Abstract
At the prospect of a lightening of the automobile
structures, welded spots have been realized on a stacking of
two sheets (a 6008 aluminum alloy on steel) Friction Stir
Spot welding (FSSW). Different process parameters have been
tested, but only the influence of the dwell time will be
described in the present paper. The dwell time corresponds to
the time during which the probe stays in rotation at its
bottom location before extracting. A study of the
microstructures and textures associated to mechanical tests
(tensile shear tests) allowed determining the best set of
welding parameters. The recrystallized area around the welding
spot has been characterized by electron back-scattered
diffraction (EBSD). A mechanism of continuous dynamic
recrystallization has been identified since the misorientation
of subboundaries increases close to the weld, and this is for all
the dwell times tested. Elsewhere, the increase of the dwell
time induced a larger recrystallized zone. It has also been
found that a long dwell time induced a larger welded area but
also a higher quantity of intermetallic compounds (especially
FeAl,