<VV> Bolt Grades

[jvhroberts at aol.com]

 The SS bolts with two lines on the head. This is what's commonly available at marine and hardware stores. For marine use, the SS bolts are generally a fair bit larger than what you'd expect, to compensate for the crappy fatigue life. 

All the rest is, well, flak!

 

John Roberts
 

 

-----Original Message-----
From: John Kepler <jekepler at amplex.net>
To: jvhroberts at aol.com; patiomatt at aol.com; virtualvairs at corvair.org
Sent: Sat, Nov 14, 2009 7:53 am
Subject: RE: <VV> Bolt Grades






















 



 






Most SS bolts are Grade 4. 



 



Impossible!  An SAE fastener specification includes the MATERIAL
to be used…and “SS” ain’t it!  It may be advertised as
an SAE equivalent strength….but that means about as much as a “guarantee”
on your Ronco Pocket-Fisherman!



 



However, SS isn't much like steel at all,



 



And just WHAT “SS” are you talking about?  416R,
316, 316L, 304, 347,  shiny Chinese “Mystery Metal”…what? 
There are THOUSANDS of alloys classed as “Stainless Steel”, some of
them may be suitable for fasteners….most aren’t!  There ARE
mil-spec 304, 316 and 316L fasteners….they work and are close to an SAE
Grade 8…..they also cost several bucks a pop in something as small as a ¼-20! 
They are NOT what you find in a “bubble pack” at Lowe’s!



 



 it galls, it has far lower fatigue strength, etc., so, grade
number, which just states tensile strength, doesn't even come close to telling
the whole story!



 



As in most of life….the Devil is in the details!  If you
are talking about the Chinese “Mystery Metal” fasteners you’ll
find at Lowe’s or Homer’s Depot…then you are probably correct. 
If you are talking about a mil-spec 316 fastener, you aren’t!



 



John