Steel-to-Aluminum Joining by Control of Interface Microstructures - Laser-Roll Bonding and Magnetic Pulse Welding -

Abstract

Laser-roll bonding and magnetic pulse welding are two relatively new processes that greatly minimize problems of metallurgical incompatibilities between dissimilar metals and alloys. These two processes, though technologically apart and invented for components with distinct geometries, utilize to various extents high pressures to facilitate rapid and localized interfacial heating and create reliable joints. In this paper, relations between process parameters, microstructures, and properties are discussed for aluminum-to-steel joints made by laser-roll bonding and magnetic pulse welding.

Characterization of 6061-T6 aluminum alloy to AISI 1018 steel interfaces during joining and thermo-mechanical conditioning

“…This is not likely for friction welds, in that this is well above the melting point for the aluminum substrate. It may be that the intimate contact between the species combined with the heavy working on the aluminum side of the joint can facilitate the atomic diffusion phenomena to overcome the activation barrier to form this phase [4][5][6]8,10].…”

“…The extended thermal cycles and higher temperatures/longer times that are generally associated with fusion welding result in the formation of thick intermetallic compound (IMC) layers at the joint interface. The formation of these layers is generally considered the root cause for the property degradation experienced with these types of joints [1][2][3][4][5][6]. Solid-state welding techniques provide joint formation at lower temperatures and often at very short times.…”

Joint formation in dissimilar Al alloy/steel and Mg alloy/steel friction stir spot welds

“…However, all attempts to find welding parameters settings during laser roll bonding, which consistently produce thin intermetallic layers at the bondline, have proved fruitless. 11 The factors determining intermetallic layer formation at the dissimilar joint interface during dissimilar rotary friction welding have been discussed at length in a classical paper by Ikeuchi et al 12 The chemical compositions of the intermetallic phases formed at the bondline are determined by the chemistry of the Al alloy substrate, e.g. FeAl 2 , Fe 2 Al 5 and Fe 4 Al 13 form in Al 5052/steel welds, Fe 2 Al 5 , Fe 4 Al 13 , (Mn,Fe)Al 6 , Mg 2 Si and Al 2 MgO 4 form in Al 5083/steel welds, and Fe 3 Al, FeAl, FeAl 2 Si, FeAl 4 Si, Fe 2 Al 8 Si and FeSi found in Al 6061/steel welds.…”

Influence of the jet velocity on the weld quality of magnetic pulse welded dissimilar sheet joints of aluminum and steel

“…49 50 reach this target limit. The analysis of interface, which only appeared turbulent wavy above a dis-charge current of 296 kA, revealed that despite relative similar jet velocities melt pockets behind the well-known Kelvin-Helmholtz instabilities in the middle area of the weld seam width W 2 and in particular the intermediate layer at the beginning of the weld seam formation W 1 appeared in a greater and strength critical extent when an increased acceleration distance was used [19][20][21][22], Figure 8. The intermediate layers of a sample welded with a discharge current of 346 kA and an acceleration distance of 1 mm were isolated from each other and did not exceed a thickness of 3 μm, Figure 8b, while by far continuous (500 μm) and partly cracked intermediate layer with a maximum thickness of 15 μm was found at the beginning of the weld seam formation at an acceleration distance of 2.5 mm, Figure 8c.…”