An innovative welding methodology, defined as double-side friction stir welding, was developed.

What is it about?

An innovative welding methodology, defined as double-side friction stir welding, was developed in order to obtain joints in 2-mm-thick sheets in AA6082 aluminium alloy. Such approach consists in performing the friction stir welding process on both sheet surfaces: the first welding operation is followed by a second one performed by putting the rotating tool in contact with the sheet surface opposite to the one welded by the first pass. The effect of the welding parameters, tool configuration and sheet positioning on the mechanical properties, microstructure and post-welding formability was analysed and discussed in detail. In order to evaluate the advantages offered by the new welding methodology, the experimental results obtained using the double-side friction stir welding were compared with those given by the conventional process.

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Why is it important?

A new approach, developed in order to improve joint formability, consists in carrying out the FSW process on both sheet surfaces; in particular, the first welding operation is followed by a second one performed by putting the rotating tool in contact with the sheet surface opposite to the one welded during the first pass. Such an innovative methodology, that is here defined as double-side friction stir welding (DS-FSW), offers the advantage represented by the closure, by means of the second welding operation, of the geometric discontinuity produced by the first one; furthermore, the proposed approach allows obtaining more uniform values of hardness and recrystallised grain size across the welded zone as compared to the conventional FSW. Such improvement in the joint quality is very attractive as the assembled blanks have to be subjected to post-welding forming operations.