“Micro-friction stir welding of Titan Zinc Sheets”, J. Materials Processing Technology, Vol. 216, 2015, 133-139.
Aim of this research is first to evaluate the applicability of micro-friction stir welding
(μFSW) to wrought zinc alloy sheets and then to improve the structural integrity of
such joints. μFSW tool design was based on an algorithm that considers material and
process limitations. Joining trials were performed at differentfeed rates. It is proven
that joining by μFSW thin ZnTiCu sheets is possible and it offers extremely fine
microstructures and β-phase distribution due to the mechanical fragmentation
which is the outcome of the stirring. The β-phase particles were homogenized and
precipitated inside deformed zinc grains and not at the grain boundaries, where they
used to be in fusion welds. Electron microscopy showed that its size was limited to
150 nm, which is in average 13 times smaller than the size of the 2 μm that they get
when sheets are TIG welded. Macroscopically, the μFSW joint mechanical properties
are comparable with industrially fusion-welded material. The relative low elongation
achieved, similar to fusion-welded sheets, is explained by the occurrence of three
main defects: root opening, thinning and kissing bond.