Dr. Majic and Dr. Young recommend RG45 for welding of 4130 tubes. Dr. Young also likes coathangers.
For fun, I butt welded 4130 coupons together with coathanger (RG Black) and subjected them to the big hammer
bend test. It passed. I never use them for serious work.
I keep 5 types of steel rod in my shop and I periodically round robin test them. For O/A I keep coming back
to RG45. It fillets very nicely, doesn't spatter at you, and it is a deep penetrating rod compared to
RG60. The tensile strength difference is compensated by:
We don't grind weld beads (with rare exceptions, like where a bolt/nut needs a flat) so the bead is always
thicker than the parent metal.
Proper joint design for aircraft should never put a weld in pure tension. At least 50% of the load is carried
in shear. If we were pipefitters I would have a different opinion. As part of the cert process,
the test coupons cut from your joint are ground/sanded flat, then tested in tension. RG45 might well
fail the test on high strength steel pipe.
Lots of salesman push the E-rods for gas welding. That's a poor recommendation as the chemistry isn't right
for gas welding. Too much sparking, spattering, and a nasty tendency to crater the end of the bead.
Dr. Joseph Maj
The Dow Chemical Company
Analytical Sciences Laboratory
Dr. Maj very kindly participated in our 5 hr.
Instructional video on Aircraft Chromemoly
He has been teaching at Osh for many years, and welds a very fine tubing cluster. "Dr." Young is Joe "The
Polish Ace" Young, a veteran torch welder of 50 years' experience, and a veteran instructor at Osh.)