Many aluminums (and other materials) require stress annealing after
bulk machining and prior to a finish machining. I have not been able
to find anything one way or the other regarding this material. Does
anyone have an answer? If the answer is yes, what are the annealing
I found the following information in a couple of old books:
ALCAN, "Heat Treating Aluminium" : "Castings that are used in
applications involving elevated temperature or where extremely close
machining tolerances are necesarry may require a stress-relieving and
degrowthing treatment which involves heating the casting at a
temperature of 280°C (536°F) for 10 hours"
Reynolds Metals Company, "CASTING Aluminium, Table 19": "Stress
relieving of Die Castings to reduce internal stress 350-500°F for 4-6
hours and cool in still air"
Neither of the books give anything on heat treating of specific alloys.
Kai Wøldike Sørensen