Forge Welding of Magnesium Alloy to Aluminum Alloy Using a Cu, Ni, or Ti Interlayer

Abstract

HIDEKI YAMAGISHI, JUNJI SUMIOKA, SHIGEKI KAKIUCHI, SHOGO TOMIDA, KOUICHI TAKEDA, and KOUICHI SHIMAZAKI The forge-welding process was examined to develop a high-strength bonding application of magnesium (Mg) alloy to aluminum (Al) alloy under high-productivity conditions. The effect of the insert material on the tensile strength of the joints, under various preheat temperatures and pressures, was investigated by analyzing the reaction layers of the bonded interface. The tensile strengths resulting from direct bonding, using pure copper (Cu), pure nickel (Ni), and pure titanium (Ti) inserts were 56, 100, 119, and 151 MPa, respectively. The maximum joint strength reached 93 pct with respect to the Mg cast billet. During high-pressure bonding, a microscopic plastic flow occurred that contributed to an anchor effect and the generation of a newly formed surface at the interface, particularly prominent with the Ti insert in the form of an oxide layer. The bonded interfaces of the maximum-strength inserts were investigated using scanning electron microscopy-energy-dispersive spectroscopy and electron probe microanalysis. The diffusion reaction layer at the bonded interface consisted of brittle Al-Mg intermetallics having a thickness of approximately 30 lm. In contrast, for the three inserts, the thicknesses of the diffusion reaction layer were infinitely thin. For the pure Ti insert, exhibiting the maximum tensile strength value among the inserts tested, focused ion beam-transmission electron microscopy-EDS analysis revealed a 60-nm-thick Al-Ti reaction layer, which had formed at the bonded interface on the Mg alloy side. Thus, a high-strength Al-Mg bonding method in air was demonstrated, suitable for mass production.

High-Productivity and High-Strength Fe/Al and Al/Al Dissimilar Joining by Spot Forge-Welding

“…In a basic study for the development of next-generation spot-joining equipment, it was demonstrated that the forge-welding method [20][21][22] can be applied to Fe 9 Al spot welding. [23,24] Forge welding is a method whereby a contaminated layer (e.g., an oxide at the interface) is removed by plastic flow; diffusion bonding occurs on the new surface within a short period of time.…”

“…Moreover, as a quality assurance advantage of this joining method, the joint strength could be guaranteed at all points, depending on the thickness of the joint or the amount of punch insertion. There is a wide range of applicable material combinations, such as Fe 9 Al and other dissimilar material combinations described thus far [20][21][22] ; these combinations include Al 9 copper (Cu), Al 9 titanium (Ti), Al 9 nickel (Ni), Cu 9 magnesium (Mg), Ti 9 Mg, and Ni 9 Mg. Furthermore, this method can use Al 9 Al joints, for which ordinary resistance spot-welding is difficult due to the high current required by the electrode.…”

Influence of Zn coating on friction stir spot welded magnesium-aluminium joint

“…For other welding processes, adding metal interlayer is an important way of reducing the formation of IMCs, such as resistance spot welding with a Zn coated steel interlayer [22] or Zn interlayer [23], forge welding with a Cu, Ni, or Ti interlayer [24], laser welding with a Ti interlayer [25], diffusion welding with a Zn interlayer [26], pre-roll-assisted A-TIG welding with a Zn interlayer [27] and ultrasonic spot welding with a Sn interlayer [28]. However, for Mg–Al FSSW, welding temperature is not high, so the insertion of metal layer with low melting point between the Mg and Al sheets is a more promising way of mitigating the formation of undesirable IMCs.…”

Evolution of microstructure and enhanced mechanical properties of dissimilar Al and Mg joints with Cu interlayer fabricated by friction stir welding

“…Zhang et al 12 added a Cu layer to the Al-Zn-Mg-Cu FSW lap joints and found a significant positive relationship between the Cu layer and the joint strength. Although Wang et al 13 and Yamagishi's team 14 used Cu interlayer for butt and lap welding, the former mainly studies the improvement of the joint strength by pulse current. At the same time, the latter had a Cu layer lap joint strength of 100 MPa, which lacks further improvement.…”