Porosity evolution in aluminum alloy 2024 bop and butt defocused welding by Yb-YAG disk laser

Vittorio Alfieri, Francesco Cardaropoli, Fabrizia Caiazzo, Vincenzo Sergi

Abstract


In many industrial applications, in order to obtain good results in laser welding processes, it may not be sufficient to use a focused beam on the upper surface, so a defocused beam is required instead. This study aims to investigate which advantages a defocused beam may offer in welding aluminum alloy 2024 using Yb:YAG disk laser. A characterization of laser beam geometry is preliminary necessary, in order to correlate bead features and effective specific energy provided. Porosity content decrease and enhanced penetration depth have been obtained with defocused beam; welding behavior has been related to magnesium loss via EDS analysis. Considering the shape of the cross sections of the bead in butt welding, the relation between key-hole instability and porosity formation has also been discussed. For the alloy in exam, the welding range to perform structurally sound and defect-free welds is found to be tight.

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ISSN 1330-9587 (Print), ISSN 1849-0433 (Online)

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