Welding 4130 with 309 or 312 happens on a regular basis in a lot of shops. By the book, er70s-2 (or -6) or er80s-d2 is a more appropriate choice, but fabricators make their own choices unless a specific rod is called out on a print.

To his specific point about crack sensitivity, with proper prep and technique, the mild steel fillers will produce an adequately ductile weld deposit.

 

Ok cool deal. Just wanted to get a idea on this cuz I have some chrome moly to weld..

 

The aerospace world uses ER70s-2 for 99% of tig welding on SAE 4130. Racing people use......seemingly whatever depending on the latest flashy magazine article, loudmouth builder or web article. The "stainless" fillers no not make the HAZ less brittle.

 

I agree, use er70s-2

 

70s-2 costs much less to purchase. Stainless filler costs much more.

 

2003 article by an ESAB welding engineer and consultant to NASCAR fabricators: http://www.aws.org/wj/apr03/AWfeature.html.

 

I have always used 80sd2 on chromoly

 

ok so I can just use a normal ole er70s-2 rod and be just fine? just making sure cuz im fixing to build a set of upper and lower control arms for my drag truck.. they take a beating an don't want them to break by using the wrong rod..

 

70s-2 is fine, if you want extra security do a localized PWHT on each weldment.

 

http://www.lincolnelectric.com/en-us/support/welding-how-to/Pages/chrome-moly-detail.aspx

http://www.netwelding.com/Metalurgical_Definitions.htm#Local Buckling:

http://www.millerwelds.com/resource.../resources/communities/mboard/showthread.php?12364-welding-4130-chromoly-tubing..

 

ok fixing to build a set of control arms and the ball joint cups I get, I can only get them in mild steel. is this going to be a big problem welding the 1inch 095 wall chrome moly tubbing to the mild steel and not have it break?

also if im welding a say the 1 5/8 083 wall tubbing to say the 1/8 thick mild steel frame what rod would I use? ER80S-D2 or the ER70S-2 or 6?

 

I'm pretty sure it would be ER70S-2/6. The ER80S-D2 would be suitable if doing CrMo-to-CrMo and you needed a stronger, but less ductile weld.

 

Right on Oscar!

 

Stroker, are you sure your capable of producing the quality of welds required on control arms for a dragtruck? The questions you're asking are usually answered in books that most of us have/had.

 

im new to the tig welding world but have been doing fab work for a long time. I would just use my mig and build them out of mild steel but I want them built out of something lighter and stronger. so to answer your question yes I feel that iam, but I just needed a few details covered before I tackle them. I will do some trial runs before I jump on them so I can get the feel for the tig and post pix for yall..

 

I haven't seen oxy/fuel brazed joints as pretty as TIG brazed, though.

One example of TIG brazing

 

You are right, they are usually prettier Unless you like the look of lobster tails on your parts......
The key to "pretty" OA fillet brazes is using a gas fluxer.

 

Wow that is beautiful!!! Someone has got some skills. .

 

Hey, those remind me of something