RE: (ET) stainless steel

["Elie, Larry (L.D.)" <lelie ford com>]

Better yes, perfect no.

There are only a few places stainless doesn't fit....

#1, Most stainless hard wear is 303 or 18/8, a non-magnetic alloy that is 
about grade 3 through 5, relatively weak.  If the fastener needs better, 
use something else.  18/8 is fine for most ET things, like deck and flange 
bolts.  If you need stronger, 304L and 316L bolts ARE available.  They are 
usually marked.  304 is over grade 8, 316 is higher, but I don't have the 
specs in front of me.  The caps may also have some radial lines indicating 
the grade.  316L usually are in 12 point caps, but I doubt any ET bolt 
needs that sort of strength.  316 is expensive.

#2, Stainless WILL corrode in some environments; pure chlorine will leach 
the nickel out and it will pit very badly.  Pure battery acid may as well, 
but not quickly, and the vapor has not attacked any of my bolts in any way.

#3, Stainless will gall very badly at times when heated.  Actually, what 
happens is that bolts under load deform slightly.  Stainless, being 
relatively soft compared to tool steel will deform more.  When it is 
heated, any oil type lubes will evaporate and the result is 'cold welding' 
of two clean surfaces.  The bolts are often 'golden' colored after that 
sort of heat from re-deposit of lubricants.  I have done this many times, 
but not yet on an ET, probably because I use Moly-di-sulfide, a powder 
lube that doesn't displace at high temperatures.  The Cable bolts may 
indeed get hot enough to Gaul, especially because the lead posts will 
expand at a different rate than the stainless, and the lead will flow.  
Next time you run current, the connection is loose.  I use stainless lock 
washers as well (these are ALWAYS 400 level or magnetic stainless, just 
like your 'silver' wear) so that the connection is not 'loose' the next 
time.

Larry Elie


-----Original Message-----
From: SteveS [mailto:ssawtelle fcc net]
Sent: Friday, February 08, 2002 8:59 AM
To: elec-trak cosmos phy tufts edu
Subject: (ET) stainless steel


As I've been going thru my tractor, I've been replacing fasteners with
stainless counterparts. I do this on my old motorcycles as SS looks good 
and
is easier to deal with on the next disassembly. However I've never dealt
with battery corrosion very much. So the question is: Is stainless any
better in the ET environment (battery gases and liquids)? I searched the
web, but didn't find much that addresses this particular use of SS.

- Steve S
E12S