Best welding rod (tig) for welding 4130 chromoly tubing

[Dynasty2OO]

I was actually talking about this with my boss at the hot rod shop and he pulled out this spec sheet that showed what filler rod should be used on 4130 depending on the governing association and it was different from Indy, Nascar, NHRA, etc. Some used er70s, others D2, and other 308. I dont remember which were for what, but I guess it varies.

[Dynasty2OO]

I just found this, pretty interesting.

http://www.netwelding.com/Welding%204130.htm

[speed racer]

Hello all,
The filler I was sold is stamped R60 on the flats. I was told it would work for mild steel or moly just fine. Any input on this?
Thanks in advance

[Miller Swartz]

Hello all,
The filler I was sold is stamped R60 on the flats. I was told it would work for mild steel or moly just fine. Any input on this?
Thanks in advance

Hey SR,

I'm not sure of the welding process you are planning on using or the application, but the rod you were given was designed for gas welding as noted by the numbering code embossed on the rod. Aside from the tensile strength between R60 and ER70 or ER80 filler rods (the "60", "70" and "80" denote the rated tensile strength of the deposit in thousands of psi), the "R" rods possess a slightly different chemical make-up with deoxidizers for the gas welding process. The “ER” rods are designed for the arc welding processes (the “E” stands for “electrode” and can be used to carry current as in the MIG, or GMAW process). Will the filler rod you have “work” on mild steel or chromoly? Yes. Is it the best choice? Quite frankly I would opt for a higher tensile strength rod, and if you’re TIG welding, I would ask for an “ER” designated filler.

This is just my opinion and you can see through this thread, there are many. Personally I used ER70S-2 as the filler on my chassis. I leave the frame unpainted to allow me to inspect the joints easily as well as allow for easy additions for brackets, etc. as needed. I do wipe down frequently with WD-40 to prevent corrosion, but I do this while inspecting the chassis anyway.

Hope this helps.

[aametalmaster]

Hey John nice ride!!!!...Bob

[steven_oharra]

When we did our AWS cert in 4130, our first run failed using ER70.
The as-welded strength of ER70 is 70ksi.
The normalized state of 4130 is 90-95ksi.
Our welds had excellent fusion, penetration, and inter-pass cleaning.
The visuals looked great, then came the 20 ton bend test.
The 4130 coupons tried to remain straight while all the bending-stretching was being done by the filler on the 2" ram (2" used due to higher ksi of 4130).
The effect was almost a T-Pee or V bend instead of a U-bend and ultimately, the filler was stretched to the point of breaking into two coupon fragments.

A second run was made using ER80 (still weaker as-welded than the normalized 4130) and you could see more stretch of the weldment but in the end, the 4130 coupons were forced to follow the 2" ram shape and create a perfect U-bend that passed AWS criteria. Not that you'll be bending your welds into U-bends but as always, you try to make sure your filler is as close a match to the base as possible for a more homogenous weld.
(closer match of 80ksi/ER80 to normalized 4130's tensile of 90-95ksi)
-Steven L. O'Harra

[steven_oharra]

When we did our AWS cert in 4130, our first run failed using ER70.
The as-welded strength of ER70 is 70ksi.
The normalized state of 4130 is 90-95ksi.
Our welds had excellent fusion, penetration, and inter-pass cleaning.
The visuals looked great, then came the 20 ton bend test.
The 4130 coupons tried to remain straight while all the bending-stretching was being done by the filler on the 2" ram (2" used due to higher ksi of 4130).
The effect was almost a T-Pee or V bend instead of a U-bend and ultimately, the filler was stretched to the point of breaking into two coupon fragments.

A second run was made using ER80 (still weaker as-welded than the normalized 4130) and you could see more stretch of the weldment but in the end, the 4130 coupons were forced to follow the 2" ram shape and create a perfect U-bend that passed AWS criteria. Not that you'll be bending your welds into U-bends but as always, you try to make sure your filler is as close a match to the base as possible for a more homogenous weld.
-Steven L. O'Harra

[Aerometalworker]

Steven,
What you were testing sounds like guided bend tests on heavy plate, butt welds im guessing? Thats a completely different set of criteria than a welded tubular structure, and has little value. We have fillets, and a much lager weld area to CSA ratio. We also have more relative movement and fatigue issues. SO nothing against your comments, just realize that not everything translates from one application to another.

[Silverback]

Not to detract from some of the other answers, but I would listen to "AskAndy". He deals with this subject on a daily basis with the Nascar Sprint Cup builders and I feel like his knowledge is right on concerning this.

I was under the impression that NASCAR doesn't allow 4130 at all in their cages, it has to be mild steel if it's around the driver for safety reasons.

[Aerometalworker]

You know this brings up an interesting point. I think many times recommendations on say filler materials, are transferred too much from one application to another. Even on the very same material! Take for instance filler metals on 4130 tubing. Every company and their uncle has a recommendation. However their recommendation may not mean squat to someone else. I have noticed that Lincoln electric has in their 4130 literature, the mentioned uses of their procedure on race cars, go-karts, and EXPERIMENTAL aircraft, and they make a point to be specific about it. To anyone not in the aviation field that may seem to be no big deal, but it is. The experimental category does not have to follow the same materials and process controls as certified aircraft.....so basicly you can do anything you want within reason. The reason Lincoln had to specify EXPERIMENTAL aircraft on their 4130 literature is twofold, for one in conflicts with the latest recommendations from the FAA on the subject, and 2 Lincoln has no ability to recommend ANYTHING on a certified aircraft. Problem is, many people think that since Lincoln says to do it, it must be right, and transfer that recommendation to any application they want, even ones they shouldnt. Sorry to be long winded, I have just been seeing way too many generalizations of welding lately.