Stainless steel bolts/metallurgic question

[Emma-Knight]

...did somebody ever fit stainless steel bolts into bobbins?
- will they dissolve
- or corrode badly
- or would it work, dry, wet, salted?

Anna

[M100]

I can't see it being a huge problem. Because the metals are further apart on the reactivity scale the (presumably aluminium) bobbins will erode slightly faster than if mild steel or zinc/cadmium plated fasteners were used. The stainless/aluminium mix is also widely used on marine structures without too much of a problem. Fit them with a coating of duralac and its probably fit and forget.

Some years ago I witnessed stainless fasteners being used with a galvanized steel structure and it wasn't a complete success as an acid rain type environment appeared to cause much more rapid erosion of the galvanising than zinc or cadmium plated bolts would. Salt exposure trials were arranged but I never saw the outcome.

[marcfuller]

There are a number of different types of stainless steel that may be used in making fasteners, or any thing. Plus the consideration of rolled or cut threads.

This link may be of help-
http://www.assda.asn.au/asp/index.asp?pgid=18732

[cliveyboy]

Anna
As mentioned above, there is no real chemical reaction problem between the two materials.

I would not worry to much about lasting longer as the steel ones you took out are probably 20 years plus. Stainless would look more attractive for longer and if greased up prior to fitting should be easier to remove later.

If you can get hold of a tap to clean out the threads before hand it is always worth doing on aluminium.

Just in case you do not know. Most stainless steel bolts will have either A2 or A4 embossed on the head. This is the stainless steel grade and either grade will do.

Clive

[vikebo]

Not sure what a bobbin is, but you may want to consider that stainless can be weaker than other steel bolts.

Some info:
http://www.boltdepot.com/fastener-infor ... rials.aspx
http://www.boltdepot.com/fastener-infor ... Chart.aspx

Eivind

[Emma-Knight]

...very nice links... only sub-optimal thing is that bobbins
are made of "Mazak" - magnesium-zink-aluminium castings. The galvanic combination with stainless steel is not highly recommended in a corrosive
surrounding. Aluminium would be acceptable. But some anti seeize oil
could help, as mentioned before.

This forum is always watch and learn...