Metallurgy Experts
 

Ok all you Metallurgy experts, plan on installing a Stainless Steel railing
around my deck, the vertical posts will also be made of Stainless Steel which will hold the glass panels in place.
Our weather in BC Canada is hot and dry with occasional rain in the summer and definitely have snow in the winter, no where am I near a salt water ocean.
Do I use 304 Stainless Steel or would you recommend 316 Stainless Steel.
I know if money was not a factor 316 S.S. would be the way to go but it is and 316 is about 35-40% higher in cost. Will I have rust problems or discoloration
if I use the cheaper 304S.S.

Thanks for all the advice in advance

i'm no expert..but we just put up a maint building. the main doors are 304. we are right next to the ocean, and the stuff is corroding. in our area, we spec'd out the wrong stuff..i bet 304 would be sufficient for you. we took out some park benches made with 304. they were 20 years old and barely scuffed. this was in san mateo..more inland, but still relatively close to the ocean.

304. We use 316 on off shore platforms. Other than that, 304 should be fine.

316 is stronger and good for higher temps, and it is a lot harder and tougher to machine. So manufacturing costs are higher as well as material cost.

You might also consider, if you can find it, 6063-T6 aluminum. It is extremely corrosion resistent, light and strong. 6061-T6 is 1/3rd the weight of steel and has similar strength. Either of these would be easier to drill and about 1/2 the cost of 316 Stainless.

What size are the vertical posts?

Red-can you TIG or MIG 6063 if they need to weld it?

Not really a vertical post but rather 8.5" spigot with two M8 screw that will clamp
down on 12mm tempered glass panels. The spigots will be surfaced mounted
and secured to the deck.

Yes. Straight forward. TIG welds look a lot better, though. For TIG use 4034 or 5356 rod

For what it's worth, we used to passivate 304 all the time to reduce the propensity for corrosion. Passivation is really only a nitric acid based cleaning process. That really helps. Many times, what is actually corroding is the impurities left over from machining or other operations - not the stainless itself. Having said that, stainless steel is really more correctly called "corrosion resistent steel" or CRES.

I have a "stainless steel" grill that is rusting. I expect that in the burnishing process, they used standard wire brushes, not stainless ones.

Can you put a protective clear coat of paint on it?

Not on a grill. I'll se what I can do about passivating it, per Mike. Trouble is, nitric acid is not so easy to come by these days.

Mike, do you know of any other acids to do this?

Lots of options for aluminum railing. It is 6063 t6. I worked for a major manufacturer of the stuff. Canada is a big market. My only concern is galvanic corrosion with different metals at areas like the base.

Larry

So I guess the general consensus is that 304 s.s. should stand the elements
and time in an outdoor environment in Canada away from any salt water ocean
just be very careful of impurities within the machining and never use a steel wired
brush to clean. Also heard that if I spray clear polyurethane over the pieces of
stainless it might help with the pitting and keep the appearance? Any thoughts?

I'm not intimately familiar with the actual passivation process itself, so I'm not sure whether or not it is a do-it-yourself project.

I saw some passivation on Modern Marvels. It did not look like something you would want to F with (the acid). Send it out to an electroplater. They should be able to passivate as well, or you could just chrome plate it. :cool::D

Seems like any precipitation hardened Aluminum alloy that was not anodized well would suffer from galvanic corrosion with itself due to the grains of precipitate also being present at the surface next to the Aluminum matrix, thereby forming a galvanic corrosion reaction in the presence of water with ions in it.