Special Issue "Gas Tungsten Arc Welding"

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Mechanical Engineering".

Deadline for manuscript submissions: closed (31 May 2017) | Viewed by 18218

Special Issue Editors

Dr. Hai-Lung Tsai
E-Mail Website
Guest Editor
Department of Mechanical and Aerospace Engineering, Missouri University of Science and Technology, Rolla, MO 65409-0500, USA
Interests: laser-material interactions; additive manufacturing
Special Issues, Collections and Topics in MDPI journals
Dr. Junling Hu
E-Mail Website
Guest Editor
Department of Mechanical Engineering, University of Bridgeport, Bridgeport, CT 06604, USA
Interests: gas metal arc welding; laser welding; additive manufacturing; electronics cooling
Special Issues, Collections and Topics in MDPI journals

Special Issue Information


Dear Colleagues,

Gas Tungsten arc welding (GTAW) is an arc welding process that uses a non-consumable tungsten electrode to produce an arc and form a weld.  It is widely used in joining thin sheet metals because of its high weld quality and its suitability for most commercial metals.  GTAW is also a complex process, which involves interaction of arc plasma, weld pool dynamics and solidification, with simultaneous interaction of materials at the plasma, gaseous, and solid states.  Extensive experimental and numerical studies have been carried out to study a large number of phenomena in a GTAW process, including electromagnetics, heat transfer, fluid flow, metal transfer, microstructure evolution, and thermal mechanical effects. 

The Special Issue of the journal Applied Sciences, “Gas Tungsten Arc Welding” aims to cover recent advances in the development of numerical modeling and experimental study of GTAW processes, sensing and control of GTAW processes, process optimization, and new applications of GTAW.

Dr. Hai-Lung Tsai
Dr. Junling Hu
Gues Editors

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Keywords

  • Gas tungsten arc welding
  • Arc plasma
  • Weld pool dynamics
  • Arc sensing
  • Weld penetration control
  • Process optimization
  • Robotic welding

Published Papers (6 papers)

