Age Hardening of AN470AD (2117-T4) Rivets

[Vidaman]

Hello All,

I'm building a kit plane that is taking longer than anticipated to complete. I have some AN470AD an AN426AD rivets that are over 4 years old. I have heard, but have been unsuccessful in confirming, that aluminum alloy 2117-T4 will age harden. My question is, if true, what is a legitimate working life for these rivets?

The reason I ask is that the rivets seem more difficult to buck than they have in the past. I'm not sure if this is true or all in my head. None of my engineering references provide the specific information of acceptable life.

Anyone with good experience or a real reference out there?

Thanks,

-Mike

 

[debarra]

Hi Vidaman.
rivets with AD letter code are made of 2117 T3 and havent
expirity date .
If you found some difficult to buck them you should check the rivet gun press and the bucking bar weigth.
If the difficulty continue try to do a heat treatment
495º Cº during 20 minutes, quenching in water about 30ºCº
as quickly as you can. now you have 15 minutes to install
them. the result will be soft aluminium rivets which in 96 hours will have the oririnal hardness.
the rivets that you can,t install in that period hold them in a ice box under - 18º Cº use them during the next 3 months :

 

[Sparweb]

My aircraft worker's handbook states that AD rivets should NOT be re-heat-treated. Can you provide a source for your information, debarra? Won't the surface treatment be lost?

STF

 

[debarra]

hi.All
due an unforgivable mistake I tell to Vidaman that he could do an heat treatment on rivets AD. THAT IS NOT TRUE.
and I hope you escuse me
[sadeyes}

 

[Sparweb]

Vidaman,

Noticing a different "feel" in your rivets probably doesn't mean they have age-hardened. I doubt that the AD rivets do that, anyway. What you should be checking are the settings on your rivet gun/squeezer. Perhaps the gun just doesn't work as well as it did years ago (have you cleaned it recently?).

Perhaps you chould also check that you actually have AD rivets: they should have one small circular dimple in the center of the head. If the dimple is different, or isn't there at all, then you've probably gotten your rivets switched with another type. That could be disastrous, indeed.

You're forgiven, debarra


STF

 

[Vidaman]

SparWeb,

The rivet age hardening thing is something I heard in the builder forums I participate in, yet no one has ever provided hard evidence (which is why I came here). My guess is that it's a concept mistakenly applied from the days of icebox rivets.

The rivets are AD's. The first thing I check for is the dimple ever since I had a bunch of "A" rivets get into my "AD"'s. Talk about potentially disastrous!

I guess all that's left is the rivet squeezer. It was working fine last week though. I oil it regularly but I guess guess something could be dragging reducing the output force. I guess it's time to bite the bullet and send it in for service.

Thanks for info. Much appreciated!

-Mike