6063-T4: Question about natural aging 3

[Ryan615]

I've had a few discussions with some coworkers over the last couple days about 6063-T4 and its potential to naturally age at room temperature. Comments like, "don't worry, it will be T6 by the time we ship" seem common with a few coworkers. We do a lot of work with 6005-T5 and have to deal with the rapid aging of that alloy, post extrusion. A lot of folks here think that this rapid aging is just a property of all 6xxx series Aluminum alloys. I am skeptical for a number of reasons, particularly because I have found references referring to the rapid aging of 6005, but see nothing about 6063. A document from Sapa addressing 6005 alloy properties specifically suggests that 6005 will naturally age faster than 6061 and 6063, but there is no quantification of the statement. I guess the question is, will 6063-T4 ever reach a T5 or T6 temper at room temperature, and how long might it take? 10 weeks, 10 months, 10 years, 10 decades?

Any input would be greatly appreciated!

Thanks.

 

[FennLane]

If it naturally ages how long does it take to overage and become brittle?

I think that 6005 will only naturally age to a T1 condition which has significantly lower strength than the T5 you are describing.

The increased Silicon of the 6005 compared to 6063 results in this ability

 

[swall]

Just curious, Ryan615--what prompted the discussion? Was there a field problem?

 

[TVP]

There is some data on 6061, not 6063, in ASM HANDBOOK Volume 4:
UTS/Elongation as quenched ~ 175 MPa / 28%
after 1 day at RT ~ 225 MPa / 26%
after 1 week at RT ~ 250 MPa / 25%
after 1 year at RT ~ 270 MPa / 22%

6063 will almost certainly be more sluggish than this.

 

[Ryan615]

swall: I think the best answer to that question is, growing pains. We're still a new company pumping out our first commercial projects. We have extrusions at different tempers (incorrect tempers according to our drawings) in our warehouse as a result of months old emails to vendors from people that may or may not have known the full impact of their requests.

I know when our vendors fabricate and cold work our 6005 tube, they have only a few days after extrusion before the material is too brittle to work. The 6063-T4 we have is Play-Doh and well over a month old. I really doubt we'll see any aging with this material. But, I'm hoping to get a few additional opinions.