wire edging aluminum with sswire?

[marioD]

Hi there
I need to make a set of fenders for a 1935 Daimler for a customer and these
fenders have to be wire edged. i did that before a couple of times but with steel
fenders. So my question is now should i use stainless wire or aluminum wire. stainless seems to be easier to workout but will it corrode in the future as a stainless and steel combination? Any suggestions?

Cheers Mario

[Gonejunking]

Hi Mario
I would use the aluminum wire as my first choice.
It's always better to use the same material, so you don't build in a battery!
Just my 2c

[Rick Mullin]

Hi Mario,
I would use the stainless wire. The aluminum will likely not provide the support you need to the finished edge. Assuming that you are wiring by hand, the aluminum will be more difficult to work with compared to steel. If you are sold on using aluminum wire, I would try some 6000 series that will be able to give the finished edge support and withstand the abuse of the wiring process.
A 304 stainless will not give the galvanic corrosion problem of a non coated mild steel wire. Stainless rivets are commonly used in aluminum vehicles now. I often use copper coated steel wire and etch prime the wire and the aluminum prior to closing the edge. I have never had a problem with this method. Lamboghini used copper rivets to attach aluminum panels to steel structure with no corrosion issues. Although I have never tried, perhaps you could use a copper alloy wire that is stiff (Monel or Inconel).
Rick

[Peter Miles]

Interestingly, I was talking today to a Milwaukee-based artist at a sculpture and art show in Newport News, VA about some fabricated aluminum sculptures that he has had on extended outdoors display in Florida (whew!).

The sculpture is 7075-T6 aluminum and he used 304 Stainless steel threaded fasteners on it.

In that warm, marine environment he said that he (actually the sculpture) has had significant corrosion of the aluminum under the heads of the SS bolts and nuts.

He hasn't had similar problems in any other outdoor environment, however.

Peter Miles

[Boogiemanz1]

Hi Peter, I wonder if the corrosion is under the fasteners because maybe the rest of the sculpture was coated with something or polished with a wax based polish? I would think that the salt air near the ocean (if indeed that is where the sculpture is located) would corrode all of the aluminum without protection, and maybe the protection didn't penetrate under the fasteners...........john

[Ernie Ferrucci]

Hi Mario

I've had good luck with SS fasteners in aluminum and think SS would OK for the wire edge in an aluminum fender. I assume it will be finished with paint, and a 1935 Daimler probably won't be left outside to rot http://www.metalmeet.com/forum/images/icons/icon12.gif.

Ernie F.

[DanGunit]

Hi Guys,

My name is Daniel, I've been watching this site for a while now and trying to absorb all this info, but this is my first post so bear with me.
First off, Rick, Monel and Inconel are both corrosion resistant Nickel alloys, not copper. Although either would work in conjuction with aluminum, choose Monel as Inconel is a hardenable alloy.
Second, Peter, your friend's corrosion problem was most likely caused by using the 7075 alloy, while it is among the highest strength aluminum alloys, it is always recommended that it be hard coat anodized for any outdoor service.
I don't think there should be any problems using S.S. with aluminum if the right alloys are chosen. Use 304 or 316 S.S. with any of the 1000, 3000,5000, or 6000 alloys and they should live in harmony.
Cheers

[hardtailjohn]

I've been working on float planes and amphibians for over 20 years, and we always try to keep stainless and aluminum from coming in contact..it's a great battery!! The 7075 is one of the highest strength aluminum alloys available and it's major alloying agent is zinc. You can get it alclad (thin layer of pure aluminum for sacrificial corrosion). Gonejunking hit it just right when he said to try to use the aluminum wire so you don't build a battery... that's all corrosion is.. two dissimilar metals (one anode, one cathode) and an electrically conductive path between... salt water makes a great path.
John H.

[marioD]

Cheers guys for your suggestions but i still didnt decide which way to go.....
Mario

[Avalonjr]

I own a sailboat which was in salt water for most of its life. In a few places, the bronze winches were fastened through the deck with Stainless bolts and aluminum backing plates. The aluminum backing plates swelled to twice their size and took on a sponge appearance. You could take a screwdriver and knock it away since it had all the strength of bread crust.

After finding such dramatic galvanic corrosion, I read a bit on the subject and found several references which condemned any copper aluminum combinations, but described methods of construction which used plastic insulators and dialectric grease to minimize the effect in cases where the combination can't be avoided. Even stainless in aluminum should be greased to prevent galling at the contact points.

I guess I'm with the others in thinking that sticking with similar metals is the safest.

John