[AX-O]

Just wondering when is a rivet too old. I was inventorying my wing kit (built in 2004) and some of the rivets were from late 2003. Are they too old to use?

 

[Captain_John]

These rivets don't have an age limitation on them.

I always try and take out the bad ones first. Take all the ones that will club later out now so you won't have to drill them out later!

CJ

 

[AlexPeterson]

There is a persistent wive's tale about the rivets changing metallurgy at room temperature over the course of only years or decades, but it is untrue.

If someone has some hardness data, taken with a microhardness tester, showing this to be true, I'll hunt down a crow.

 

[Highflight]

I sure hope there isn't an expiration date on rivets or a whole lot of WWII vintage airplanes will soon be falling out of the sky since they're approaching... 60 YEARS OLD!.

 

[RatMan]

I don't know, they're starting to get pretty old. Ya better hurry up and use them, quick! Get those wings built before it's too late!

 

[Dgamble]

There is a persistent wive's tale about the rivets changing metallurgy at room temperature over the course of only years or decades, but it is untrue.

If someone has some hardness data, taken with a microhardness tester, showing this to be true, I'll hunt down a crow.

I think the idea comes from the fact that some aluminum alloys will age harden. Some rivets made of alloys other than the 2117 (which are called field rivets, and are identified by the single dimple in the head) require refrigeration to keep them from hardening, such as the 2017 and 2024 "icebox" rivets, which reportedly do harden with age.

I think RVs are built nearly exclusively with 2117 alloy rivets, so age hardening is not an issue.

 

[fl-mike]

Now way back in the dark ages when I was building my RV-4, ya know, when we had to smelt our own ore, I tried solution heat treating some rivets after reading the article in Sport Av. The freshly treated rivets are softer and easier to drive. They age harden just like the supplied rivets. After treating some, I made some test coupons and tested them on a materials tester at work. The "fresh" rivets shear strength was right at book value. The "as-received-from-Van's" rivets tested higher. I would assume that all strength calculations are done with the book value.

So yes, rivets do age harden, but unless you do your own heat treating, most, if not all of the age hardening will have occured by the time you get them.

FWIW, the freshly treated rivets were very easy to squeeze and drive. -4's felt like normal -3's. Flush were no problem, but the universal head tended to get tool marks from the set as the heads were also soft.

BTW, the solution heat treating is done by taking the rivets up to a certain temp. (I've forgotten), soaking them there, and then quenching them quickly in ice water.