356 is likely the most common aluminum sand and permanent mold casting
alloy, especially due the the automotive industry. It is rarely used
"as-cast". The "as-cast" temper is called "F". In F temper it would have a
tensile of about 20 ksi and 3% elongation. It can be "aged" at 440 degrees
for 7-9 hours which improves tensile to about 24 ksi this is called "T5"
temper. It can also be brought to a temper of "T6" by heating to 1000
degrees, holding for 6-12 hours, quenching in water and then aging at 310
degrees for 3-5 hours. Tensile goes to 25+ ksi, yield strength is 18 ksi
and elongation perhaps 3.5%. 356 casts easily. It is an aluminum with a
nominal 7% silison content. Copper is considered an impurity.

319 is a common casting alloy, with slightly less silicon than 356 (about 6%
silicon) but also about 3.5% copper. The aim of this alloy is to produce a
cast aluminum alloy with fair strength as cast. It is a little more
difficult to cast without internal shrink problems and is generally used as
cast.

201, 204 and 206 are aluminum alloys containing 4 to 6% copper. 201 also
contains some silver, (only a tiny amount) but the price is higher. These
alloys should all be used after a heat treatment. The procedure is a more
complicated heat treatment involving slow heating to about 980 degrees, with
a water quench. With good quality material the aging may be eliminated but
a lot of designers wish to "over-age" the casting because it will be
dimensionally more stable than in the t^ temper. This overaging is called
T7. These alloys are often used in military applications.

535 aluminum is an alloy of aluminum with magnesium plus other elements. It
is difficult to cast but has the advantage of an alloy which is of good
strength as cast. Heat treating is not done. This alloy is very bright on
surface appearance and polishes well. It also will anodize very nicely and
has good corrosion resistance, even in seawater.

713 aluminum is an alloy of aluminum with about 7% zinc. It is reasonably
easy to cast, a bit more difficult than 356 or 319 but develops its strength
naturally. It is called a "naturally aging" alloy. It will develop full
strength 21 days after casting at which time is machines easist. If
machined immediately after casting it will be gummy and machined surfaces
will be rough. To speed up the process if can be given a T5 treatment of
aging at 250 degrees for 12 hours.

There are many other aluminum casting alloys but these are some of the more
common ones.

Mark


"Roy" wrote in message
...
I buy ingots from a supplier not to far from me. The info he gave me
wsa that virtually all the aluminum found in automotive wheels, head
cases etc can be treated as 356 alloy, and everythng should work ouyt
just fine. There are some odd ball propreiatary alloys used by some,
but treat it as if it was 356.

The smelter that I buy from on occasion uses automotive andother
precast junk as hie main ingredients for 356, and IIRC is it 380
alloy. Heck I can't remember my own age anymore yet alone aluminum
alloys I do not use anymore. I tend to stick with what can be used in
356 applications.

On 20 May 2006 18:31:37 -0700, wrote:
Roy,

Thanks for the info--it looks like 356 has no copper in it so I guess I
won't be stirring it with a copper pipe. ;-))

Tut