Effect of changes in the composition of the gas shielding medium on the properties of arc welded joints in aluminium alloys

Novikov, O. M.; Persidskii, A. S.; Rad'ko, E. P.; Baranovskii, A. V.; Khasyanov, B. A.

doi:10.1080/09507116.2012.715891

Cited by 6 publications

(2 citation statements)

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“…Subsequently, a valve-regulated gas delivery system that alternated the shielding gases in the same feed line to the welding nozzle was used for the same purpose in [2]. Variations in the arc conductivity were noted, and it was suggested that these produced a higher total power and caused a varying pressure and effective diameter of the arc.…”

Section: Introductionmentioning

confidence: 99%

“…The pulsed gas delivery method has been used in both gas metal arc welding (GMAW) and gas tungsten arc welding (GTAW) of aluminium alloys [2][3][4], as well as of carbon [5][6][7] and stainless [8,9] steels. Several benefits were reported, such as improved distortion control and re-work reduction [7,10] or refinement of weld structure and thus better mechanical the mechanical properties of the weld [2,8]. The pulsing frequency was shown to influence the dynamics of the melt pool [9] and final geometry of the solidified weld [8,10].…”

Section: Introductionmentioning

confidence: 99%

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Visualisation of alternating shielding gas flow in GTAW

Bitharas¹,

Campbell²,

Galloway³

et al. 2016

Materials & Design

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The alternating shielding gas technique is a method of achieving transient arc characteristics during arc welding; however the complex flow that occurs through its use has not been investigated previously. A schlieren system was used to image density gradients that arise when alternating argon and helium shield gases, under varying flow parameters, with gas tungsten arc welding (GTAW). A theoretical analysis was carried out to determine the conditions under which the technique facilitates arc pulsing, in particular to avoid mixing the shield gases in the delivery pipe prior to the welding nozzle. At appropriate pulsing frequency and flow rates, a stable horizontal region of helium was obseved in the weld region, maintained in position by the denser argon from the preceding pulse. This higher than average mass fraction of helium when applying the shielding gases alternately, compare to a premixed gas with the same volume of argon and helium, increased the weld penetration by 13% on average, suggesting a modest improvement in heat transfer

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Visualisation of alternating shielding gas flow in GTAW

Bitharas¹,

Campbell²,

Galloway³

et al. 2016

Materials & Design

View full text Add to dashboard Cite

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Effect of shielding gas parameters on weld metal thermal properties in gas metal arc welding

Ley

Campbell

Galloway

et al. 2015

Int J Adv Manuf Technol

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This study considered the effect of shielding gas parameters (composition, supply method and flow rate) on the post weld thermal properties (thermal expansion, specific heat capacity, thermal diffusivity and thermal conductivity) of the weld metal in gas metal arc welding. This is of importance as the thermal properties influences the temperature distribution and therefore the residual stresses and distortion present within the final structure. Due to the lack of accurate thermal data, computational modelling techniques (such as FEA, CFD, etc.) used for modelling the welding process generally make assumptions regarding the material thermal properties, and it is often the case that the parent material thermal properties are extended to the weld metal, introducing errors to the simulation. It was determined that the weld metal posses considerably different thermal properties to the DH36 grade steel parent material, and that the shielding gas parameters significantly alter key thermal properties of the solidified weld metal. A lower shielding gas flow rate exhibited beneficial properties including a lower thermal expansion, and higher specific heat capacity and thermal conductivity than a higher shielding gas flow rate

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