NEHA

After all this discussion about cage materials and design, I'm at the point where I need to start ordering materials. Home Depot still sells threaded pipe, right?

In all seriousness, I've come across a bunch of places that I can get various mild steels that are DOM, but haven't been able to find a supplier that has 1020/1026 CDS in 1.75x0.095. Can anyone point me in the right direction? Here's an example of a supplier who doesn't have CDS in any sizes that I need, but plenty of DOM:
http://www.teamtubellc.com/en/products/ ... mless.aspx

My impression was that CDS is a bit more rare in the US, and it typically sized different.
Let me find out where we get our tube from.

That would be great, thanks Seth. I don't mind using DOM, but since the consensus appears to be that 1020/1026 CDS is universally better than just drawing it through a mandrel, I don't see any reason not to try to pursue the better material.

I think DOM is better than CDS as well as being more available in the US. Slightly higher tensile and yield and about double the elongation. Bigger issue is getting it (or any structural tube) thru a reputable source so you are getting the product you order.

onlinemetals.com They ship out of Ct.
http://www.onlinemetals.com/merchant.cf ... &top_cat=0

A513 (alloy 1020-1026) Steel
This alloy is generally used for DOM tubing. Its higher carbon content means higher strength, but lower weldability and machinability.

ASTM A513 alloys 1020 - 1026 Mild (low-carbon) steel
Minimum Properties Ultimate Tensile Strength, psi 87,000
Yield Strength, psi 72,000
Elongation 10.0%
Rockwell Hardness B89
Chemistry Iron (Fe) 99.08 - 99.53%
Carbon (C) 0.18 - 0.23%
Manganese (Mn) 0.3 - 0.6%
Phosphorus (P) 0.04% max
Sulfur (S) 0.05% max

8620 Alloy Steel

Thanks guys, there seem to be so many different specifications for all the different sanctioning bodies that it's hard to put them all into one pile and make sense of them.

Sherm,
The FIA 2012 roll cage construction document agrees.

4.5 Cage Tubing Material Requirements
Material: All new cages shall be constructed of either CDS (Cold Drawn Seamless) or DOM (Drawn Over Mandrel)
unalloyed carbon steel tubing containing a maximum of 0.3% of carbon and with a maximum content of additives of
1% for manganese and 0.5% for other elements. It is required that mild steel be used for all new cages.
Use of heat-treated or high carbon steels is not allowed after 3/1/2005.

I may try to chase down Dave Patten to see where he picked up his cage steel. I think he may only have 1.5" OD though, and I'd really prefer to go with 1.75"

On our end, it comes from europe. You won't find it to be an economical choice.

DOM it is, then.

Actually, Walter, 1026 DOM has about HALF the elongation of 1018 CDS, not "double".
http://www.stockcarsteel.com/ Carbon content is in the optimum range for welding, and ground finish means that no descaling is required.

I purchased my DOM from Marmon Keystone.
1 clark St. Southhampton MA. 01073

They delivered via truck freight to Nashua NH no problem