Improved microstructure and properties of 6061 aluminum alloy weldments using a double-sided arc welding process

Zhang, Y. M.; Pan, Chun; Male, Alan T.

doi:10.1007/s11661-000-0198-8

Cited by 78 publications

(33 citation statements)

References 15 publications

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“…[27] Zhang et al [16] reduced the formation of columnar structures in Al 6061 weldments by double arc welding, and consequently, metallurgical properties of welds were improved. Yongyuth et al [28] and Qiu et al [29] found that the toughness of castings and welds could be improved by increasing the volume fraction of the equiaxed zone.…”

Section: Effects Of Microstructurementioning

confidence: 99%

“…[16] Consequently, the width of CDZ would decrease with the increase in welding current. According to the theory of Hunt, fully equiaxed growth occurs when the following is true [32] :…”

Section: Effects Of Welding Currentmentioning

confidence: 99%

“…[9,12] Various techniques have been employed to promote CET and increase the percentage of equiaxed grains in the weld, such as magnetic arc oscillation, [13] ultrasonic vibration, [14] exciting the electric arc, [15] or double-sided arc welding. [16] However, changing the welding parameters [9] and the addition of heterogeneous nucleation elements [17] are the most prevalent and straightforward methods used in industrial welding practice.…”

Section: Introductionmentioning

confidence: 99%

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Resistance Spot Welded AZ31 Magnesium Alloys, Part II: Effects of Welding Current on Microstructure and Mechanical Properties

Liu

Xiao

Feng

et al. 2010

Metall Mater Trans A

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Resistance spot welding of AZ31 magnesium alloys from different suppliers, AZ31-SA (from supplier A) and AZ31-SB (from supplier B), was studied and compared in this article. The mechanical properties and microstructures have been studied of welds made with a range of welding currents. For both groups of welds, the tension-shear fracture load (F C ) and fracture toughness (K C ) increased with the increase in welding current. The F C and K C of AZ31-SA welds were larger than those of AZ31-SB welds. The fracture surfaces of AZ31-SB welds were relatively flatter than those of AZ31-SA. Microstructural examination via optical microscope demonstrated that almost all weld nuggets comprised two different zones, the columnar dendritic zone (CDZ), which grew epitaxially from the fusion boundary, and the equiaxed dendritic zone (EDZ), which formed in the center of the nugget. The nature and extent of the CDZ seemed to be critical to the strength and toughness of spot welds because of its position adjacent to the inherent external circular crack-like notch of spot welds and the stress concentration in this region. The width and microstructure of the CDZ were different between AZ31-SA and AZ31-SB. The AZ31-SA alloy produced finer and shorter columnar dendrites, whereas the AZ31-SB alloy produced coarser and wider columnar dendrites. The width of the CDZ close to the notch decreased with the increase of current. The CDZ disappeared when the current was higher than a critical value, which was about 24 kA for AZ31-SA and 28 kA for AZ31-SB. The microhardness of the two base materials was the same, but within the CDZ and EDZ, the hardness was greater in AZ31-SA than AZ31-SB welds. It is believed that the different microstructures of spot welds between AZ31-SA and AZ31-SB resulted in different mechanical properties; in particular, K C increased with the welding current because of the improved columnar-to-equiaxed transition.

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Section: Effects Of Microstructurementioning

confidence: 99%

“…[16] Consequently, the width of CDZ would decrease with the increase in welding current. According to the theory of Hunt, fully equiaxed growth occurs when the following is true [32] :…”

Section: Effects Of Welding Currentmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Resistance Spot Welded AZ31 Magnesium Alloys, Part II: Effects of Welding Current on Microstructure and Mechanical Properties

Liu

Xiao

Feng

et al. 2010

Metall Mater Trans A

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“…However, when applying conventional fusion welding techniques, butt joints or lap joints, typically encountered in the assembly of long and (or) large structural products, are especially challenging to manufacture without distortion and defects. Aluminium alloys of the 6000 series have high thermal conductivity, high strength, and low weldability; this combination of properties necessitates the use of special welding procedures to prevent solidification cracking and to minimize residual stresses (Indira Rani et al, 2011;Zhang et al, 2000).…”

Section: Introductionmentioning

confidence: 99%

Process operational windows and industrialization scenarios for assembly of large aluminium structures by robotic friction stir welding

Wanjara¹,

Monsarrat²,

Larose³

2015

Can. Aeronaut. Space J.

