Are stainess and carbon steel "dissimilar metals" re: electrolysis?

[sixdogs]

Is this a keyed saft , square , hex . The corrosion wont happen till mother moisture shows up . Rotate it up , put a drop of SG on it and be done . You girls worry to much .

No on the worry too much. Car never gets wet or even humid and the set screw was all gummed up and broke off in the stainless steel u-joint. "D" joint on the SS u-joint shaft end and welded on the other to a steering wheel adaptor..

 

[swines]

1. Stainless steel set screws.
2. Tef Gel You can buy Tef Gel from Amazon, Jamestown Distributors and a number of other sources.

I have used Tef Gel on a number of outdoor projects with dissimilar metals. You really only need a very thin coat of Tef Gel for it to work, as the PTFE has been ground so fine that it rests in the asperities of the two metal surfaces and keeps them from touching. It is often use in marine applications like propeller shaft strut bolts & nuts that are in water all of the time. It works.

 

[Tractor Seabee]

Steel and some of the SSs are close on the galvanic scale. SS like 304 and 316 are further apart. Salt water makes an excellent ion transfer media so that compounds the corrosion effect. Most SS fasteners are either 18-8 or 316. Steel and SSs are both in the neutral zone so work well together. The worst corrosion problems I have seen are things like copper/brass with others like zinc and aluminum. I always use SS fasteners for surfaces exposed to moisture. Corrosion has to have water or some other transfer media for corrosion to start. Once started it moves fast. Zinc being very agressive it is used as a sacrificial anode so it corrodes away instead of the metal it is attached to. When you see those black streaks running down from a fastener you know you have a corrosion problem that won't go away on its own till something is all eaten away. This is such a big subject that it is a specialized engineering field.

If you work buried pipelines like I have you learn all this esoteric stuff.

Ron

 

[mike69440]

My small street rod has a steering shaft with a stainless steel u-joint. As a safety system the u-joint has threaded holes to use set screws to lock the steering shaft in place. Trouble is, I can't find stainless set screws and there is not enough room to use a stainless bolt. Note here--I add a lock nut to hold the set screws in place.

I would prefer not to use anti-seize Because of the potential to get it on my interior.

So, will carbon steel react with stainless steel? Will anti seize stop the problem? Any other ideas?

For this particular application, a little Loctite 22 and 416 S/S hardened setscrews from McMaster, or whatever. 316 galls and is too soft.

Most of the comments here ate correct.

 

[Raspy]

You have to be careful when using anti-seize too. Since stainless and aluminum don't work well together, you should not use aluminum based anti-seize on stainless fasteners. Copper based or nickel based, is better.

Around boats, and not underwater, teflon paste type pipe dope works reasonably well on threads where no "locking" is needed. For mild locking and to prevent corrosion or galvanic action, silicone caulk works well on threads. I've used it for years.

Seems like where the OP needs a set screw to stay tight under varying loads, and needs to be able to reliably dis-assemble it later, a mild locktite would be best. That would also seal out atmospheric moisture and stop any galvanic corrosion.

Underwater, it would be best to have the fasteners and the base metal made of the same material.