View Full Version : mig welding chrome olly
02-24-2005, 08:46 AM
In my short experience with metal fabrication, i have come to know the saying goes "you cant mig weld chrome olly"
I have test welded a few peices of it with my lincoln mig(hard wire/argon Co2), and it seems to work fine. I know that chrome olly can crack and so forth, but ive tested the welds strength and it seems fine all around.
If anyone has more experience and can de-mystify this, id love to gain knowledge, and not build something out of this metal and mig it, only to run into problems.
Any further advice about migging chrome olly to a hot rolled steel would be great as well. thank you all,
02-24-2005, 09:11 AM
Lincoln welding has a discussion on this subject. Follow the link below.
This is a TIG welding article but has some good information that may help.
02-24-2005, 09:12 AM
Yes you can use Mig to weld 4130 chromemoly tubing.
But my preference is to Tig weld it. For more reading on the subject
read this thread:
Then use the search to dig for more info that may be buried within the site
02-24-2005, 09:15 AM
That saying is wrong. You can mig that stuff, You can use about any welding process known to weld it. Having the right filler wire is the main thing and gas mixture goes along with the filler wire. As far as mig welding 4130 to HR steel, yes that will work too. I was always taught to use wire that was equivilant to your best metal. In this case tho, you dont want to use 4130 wire but instead something like a er80 wire. In my experience, mig welding the 4130 was never a problem, i always had trouble bending the 4130 tubing. I would go to the local welding supply store and have them recommend a wire and gas mixture for your particular metals. For me it would also depend on what i was making. Right now I make a header for a guy that does those Jr. Dragsters and I just use the e71 wire. I weld the 4130 tubes together and then weld them to a low carbon flange with no problems. If I was going to weld something that could be a danger if it broke, I would change filler.
02-24-2005, 09:59 AM
Grade 4130 steel, while containing both chromium and molybdenum as strengthening agents, is considered a heat treatable low alloy (HTLA). Generally referred to as chrome-moly, this HTLA is used largely for aviation, racing and welded tube structure applications.
When GMAW (MIG) welding 4130, preheating to 300°F is strongly recommended by the American Welding Society (AWS) to relieve stresses in the metal. When choosing a MIG wire, most people opt for ER80S-D2 or ER70S-2. ER80S-D2 will provide the most weld strength. The ER70S-2 is easier to find and provides a strong weld, but you’ll be sacrificing some strength by choosing this filler metal over ER80S-D2. When it comes to shielding gas, 75/25 (Ar/CO2) is recommended for most applications and 98/2 (Ar/CO2) for anything over 3/16 in.
Wire Size-Amperage Range- Wire feed speed Range Relationships for Short Circuit Transfer on Steel
Wire Size Amperage
----- ---- Range--- Wire Feed Speed
.023" --- 30-90 --- 100-400
.030"--- 40-145 --- 90-340
.035" --- 50-180 --- 80-380
.045" --- 75-250--- 70-270
Cleanliness is critical when welding 4130. Make sure that all mill scale and oils are removed using mild abrasives and/or acetone. When you strike an arc, keep your heat input low to reduce stresses in the metal.
Post-weld heat treatment of 4130 varies from one application to another. If ductility and toughness are your goal, post-weld heat treatment is recommended up to 1,200°F. If the material you are welding is thinner than .120 in., stress relief through heat treatment is not as critical.
Rule of Thumb:
1 ampere for every .001 thickness
1/8" material=.125=125 Amperes
Wire Burn Off:
.023-3.5" wire/amp - 125 amps=437 IPM
.030 - 2" wire/amp - 125 amps=250 IPM
.035 - 1.6" wire/amp - 125 amps=200 IPM
.045 - 1" wire/amp - 125 amps=125 IPM
GMAW (MIG) Welding 4130 is a lot like welding mild steel and is easy if you know how. These are just some of the reasons 4130 is considered so flexible and is used on everything from airplane engine mounts to bicycle frames.
02-24-2005, 10:04 AM
Well that opens alot of doors!
I had my mini chopper frame tig welded since that was the best suggested method. I now own a nice mig and i want to modify the frame but have been reluctant to do so. I guess i can go ahead with confidence!!
As far as the wire used......does 4130 come in standard rolls for mig machines? Dumb question i know, but i havent actually asked the welding shops. And like i said before, the hard wire standard to my lincoln seemed to fuse everything decently, but if i know a better spool will ensure strength, i would defanately switch for the metal to be welded.
Lots of replies! thanks to all for your help! Josh
02-24-2005, 07:13 PM
Josh, It isn't that you cannot MIG weld 4130 - it is more that it is NOT recommended. For instance NHRA requires you to TIG 4130 - nothing else is acceptable to them. However we all know that the airctaft industry has O-A welded 4130 with great sucess. SO clearly there are more than 1 way to achieve sucess.
The "problem" with MIG is that it is easy to lay down a "good looking" yet inferior weld. It takes quite a bit of MIG experience to put down welds that are actually as strong as they look.
As far as the wire - many authorities on the subject recommend the "lesser" strength ER70S-2 and NOT because it is easier to obtain, but rather it is more ductile and while it is technically weaker than an "appropriate" 4130 filler the idea is that most welded joints are over welded to begin with and the weld strength itself is NOT your weak link - so while you technically give away a small amount of weld strength you do so wisely as you have plenty to spare and you are rewarded with a less brittle joint.
Just thinking out loud
Jacin in Ohio
02-24-2005, 07:53 PM
I agree with your statement Jacin. When we ran the sprinter it was inspected very often for cracked paint at the joints or any hit. Our opinion was that we would rather have the joint bend a little and crack the paint rather than break a joint loose. I do believe there are some places on some cars that act as shear points for safety of the driver. I have welded 4130 in industrial applications with plain old mild steel wire with good success. I agree also that it must be clean. (as all welds should be)
02-25-2005, 06:31 AM
[quote="Hemirambler"]However we all know that the airctaft industry has O-A welded 4130 with great sucess. SO clearly there are more than 1 way to achieve sucess.
The aviation industry even had one (that I know of personally) manufacturer that stick welded 4130 airframes for years, and I've never heard of one failing. That manufacturer was Stinson, on the 108 series aircraft.
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