For AA 6061, the high temperature during FSW destroys the original work hardened
state in the NZ, TMAZ, and HAZ and leads the mechanical properties to weaken greatly.
When this is done properly, the austenitic grain structure is fixed, the casting becomes tough and is then capable of being work hardened
"If you keep it work hardened
, it lasts longer." Therefore, the more impact manganese wear parts receive, the more life you will see out of them, he notes.
However, unlike the ductile metals that are typically work hardened
, bulk silicon is brittle, so it would shatter if subjected to those operations.
This can result in chips improperly flushed from parts and workholding, premature tool wean inaccurate tool compensations, and higher heat that can work hardened
areas of the part.