[MidFloridaTech]

I've got about 80lbs worth of aluminum wheels, but I'd like to know what alloy they are. They're good ol' factory ford wheels from a tbird and a ford ranger. Seems like they'd use 6061 but I was hoping someone would know for sure.

[ckm]

They are probably a casting alloy, not 6xxx or 7xxx, which are wrought alloys... Most aluminum wheels, AFAIK, are 356.

HTH,

Chris.

[MidFloridaTech]

I will likely need to do machining on some of these casting, but I cant really wait a year for it to age, nor can I afford heat treatment. Is there a book that will tell me hey bake this at 300* for 12 hours to age it so I can machine it? ANy hints as to whaty temps or times I chould use for 356 alloy parts?

Most of the stuff I am doing won't be structural stuff.

[ckm]

The biggest danger is that the parts will move after machining, AFAIK. This may not be a problem if the parts are decorative. Wrought alloys are achieved by hammering the billets when they are still hot, which tightens the grain structure. I don't know if it works with aluminum, but blacksmiths used to hammer iron by hand to turn it into a wrought material (from cast iron...).

Chris.

[MidFloridaTech]

I figured I would cast them, bake them, and then machine them leaving maybe an extra 1/16-1/8 for finish machining is that not what companies normally do?

[tool_man]

I would also like information on treatment processes of aluminum alloys.I have searched the net extensively without sucess.Machinery's handbook gives a description but,no details.If you find this information,please post it.I cast several heavy parts from 356 without any heat treatment.I let them age for 2 weeks before machining.

[ckm]

I figured I would cast them, bake them, and then machine them leaving maybe an extra 1/16-1/8 for finish machining is that not what companies normally do?

According to a old version of the Metals Handbook I have around, you can heat a casting to 250F to 400F to heat treat it, although this is usually done AFTER solution heat treatment (but not necessarily), with treatment time ranging from a few minutes for sheet to a few hours for large castings. The part must be fully heated and then quenched appropriately. The book recommends quenching in cold water, but warns of warpage. Some corrosion resistant alloys can be quenched in boiling water, which reduces warpage, apparently.

There is also a note that solution treated casting will naturally be fully aged in 3 months, and this can be accelerated through low temp treatment (see above).

So the best thing is to solution treat them not more than 2hrs to 2days after casting, then either heat them as above for enough time for a thorough heat or let them sit for 3 months. Just to be sure, I would let them sit for a few weeks after any treatment. It does say that most of the changes occur in the first several of weeks after treatment

This is out of the 1948 version of the Metals Handbook. I like it that old as it's much more likely that the techniques described will be at a technology level I can actually replicate.... The current version of the book is here: http://products.asminternational.org/hbk/index.jsp (but not free)

You can also look here http://books.google.com/books?q=meta...-8&sa=N&tab=wp for more up to date versions (and much older, but still valid, versions) of the same info... Unfortunately, industry likes to keep this info secret, so not much of it is available electronically unless you pay. However, you can usually find it at your local library, and used book stores usually have copies of it.

BTW, that's not where I learned about what alloys alu wheels use... In fact, modern alloy designations are not used in older texts.

Oh, and I'm no expert. I've never cast anything, most of my knowledge comes from knowing how to shape sheetmetal, machining stuff and good reference books, so Cavae Emptor and don't blame me when it all goes wrong...

HTH,

Chris.

[ckm]

I would also like information on treatment processes of aluminum alloys.I have searched the net extensively without sucess.Machinery's handbook gives a description but,no details.If you find this information,please post it.I cast several heavy parts from 356 without any heat treatment.I let them age for 2 weeks before machining.

Get a relatively recent copy (1970 or newer) of the Metals Handbook from a used bookstore or photocopy the relevant pages at the library. The net-net of it is that most metals are solution heat treated, which makes them harder, then artificially aged in an oven.

I think two weeks is probably too short of a time frame for natural aging. If 3 months is fully aged, and most of the changes occur in the first 'several' weeks, I would think that 3 weeks to a month would be the right period of time. Also, make sure you put them outside. This is routinely done with large cast iron castings. The hot/cold cycle of day/night is great for aging, apparently. Full sunlight is best. I've heard that Japanese makers of precision machine tools cast their parts, then throw them 'out back' for a couple of years to age...

PS. There is a good article on Wikipedia about "Precipitation Strengthening", which is the technical term for 'sticking your part in an oven': http://en.wikipedia.org/wiki/Precipi..._strengthening

HTH,

Chris.

[tool_man]

Thanks for the links CKM.I will order a copy today.As I understand solution heat treatment of aluminum,it is done in a brine solution close to the melting point of the alloy.Metals in the alloy like zinc,copper,ect. tend to migrate to cooler or warmer areas in the casting as it cools.Solution heat treatment,redistributes them evenly throughout the casting.I am not sure how economical it would be for the person like myself who makes the occasional casting

[MidFloridaTech]

I love you internets!!!!

http://www.patentstorm.us/patents/53...scription.html

Funny that I got the temp right for aging, but was off on the time.

For aging the military suggests 300*->320* for about 1-6 hours. If you want to heat treat it it gives info on that too.

[tool_man]

Oh yes.....thats what I needed to know.Thanks much