Welding 6061 aluminum

Although I do know the correct way to weld 6061 alum. to get max strength, does anyone know the best "cheat" method of welding it to retain the most
strength? 6061-T6 is approx 45K tensile. After welding, the area around the weld is approx 15K tensile or 1/3 of it's original strength. Would one weld, then cool slowly or quench in water quickly? Possibly short quick beads to minimize heat affected zone? I have a lot of 6061 T6 on hand, and I'm looking to get the least softening at the weld area as possible. The very best procedure I know is to buy 6061 T0, weld, then heat treat to T6. So, what's a good "second best method"? Dixon
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Just wait. Yes the heat affected zone will drop in hardness from T6 to around T2 after the weld, but if you just wait a few weeks it will eventually regain most of it's hardness through precipitation hardening. The most it can achieve by natural age hardening is a T5. The only way to regain T6 is through re-heat-treating the aluminum.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Ernie, I used to work in an aircraft materials testing lab and have pulled thousands of tensile specimens. The idea of the alum gaining most of it's strength back at room temp has raised my eyebrows. If I still had use of the tensile machine, I would love to machine some test bars from welded alum. and test them over a period of weeks to see the results for myself. Because of your high credibility on this site, I'll consider your reply highly possible, but I'd really like to put this one to the test. Dixon
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Dixon wrote:

How about building a tester? For a non critical application like this I expect it could be pretty simple and inexpensive. Hydraulic jack pushing up against a lever with the test specimen attached between the jack and the pivot point? Pressure gauge added to the jack and a camcorder aimed at it to capture the peak pressure reached? Sounds like a $50 project to me...
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Heh, I wandered off to the bookshelf for the metallurgical text book. Found 6061, interesting stuff. Heat to 750F, cool 50 degrees per hour to 500F and it is -T0 (annealed). Heat to 975F long enough to get even temp, quench in water (or water spray for large items) and you have -T4. Age harden by heating to 320F for 16 hours or 350F for 8 hours and you have -T6. If you let -T4 sit for several years, it will gradually drift to almost -T6
That tells me that the HAZ zone does not get cooled slowly enough to anneal it too much , the weld itself should be -T4
Ernie says it will be slightly softer than that would indicate for all cases. I certainly won't argue.
Sounds like a nice student project. Think I'll have to turn a bunch of them loose on it!
Dixon wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

I'm not sure which cold finished aluminum alloys self age, but we work with a cast aluminum (713) that naturally ages at room temperature in 21 days. When aged it offers very comparable properties to heat treated alloys like 355 and 356.
You can read a little about it here: www.abbottworkholding.com/tenzaloy.html
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

OK after a little googling it gets much more complicated.
Here is a very detailed list of aluminum temper designations.
http://www.engineersedge.com/aluminum_tempers.htm
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

What's the best filler to get preciptation hardening in 6061? ER4043?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
In article

4043 is a better choice for color match, especially when getting parts anodized. 5356 is stronger and harder.
The other solution to this is to use 7005 aluminum. 7005 is used for bicycle frame tubing because it has the same tensile strength as T6-6061, but it's hardness is from it's alloy, not heat treat, so you can weld it all you like. It saves million of $ in bicycle manufacture.
Unfortunately it is only available in bike frame tube sizes as far as I can tell.
These guys carry it
http://www.fairing.com
Actually checking their site it looks like they have some plate and bar in 7005.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.