Welding chrome moly

Is it OK to weld chrome moly tube with a mig welder? I'm joining moly tube to mild steel plate, and moly tube to moly tube

 

No !

 

TIG is the way to go for CrMo tube. With the thickness of the tube you don't have to heat treat after welding though as some worry about.

 

Nope, TIG or gas. Everyone forgets gas welding!

 

Helicopters are mig welded moly tubing.
of course you can mig it.

 

Depends on what you are building. A top fuel car, no mig welding. If you are building a go kart it works just fine.

 

Yep there are lots of things that are MIG welded chrome moly.

 

Maule Aircraft company MIG welds their 4130 fuselages. As does American Champion Aircraft.
I TIG my race car ch***is and I normalize after welding. Ideally I would then bolt them to a fixture and have them treated to around 90k. Would be expensive but the right thing to do to realize the full benefit of using the CrMo. As it is they work well and crash well.

 

I found that it can help to pre-heat the area to be mig welded. It can help even out the quick heat input of a mig welder. You dont have to heat it red hot, I found a temp in one welding manual, but cant find it again.

I used mig for some of the hard to get to spots on off road race parts, and they took a beating.

 

You can braze (gas weld)it as well, lots of brazed motorcyle frames out there, a handfull in my garage..

 

Everything depends on intended use.

NHRA specs that all ChroMO is TIG welded and with regular ER70s6 steel TIG rod.

Here, read some of these

 

I can make a jack*** ***umption that you are comtemplating putting in a CrMo roll cage. It is ALOT easier to fix a mild steel structure out in the field with finding tube etc and someone with a mig and a generator. Unless you have a superlight race only vehicle, just do it in mild steel....

 

Of course you can mig it but a qualified ticketed welder with strict rules not a back yarder with a 110volt mig,or someone that welds on weekends only.Walk around and look at the welds on some home built cars pretty scary.If he is an experienced welder then have at it but by the sounds of the orig post he doesn't know and is asking which is acceptable.That in itself an admission of lack of knowledge.But to answer the question blindly yes it is miggable.

So is cutting your lawn with nail clippers an acceptable way of cutting gr*** just long and tedious.No where near as dangerous as an incorrect weld.

Tig.

 

What thickness are we working with?

 

tube thickness .0875" - .100", mild steel plates 1/8 - 3/16",

 

To weld Chrome Moly successfully, and safely, you need to use
the correct filler and preheat. Otherwise you can very easily
end up with a brittle weld. The kind of weld that will break when
you really need it.

 

I have mig'd CM. A**** many other things I was not supposed to do.

 

Different scenario, but maybe similar, different failure observation.
Weld a piece of 1/8" mild steel or DOM round tube about 2' long to a cast brake rotor wheel face with a MIG. Tip over the newly welded parts. The weld penetration is pulled from the cast rotor and is still attached the weld at the end of the tube.
CrMo? It will shatter at its side of the weld at some point away from the weld because of ___________________ embrittlement. Thinking carbon. Please fill in the blank and correction if necessary.
More cl***room educated guys should be able to fill in that blank for me. Some seat of pants guys will to.

 

Hydrogen embrittlement is the term

http://en.wikipedia.org/wiki/Hydrogen_embrittlement

But you are comparing apples to oranges when you talk about welding alloy steel to cast iron as opposed to joining two pieces of alloy steel.

 

I thought that, wanted knowledge. Thanks.
Breakage difference is with mild steel plate to CM steel round tube would be breakage or shattering of the CM above the weld due to carbon content collection in the steel around the weld area.
Correct me if I'm wrong again please.
I heard of a dirt car driver with a tubing mark when the ch***is failed. NONE of the subject had my welding involved.
I also think of hydrogen embrittlement to be ***ociated with after chrome plating.
I have carbon in mind because of having the need to buy carbon steel tubing for work.

 

You can mig weld no problems, pm me or call me if you need instruction or filler wire for mig, but yes theres a time to mig and tig.

 

For the best thread on this ever, with pics see below link. This is from the LSR site and from Willie Butcha. Willie unfortunately p***ed away earlier this year, but was a master of a guy in all respects. Read the eintre thread and inform yourself, dont just jump around an look at pics and then become an expert. Thanks

http://www.landracing.com/forum/index.php/topic,3837.0.html

 

I teach welding and have been welding moly for over 30 years , TIG welding is the only process i would use , it's a proven method .

 

As stated in a couple of posts there are some MIG welded airframes out there but those are done under very controlled conditions by qualified weldors. Doing it in your garage with a 110 MIG is probably not a good idea. That said if you use a pro grade machine and a weldor to match you will most likely not have any issues with the thickness that you are planning to weld.
The main point to keep in mind is that as stated in one post, the drag race sanctioning bodies specify TIG welding for all 4130 tubing. Also I have usually found that an average TIG weldor has more chance of getting the parts stuck together safely than an average MIG weldor. I have seen a lot of MIG welds that are more surface "decoration" than a bonding medium.
(note weldor is the machine operator and welder is the machine)

Roo

 

CM can be welded with the proper tig rod etc. the important thing is putting the whole item in a oven and annealing the whole ch***is, roll bar etc. etc.. Annealing is the process of getting the molecules the relocate around the welds.

 

There wouldn't be any molecules left if I welded it. I'd burn them all away.

 

Why are you welding 4130 tubing to mild steel plates?

I ***ume to attach cage/tubing to ch***is. There are some definite do's and dont's.

I'll look for the video of the Mustang landing on roof and pushing the cage up through the floor.

J

 

Another post with the blind leading the blind

 

Yup - i'd like to see the oven i'm supposed to to put my ch***is' into so they don't shatter 'cause i been worrien about that a lot. O'course i could be with Lippy and have burned them molecules all up.

 

Years ago I had a 4130 axle that I Arc welded cold rolled plate too. Since I had never done this, I went to see an old welder I knew who explained how to preheat the axle and plates and weld them using E7018 low hydrogen rod. After welding I w****d the axle in an old blanket and allowed it to cool slowly. Never had any signs of fatigue or cracking. Never heard of any after I sold the car. I would recommend using only cold rolled plate to attach to the chrome moly.
At that time my day job was welding. Also you know you can rent a tig machine and the cost is not all that bad. These days I own a Miller Dynasty 200 Tig so I do very little arc, mig, gas welding. Don't need to when you have tig. Please post your results. Gordon