filler for welding 316SS for no galvanic corrosion

[Schwob]

I may get temporary access to a tic welder. My example for the question is on the "simpler" side, but still good to ask that question:
I have a (trapezoidal shape) D ring from a tank strap that is missing the weld. Seems like I might learn something trying to weld it. It is stainless steel and by checking how magnetic it is (absolutely not) I am going to say it is 316SS.
So, if I weld that, what kind of filler rod could should I use if I do not want to create a galvanic element (that and saltwater seems like a bad idea)?
Could I just use 316SS wire or a turned down rod that happens to lay around?
If using a proper filler rod, is it important (corrosion resistance wise, galvanic element corrosion resistance wise, gap corrosion resistance wise) that it is exactly 316SS or might another grade of SS or high nickel content Steel do?
What do you guys use (and get away with using) for filler, welding 316SS for in saltwater use?

These filler rods below I may have access, night one work for all intents and purposes (buying a box makes no sense for a ring...)?

- scrap 316SS rod (not filler rod, just bar-stock) turned down (not magnetic)
- TigTectic® 680 | Castolin Eutectic
It says suitable for joining SS of unknown composition on the website, on the box (TIG 680) it says "Deposits high chromium-nickel (label torn here) corrosion, heat and oxidation resistance. Does not seem to say if it is consideried to be SS or what grade. It is magnetic.
- Blue Demon ER312, stainless, magnetic - not called out for welding 316SS (says similar cast metals...)
(there is am ER216 grade and it's meant to weld 316SS, but it's not "around"...)

 

[lowviz]

With TIG, cleanliness and fit is everything. Get a bunch of short pieces of SS of the same diameter and practice butt welds until you get the current right. Stainless warps under heat so I would start by cleaning, fitting, and clamping both ends. Start with a tiny tack weld on each side. (probably all you need, if any weld at all)

No filler rod/material should be necessary with a clean tight fit. 4 Popular Types of Welding Procedures

On the upside, clean stainless and tight fits are a joy to tig weld. Lots of "live" info on youtube.

 

[lowviz]

Start with these two and you will be dangerous.

 

[JohnnyC]

If the fit up isn't tight enough for an autogenous weld, just grab some 316 filler rod. It's cheap and easy to source. Why mess around trying to find something random that will work?

Or grab some Hastelloy. That'll weld'em. Go big or go home.

 

[Charles2]

I'm with @JohnnyC. Use a 316 filler rod. Even if your D-ring is 304 or 306 stainless, it will work well.

In reality, you can use practically any steel filler rod to weld this (even a coat hanger); however, the filler material will begin to corrode quickly unless it is 316 (or 308). That is why many of the products that you list are rated for 316. If you want the corrosion resistance of 316, you must use 316 filler.

 

[lowviz]

No complaints as to fill rod. But it sounds to me that we are talking to someone who is just getting started in tig.

Nothing more satisfying than initial success. No filler material means that you can focus only on the stinger. Baby steps. Fill rod is an art.

I still suggest clamping the gap totally closed, getting the current right, DCEN with penetration set high, nice fresh tip on your tungsten and plenty of argon flow. -don't pull the tip away when you finish tack/welding your part. Keep the argon post-flow focused on the weld until the gas cuts off.