On Aug 8, 9:44 am, wrote:
On Aug 8, 12:35 am, wrote:





On Aug 7, 11:33 pm, Fortunat1 wrote:

cavelamb himself wrote link.net:

Fortunat1 wrote:

I have access to a plating facility (aviation, but it's a jet engine
rebuild shop) where I can get my wing fittings plated. My
understanding is that 4130 cad plating is just that, cadmium and
nothing else, but this shop does it's cad plating by a coating of
nickel first and then cad plating.. I'm reluctant to do this for the
obvious reasons until I find out what the story is...
Anyone know?

You might want to research "Hydrogen embrittlement".

Yeah, I was aware of hydrogen embritlement which is why I asked, but a lot
of people seem to be doing this to things like wing attachment brackets all
the same. Seems strange that AN hardware and such can be plated when such
small pieces are taking such high loads..

Standard AN bolts are cadmium plated, and the bolts are usually made
from 8740 alloy (although they can be made from 4130) that is heat
treated to a minimum strength of 125 Ksi. So I would think that you
can have them cad plated if you use the proper process.

I thought AN bolts were 2330 nickel steel. That's what the
textbooks say. Maybe NAS bolts are 8740?

Dan- Hide quoted text -

- Show quoted text -

Going from memory of the last time I read the procurement spec, AN
bolts presently can be made from either 8740, 4130, or 4140 alloy. The
Aircraft Spruce catalogue states this as well where it shows AN bolts.
4037 alloy is an old one and has been superceeded, however I'm sure
you would find many of them on old aircraft. 8740 is usually used
because it heat treats easier than 4140 or especially 4130 alloy and
is therefore cheaper to manufacture, although all are suitable as long
as they meet spec.
There are much better alloys of course, but for relatively low
strength 125 ksi bolts, they are fine. Most large aircraft
manufacturers use 160 ksi minimum bolts for all structural
applications except where absolutely necessary, because 160 ksi bolts
are about as cheap as AN bolts.

Regards,
Bud