A pathway to microstructural refinement through double pulsed gas metal arc welding

Wang, Leilei; Wei, Huiliang; Xue, Jiaxiang; DebRoy, T.

doi:10.1016/j.scriptamat.2017.02.034

Cited by 45 publications

(21 citation statements)

References 23 publications

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“…The poles figures (PFs), shown in Figure 11, indicate that the microstructure is oriented near the easy growth direction for the metals with cubic (<100>) crystalline structure [22]. Further, the higher intensities presented by SMAW were attributed to the formation of a slag, which reduced the heat loss by convection and radiation, intensifying competitive growth and, consequently, the formation of a more oriented microstructure than the one obtained by GMAW [23].…”

Section: Microstructural Characterizationmentioning

confidence: 95%

The Influence of the Welding Process on the Ultrasonic Inspection of 9%Ni Steel Pipe Circumferential Welded Joints

et al. 2020

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This work aims to compare the ultrasonic inspection of 9%Ni steel joints welded with the Gas Metal Arc Welding (GMAW) process and Shielded Metal Arc Welding (SMAW) process. These are the two most widely used processes used to weld pipes for CO2 injection units for floating production storage and offloading (FPSO) in the Brazilian oil and gas industry. The SMAW equipment is simple and portable, which is convenient for the FPSO; however, the GMAW process has the advantage of welding with high productivity. In this study we performed a numerical simulation using the software CIVA, 11th version, to analyze the behavior of ultrasonic longitudinal wave beams through GMAW and SMAW dissimilar weld joints. Ultrasonic tests were performed on calibration blocks drawn from both welded joints to evaluate the simulation results. The results are discussed with regard to the microstructure of the weld metal via electron backscatter diffraction (EBSD) analyses. The SMAW process presented better inspection performance than the GMAW process in terms of attenuation and dispersion effects. Although the SMAW had a better outcome, for both processes the configuration of 16 active elements and a scanning angle of 48° resulted in an optimized inspection of the entire joint.

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Section: Microstructural Characterizationmentioning

confidence: 95%

The Influence of the Welding Process on the Ultrasonic Inspection of 9%Ni Steel Pipe Circumferential Welded Joints

et al. 2020

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“…Another outcome is that the ripple wave length reduced with higher TF. Figure 2 illustrates the weld penetration versus time of CP-GMAW and DP-GMAW [29]. The results indicate that the weld penetration of the CP-GMAW lies between the maximum weld penetration and minimum weld penetration of the DP-GMAW for the same heat input.…”

Section: Weld Pool and Bead Characteristicmentioning

confidence: 98%

“…Main driving forces for molten pool convection are buoyancy, electromagnetic, and Marangoni force [30]. Wang et al [29] developed a well-tested, transient, and three-dimensional heat transfer and fluid flow model of DP-GMAW, by solving the equations of conservation of mass, momentum, and energy. The results indicate that the molten pool expands during the TP phase, due to high-level heat input, and subsequently shrinks during the TB phase, due to low-level heat input.…”

Section: Weld Pool and Bead Characteristicmentioning

confidence: 99%

Perspective on Double Pulsed Gas Metal Arc Welding

Wang

Xue

2017

Applied Sciences

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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.

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“…However, the outline was not shaped into the final curve by one single droplet impingement; each The upward flow shaped the grain morphology along the wall into three stages (Figure 4d): large size before the impact point (IP), reduced size at the IP and in a near neighboring region, and large size again far after the IP. The variation in the grain size with increased distance from the SIP, as illustrated by Figure 4f, may have resulted from the corresponding change in flow magnitude [3]. Different regions suffered different order-of-magnitude impacts and heat inputs from the droplets.…”

Section: Shallow Penetration With An Inclined Torchmentioning

confidence: 99%

“…These components are often fabricated into industrial structures by fusion welding processes [2]. Gas metal arc welding (GMAW) is an important fusion welding method of joining aluminum alloys [3]. In GMAW, the weld profile and microstructure are strongly affected by the molten pool behavior [4], which in turn is strongly affected by various driving forces, such as the arc pressure, plasma shear force, Marangoni force and electromagnetic force (EMF) [4,5].…”

Section: Introductionmentioning

confidence: 99%

Effect of Droplet Impingement on the Weld Profile and Grain Morphology in the Welding of Aluminum Alloys

et al. 2018

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To achieve a better understanding of the effect of droplet impingement on the weld profile and grain morphology, welding with vertical and inclined torches in the double pulsed-gas metal arc welding of aluminum alloy were compared. When using vertical welding, the grains along the wall of the finger-like penetration (FLP) were refined by a more violent flow driven by droplet impingement running in the confined space created by FLP. When using inclined welding, the sharp inflection point disappeared and the curved columnar grains emerged on the non-impact action side, which was attributed to the gradually weakened impingement at that location. Moreover, when the penetration became shallower due to a low mean current, the droplets impinged alternately along split trajectories, causing significant changes in the grain morphology, such as creating grains which were sharply shortened by the direct impact of droplet impingement at impact point. The change of trajectory was ascribed to the variation of the width/depth ratio of FLP, which changed the magnitude of the contradiction between the room required by the fluid flow driven by droplet impingement and the space supplied for that by FLP.

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A pathway to microstructural refinement through double pulsed gas metal arc welding

Cited by 45 publications

References 23 publications

The Influence of the Welding Process on the Ultrasonic Inspection of 9%Ni Steel Pipe Circumferential Welded Joints

The Influence of the Welding Process on the Ultrasonic Inspection of 9%Ni Steel Pipe Circumferential Welded Joints

Perspective on Double Pulsed Gas Metal Arc Welding

Effect of Droplet Impingement on the Weld Profile and Grain Morphology in the Welding of Aluminum Alloys

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