Determination of the momentum of droplets impinging on the pool during aluminium GMAW

Scotti, Américo; Rodrigues, Carlos Eduardo Aguiar Lima

doi:10.1590/s0104-92242009000400008

Cited by 7 publications

(2 citation statements)

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“…A metal transfer with large droplets, for instance, may produce a large momentum, but it does not necessarily act significantly in the weld bead penetration. Thus, Scotti and Rodrigues [23,24] proposed expressing and quantifying the momentum, concerning its role in the weld bead formation, in a different way. According to these authors, it would be reasonable to think of a better way to take into account the effect of such a mechanical characteristic of the metal transfer.…”

Section: Effect Of Wire Feed Pulsation On the Weld Bead Penetrationmentioning

confidence: 99%

The potential of wire feed pulsation to influence factors that govern weld penetration in GMA welding

Jorge

Scotti

Reis

et al. 2020

Int J Adv Manuf Technol

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Derivative welding processes are in many cases capable of altering phenomena that determine fundamental aspects of weld bead formation. Some of these evolutions act over the wire feed dynamics. However, in this scenario, the effects of the wire feed pulsation on the weld bead formation governing factors have not been fully explored yet. Therefore, this work aimed at examining how a wire feed pulsation approach affects the droplet transfer in gas metal arc welding and how its interaction with the molten pool defines the weld bead penetration. Bead-on-plate weldments were produced by varying the wire feed pulsation frequency, yet keeping the same levels of arc energy and wire feed speed, with the power source operating in constant voltage and current modes. To assess the droplet transfer behavior, high-speed imaging was used. The geometry of the weld beads was compared in terms of fusion penetration. The results showed that an increase in the wire feed pulsation frequency intensifies the detachment frequency of the droplets, being possible to accomplish a stable metal transfer with them straightly projected toward the weld pool, which contributed to a centralized-increased penetration profile. Based on a descriptive model, it was demonstrated that the increase in droplet momentum or kinetic energy, due to the wire feed pulsation, was not enough to justify the penetration enhancement. It was concluded that the wire feed dynamics can also stimulate surface tension variations in the weld pool and therefore disrupt the behavior of its mass and heat convection, supporting fusion penetration.

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Section: Effect Of Wire Feed Pulsation On the Weld Bead Penetrationmentioning

confidence: 99%

The potential of wire feed pulsation to influence factors that govern weld penetration in GMA welding

Jorge

Scotti

Reis

et al. 2020

Int J Adv Manuf Technol

Self Cite

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“…The crater generated in the molten pool has similarities with the keyhole mode achieved in the high current plasma and GTAW processes [13,14]. As in these processes, the welding current in GMAW is the main parameter governing the depth of the weld pool crater, along with the droplets' momentum [15,16]. However, there is a collateral factor that acts unfavorably in this regard, which is the inherent interdependence between the current and the wire melting rate.…”

Section: Introductionmentioning

confidence: 99%

A New Interpretative Basis for the High Performance GMAW Process

et al. 2021

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Numerous GMAW processes have appeared for one-pass welding of medium to high thickness. This concept originated in the 1980s with the T.I.M.E. technique and the 1990s and 2000s saw the emergence of Rapid Arc, Rapid Melt and Buried Arc techniques. These processes did not include any special control features, but rather parameter combinations to improve bead geometry. A new interpretation of the factors that are critical to achieving high performance GMAW (penetration) is presented herein. Tests with a voltage controlled power source with inductance control and the Rapid Arc process were conducted on bead-on-plate for high speed videography. Later, validation tests were conducted on butt joints, with the technique developed, with and without groove on AISI 1020, 3/8" thick steel plates. The power source may be of voltage control but has to provide a dynamic response able to sustain a metastable equilibrium of the molten pool applying the semi-keyhole technique. The technique developed was able to weld, in a single pass, 3/8" thick butt joint steel plates. The results showed that a power source, to achieve the GMAW buried arc condition, only needs to provide dynamic characteristics able to maintain the molten pool in a metastable equilibrium.

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