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Mig welding 4130 tubing

by Adrian
(Ontario)

I am building an ultralight aircraft called a trike.

I wish to use my MIG welder to weld the 4130 N tubing which is .049" wall for the trike frame.

I am reasonably good with my MIG welder and intend on pre-heating the material before welding.

I would like to weld the frame myself and prefer to avoid the purchase of a TIG welder which I have never used.

I could also use my Oxy-Acetilene torch to weld the frame but I have waaaay more experience with the MIG.

Can I use my MIG to get good welds on 4130 chrome moly?

Thanks


------------------------------------------------

Adrian,

I have to say that even though I would not recommend mig welding for a 4130 ultralight, I do think it is possible with a good preheat.

but it will depend on establishing good procedures and following them.

if you have a temp crayon, it will help you to get the same preheat each weld.

and if you decide to do it, i would recommend welding a bunch of test welds using scrap pieces of the same size and thickness and beating them in a vise with a big hammer to check ductility.


thanks

Comments for Mig welding 4130 tubing

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Feb 17, 2014
Rating
starstarstarstarstar 		MIG welding 4130 is no issue NEW
by: Paul

The EAA have acknowledged the use of MIG welding for 4130 tube, have a search on their website and when questioned they have no issue.

For all the nay sayers, Maule MIG weld every airframe, American Aircraft MIG weld every airframe just about all Kitfoxes were MIG welded etc etc

Practice and be very good, also look at the high end Synergic pulsed MIG's not a bargin basement Harbour Freight Special
Feb 17, 2014
Rating
starstarstarstarstar 		MIG welding 4130 is no issue NEW
by: Paul

The EAA have acknowledged the use of MIG welding for 4130 tube, have a search on their website and when questioned they have no issue.

For all the nay sayers, Maule MIG weld every airframe, American Aircraft MIG weld every airframe just about all Kitfoxes were MIG welded etc etc

Practice and be very good, also look at the high end Synergic pulsed MIG's not a bargin basement Harbour Freight Special
Feb 19, 2012
Rating
starstarstarstarstar 		DANGER NEW
by: Have Torch Will Travel

Warning! Do not mig weld 4130 tubing, do not pre heat it, do not stress relieve it and do not powder coat it. This very light, very strong metal is at it`s strongest from the foundry. Expert tig weld only. Every heat cycle you put it through weakens it. The key is perfect full pen precision welds with the least amount of heat as possible. Don`t risk your life, use the right process. I am an aerospace tig specialist of many decades. Ask any top fuel chassis builder, he`ll tell you the same thing. Fly safe, your life depends on it.
Feb 28, 2010
Rating
starstarstarstarstar 		4130 Material
by: Anonymous

We weld 4130 material all the time in our shop, we preheat it to about 500 deg, then tig weld and stick to finish, then put in a hot box to cool down at a controlled rate. We are welding lubricators for wellheads, that have flanges on them. The welds are full penetration. I have seen pipe vessels and such welded out completely with mig before and they worked out fine, but they are pressure tested to make sure they will work at the proper working pressure. Unfotunaltely for you, you cant test your plane before you use it.

I agree with the other post, tig weld definately will yield a better weld, but if you are completely confident in your mig, try some test pcs. It is your life at risk here.
Feb 13, 2010
Rating
starstarstarstarstar 		Not recommended
by: Gerry

I am an EAA Flight Advisor. Mig welding 4130 tubing is not considered proper due to the difficulty of ascertaining proper penetration. Gas welding is an approved technique, as well as Tig. It is generally recommended that all welds be stress relieved. With gas welding, this can be accomplished by heating the tubing adjacent to the welds. An alternative would be to weld the entire structure and then heat it to stress relieve it.
I can't stress this enough- you are betting your life on your welds! Why take a chance with a technique that is not recommended? I have been to too many funerals for homebuilders that cut corners.

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