welding 4130 chromoly tubing

[weldr123]

Yes you can use the GMAW wire as a filler for GTAW as long as it's classification is ER70S-6 etc. The S in the filler metal classification tells you that this is a solid wire. Hope this helps!

[jdustu]

I was doing some certs up at our tech center a few months ago and helped do some welding on a procedure qualification for 4130(3/8 dia. tubing, .062 wall). I'm back up there again this week, and I got a chance to see the results today.
Some of the test coupons were done with er70s-6, and some were done with er80s-b2. Some were not pre- or post heated, some were done with one and not the other(300pre, 500 post air cooled), some were stress relieved(1150 then furnaced cooled), others were tempered(500 for 2 hours then air cooled). All of them passed the tests. The specimens welded with er80s-b2 had a higher ultimate load, were more ductile, and had higher tensile strength, but not to an extreme extent. The visual inspection, bend test and etching was done at the center, the pieces were sent out to a lab for the other results.

Take it for what it's worth

[Aerometalworker]

I was doing some certs up at our tech center a few months ago and helped do some welding on a procedure qualification for 4130(3/8 dia. tubing, .062 wall). I'm back up there again this week, and I got a chance to see the results today.
Some of the test coupons were done with er70s-6, and some were done with er80s-b2. Some were not pre- or post heated, some were done with one and not the other(300pre, 500 post air cooled), some were stress relieved(1150 then furnaced cooled), others were tempered(500 for 2 hours then air cooled). All of them passed the tests. The specimens welded with er80s-b2 had a higher ultimate load, were more ductile, and had higher tensile strength, but not to an extreme extent. The visual inspection, bend test and etching was done at the center, the pieces were sent out to a lab for the other results.

Take it for what it's worth

How was the ductility determined?

Good to see that kind of testing done! However, the results from a test are only valid for that exact application, I.E. 1" tubing could act entirely differently. Thats why in engineering, the only "hard set" rules are those that are very conservative.

[jdustu]

How was the ductility determined?

Good to see that kind of testing done! However, the results from a test are only valid for that exact application, I.E. 1" tubing could act entirely differently. Thats why in engineering, the only "hard set" rules are those that are very conservative.

Thus the "take it for what it's worth" comment This test probably wasn't the best indicator of how it would handle the stress a bike frame would endure.

The man responsible for the testing is working on certifying a procedure for welding up an aircraft frame, and he's a cwi, and he's pretty freaking ****, thus the testing. I can see how 1" tubing could act somewhat differently, but why would it be "entirely" different? I would think the results would by somewhat similar?
The elongation was measured to the point where the tubes fractured to give some sense of ductlity. The fractures were characturized as "ductile" in nature, I haven't seen them yet. Then just for the heck of it he put some additional samples in an apperatus he built to break stuff at a certain shock force(a swinging hammer) and rather than break, they bent over.

Just like in engineering, in welding there's usually more than one way to skin a cat!

[Aerometalworker]

Thus the "take it for what it's worth" comment This test probably wasn't the best indicator of how it would handle the stress a bike frame would endure.

The man responsible for the testing is working on certifying a procedure for welding up an aircraft frame, and he's a cwi, and he's pretty freaking ****, thus the testing. I can see how 1" tubing could act somewhat differently, but why would it be "entirely" different? I would think the results would by somewhat similar?
The elongation was measured to the point where the tubes fractured to give some sense of ductlity. The fractures were characturized as "ductile" in nature, I haven't seen them yet. Then just for the heck of it he put some additional samples in an apperatus he built to break stuff at a certain shock force(a swinging hammer) and rather than break, they bent over.

Just like in engineering, in welding there's usually more than one way to skin a cat!

Very good to see the testing done. As far as a different tubing size being completely different, its very common. More mass quenching area means diffrerent cooling rates, mass versus welding length, etc. Even the joint configuration does things entirelt differently at times, a tee joint in tubing cools differently then a butt weld. The only testing I havent seen you mention is fatigue testing. Unfortunately its the most laborious to test, and the single highest mode of failure in aircraft 4130 structures. A simple impact or tensile test wont show the problems. Your friend could probably find a facility to do the testing for them. Again this is geting a bit off the original discussion, but its good to see people actually testing their work, and caring. A flyer friend of mine that was a production welder for Piper had a cute saying for the people that carelessly welded components: " Zapp and Go , Soon 6 feet below ".

-Aaron

[cncmachinist]

i did i project similar to this later year i race 4cross and downhill mtb and frames are $$$ so i found a deign i liked changed it up a bit and fabricated it my self out of 4130 and used plain old er70s-6 tig wire to weld it up chromed out the bike is beautiful and rides great i got to dig out the camera and post a pic of it


anyway good luck with it mines ridden great all of last year and was cheaper than buying the same style

[jrscgsr]

If it were my frame I would order up er80s-d2 and weld the frame up like mentioned earlier with a tight arc length and enough amps to have the toes wet in well than let the welds air cool and be done with it. Welded several dragsters this way with no failures after hundreds of passes. Stress reliving the joints after welding on a recumbant bike frame in my opinion is a waste of time and materials If I was building an air craft engine mount or something super critical, than I would weld it with 4130 filler and post heat treat.