Grades of stainless steel

[Big Jim]

Hey guys, what are the different grades of stainless steel? The higher the number better or the opposite? What is a good grade of marine stainless? I heard that surgical stainless is not that rust resistant as it needs to be sharpened and hold a razor-sharp edge (has more carbon in it?).
Thanks,
Jim

[JOAT]

It doesn't work that way. You can't say one alloy is "better" than another just because the number is higher. It all depends on exactly what you want the steel to do.

There is a good break down of alloys on this wiki article...

http://en.wikipedia.org/wiki/Stainle...tainless_steel

[Alasgun]

Stainless!

Simple and Stainless steel should not be used in the same sentence! There is an overwhelming number of choices and from a purely FYI perspective the afore mentioned "wikipedia" site will give you SOME insite.

If you want to keep it simple, use 316. Now if your a geek with unlimited cash flow you might look at inconel,kmonel,furrilium255,cd4mcu or a host of other exotics that NO boating accessory manafacturer would consider using. You'll have to roll your own using these materials.

As a machinist of over 30 years I sure enjoy the look on their face when I tell them what I made this or that out of!
Mike

[mnfish365]

Alasgun

I have a fireplage grate made out of inconel, probably the most expensive grate in existance. It was given to me from a friend who builds racecars. I'd say it's the "best" I can get for that application. I agree, there is no formula for stainless steel grades, just different materials for different characteristics.

[Paul H]

It would help to know what application you have for the stainless steel before possibly suggesting an allow for the application.

The two most common grade of stainless steels used in marine fittings are 304 and 316. For a trailored boat that is washed off after use and stored away from the shore, you'll likely find that 304 is sufficient, if the boat lives in the harbor you'll find that 304 starts rusting and hence you'd want to go with 316.

There are also different grades within a given alloy, for instance there is 316, 316L and 316H. I'd also be somewhat suspect of products touted as 316 originating from some Eastern countries, as it just might not be what they proport to be.

Stainless alloys are prone to stress corrosion cracking, so you need to have a firm understanding of this before designing structural assemblies.

[Big Jim]

Wow,

didn't know there were so many types! Just mainly have heard of 304 & 316. JOAT, thanks for the wiki link, pretty much opened my eyes! You guys sure sound like you know your stuff! I was explaining to someone the other day that even stainless can rust and they said "how's that possilble, it's supposed to be bullet-proof?!". My view is in the name itself and personal experience: STAIN-LESS doesn't mean STAIN-FREE, there's a difference; it just means LESS stain! Just like most people think "painless" means without any pain whatsoever; also from personal experienc, it just means LESS pain! My .02.
Jim