Improvement of TIG lap weldability of dissimilar metals of Al and Mg

Liu, X. J.; Huang, Runsheng; Wang, H. Y.; Liu, S. H.

doi:10.1179/174329307x173670

“…Furthermore, it also improves the wettability of Mg and Al during the welding process. 13 Thus, the surface tension of the liquid is reduced, so more liquid spreads evenly over the surface of the base metal. Figure 3a and b shows the matching fracture surface morphology of the Al and Mg sides at an energy input of 1000 J.…”

Section: Microstructural Evaluationmentioning

confidence: 99%

“…Therefore, the aim of this research was to improve the joint strength in dissimilar USW of AZ31B-H24 with Al5754-O alloys by reducing the tendency for the formation of a brittle intermetallic layer using a tin (Sn) interlayer that could interact with both Mg and Al, as seen from their respective binary diagrams. 11,12 The selection of Sn in the present study was also based on the findings that Sn improved the wettability of Mg and Al alloys during the welding process 13 and also refined the grain size in the Mg alloy. 14,15 Experimental In the present study, a commercial 2 mm thick sheet of AZ31B-H24 (Mg-3Al-1Zn-0?6Mn-0?005Ni-0?005Fe) Mg alloy and a 1?5 mm thick sheet of Al5754-O (Al-3?42Mg-0?63Mn-0?23Sc-0?22Zr) Al alloy provided by General Motors Company were selected for USW.…”

Section: Introductionmentioning

confidence: 99%

Improving weld strength of magnesium to aluminium dissimilar joints via tin interlayer during ultrasonic spot welding

Patel

¹

,

Bhole

²

,

Chen

³

2012

Science and Technology of Welding and Joining

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Welding of magnesium to aluminium alloys is enormously challenging due to the formation of brittle Al 12 Mg 17 intermetallic compounds (IMCs). This study was aimed at improving the strength of dissimilar joints of AZ31B-H24 magnesium alloy to 5754-O aluminium alloy by using a tin interlayer inserted in between the faying surfaces during ultrasonic spot welding. The addition of tin interlayer was observed to successfully eliminate the brittle Al 12 Mg 17 IMCs, which were replaced by a layer of composite-like tin and Mg 2 Sn structure. Failure during the tensile lap shear tests occurred through the interior of the blended interlayer as revealed by X-ray diffraction and SEM observations. As a result, the addition of a tin interlayer resulted in a significant improvement in both joint strength and failure energy of magnesium to aluminium dissimilar joints and also led to an energy saving because the optimal welding energy required to achieve the highest strength decreased from y1250 to y1000 J.

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“…The addition of Sn to the lap joint was observed to refine the grain size in the fusion zone and the base Mg alloy [92,128] due to the presence of a eutectic structure, which restricts the growth of the Mg grains. Furthermore, it also improves the wetability of Mg and Al during the welding process [127]. Thus, the surface tension of the liquid is reduced so that more liquid spreads evenly over the surface of the base metal.…”

Section: Energy-dispersive X-ray Spectroscopy Analysismentioning

confidence: 99%

Ultrasonic spot welding of lightweight alloys

Patel¹

2021

Preprint

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Automotive and aerospace sectors have a pressing need for structural components that are lighter and stronger, aiming to improve energy efficiencies and reduce anthropogenic environment. Steel has already a wide variety of structural applications in the transportation industry due to its excellent properties. To further reduce CO2 emissions, lightweight magnesium (Mg) and aluminum (Al) alloys have increasingly been used in the vehicle fabrication due to their lower density, higher specific strength and stiffness, excellent size stability and process ability. The structural application of these alloys inevitably involves welding and joining of similar Mg-to-Mg and Al-to-Al, and dissimilar Mg-to-Al, Mg-to-steel and Al-to-steel. Resistance spot welding produces coarse grains, large defects and thick brittle intermetallic compounds (IMCs) in the weld metal. Alternative solid-state welding processes are being considered such as ultrasonic spot welding (USW), which produces coalescence through the simultaneous application of localized high-frequency vibratory energy and moderate clamping forces. In this study, USW was successfully carried out on similar Mg alloy and dissimilar Mg-to-Al, Mg-to-steel and Al-to-steel alloys. The overall objective of this work is to gain a better understanding of the dominant factors determining the joint performance, with particular emphasis on the microstructural evolution, crystallographic texture, micro-hardness, lap shear strength, fatigue resistance, fatigue life prediction model and fracture analysis of similar and dissimilar USWed joints. Overall, USWed Mg-to-Mg is stronger and more consistent in terms of weldability than the dissimilar USWed Mg-to-Al, Mg-to-steel and Al-to-steel. This was attributed to the large volume of thick brittle IMCs and significantly higher welds center hardness in dissimilar metals welding, which is the main cause of joint failure. The IMCs were confirmed by XRD, EDS and micro-hardness measurement tests.. Therefore, another objective of this study is to minimize the presence of brittle IMCs and engineer an acceptable intermetallic layer to produce sound joints between Mg-to-Al, Mg-to-steel and Al-to-steel. A third material (tin foil or zinc coating) was placed in-between the work pieces. With this procedure, the lap shear strength of the welded samples was increased. The detailed microstructural characterization and mechanical properties of welded joints with an interlayer are presented.

