Docol tube for fuselage?

[Russellmn]

Has anyone looked into using Docol tubing rather than 4130?
From the SSAB website:
Docol® R8 Tube features excellent weldability and has a low risk of welding defects due to the low CE-value, low amount of impurities and a clean oxide-free surface. To reduce the width of the HAZ as much as possible, we recommend that you keep the heat input as low as possible.
For both TIG/GTAW and MAG/GMAW the following filler material is recommended: AWS A5.28 ER80X.-X and AWS A5.28 ER110X.-X. Welding parameters might need to be adjusted.

[alaskabearhawk]

Looks like the smallest they make is 1in dia, .049 wall. Also, aircraft stresses/load paths are different than a car. It would be interesting to find out more.

https://www.eaa.org/eaa/aircraft-building/BuilderResources/while-youre-building/building-articles/tubing/aircraft-welding-and-steel-tube-fabrication-part-3

[Russellmn]

I've seen down to 5/8" advertised. Don't recall wall thickness off hand. Tensile strength is higher slightly (100ksi), I believe ductility is similar as well. NHRA allows it as a direct replacement for 4130, and there's far less chance of weld defects from cooling too quickly, heating too much, etc... I've used it for off road stuff, but that's all much heavier material.

edit: just checked, A.E.D. Motorsports lists .625 x .035 as the smallest sizing...

[alaskabearhawk]

Just looked, and it is an interesting product, but the sizes for our uses just aren't there. Glad someone is looking forward in the steel industry!

Docol tube size snip.jpg

[Jpettygrove]

I just got a quote from aed motorsports and they substituted docol for 4130 in a few sizes. I was wondering the same thing, if it is a valid substitute.