Tig Welding HREW tube

[badbu]

I will be welding a rollcage for a friends mustang in the next couple of weeks and have a few questions. He bought a 10 point kit, typical HREW tubing nothched w/ a plasma cutter. It will be a blasty blast trying to get all the tubes fit-up properly!

I was wondering if anyone had tig welded a cage kit such as this before. I have heard that hot-rolled material is not the greatest material to be tig welding, and i think that the instructions recomended the kit be mig welded. Is this just to discourage some hill-billy w/ a buzz box, or does it actually mean something? I have personally only worked w/ DOM and moly round tubing using the tig, never hot-rolled material.

I plan on using the following set-up: Syncrowave 250DX, 135 amps, 3/32 2% thoriated tungsten, and 3/32 er70s2 filler. Is there anything else you would suggest?

I would mig weld this together if that was an option, but neither of us have a capable mig machine. This is the first time I will be able to operate my machine i finally got paid off, on a bona - fide 100 amp circuit. Can't wait!

[Laiky]

the material doen't sound right, never heard of using hr for a cage also, it's not seamless if i understand right. Where did this kit come from?? I wouldn't use it!

[Billet Benny]

I have personally only worked w/ DOM and moly round tubing using the tig, never hot-rolled material.

What do you think your DOM was made of??

The work's a piece of cake if you're any good. Filler choice is fine, but I prefer 1/16" for your project. Fit it up tight and let 'er rip.

[Billet Benny]

the material doen't sound right, never heard of using hr for a cage also, it's not seamless if i understand right. Where did this kit come from?? I wouldn't use it!

The material works and is used often. It's similar to DOM. It just lacks a little strain hardening and what not. You know DOM isn't "seamless."

[dandimand]

make sure you clean the scale off if any use s2 rod and use a foot or hand control as you will have to vary your amperage when welding around the tubes . if its your first one and your unsure of your abilities just lay rod in without dabbing and wash over it with your torch watch the undercut . ps fit up is critical im not sure how good of a fit you can get with a plasma i mill fit all tubes to a zero gap . if you cant get the good fit dont bother tigging it. mig weld it .

[Laiky]

The material works and is used often. It's similar to DOM. It just lacks a little strain hardening and what not. You know DOM isn't "seamless."

no i did not! i thought dom was seamless and cold rolled. live and learn

[hankj]

DOM (Drawn-Over-Mandrel) tubing is made from HREW (Hot-rolled, Electrically Resistance Welded) tubing that is first processed to remove all interior and exterior flash from the weld, and is then cold-drawn over a mandrel and through a die. The cold working produces high tolerances for ID and OD, as well as work-hardening of the tube. The act of cold-drawing also alters the crystaline structure of the steel, producing an ssentially "seamless" tube. Even though the tube was welded, the weld becomes homogenized during the cold work drawing process. DOM, for all intents and purposes, is considered to be "seamless".

Hank

[Billet Benny]

no i did not! i thought dom was seamless and cold rolled. live and learn

http://www.millermotorsports.com/mboard/showthread.php?t=4074&page=2&pp=15

[hankj]

OK, are we talking "DOM" or "CDS" here?

DOM (ASTM A513, Type 5) is as I described it in post #7 above.

CDS (Cold-drawn seamless) IS a seamless tube per ASTM A519, but it ain't DOM!

Am I splitting hairs here?

Well, it's raining, it's cold, and I'm gonna give it up and have a hot brandy and build a fire!

Later,

Hank

[Billet Benny]

OK, are we talking "DOM" or "CDS" here?

DOM (ASTM A513, Type 5) is as I described it in post #7 above.

CDS (Cold-drawn seamless) IS a seamless tube per ASTM A519, but it ain't DOM!

Am I splitting hairs here?

Well, it's raining, it's cold, and I'm gonna give it up and have a hot brandy and build a fire!

Later,

Hank

No, you're not. A519 covers your true seamless tube that is extruded from solid stock. A513 covers most all rolled and welded tube (not just resistance welded) and this includes DOM. There is more than one kind of DOM. A513 type 5 is the most common. But you can get other types that are cold rolled or have more exact inside diameters for instance. The thread I linked above has a bunch of information I typed up a while back.