Influence of subsequent cold work on the superplastic properties of a friction stir welded (FSW) aluminium alloy

Friction stir welding (FSW) can dramatically reduce grain size conferring excellent superplastic properties in certain aluminium alloys. Consequently, FSW of thick plate followed by rolling to sheet could potentially be used as a method of producing wide superplastic sheet from extrusion blanks for automotive applications.An extruded Al–4Mg–1Zr alloy was FSW prior to rolling to sheet. The structure of the FSW region after rolling was complex and in certain cases significant grain coarsening resulted during heating to the superplastic deformation temperature. A detailed investigation of the factors responsible is available here.