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“…The selection of Sn in the present study was based on the Mg-Sn and Al-Sn binary phase diagrams [91,126], which show that Sn may interact with Mg and generate IMCs, while Sn is dissolved into Al to form a solid solution of Sn-Al. Furthermore, Sn was selected on the basis of the findings that it improved the wettability of Mg and Al during the welding process [127] and also refined the grain size in the Mg alloy [128].…”

Section: Chapter 5 Ultrasonic Spot Welding Of Magnesium-to-aluminum Alloys †mentioning

confidence: 99%

Ultrasonic spot welding of lightweight alloys

Patel¹,

Bhole²,

Chen

³

2021

Preprint

0

View full text Add to dashboard Cite

Automotive and aerospace sectors have a pressing need for structural components that are lighter and stronger, aiming to improve energy efficiencies and reduce anthropogenic environment. Steel has already a wide variety of structural applications in the transportation industry due to its excellent properties. To further reduce CO2 emissions, lightweight magnesium (Mg) and aluminum (Al) alloys have increasingly been used in the vehicle fabrication due to their lower density, higher specific strength and stiffness, excellent size stability and process ability. The structural application of these alloys inevitably involves welding and joining of similar Mg-to-Mg and Al-to-Al, and dissimilar Mg-to-Al, Mg-to-steel and Al-to-steel. Resistance spot welding produces coarse grains, large defects and thick brittle intermetallic compounds (IMCs) in the weld metal. Alternative solid-state welding processes are being considered such as ultrasonic spot welding (USW), which produces coalescence through the simultaneous application of localized high-frequency vibratory energy and moderate clamping forces. In this study, USW was successfully carried out on similar Mg alloy and dissimilar Mg-to-Al, Mg-to-steel and Al-to-steel alloys. The overall objective of this work is to gain a better understanding of the dominant factors determining the joint performance, with particular emphasis on the microstructural evolution, crystallographic texture, micro-hardness, lap shear strength, fatigue resistance, fatigue life prediction model and fracture analysis of similar and dissimilar USWed joints. Overall, USWed Mg-to-Mg is stronger and more consistent in terms of weldability than the dissimilar USWed Mg-to-Al, Mg-to-steel and Al-to-steel. This was attributed to the large volume of thick brittle IMCs and significantly higher welds center hardness in dissimilar metals welding, which is the main cause of joint failure. The IMCs were confirmed by XRD, EDS and micro-hardness measurement tests.. Therefore, another objective of this study is to minimize the presence of brittle IMCs and engineer an acceptable intermetallic layer to produce sound joints between Mg-to-Al, Mg-to-steel and Al-to-steel. A third material (tin foil or zinc coating) was placed in-between the work pieces. With this procedure, the lap shear strength of the welded samples was increased. The detailed microstructural characterization and mechanical properties of welded joints with an interlayer are presented.

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Improvement of TIG lap weldability of dissimilar metals of Al and Mg

Cited by 17 publications

References 12 publications

Improving weld strength of magnesium to aluminium dissimilar joints via tin interlayer during ultrasonic spot welding

Improving weld strength of magnesium to aluminium dissimilar joints via tin interlayer during ultrasonic spot welding

Ultrasonic spot welding of lightweight alloys

Ultrasonic spot welding of lightweight alloys

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