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Research

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Article
Optimization of Hybrid Ultrasonic Frequency Pulsed VP-GTAW Process Parameters on Tensile Properties of AA 5456 Alloy
Appl. Sci. 2017, 7(5), 485; https://doi.org/10.3390/app7050485 - 08 May 2017
Cited by 7 | Viewed by 2809
Abstract
Tensile properties optimization of AA 5456 aluminum alloy was carried out with hybrid ultrasonic frequency pulsed variable polarity gas tungsten arc wending (HPVP-GTAW). An orthogonal method was employed to conduct the experiments, and the tensile properties of AA 5456 aluminum alloy welded joints [...] Read more.
Tensile properties optimization of AA 5456 aluminum alloy was carried out with hybrid ultrasonic frequency pulsed variable polarity gas tungsten arc wending (HPVP-GTAW). An orthogonal method was employed to conduct the experiments, and the tensile properties of AA 5456 aluminum alloy welded joints were measured and analyzed. Regression models were developed based on the least square estimation by taking tensile strength, yield strength, percent elongation, and ratio of reduction in area as response functions of variable polarity frequency fL, pulse frequency fH and a dimensionless parameter ψ, which were calculated by background current Ib, peak current Ip, and pulse duration δ, respectively. The developed regression equations were checked for validity by coefficient of correlation r2 and confirmatory experiments. Optimum parameters of HPVP-GTAW were achieved through the discussion on response surfaces and contour plots drawn using the regression equations. Full article
(This article belongs to the Special Issue Gas Tungsten Arc Welding)
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Article
Influence of Welding Parameters on the Weld Pool Dimensions and Shape in a TIG Configuration
Appl. Sci. 2017, 7(4), 373; https://doi.org/10.3390/app7040373 - 08 Apr 2017
Cited by 9 | Viewed by 2646
Abstract
The weld pool shape created by the plasma arc interaction on a workpiece depends on many geometrical and physical parameters and on the operating conditions. Theoretical models are developed in such a way as to predict and to characterize the material. However, these [...] Read more.
The weld pool shape created by the plasma arc interaction on a workpiece depends on many geometrical and physical parameters and on the operating conditions. Theoretical models are developed in such a way as to predict and to characterize the material. However, these models first need to be validated. Experimental results are hence proposed with parametric studies. Nevertheless, the interaction time is often short and the weld pool shape evolution not presented. In this work, the experimental setup and the diagnostic methods characterizing the workpiece are presented. The weld pool shape was evaluated versus time according to several parameters such as the current intensity value, the distance between the two electrodes, the cathode tip angle or the plasma gas nature. The results show that the depth-to-width ratio alone is not enough to compare the impact of the parameters. The analysis points out the great influence of the current intensity on the increase of the width and depth compared to the influence of the value of the cathode tip angle. The rise of the arc length leads to an increase of the power through a higher arc voltage; nevertheless, for distances of three and five millimeters and a characteristic time of the welding process of one second, this parameter has a weak influence on the energy transferred. The use of helium leads to a bigger volume of the weld pool due to an increase of width and depth. Full article
(This article belongs to the Special Issue Gas Tungsten Arc Welding)
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Article
Welding Robot Collision-Free Path Optimization
Appl. Sci. 2017, 7(2), 89; https://doi.org/10.3390/app7020089 - 08 Feb 2017
Cited by 18 | Viewed by 2628
Abstract
Reasonable welding path has a significant impact on welding efficiency, and a collision-free path should be considered first in the process of welding robot path planning. The shortest path length is considered as an optimization objective, and obstacle avoidance is considered as the [...] Read more.
Reasonable welding path has a significant impact on welding efficiency, and a collision-free path should be considered first in the process of welding robot path planning. The shortest path length is considered as an optimization objective, and obstacle avoidance is considered as the constraint condition in this paper. First, a grid method is used as a modeling method after the optimization objective is analyzed. For local collision-free path planning, an ant colony algorithm is selected as the search strategy. Then, to overcome the shortcomings of the ant colony algorithm, a secondary optimization is presented to improve the optimization performance. Finally, the particle swarm optimization algorithm is used to realize global path planning. Simulation results show that the desired welding path can be obtained based on the optimization strategy. Full article
(This article belongs to the Special Issue Gas Tungsten Arc Welding)
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Article
A GTA Welding Cooling Rate Analysis on Stainless Steel and Aluminum Using Inverse Problems
Appl. Sci. 2017, 7(2), 122; https://doi.org/10.3390/app7020122 - 25 Jan 2017
Cited by 9 | Viewed by 3058
Abstract
This work presents an analysis of the thermal influence of the heat transfer by convection and radiation during GTA (gas tungsten arc) welding process. The authors’ in-house C++ previously-developed code was modified to calculate the amount of heat transfer by convection and radiation. [...] Read more.
This work presents an analysis of the thermal influence of the heat transfer by convection and radiation during GTA (gas tungsten arc) welding process. The authors’ in-house C++ previously-developed code was modified to calculate the amount of heat transfer by convection and radiation. In this software, an iterative Broydon-Fletcher-Goldfarb-Shanno (BFGS) inverse method was applied to estimate the amount of heat delivered to the plate when the appropriate sensitivity criteria were defined. The methodology was validated by accomplishing lab-controlled experiments on stainless steel AISI 304L and aluminum 6065 T5 plates. Due to some experimental singularities, the forced thermal convection induced by the electromagnetic field and thermal-capillary force were disregarded. Significant examples of these singularities are the relatively small weld bead when compared to the sample size and the reduced time of the welding process. In order to evaluate the local Nusselt number, empirical correlations for flat plates were used. The thermal emission was a dominant cooling effect on the aluminum cooling. However, it did not present the same behavior as the stainless steel samples. The study found that the heat losses by convection and radiation of the weld pool do not affect the cooling process significantly. Full article
(This article belongs to the Special Issue Gas Tungsten Arc Welding)
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Article
Arc Shape Characteristics with Ultra-High-Frequency Pulsed Arc Welding
Appl. Sci. 2017, 7(1), 45; https://doi.org/10.3390/app7010045 - 03 Jan 2017
Cited by 14 | Viewed by 3139
Abstract
Arc plasma possesses a constriction phenomenon with a pulsed current. The constriction is created by the Lorentz force, the radial electromagnetic force during arc welding, which determines the energy distribution of the arc plasma. Welding experiments were carried out with ultra-high-frequency pulsed arc [...] Read more.
Arc plasma possesses a constriction phenomenon with a pulsed current. The constriction is created by the Lorentz force, the radial electromagnetic force during arc welding, which determines the energy distribution of the arc plasma. Welding experiments were carried out with ultra-high-frequency pulsed arc welding (UHFP-AW). Ultra-high-speed camera observations were produced for arc surveillance. Hue-saturation-intensity (HSI) image analysis was used to distinguish the regions of the arc plasma that represented the heat energy distribution. The measurement of arc regions indicated that, with an ultra-high-frequency pulsed arc, the constriction was not only within the decreased arc geometry, but also within the constricted arc core region. This can be checked by the ratio of the core region to the total area. The arc core region expanded significantly at 40 kHz at 60 A. A current level of 80 A caused a decrease in the total region of the arc. Meanwhile, the ratio of the core region to the total increased. It can be concluded that arc constriction depends on the increased area of the core region with the pulsed current (>20 kHz). Full article
(This article belongs to the Special Issue Gas Tungsten Arc Welding)
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Review

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Review
Perspective on Double Pulsed Gas Metal Arc Welding
Appl. Sci. 2017, 7(9), 894; https://doi.org/10.3390/app7090894 - 01 Sep 2017
Cited by 14 | Viewed by 3551
Abstract
Aluminum alloy welding suffers from problems such as solidification cracking and hydrogen-induced porosity, which are sufficiently severe to limit its potential applications. Because mitigated porosity incidence and solidification cracking are observed in aluminum welds using double pulsed gas metal arc welding (DP-GMAW), a [...] Read more.
Aluminum alloy welding suffers from problems such as solidification cracking and hydrogen-induced porosity, which are sufficiently severe to limit its potential applications. Because mitigated porosity incidence and solidification cracking are observed in aluminum welds using double pulsed gas metal arc welding (DP-GMAW), a comprehensive review of the mechanism is necessary, but absent from the literature. The oscillation of arc force and droplet pressure causes a weld pool stir effect. The expansion and shrinkage of the weld pool cause unusual remelting and resolidification of the previously solidified metal. DP-GMAW has an increased solidification growth rate and cooling rate, compared with conventional pulsed welding at same heat input. Both numerical and experimental results reveal the remarkable concept that refined microstructure in the fusion zone is obtained by using DP-GMAW. The mechanism of microstructural refinement is revealed as a weld pool stir effect and increased cooling rate. Hydrogen bubbles easily float out and then release from the weld pool originated from the weld pool stir effect. Reduced solidification cracking is achieved due to the refined solidification structure that originated from the increased cooling rate. The advantages, evolution process, and future trend of DP-GMAW are discussed. Full article
(This article belongs to the Special Issue Gas Tungsten Arc Welding)
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