Heat Treating Aluminium [Easy DIY method]

[Bongodrummer]

I wondered how difficult it would be to do a T5 heat treatment on the aluminium parts I have been making recently? If it was possible, would it be worth doing?🧐🔧
Turns out that it was easy, requiring no special equipment, and, yes(!) very much worth doing! Here's the video, where I explore the process.

[tonyfoale]

You might find this of interest in regard to hardness testing of your samples.
http://www.homemadetools.net/forum/s...832#post102624

[jimirwin]

Nice but minimal introduction to the topic.
You do not mention the specific alloy(s) or family of alloys you're using.
Makes a HUGE difference!
You also mention casting the alloy. 60xx alloys are wrought, typically rolled or extruded.
Smelting and casting these makes them something different.
T5 is an artificial aging heat treatment to some common aluminum alloys. 6063 or 6061 typically.
Increases hardness and strength.
Water quench from above critical temperature actually anneals the same alloys.
Water quench from elevated temp simply stops the heat treatment process at that time.

[ncollar]

I have a movie about metal and the properties. In it when aluminium was first made they questioned the same thing. I'll look through my library to see if I can find it.
Aluminium can be hardened but not with the normal heating. I get back when I find it, I might have hours of movies to look through so it might be a while.
Nelson

[jimirwin]

Nice but minimal introduction to the topic.
You do not mention the specific alloy(s) or family of alloys you're using.
Makes a HUGE difference!
You also mention casting the alloy. 60xx alloys are wrought, typically rolled or extruded.
Smelting and casting these makes them something different.
T5 is an artificial aging heat treatment to some common aluminum alloys. 6063 or 6061 typically.
Increases hardness and strength.
Water quench from above critical temperature actually anneals the same alloys.
Water quench from elevated temp simply stops the heat treatment process at that time.

------------------------------------------------------------------------------------------------------------------
Each alloy family has its own processes. Some are quite unique. I worked in an aluminum alloy extrusion and door & window manufacturing company as an intern during my senior year. One of my jobs was to study and characterize heat treatment of 6061/6063 alloys using the metallurgy labs at Texas A&M.

I also worked in the physics dept machine shop during my junior year. (Been a metal cutter/mangler since age 10...73 now!)

heat treating, as we have come to call it, is really artificial aging. i.e. the same physical properties will develop over time even under normal temperatures. Elevated heat just speeds the process.

Other alloys have their own processes.
7075 high strength alloys have a troubling propensity to change dimensions over time. One must design in such considerations.
Just one of many examples.

[ncollar]

Bongodrummer
I was able to find the video I spoke about. It is almost an hour but around 38 minutes will get around to a surprising aluminium hardening that will blow you away.

The video can be had at:
https://www.bing.com/videos/search?q...6&&FORM=VRDGAR

If that link does not work try to google: I use the BING search engine that might make a difference.
Documentary - How It Works 1of3 Metal
Good luck and enjoy the movie.
Nelson

[olderdan]

Bongodrummer
I was able to find the video I spoke about. It is almost an hour but around 38 minutes will get around to a surprising aluminium hardening that will blow you away.

The video can be had at:
https://www.bing.com/videos/search?q...6&&FORM=VRDGAR

If that link does not work try to google: I use the BING search engine that might make a difference.
Documentary - How It Works 1of3 MetalGood luck and enjoy the movie.
Nelson

Absolutely fascinating video Nelson, thanks for posting.

[Bongodrummer]

Thanks Nelson! I actually remember watching this on TV years ago! It's a good one. I especially liked the creep resistant, single crystal castings at the Roles Royce factory. Though I wish there was a little more detail about why the little spiral at the bottom only let one crystal through...

[ncollar]

Bongodrummer
It is the way we think sometimes that just leads to another question.
Good Luck with your venture.
Nelson

[DIYSwede]

Thanks for posting and comments!
(Tip for coarse checking what alloy you're just holding below)

Being a dabbler myself in this area, 2 friendly cents' worth:
-I guess your melt consisted of cast pulleys, probably press die-cast, but could've also be sand casted? 360 alloy perhaps?
These casting alloys are also containing mainly silicon between 8-12 percent, some copper, iron and perhaps magnesium,
which (supposedly) isn't heat treatable, just cold aging over 30 days.

I've done some different tests for casting my own aluminum over the last few years, and have come to like the die-casting AlSi9Cu3Fe alloy best,
for its good melting, casting and machining properties (but also that it's free and readily available at work, mostly from discarded office chair wheelstands).
For getting a real nice surface from this, I use shear tools for final turning and fly-cutting.
Drop-forged hard drive casings are also plentiful and free at work: casts and machines just excellent, though I haven't tried HT-ing it (yet).

Now, there's some intrepid Polish metallurgists that have tried HT for AlSi9Cu3Fe (that perhaps others might find interesting):
https://www.researchgate.net/publica...cal_properties

Other casted stuff I've found is different Zamac (ZnAl) alloys and even AlMg.

-Now, to make a rough check of what you've got:
1) Zero a digital scale and weigh the piece- note its dry weight.
2) Fill a container with water just to cover the piece completely.
3) Weigh that container (w/o the piece in it) - zero the scale, or note that weight.
4) Now, drop in the piece in, covered by water, but hanging free within the container by a supporting wire held by you. Note weight again.
5) If you couldn't zero the scale in 3): Subtract weight in 4) from the one in 3): you get the piece's "wet weight".
6) Divide "Dry weight" from 1) by "Wet weight" from 5), and you get the material's density- which could be checked against online alloy tables.

To avoid nit-pickers: "Wet weight" IS indeed a lousy word - replace with "Displaced Water Weight" then, if that floats your boat?

NOTE: -This is only a quick, rough method of separation: Zamac from, and in-between Al alloys, and to avoid getting unwanted Mg in your melts.
After a while you'll develop a certain feel for density, but also by distinguishing alloys' shine and surface when filed- a real fast method!

Personally, I don't use any pure aluminum, extrusions, beer cans or kitchenware in my melts,
'cos I don't dig streamers or gumminess when machining. I don't try machining low-Al content Zamac any longer for the same reason,
but have some 20 kgs of that crap for an upcoming casting mix: DIYSwede's Hi-Perf "Bronze Ersatz"
Just gotta get my electric 4 kW foundry together first.

Bonus for the Al alloy curious: https://www.mah.se/upload/_upload/Al...g%20alloys.pdf