Depends on the consumable and parent with alu. But your absolutely right quite often they split down the face during a bend test.
where would you expect a weld to fail?
with steel it would be the on the metal but any 'destructive' test I've tried with alu it breaks pretty much through the middle of the weld, 6082 T6 and 5356 filler
The other major difference between welds in aluminum alloys and those in steels is that a weld in steels normally is about the same strength as the surrounding material, while in aluminum alloys, the weld and the adjacent heat-affected zone (HAZ) usually are much weaker than the surrounding material.