316 and 304 steel - whats the difference?
 

Hi, I need a forestay attatchment for my boat, someone has proposed
304 stainless steel instead of 316. As its a pretty important part of
my rig, I'm a bit dubious, but I don't know if its any more likely to
be corroded. A lot of it will be buried in the stem, but a lot of it
will also pop out above deck to take the forestay.

Any advice? I feel uneasy about 304.

Cheers, Pete

316 and 304 steel - whats the difference?
 

Insist on 316. 316L if any welding will be done on it. All stainless can
rust to some degree but 316 is far better at resisting it.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

"pete" wrote in message
...
Hi, I need a forestay attatchment for my boat, someone has proposed
304 stainless steel instead of 316. As its a pretty important part of
my rig, I'm a bit dubious, but I don't know if its any more likely to
be corroded. A lot of it will be buried in the stem, but a lot of it
will also pop out above deck to take the forestay.

Any advice? I feel uneasy about 304.

Cheers, Pete

316 and 304 steel - whats the difference?
 

In the pulp and paper industry we used 316 2B finish 304 was out of the
question. All welds have to be pacified to minimized rusting. Contact or
welding with another metal like aluminums, steel or iron will produce white
intergranular corrosion that is hard for the human eyes to see. It is hard
to recognized 316 from 304 and many suppliers and manufacturers are selling
304 for 316.
As previously mentioned 316L is a good choice for welding.


"Glenn Ashmore" wrote in message
news:1t7rg.115845$Ce1.76526@dukeread01...
Insist on 316. 316L if any welding will be done on it. All stainless can
rust to some degree but 316 is far better at resisting it.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

"pete" wrote in message
...
Hi, I need a forestay attatchment for my boat, someone has proposed
304 stainless steel instead of 316. As its a pretty important part of
my rig, I'm a bit dubious, but I don't know if its any more likely to
be corroded. A lot of it will be buried in the stem, but a lot of it
will also pop out above deck to take the forestay.

Any advice? I feel uneasy about 304.

Cheers, Pete

316 and 304 steel - whats the difference?
 

Bag the stainless and use bronze instead - you'll slep more soundly.

Also, download this .pdf onto your desktop for future reference:

http://www.kastenmarine.com/mbqMetRef.pdf#search='marine%20metals%20%20pdf'

MW

316 and 304 steel - whats the difference?
 

Excellent info! Thanks for the link!

Brian


wrote in message
oups.com...

Bag the stainless and use bronze instead - you'll slep more soundly.

Also, download this .pdf onto your desktop for future reference:

http://www.kastenmarine.com/mbqMetRef.pdf#search='marine%20metals%20%20pdf'

MW

316 and 304 steel - whats the difference?
 

All welds have to be pacified to minimized rusting.

I think you mean, "passivated".

316 and 304 steel - whats the difference?
 

Thanks for correcting me. Yes, I mean "passivated" and inadvertently typed pacified.

Here is an extract: " According to ASTM A380, passivation is "the removal of exogenous iron or iron compounds from the surface of stainless steel by means of a chemical dissolution, most typically by a treatment with an acid solution that will remove the surface contamination, but will not significantly affect the stainless steel itself." In addition, it also describes passivation as "the chemical treatment of stainless steel with a mild oxidant, such as a nitric acid solution, for the purpose of enhancing the spontaneous formation of the protective passive film."

Also http://www.mmsonline.com/articles/100304.html

Over the years I have found out that most welding job done without proper cleaning, passivation and polishing started to show brown rust as early as the first year.


"Richard J Kinch" wrote in message . ..
All welds have to be pacified to minimized rusting.

I think you mean, "passivated".

316 and 304 steel - whats the difference?
 

On 2006-07-06 13:50:52 -0400, "Brian D" said:

Excellent info! Thanks for the link!

Brian


wrote in message
oups.com...

Bag the stainless and use bronze instead - you'll slep more soundly.

Also, download this .pdf onto your desktop for future reference:

http://www.kastenmarine.com/mbqMetRef.pdf#search='marine%20metals%20%20pdf'

MW

I'd have to say that 316 is the way to go, if you need the strength of
stainless steel. Otherwise, you should go with the marine bronze.

The 304 has some serious issues, especially in an area where it has
exposure to chlorine ions.

316 and 304 steel - whats the difference?
 

I can tell you from years of working on clean room equipment and toxic
gas systems that 316 stainless is the only way to go. I've always
bought the highest grade stainless fasteners I can find for above and
below the waterline, in salt water, and they hold up great. I seldom
use bronze, so I can't compare it to that.

Watch out when you buy a "stainless" item from the mail order or chain
marine supplier. If the description doesn't specifically say 316 grade
stainless, it's a good bet that it's been "watered down" with cheaper
metal. I once bought a chart light that plugged into a cigarette
lighter. It was "stainless", but you could have fooled me because it
was totally rusted and pitted in just a few months from the ocean air.
I had to get pretty assertive to get my money back on that pricey piece
of junk. If the price seems unusually low, it's a good bet the grade
is inferior. But you'll find high priced junk too.

One thing I've noticed about good stainless is that it will have a very
slight (if at all) attraction to a magnet. The cheap stuff, depending
what the metal content is could be drawn to a magnet in a much stronger
way.

There really is a huge difference.


pete wrote:
Hi, I need a forestay attatchment for my boat, someone has proposed
304 stainless steel instead of 316. As its a pretty important part of
my rig, I'm a bit dubious, but I don't know if its any more likely to
be corroded. A lot of it will be buried in the stem, but a lot of it
will also pop out above deck to take the forestay.

Any advice? I feel uneasy about 304.

Cheers, Pete

316 and 304 steel - whats the difference?
 

316 has a different color and shine as well. It reminds me of a chrome type
shine while 18-8 or 304 tends to have a 'darker duller' shine than 316.

For wood, I use silicon bronze fasteners exclusively, while through-bolts
(and similar) or anything that must sustain high impulse (impact) type loads
gets 316. Seems to be a good mix.

Brian D


"Handyman" wrote in message
ups.com...
I can tell you from years of working on clean room equipment and toxic
gas systems that 316 stainless is the only way to go. I've always
bought the highest grade stainless fasteners I can find for above and
below the waterline, in salt water, and they hold up great. I seldom
use bronze, so I can't compare it to that.

Watch out when you buy a "stainless" item from the mail order or chain
marine supplier. If the description doesn't specifically say 316 grade
stainless, it's a good bet that it's been "watered down" with cheaper
metal. I once bought a chart light that plugged into a cigarette
lighter. It was "stainless", but you could have fooled me because it
was totally rusted and pitted in just a few months from the ocean air.
I had to get pretty assertive to get my money back on that pricey piece
of junk. If the price seems unusually low, it's a good bet the grade
is inferior. But you'll find high priced junk too.

One thing I've noticed about good stainless is that it will have a very
slight (if at all) attraction to a magnet. The cheap stuff, depending
what the metal content is could be drawn to a magnet in a much stronger
way.

There really is a huge difference.


pete wrote:
Hi, I need a forestay attatchment for my boat, someone has proposed
304 stainless steel instead of 316. As its a pretty important part of
my rig, I'm a bit dubious, but I don't know if its any more likely to
be corroded. A lot of it will be buried in the stem, but a lot of it
will also pop out above deck to take the forestay.

Any advice? I feel uneasy about 304.

Cheers, Pete