Author Topic: Chromoly Welding Process?  (Read 4643 times)

pilotdude

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Chromoly Welding Process?
« on: April 02, 2004, 03:23:06 PM »
I had thought that chromoly tubing haad to be TIG welded. However I was reading the April issue of OFF ROAD magizine. On pg 84 while reading about the build up of a Toyota tundra, it said how the rear bed cage for the shocks and spair tire were made out of 4130 Chromoly tubing and MIG welded. I was told that you couldnt use a MIG on that. So whats the truth, can you or can you not mig weld chromoly?

PD

dhjunkie

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Chromoly Welding Process?
« Reply #1 on: April 02, 2004, 05:12:45 PM »
here is the deal about chromoly and mig welding.  You can mig weld chromoly.  The mig wire HAS to be er70s wire or better.  The only problem is that the joint will not be as strong as the tubular substrate (chromoly) but plenty strong for what we do. IT IS ALSO A PLUS IF YOU DO KNOW HOW TO REALY WELD!
  To weld chromoly correctly you do need to tig weld it. TIG is considered structural welding where as mig is not (there are some forms of mig that are structural, but our type of machines are not capable of it and there is a certain technique to do it). You should also use the same filler rod as the substrate to make an even joint stregnth, ie. 4130 tube with 4130 rod, 316 stainless tube 316 rod and so forth.
 Then once you have TIG'd you chromoly part, you will need to aneal it and then re-heat treat it to get the part to a consistant hardness and structural integrity. there are different hardnesses to reach for different materials and part requirements.  One problem with the heat treating process is that if the part goes in true it may come out not in tolerance.

pilotdude

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Chromoly Welding Process?
« Reply #2 on: April 02, 2004, 05:21:38 PM »
Thanks DH. I am still woundering why a shop would thne MIG the shock mount on a truck that would be used off and on road.....

PD

dhjunkie

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Chromoly Welding Process?
« Reply #3 on: April 03, 2004, 07:53:50 AM »
Most shops just use a mig welder cause it is quick and easy.  place it, tack it, check fit up, weld and send out.

Vrroom

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Welding Cr/Mo steel
« Reply #4 on: April 14, 2004, 06:24:23 AM »
If you guys really want to know the specifics of welding Cr/Mo steels, I can tell you more than you would ever want to know. I've got about 23 years of experience in welding and a BS in Welding Engineering to boot. (yes, there is such a degree).

Truth be known, Cr/Mo steels can be welded with any welding process GTAW (TIG), GMAW (MIG), SMAW (stick), SAW, FCAW, OFW, RW, EB, Laser and several more, however, some processes are better than others for fabricating thin wall tubular structures. With the assumption that the welder is able to make a sound weld, the single most important thing is that the weld joint be "ultra" clean and free from any moisture, dirt, oils or any other hydrocarbon containing materials. Even oil from a fingerprint can affect the quality of the weld. The second most important item is that the weld gets the correct pre-heat and post weld heat treatment. Although Cr/Mo steels are very strong, neglecting either one of these items is a potential recipe for weld failure. Selection of filler material is also of key importance when you're designing a welded structure that is being made to protect your body.

If you need a recommended practice, don't hesitate to contact me.

Vrroom

Ramjet

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Huh?
« Reply #5 on: April 14, 2004, 07:42:10 PM »
"GTAW (TIG), GMAW (MIG), SMAW (stick), SAW, FCAW, OFW, RW, EB, Laser"

Be a Pal, Translate Please  :D

(and I thought aviation had a lot of wacky lingo)

dhjunkie

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Re: Huh?
« Reply #6 on: April 14, 2004, 10:12:49 PM »
Quote from: "Ramjet"
"GTAW (TIG), GMAW (MIG), SMAW (stick), SAW, FCAW, OFW, RW, EB, Laser"

Be a Pal, Translate Please  :D

(and I thought aviation had a lot of wacky lingo)


GTAW = Gas Tugnston Arc Welding
GMAW = Gas Metal Arc Welding
SMAW = Shielded Metal Arc Welding
SAW = Submerged Arc Welding
FCAW = ???  beyond my welding knowledge
OFW =  Oxygen Fusion Welding (???  sounds good doesn't it)  
RW = Resistance Welding
EB = ???  not sure
Lazer = using a lazer as the focal point of forming the heated weld puddle

Hmmmm...  Did I pass????

PilotHawK

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Chromoly Welding Process?
« Reply #7 on: April 15, 2004, 07:48:25 AM »
fcaw=flux core arc welding?
eb=electro brazing?

hehe my guesses to fill in the blanks

Vrroom

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Welding Cr/Mo steel
« Reply #8 on: April 19, 2004, 04:55:51 AM »
EB = Electron Beam
FCAW = (correct) Flux core arc welding.

Here are some interesting web sites (at least for welding nerds like me)
http://weldinghistory.org/
http://www.adtdl.army.mil/cgi-bin/atdl.dll/tc/9-237/toc.htm
http://iwse.eng.ohio-state.edu/we/

Vrroom

jms

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welgrinding
« Reply #9 on: April 19, 2004, 10:45:50 PM »
you mean i cant braze the tubes together...
damn now i got to start all over...... :roll: