304 vs 316 ss for railings and fittings

C

clayhubler

Member
I am going to make a cargo roof rack and radar mount for hammerhead. I have lots of 304 ss tubing and fittings that I was planning to use, but after doing a quick test and dunking in salt water the tubing and fitting got small amounts of surface rust after only one day. I was surprised by this, because I see that lots of marine deck cleats and various fittings are offered in 304ss. The rust is just on the surface, and came off easily with just a scotch brite pad.

Is there a way to polish/ wax the railings so they do not rust, or do I need to use 316 material? Thanks!
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I've have had what you describe happen to me before because I used steel tools to make the bend. Or because it simply put the stainless part in the vice to hold it while I welded on it. Cleaning it up really made a difference in my case. But, I have since switched to making everything out of 5052 aluminum since it is easier for me to work with and doesn't really corrode at all.
 
T.R. Bauer":31ea5p09 said:
I've have had what you describe happen to me before because I used steel tools to make the bend. Or because it simply put the stainless part in the vice to hold it while I welded on it. Cleaning it up really made a difference in my case. But, I have since switched to making everything out of 5052 aluminum since it is easier for me to work with and doesn't really corrode at all.
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5086 is better for salt water :thup
 
tsturm":3hhr0h9f said:
T.R. Bauer":3hhr0h9f said:
I've have had what you describe happen to me before because I used steel tools to make the bend. Or because it simply put the stainless part in the vice to hold it while I welded on it. Cleaning it up really made a difference in my case. But, I have since switched to making everything out of 5052 aluminum since it is easier for me to work with and doesn't really corrode at all.
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5086 is better for salt water :thup
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Thanks for the tip. My TIG stuff will never see that kind of salt - bike and truck stuff :-)
 
Clay, 316-L stainless is the best choice for marine applications. The "L" stands for low carbon and is difficult to locate. If you can find low hydrogen filler wire when TIG welding the railings, it will be porous free and buff up to match the base metal. Then, if you really want to prevent rust and dulling of the finished weldment prior to installation, have it "passivated" at a plating shop. If you decide to use aluminum, look for tubing that has not been tempered. It is more ductile and will yield to the bending without cracking not to mention easier to weld. Post a photo of your work when completed.
 
clayhubler":25z7ag9l said:
Alu is much easier to work... How does it compare to 6061? If I remember right 5086 will bend okay too.
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I've been TIG welding aluminum for a really long time and have never really noticed a big difference welding any of it. However, I have never welded 5086, at least I don't think I have, but all 5000 series alloy is supposed to weld about the same - as it all 6000 series alloy. 5086 is considered plate and a bit hard to get which is why I never use it. I have no first hand experience, but it's also more prone to cracking so the real pros say. But don't get me wrong, I have heard it is great stuff - lots of boats have it on the bottom. The front though, where all the bends are, is usually 5052 - as are the railings, at least I think.....probably depends on who is making them. I love aluminum welding, but I am certainly not a pro by any means - thrown so much of it away over the years.....lol....
 
Thanks guys, I know I'm not going to bother having it passivated so I think I'm going to try to source some 5052. I'm thinking it will probably be cheaper than the ss also. I'll post some pics when it's done. Will probably be in a couple months tho.

I've actually only made one project from aluminum, which was a hand railing. I am much more comfortable welding ss. Does alu pull and warp as badly when welding?
 
clayhubler":1979q1wr said:
Thanks guys, I know I'm not going to bother having it passivated so I think I'm going to try to source some 5052. I'm thinking it will probably be cheaper than the ss also. I'll post some pics when it's done. Will probably be in a couple months tho.

I've actually only made one project from aluminum, which was a hand railing. I am much more comfortable welding ss. Does alu pull and warp as badly when welding?
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The extruded stuff will be 6061(tubing, angle etc.) it all welds the same & will be just perfect!! If your welding sheets it pulls & warps like everything else :thup
 
He's right about the tubing being 6061, but if all they have is 6063, it is very similar stuff. And he's right about it warping. You can control that with patience and technique with TIG. With MIG it will be a bit harder since you can't control amps dynamically, but if you only weld a couple inches at a time, let it cool, and don't cook the workpiece, it will not warp very much - if at all. I do that with TIG also when welding sheet and it comes out good. Also, it really helps to use 1/4 of 3/16 as a base instead of 1/8. But, again, I am not a pro - just a hobby for me.
 
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