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Grooveless Laser Keyhole Welding-Brazing (LKWB) of Automotive Aluminium Alloy to Galvanized Steel in a Butt Weld Configuration
C.G. Ren, X.L. Shen, M.J. Zhang and G.Y. Chen

Laser keyhole welding-brazing (LKWB) of automotive 6016 aluminium alloy to galvanized steel in butt configuration was conducted using a fibre laser without any grooves. The results indicate that the galvanized steel is brazed by the molten aluminium alloy without melting, and the top and bottom surfaces of the galvanized steel have been wetted well by filler metal. There is a thin layer of the intermetallic compounds (IMC) on the interface between the galvanized steel and the welded seam. The thickness of IMC layer varies with the joint zone. The main IMC are τ5-Al8Fe2Si and θ-Al13Fe4 phases. At the outermost part of the edges of the joint, Al-Zn eutectic and areas with hypoeutectic Al-Zn compositions are obtained. The tensile test indicates that the joint is ductile fractured at the base metal of the aluminium alloy with obvious appearance of necking in tension.

Keywords: Fibre laser, aluminium alloy, galvanized steel, laser keyhole welding-brazing, keyhole (LKWB), butt joint, intermetallic compounds, intermetallic layer

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