Microstructural characterisation of interfaces in magnetic pulse welded aluminum/aluminum joints

Sharafiev, Semen; Pabst, Christian; Wagner, Martin F.‐X.; Groche, Peter

doi:10.1088/1757-899x/118/1/012016

Cited by 6 publications

(6 citation statements)

References 4 publications

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“…As a first step to evaluate our hypothesis that part of the material in the jet can indeed be trapped in the magnetic pulse welding weld interface, we Although discharge energy (E = 16 kJ) and acceleration gap (d = 1.5 mm) were the same, the difference between both weld seams is significant. While the compound manufactured at normal pressure shows a pronounced porous interlayer (similar to previous reports [3]), there is no such layer in the low pressure sample. Note that the main difference between both experiments is that the jet can reach much higher velocities in low pressure environments compared to normal ambient pressure [17].…”

Section: Influence Of Ambient Pressure On the Microstructure Of Alumisupporting

confidence: 87%

“…Compared to previously investigated interfaces in aluminum/aluminum joints [13], the aluminum/ steel welds show a much more complex interface structure, Figure 2. The different brightness levels in the backscatter electron micrograph show several discrete phases present within the weld seam.…”

Section: Interface Microstructure In Aluminum/steel Jointsmentioning

confidence: 83%

“…Magnetic pulse welding is based on the acceleration of a sheet metal workpiece (the so-called flyer) via the magnetic pressure that is generated when a high frequency current is driven through a coil close to the flyer, Figure 1a. Several key aspects of magnetic pulse welding are not yet sufficiently understood, as the process itself takes only a few microseconds and can therefore in most cases only be analyzed post-mortem or via extensive simulations [3,4]. The two main aspects currently under investigation are: * the relation between process parameters and the waviness and phases of the formed interface between the joint metals, and * the so-called jet, the material which gets ejected from the rapidly closing gap between the weld partners during the process [4][5][6][7], Figure 1b).…”

Section: Introductionmentioning

confidence: 99%

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On the microstructure and the origin of intermetallic phase seams in magnetic pulse welding of aluminum and steel

Böhme

Sharafiev

Schumacher

et al. 2019

Materialwissenschaft Werkst

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The microstructure of aluminum‐steel compounds fabricated by magnetic pulse welding are investigated. Electron backscatter diffraction, energy dispersive x‐ray spectroscopy and scanning electron microscopy revealed the existence of several different phases along the weld seam. While one layer could be identified as aluminum solid solution, a very thin layer close to the steel side of the compound eluded detailed characterization by scanning electron microscopy techniques. Transmission electron microscopy and selected area electron diffraction investigations of this layer revealed a mix of nanocrystalline and amorphous parts. When ambient pressure was reduced to 1 mbar during welding, no interlayers were observed in the samples. This suggests that the interlayers are precipitates of the jet that is formed during conventional impact welding.

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Section: Influence Of Ambient Pressure On the Microstructure Of Alumisupporting

confidence: 87%

Section: Interface Microstructure In Aluminum/steel Jointsmentioning

confidence: 83%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

On the microstructure and the origin of intermetallic phase seams in magnetic pulse welding of aluminum and steel

Böhme

Sharafiev

Schumacher

et al. 2019

Materialwissenschaft Werkst

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“…Sharafiev et al reported sharp boundaries between the base materials and an intermediate layer of impact welded A-Al joints. New, recrystallized grains in the size of nanometers and high dislocation densities give evidence for melting and rapid solidification [11]. Amorphous structures have also been described by metallurgists [12,13] that can be attributed to solidification with cooling rates in the order of 10 7 K/s [9].…”

Section: Introductionmentioning

confidence: 95%

Thermal Effects in Dissimilar Magnetic Pulse Welding

Bellmann

Lueg‐Althoff

Schulze

et al. 2019

Metals

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Magnetic pulse welding (MPW) is often categorized as a cold welding technology, whereas latest studies evidence melted and rapidly cooled regions within the joining interface. These phenomena already occur at very low impact velocities, when the heat input due to plastic deformation is comparatively low and where jetting in the kind of a distinct material flow is not initiated. As another heat source, this study investigates the cloud of particles (CoP), which is ejected as a result of the high speed impact. MPW experiments with different collision conditions are carried out in vacuum to suppress the interaction with the surrounding air for an improved process monitoring. Long time exposures and flash measurements indicate a higher temperature in the joining gap for smaller collision angles. Furthermore, the CoP becomes a finely dispersed metal vapor because of the higher degree of compression and the increased temperature. These conditions are beneficial for the surface activation of both joining partners. A numerical temperature model based on the theory of liquid state bonding is developed and considers the heating due to the CoP as well as the enthalpy of fusion and crystallization, respectively. The time offset between the heat input and the contact is identified as an important factor for a successful weld formation. Low values are beneficial to ensure high surface temperatures at the time of contact, which corresponds to the experimental results at small collision angles.

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“…Sharafiev et al [22] studied the interface microstructure of MPW of Al/Al joints; the interface displayed a wavy weld geometry. The created transitional layer consists of ultrafine grains and, in some regions, exhibits a columnar grain structure, and it is suggested that the microstructure was generated by rapid melting and solidification.…”

Section: Introductionmentioning

confidence: 99%

On Additive Manufactured AlSi10Mg to Wrought AA6060-T6: Characterisation of Optimal- and High-Energy Magnetic Pulse Welding Conditions

Nahmany

Shribman

Levi³

et al. 2020

Metals

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This novel research aims to examine the macro and microstructural bonding region development during magnetic pulse welding (MPW) of dissimilar additive manufactured (AM) laser powder-bed fusion (L-PBF) AlSi10Mg rod and AA6060-T6 wrought tube, using both optimal- and high-energy welding conditions. For that purpose, various joint characterisation methods were applied. It is demonstrated that high-quality hermetic welds are achievable with adjusted MPW process parameters. The macroscale analysis has shown that the joint interfaces are deformed to a waveform shape; the interface is starting relatively planar, with waves forming and growing in the welding direction. The observed thickening of the flyer’s wall after welding is the result of its diametral inward deformation, taking place during the process. A slight increase in microhardness was adjacent to the faying interfaces; a higher increase was measured on the AlSi10Mg material side, while a smaller one was observed on the AA6060 side. Along the wavy interfaces, resolidified “pockets” of material or occasionally discontinuous short layers exhibiting different morphologies, were detected. The jet residues are typically located towards the end of the weld, confirming a temperature rise that exceeds the melting temperature of both alloys. Far from the weld zone, extremely thin-film deposits were clearly observed on the inner flyer surfaces. The formation of isolated Si particles and thin-film deposits may point out that the local increase in temperatures leads to melting or even evaporation vaporisation of superficial layers from the colliding parts. It is worth noting that this type of jet residue was discovered for the first time in the present research. The current research work is expected to provide an understanding of weld formation mechanisms of additively manufactured parts to conventional wrought parts conforming to existing wrought/wrought weld knowledge.

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Microstructural characterisation of interfaces in magnetic pulse welded aluminum/aluminum joints

Cited by 6 publications

References 4 publications

On the microstructure and the origin of intermetallic phase seams in magnetic pulse welding of aluminum and steel

On the microstructure and the origin of intermetallic phase seams in magnetic pulse welding of aluminum and steel

Thermal Effects in Dissimilar Magnetic Pulse Welding

On Additive Manufactured AlSi10Mg to Wrought AA6060-T6: Characterisation of Optimal- and High-Energy Magnetic Pulse Welding Conditions

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