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Old 03-12-2012, 09:41   #31
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Re: Stainless Bolts

You want to put a lubricant on your nuts (sorry about that) if they are the same grade ie 316# with 316# to prevent galling.

I've always used a magnet to differentiate between 304# and 316# it works.

Try to go for bolts so the shaft is inside the squeeze area (not thread) with the thread doing it's job. All too often common practise now seems to be what in Australia we call using 'Screws' ie threads all the way to the head.

Cheers interesting points in this thread regarding bronze strengths as a steel boat builder i was unaware of the strengths...
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Old 03-12-2012, 09:49   #32
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Re: Stainless Bolts

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Originally Posted by Lagoon4us View Post
You want to put a lubricant on your nuts (sorry about that) if they are the same grade ie 316# with 316# to prevent galling.

I've always used a magnet to differentiate between 304# and 316# it works.

Try to go for bolts so the shaft is inside the squeeze area (not thread) with the thread doing it's job. All too often common practise now seems to be what in Australia we call using 'Screws' ie threads all the way to the head.

Cheers interesting points in this thread regarding bronze strengths as a steel boat builder i was unaware of the strengths...
Yes, great point, dont use universally threaded bots that are threaded right up to the head for sure and avoid any threads in the enclosed area as much as possible.
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Old 03-12-2012, 09:56   #33
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Re: Stainless Bolts

It's sad how commonsense is no longer, we have gone through the bolted sections of our boat replacing the threaded "SCREWS". The idiots have used them to bolt up the walkways (as an example) with the thread cutting into the glass with every twist/movement of the boat...... aaaaggghhhHHHHHH!!!!
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Old 03-12-2012, 10:01   #34
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Re: Stainless Bolts

Just as a FYI.

Magnetic testing of stainless DOES NOT DETERMINE GRADE.

While the conventional wisdom is that 304 is magnetic, while 316 isn't, this is just wrong. All a magnet can tell you for sure is that the material is either non-cold worked of either grade, or if it was cold worked that it has been thru a stress relief process.

This may be enough of a test for many things, but it is not really all that definitive. The only way to know what you have is a molybendium testing kit which start at around $250.
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Old 03-12-2012, 10:06   #35
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Re: Stainless Bolts

For a reputable supplier, I've never had problems with McMaster Carr. The stuff they sell is what they say it is!
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Old 03-12-2012, 10:07   #36
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Re: Stainless Bolts

I've yet to find magnetic 316#

Well aware of test kits have owned a few BUT a quick magnet test will at least tell you if it's less than 316#...

304# has a low attraction whilst 316# has nil....
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Old 03-12-2012, 10:56   #37
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Re: Stainless Bolts

Stumble is correct. No 300 series stainless is inherently magnetic, but may become so with cold working (as in heading or rolling threads). 304 is more susceptible to this than 316, and this is likely the reason that the magnet test seems to work in differentiating them. However, it means that 304 that has not been cold worked, or that has been annealed post cold-working could appear to be 316 if thus tested.

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Old 03-12-2012, 11:01   #38
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Re: Stainless Bolts

Get two washers out of your kit one 316# and one 304# and drag a magnet over them you will find the 304# will slightly attract.
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Old 03-12-2012, 13:38   #39
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Re: Stainless Bolts

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Originally Posted by Jim Cate View Post
Stumble is correct. No 300 series stainless is inherently magnetic, but may become so with cold working (as in heading or rolling threads). 304 is more susceptible to this than 316, and this is likely the reason that the magnet test seems to work in differentiating them. However, it means that 304 that has not been cold worked, or that has been annealed post cold-working could appear to be 316 if thus tested.

Cheers,

Jim
There is a lil'bit of difference between the two with the N & Cr content. It is the nickel which modifies the physical structure of the steel and makes it non-magnetic.

Mechanical Properties of Stainless Steel

http://www.euro-inox.org/pdf/map/Tab...perties_EN.pdf
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Old 03-12-2012, 13:46   #40
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Re: Stainless Bolts

Nice to see others concerned about threads within the hole ,i thought i was the only one who cared about this anymore, i size my bolts by the length of unthreaded shank i need and then add for nut and washers. Bronze nuts with ss bolts prevents galling which is why most quality open body turnbuckles use ss male threaded studs with chrome plated bronze barrels, unfortunatly i dont think you can buy bronze nylocs.

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Old 03-12-2012, 14:04   #41
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Re: Stainless Bolts

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Get two washers out of your kit one 316# and one 304# and drag a magnet over them you will find the 304# will slightly attract.
According to The Stainless Steel Information Center 300 series is not magnetic.

SSINA: Stainless Steel: FAQs
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Old 03-12-2012, 14:25   #42
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Re: Stainless Bolts

While it is true that 304 is more prone to becoming magnetic when you see it in billet form you can stick a magnet on it, and it just falls off. The best that can be said if its non-magnetic is that it might be any series 300 stainless that has either 1) not been cold worked, or 2) been thru a stress relief process.

Since most fasteners are cold worked, and then not stress relieved you are generally safe, but I have seen 316 that was magnetized, and 394 that wasn't.
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Old 03-12-2012, 14:44   #43
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Re: Stainless Bolts

have you considered using galvanized steel and then painting over?

everything on my old (50 years) wooden boat is galvanized, and i have been told that it lasts longer than stainless, and is stronger.
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Old 03-12-2012, 15:03   #44
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Quote:
Originally Posted by Honey Ryder
have you considered using galvanized steel and then painting over?

everything on my old (50 years) wooden boat is galvanized, and i have been told that it lasts longer than stainless, and is stronger.
I was just about to say that on a wooden boat galvanised is better, easier to see deterioration and less sudden failures.

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Old 03-12-2012, 15:10   #45
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Re: Stainless Bolts

"galvanized steel" .. which of the several hundred available grades are you referring to ?
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