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Abstract. In this work, friction stir welding (FSW) of 3.18 mm thick AA6061-T6 sheets in the butt-and lap-joint configuration was investigated with the objective of industrializing the process using low-cost serial industrial robots. The influence of weld pitch on the welding defects, microstructure, hardness, and bend performance of butt and lap welds was examined to identify process operational windows for both joint types. In parallel with these trials, a methodology based on kinetostatic analysis was developed to identify and evaluate viable robotized scenarios for FSW. On the basis of the experimental FSW process development results, this methodology was then applied to identify optimized FSW scenarios for the fabrication of large integrated AA6061 structural components with stringer-to-skin and skin-to-skin joints. Candidate workcell layouts are also presented.Résumé. Dans ce travail, le soudage par friction malaxage (mieux connu sous l'acronyme FSW pour Friction Stir Welding) de feuilles d'aluminium 6061-T6 d'une épaisseur de 3.18 mm dans les configurations bout-à-bout et par recouvrement a été étudié dans l'optique d'industrialiser le procédé via l'utilisation de robots sériels industriels à bas coû t. L'influence du pas de soudage (weld pitch) sur les défauts de soudage, la microstructure, la dureté et la performance en flexion a été examinée afin d'établir les fenêtres opératoires du procédé pour les deux types de soudure. En parallèle de ces essais expérimentaux, une méthodologie basée sur l'analyse cinétostatique a été développée afin d'identifier et d'évaluer des scénarios viables d'implantation du soudage par friction malaxage robotisé. Cette méthodologie a par la suite été appliquée en utilisant les résultats des tests expérimentaux de soudage afin d'identifier des scénarios d'implantation optimisés pour l'assemblage de composants structurels intégrés de grande dimension en AA60601 comprenant à la fois des joints lisse sur revêtement et revêtement sur revêtement. Des scénarios d'implantation potentiels ont été identifiés et sont présentés.

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“…Double-sided arc welding (DSAW) is a new arc welding process invented and developed at the University of Kentucky [1][2][3]. The DSAW system uses two torches on the opposite sides of the workpiece to force the welding current to flow through the thickness of the workpiece disconnected from the power supply ( figure 1(b)).…”

Section: Introductionmentioning

confidence: 99%

Numerical simulation of dynamic development of keyhole in double-sided arc welding

Sun

Zhang

2004

Modelling Simul. Mater. Sci. Eng.

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Double-sided arc welding (DSAW) is a novel process for joining metals that is capable of achieving deep narrow penetration in a single pass with minimized distortion. A clear understanding of the process fundamentals is critical in order to fully examine the potential of DSAW, to guide the further developments of the process, to direct the practicability study, and to design the process parameters. This paper aims at developing a numerical model for examining and simulating the dynamic keyhole establishment process, which will be a key in developing an effective control technology for DSAW. The model is used to determine the geometrical shape of the keyhole and the weld pool, and the temperature distribution in the workpiece. Quantitative information on the establishment of the keyhole in DSAW, such as the transient development of the keyhole and the weld pool, the increase rate of the depth of the surface depression, the time interval from full penetration to the keyhole establishment, the minimum span of the weld pool for describing the conditions required to complete the keyhole establishment, and variation of the overflow height of the weld pool surface on the plasma arc welding side, has been obtained through numerical analysis. The DSAW experiments show that the predicted weld cross-section is in agreement with the measured one. The results lay a foundation for guiding the further development of the DSAW process and its effective control.

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Improved microstructure and properties of 6061 aluminum alloy weldments using a double-sided arc welding process

Cited by 78 publications

References 15 publications

Resistance Spot Welded AZ31 Magnesium Alloys, Part II: Effects of Welding Current on Microstructure and Mechanical Properties

Resistance Spot Welded AZ31 Magnesium Alloys, Part II: Effects of Welding Current on Microstructure and Mechanical Properties

Process operational windows and industrialization scenarios for assembly of large aluminium structures by robotic friction stir welding

Numerical simulation of dynamic development of keyhole in double-sided arc welding

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