On Tue, 5 Nov 2013 14:20:45 -0700, "Bob La Londe"
wrote:

From what I have read slow cooling of aluminum allows minerals to
precipitate out rather than remain in a more uniform suspension and or
solution when you cast aluminum. This is why a cast aluminum part is
usually not considered to be as good (and certainly not as strong) as a
forged part where the metal is only heated up enough to be shaped by the
press.

With that thought in mind would a process to rapidly cool the mold causing
the aluminum to freeze off quicker make a better quality part? Maybe not as
good as a forged part, but better than a slow cooled cast part? I am not
sure where I am really going with this, but there are plastics that are
injected into water jacketed molds for rapid cooling and freeze off. The
differences in temperature for those plastics and water at cooling
temperatures are much lower than that of aluminum and water, but the
potential for a steam explosion in the event of a failure is still there.

Or you could simply heat treat the casting after it was removed from
the mold.
http://www.thebloughs.net/hobbies/me...uminum7075.pdf
refers to this.
--
Cheers,

John B.