Stainless Bolts

[Stumble]

The only real way to tell is with a testing kit that can test for the presence of molybendium. Unfortunately the test kits run about $300, so it isn't reasonable for most users.

You can also ask for the spec sheets, but if you are buying singles out of a bin I doubt you can get one. It requires a bit of paperwork on the manufacturers and distributors end, so unless it is a big job it typically isn't done.

The easiest way is to buy from a reputable dealer, and be sure to ask exacally what you want. 304 is pretty much to default stainless, so unless you specifically ask for 316, or 316L you won't get it.

[svadagio]

Hi
If the bolt head is stamped "F593-C" it is 316. If not china, then probable good. The ASTM spec (F593) tells about the heat treat (important) and testing to insure quality. If it is stamped "304" or "316" you only know you have the right chemistry, if it is not China. Stainless that has not been properly heat treated is not much better than mild steel.
Bob

[barnakiel]

Why 'L'? Why not plain 316?

THX

b.

[svholdfast]

Todd your doing it right replacing all the bolts. 316 or 18-8 stainless will do the job for the next 30 years, 316 is less strong but has more corrosion resistance 18-8 is stronger and slightly less corrosion resistance and cost less.
The originals are most likely 18-8.

Recommend you buy from a industrial supplier like McMaster-Carr

Myron
sv HoldFast

[boatpoker]

A magnet will stick to 304 SS but not 316L. Not totally sure but I don't think it will stick to 316 either

[Cruiser2B]

Originally Posted by boatpoker

A magnet will stick to 304 SS but not 316L. Not totally sure but I don't think it will stick to 316 either

I have never proven this but when buying my hardware the guy told me that a magnet will not stick to good quality 304

[boatpoker]

Originally Posted by Cruiser2B

I have never proven this but when buying my hardware the guy told me that a magnet will not stick to good quality 304

Google "stainless steel 304 316 magnetic" there are quite a few authoritative articles on the issue.

[Cruiser2B]

Originally Posted by boatpoker

Google "stainless steel 304 316 magnetic" there are quite a few authoritative articles on the issue.

Not trying to dispute. Just repeating what I was told by a supplier of mil-spec hardware here locally. He told this was a good way to check for quality 304. As stated originally, I never proved or cared to, just passing along some info. I have some of the 304 bolts left over from my chainplate project. I will give it a test.

[boatpoker]

Originally Posted by Cruiser2B

Not trying to dispute. Just repeating what I was told by a supplier of mil-spec hardware here locally. He told this was a good way to check for quality 304. As stated originally, I never proved or cared to, just passing along some info. I have some of the 304 bolts left over from my chainplate project. I will give it a test.

Wasn't challenging you, just suggesting it makes for interesting reading.

[clockwork orange]

Originally Posted by Stumble

Steve,

I haven't run into this question before so I would want to run it by an engineer to be honest. The best information I found is that the ultimate sheer strength is 79,800psi. So check my math, but...

A=(pie)r^2
A=3.14*.5^2
A=3.14*.25
A=.785

So 79,800*.785=62,643lbs.

I would absolutely not rely on these numbers. I am not an engineer, and didn't even stay in a Holliday Inn express last night.

Thanks Greg, i will do a little research, i have a project in mind where Titanium might be nice for the weight saving if the price were not prohibitive, its early days so im just guessing at the size, they will most likely be custom as they will be quite long. I will pm you as things progress as i dont want to hijack the thread anymore than i already have.

Steve.

[Cheechako]

18-8 stainless becomes magnetic from cold work... or if it's high on the iron limit it might to some extent also.

"Why 'L'? Why not plain 316?"

316L is low carbon formula, tighter specification, not a big deal, I doubt you can get that in bolts... maybe.. dont know.

Buy from a reputable bolt seller, not the big box store. They can tell you where it comes from. 300 series SS is not Heat Treated, it may be stress relieved or annealed, but I doubt bolts are as they are improved by the cold work . Not positive though.
When it comes to your chainplates, 316 Bolts at $2 each is probably the way to go .

[delmarrey]

Todd, I did some research and here are the numbers I came up with. Although, with the grades and manufacturers the numbers can very. They're all fairly close so it kind of comes down to $$$. If you have SS chain plates I would go with 316, $ wise. If steel, then the bronze or Titanium. IMHO

Titanium Gr 5 (Ti-6AI-4V) 550MPa = 79,800 psi

Silicone Bronze 425 MPa =61,600

316 bolts 450MPa = 68,000 psi

[svadagio]

Hi
The L is for low carbon as stated. It does make a differance. The reason stainless does not rust is the chrome. It forms an oxide on the surface which inhibits the iorn from rusting. This said chrome forms carbides when carbon is present. This is worse if the temp is high or the steel is cold worked. If the chorme is in the form of carbides it does not form oxides and does not prevent rust. There are differant ways to go about preventing carbides. Good stainless is heat treated by solution anneal. You heat it above about 1900 F hold for a time and quench it in cold water. You have to get the temp down below about 900 F before the carbides can form. If this is done well the stainless will not rust for a long time. Another way is to add Moly to the mix. This is what you do with 316. Moly makes carbides faster than carbon so more chrome is left to prevent rust. Now you can reduce the amount of carbon which helps also. This is 316L. To be F593-C the 316 was heat treated and tested for strenght. Problem is many manf. use an anneal that is not as good. It is still strong but will rust sooner than if the anneal is done right. I use 316 or 316L any time I can get it and 304 other wise. There are other factors but they are not as important.
Hope it helps
Bob

[IdoraKeeper]

Thanks to all of you for your thoughts on the subject. I cannot use bronze because of the galvanic implications. 316 stainless will be my choice. As to size, they are a variety of lengths depending on where they are installed. I am unsure of the diameter, a good steel measuring stick will be used to answer that question. They should be the same port and starboard. I will do one at a time till they are all done. Some of the nuts will be hard to reach but one flat at a time they will come out. What could be more fun than that?

Todd

[Cheechako]

Yeah, we beat this one to death! Have fun.