anti-stress corrosion cracking (SCC) performance of X52/825 clad pipe ring root welding gap was investigated in both NACE A solution and the stimulant gas field solution by four point bending testing and constant load test. Then the experiments were rerun in XX high sour gas well. In addition, the alloy diffusion and microstructure characteristics of TIG welding gap were analyzed through scanning electron microscopy and energy dispersive X-ray spectroscopy technologies. Findings The results reveal that the root welding gap is almost not corroded in the stimulant gas field solution, and no micro-cracks were observed by electron microscope. Anti-SCC test results show the root welding gap does not break, indicating a good resistance to environmental-cracking in H2S/CO2 environment. The transition layer can be obviously observed in the root welding zone, and the alloy content of transition layer is diluted. However, the transition layer does not penetrate into the inner of CRA layer, which illustrates its good anti-corrosion performance. Therefore, TIG welding technology can be well used in the welding process of composite pipe. Originality/value This paper may provide theoretical reference for manufacturing and application of clad pipe.


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