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Filler rod for 316 and 304 Stainless

Posted: Thu Nov 12, 2009 7:27 pm
by ebtfan
Hello all. I am building a rectangular stainless steel water tank for my steam loco. I have 304 for sides, top, ends, and bottom of the tank. I have purchased some 316 stainless half couplings that will be welded into the tank for outlet/inlet fittings. What would be the best filler rod to use for welding the 316 Stainless fittings to the 304 Stainless tank?

Posted: Thu Nov 12, 2009 9:44 pm
by mcostello
Hobart welding has Weld Talk BBS. Miller has one also. AWS- American welding Society has another. Welding web is another. I can't answer your question but I bet someone there can.

Posted: Fri Nov 13, 2009 12:11 am
by steamin10
I assume nothing, but hope you have a gas MIG or a TIG torch. Either would be good. If Tig, there are a bunch of rods that would be for you , just ask the Welding store. Some of the counter guys are pretty savvy, even if they dont weld.

Tig has the advantage of shearing some slivers from the base sheet scrap, and using it to be filler rod.

Posted: Fri Nov 13, 2009 4:18 pm
by david5605
304, 308, 316 take your pick. Do a search on welding 304 316 an you get a bunch of hits.

Here is one
http://www.eng-tips.com/viewthread.cfm? ... 169&page=1

Remember you should back purge the weld area (tig welding) otherwise you get that awful 'sugar' look on the back side.

Posted: Sat Nov 14, 2009 6:43 am
by Carm
For a non-critical ambient temperature water tank, practically any 300 series filler will work to join the two. The suggestion of shearing off filler will work too, but then you need to avoid any leaded alloy (weld formulated filler will have none) and also bear in mind that some of the alloy ratio is lost across the arc; autogenous welds will have lower corrosion resistance as a result. They also color differently if ground & polished.
If you have any welds crossing welds, obtain low carbon equivalents of the mentioned fillers and use only sufficient heat to obtain a small fast moving puddle. The increasing nickel content of the higher alloys makes for a sluggish bead and the typical workaround is to increase current to compensate. Avoid that.
A common industrial solution to your application would be to use 309 or 310 alloy.
There are a number of paste like products that can be applied to the backside/HAZ to avoid oxidation if you can't backpurge with argon. They do need to be removed at completion.