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Up Topic Welding Industry / General Welding Discussion / mild steel TIG filler rods
- - By Goose (**) Date 12-09-2001 19:39
I have a Lincoln Squarewave 175 Pro TIG machine that I've used casually for the past year or two in my home auto/race shop. From the beginning, I've used a ER70-S6 filler rod for my mild steel applications.

Should I rather be using the ER70-S2 rod, and what differences would I notice between using these two rods? Is there any difference in melting point temperatures or how well they flow into the arc weld pool?

Thanks
Todd
Parent - By don (**) Date 12-10-2001 02:39
The higher silicone ER70-S6 filler rods result in more surface oxides and scale in comparison to lower -S silicone filler materials. Especially when using argon as the primary gas which I am assuming you do. This is especially important when welding galvanized materials of ANY kind. If you are just welding mild steels only you will find however that the -S6 is a very good filler selection which has good flow characteristics.
Parent - By GRoberts (***) Date 12-10-2001 15:31
The main difference between the -2 and -6 is the -6 contains more deoxidizers, such as manganese and silicon. They are helpfull if you have dirty or rusty base metals because they combine with the oxygen released by the iron oxide in order to prevent porosity. If your base metal is clean, and you are doing multipass welding, the -2 would be better as using -6 over clean base metal, and/or multiple passes can lead to silicon and manganese buildup (the oxygen isn't there to combine with them), and can cause weld metal cracking.

G Roberts
Parent - - By - Date 12-10-2001 17:36
As stated by the other two gentlemen, S-6 contains more Si. There are some concern raised by some people that this extra Si can lead to weld cracking when performing multi-pass welds on clean base metal.

While this may be a theoretical possibility, I have yet to see it happen. In South Africa, we use S-6 almost exclusively for both GTAW and GMAW. I have personally never seen a weld using S-2 filler!

Another issue would be the flowability of the filler. As I have actually never used, or seen used the S-2, I can only comment from basics. Generally Si would increase the flow of a weld pool. As such, if this is what you are looking for, possibly the S-6 would be better.

In the bigger scheme of things, I believe that you will probably not see any difference, unless you are actually welding on "dirty" base metal. In this case S-6 should be better. Even better under these circumstances would be a fluxing process such as SMAW or FCAW.

Regards
Niekie Jooste
Parent - - By GRoberts (***) Date 12-11-2001 00:21
Niekie,
You are probably correct regarding the use of -6 filler metal when it comes to fabrication, which I am sure the question was about. 98% of all the hard wire made probably goes into fabrication, but the other 2% is what it seems I usally work with. I work at a foundry, where most of the welding is casting repair and buildup, and in these cases, we do experience weld metal cracking with GMAW if you aren't carefull. This is due to the fact that we sometimes have large areas of builup or repair where base metal dilution is minimal. (This is another reason that it isn't as critical for fabrication applications. Base metal dilution helps keep the Si and Mn down to good levels.) It also seems to me that we usually get better impact properties with the -2 electrode, especially when testing is carried out on thick sections.

G Roberts
Parent - - By Goose (**) Date 12-11-2001 17:11
Thanks everyone for your input. I guess I'll keep using the S6 rod. I knew about the higher oxidizer content, but didn't know if that affected the "flow" or if there were any other differences between the two.

On another note...

I read an article where a fellow was welding a new galvanized fuel tank for a car. They claim he used a silicon-bronze filler rod as it had a lower melting point than a mild steel rod which would allow for a lower heat input to the base metal and reduce the chance of warpage on thinner sheet metals. I assume the trade off with his rod selection is that the filler rod is weaker than the base metal? Is that a wise choice on his part?
Parent - - By - Date 12-11-2001 17:41
I believe that he was probably brazing the tank together rather than welding it together.

Regards
Niekie
Parent - By Goose (**) Date 12-11-2001 17:44
Well, maybe technically it might have been called brazing, but he was using a TIG machine.
Parent - By HPMTM (*) Date 12-11-2001 22:41
We use ESAB#26 to overlay the joint between tubular exhaust header pipes and the head flange. It is a copper alloy and has a low melting point which helps on these thin materials (16 & 18 ga). The puddle flows really nicely and the weld looks great. The tensile is 35ksi and the weld helps to dampen the vibrations that cause these joints to crack over time.

ESAB does list a Silicon Bronze wire recommended for joining thin gauge galvanized steel and this may also be what you're talking about. It's yield is 25ksi.

Both of these are welded with a TIG machine.
Up Topic Welding Industry / General Welding Discussion / mild steel TIG filler rods

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