Material Question

[TurboTerry87gn]

I going to order my Chomemoly tubing for my cage. 1 5/8" O.D. 4130 by 0.083" wall thickness. My question IS D.O.M.(drawn over mandrel) Is ths DOM tubing the standard for the cage material? Neither my SFI 25.5 specifications book or my old 2003 NHRA book mentions anything about the "DOM" 4130 .

Here is the quote from my SFI book. (25.5 spec)
All structural material for the roll cage, (tubing, flat bar, ect.), must be normalized 4130 chrome-molybdenum steel (4130N) purchased to the requirements of military specification MIL-T-6736B.

Is this MIL spec DOM?
I think by drawing the material over the forming mandrel it gives more consistant wall thickness. Is all 4130 DOM?

Thanks in advance.

 

[craggar]

Yes it is and if you asked for 4130 C/M you will get the right stuff. If you just say DOM you may get mild steel at just about the same price as C/M.

 

[TurboTerry87gn]

So is all 4130 drawn over a mandrel during manufacturing?
I wasn't sure. I just wanted to make sure I order the right material the first time. 1 grand for for the materail I need right now so I just wanted to make sure before I placed the order.

$4.67 /ft 20 foot sticks and I 'll need about 10 sticks to do my 25.5 spec cage.

 

[craggar]

I can't say 100% for sure. I do know that when myself or anyone else I know around here orders it we just say 4130 C/M in whatever size. I've also never seen c/m with a seam.
If you're really worried about getting the wrong stuff post your question over here, these guys do it everyday for a living.
Chassis and Suspension - Gilsbach Racecraft - Yellow Bullet Forums

 

[TurboTerry87gn]

I found the 1 5/8" 0.083 wall cm for 4.67 a foot.
Got all the hydraulics in for the tubing bender and some scrap cm from my friend to practice my welds and find the right setting.
This is my first time to weld cm, but it welds very simular to stainless and the weld color is gold :biggrin: like the stainless. Using ER70S2 rod.

 

[Alky V6]

I think your supposed to use a special rod for C/M. Don't remember the number off the top of my head. Isn't E70S2 rod for mild steel welding?

NICE welds, by the way.

 

[TurboTerry87gn]

every thing i have readabout cm says er70s2 rod. This is what the aircraft welders use for the cm.

 

[Alky V6]

I believe the ER80SD2 will give a higher strength weldment. ER70 is good for welding mild steel to c/m or if your looking for a more flexible weldment with c/m to c/m.

I've used 4140 rod, but it doesn't leave as pretty a weld.

 

[six shooter]

+1 on the 70-S2 rod. More ductile weld joint on a non heat treated part. (stress relieved)

 

[Alky V6]

correction

I checked the box at work today. That's ER4130 rod. Not 4140.

 

[TurboTerry87gn]

Welding 4130

This is where i got my info. I'm not sure who is correct but I think I will stick to the er70-s2. :wink:

quote
"Closing Suggestion
When welding 4130 chrome moly in the normalized condition, AWS ER70S-2 filler metal, with its low carbon content is the proper choice. Make sufficiently large fillets and make them flat, not concave. If the part is to be heat-treated after welding, then a filler metal matching the 4130 chemistry should be employed. This requires preheat and special precautions to avoid cracking. "

 

[Alky V6]

Good info. Thanks.