Tig Filler Metal

[Todd W]

ER70S-6 or ER70S-2 and why?

-Todd

[g-wizz]

so deoxiders? and not so pure base metal(steel in this case im assuming)

[Jeepermat]

Depends on base metal, for chromo stuff I use s-6, for all things mild I use s-2

[fj40guy]

post deleted. Sorry guys, I was quoted PART of a good tech tip that explained
the difference between the rods. I royally screwed up as it covered rod used
by both TIG and GAS Welding.

I apologize for any confusion.

[Todd W]

Cool info :)

No AL.
No 4130.

Standard mild steel.

[BumpyDodge]

Short answer: 70S6, because it welds nicer than S2 and my LWS keeps it in stock.

FJ40, Tell Bruce Frank a "young fellow" thinks he needs to mention post weld stress relieving 4130 welds first and foremost before he goes discussing modulus of elasticity and cracking of different fillers. Post weld stress relieving is necessary with TIG using *any* filler, not so with gas welding. If you use 4130 filler, heat treating is necessary. I really hope he's stress relieving his welds if he's TIG welding aircraft fuselages.
RG 45 or RG 60 rods shouldn't even be in this thread because they're not used with TIG. The G stands for Gas. Stainless rod is for stainless, not structural tubing so I don't know why he bothers to mention those fillers.
Aircraft 4130 tube welding is an entirely different ballgame than mild steel roll cage welding. The .7 x wall thickness rule for theoretical throat and 1.4 x throat for leg length doesn't apply to welds on thin wall tubing. On .083 wall tube that would work out to a ~0.16" wide bead to make it the same "scale size" as a fillet weld on a typical roll cage. I don't know any people that can weld a bead that small with OFW. A "normal" weld on an aircraft fuselage tubing is easily double the scale size of a "normal" roll cage tubing weld. That's why RG 60 is kind of a joke IMO. It's a PITA to use compared to RG 45 and the fact that it's "stronger" doesn't matter because with the size of the material you're working with, the tube's still going to fail first.

[fj40guy]

FJ40, Tell Bruce a "young fellow" thinks he needs to mention post weld stress relieving 4130 welds first and foremost before he goes discussing modulus of elasticity and cracking of different fillers.

Sigh, I shouldn't have posted. :(

I hestitated as it was a long discussion on TIG vs. GAS, different rods, and a quick summary.

[jasonmt]

ER70S-6 would be my filler of choice for mild steel due to its more fluid puddle, its ability to weld through light rust/mill scale due to the higher levels of deoxidizers and availability. Using ER70S-6 with 100% Ar. will result in slightly higher levels of Mn, P and Si in the deposited weld metal but it should not be an issue for what you want to weld.

FJ40, Tell Bruce Frank a "young fellow" thinks he needs to mention post weld stress relieving 4130 welds first and foremost before he goes discussing modulus of elasticity and cracking of different fillers. Post weld stress relieving is necessary with TIG using *any* filler, not so with gas welding. If you use 4130 filler, heat treating is necessary.

Thin wall 4130 tubing will generally not require a PWHT cycle when welded with an ER70S-2 or ER80S-D2 filler and GTAW with 100% Ar. As this is a 0.95Cr - 0.20Mo nominal material keeping it clean and keeping it warm is about as exotic as you need to get with it as the alloying of 4130 can barely be described as out of the ordinary on the weldability scale.