Reply with Quote4130 welds very nicely. I usually use oxy/acet, but I've also used tig. No need to pre heat. DO NOT braze 4130, it will crack on the back side. Watch out for drafts as it will harden if it cools to fast.
4130 chromo
ive got 71ft of 4130-chromo 1"od 3/16" wall that i was going to make a roll cage for an autocross vehicle. 1.25" od min reqd. so i plan to make other projects out of it like a dual burner stand for my beer brewery. do i need to heat the metal prior to welding with er70-s6 and 100% co2? or can i just weld it up as one does with mild steel? i don't need to xray or anything.. it only needs to support at most 2 15-gallon kegs of boiling beer.
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MoRdAnTlY [Mr. Wolf '91 - '10]
4130 welds very nicely. I usually use oxy/acet, but I've also used tig. No need to pre heat. DO NOT braze 4130, it will crack on the back side. Watch out for drafts as it will harden if it cools to fast.
For some reason, I remember preheat to 300*F for proper welding, atleast the roll cage, I wouldn't bother for the beer brewery. And yes, I've had a lot of sucess with TIG welding 4130, made quite a few motorcycle crash cages for stunt riders and I have yet to have a weld fail. The slow process of TIG welding is probably ok for no pre-heat, but if your using 100% CO2, your MIG welding, why not use a blend? And pre-heat the cage for sure. 100% CO2 is going to give you a lot of spatter.
This did not ring true with my experience so I Googled 'brazing 4130' to see how widespread this belief is. Here are excerpts from some of the first hits:Originally Posted by dgapilot
....used to work for a major aircraft manufacturing co. and they had several
4130 assemblies that were brazed together somewhat out of necessity as the
part would be tough to weld , never heard of a problem with these units ,
many years ago an EAA member got the OK from the FAA to braze his entire
four place airplane together with Eutectic FC 16 Braze filler , never heard
of any problem with this aircraft , I brazed some .035 wall 4130 specimens
with this material and couldn't break any brazed fills , just my thoughts ,
The combined experience of the hundreds, if not thousands, of people
who have brass brazed bicycle frames out of 4130 can't be ignored.
Brazing 4130 works great.
Brazing is the prefered method of constructing hand-made chrome-moly
steel bicycle frames, I have service frames that are at least 40 years
old and showing no signs of cracking despite being used nearly heavily
since purchase. One of them is (was) a light-weight racing frame too.
An open mind is a virtue...so long as all the common sense has not leaked out.
BTW, ER80S-D2 is the proper TIG filler for 4130, not sure about MIG wire.
And FWIW, brazed joints aren't generally butt joints or simple cope cuts as found in standard roll cage fabrication. There is generally enough surface area in the brazed joint that you could use a modern day adhesive for an equally reliable joint.
It's important to note the difference, made obvious as seen below. A low temperature weld, or braze, or silver solder or what ever method you would compare, will never be as strong as an arc weld. Strenth from design and surface area in which the low temp weld is applied can have acceptable finished joint streangh, but these joints aren't normally used in roll cage building.
Plus, as far as I know, brazed joints are used in bicycle frames for ease of fabrication and to save time, not nessessarly because they are stronger, but definalty easier if you've ever seen how bicycle frames are jiged and welded.
Ultralight Aircraft parts.
When I was oxy welding 4130 parts I was instructed to cut thin strips from 4130 sheet and used this for filler rod. Also made a lot of formed aircraft ribs and used the same material when welding.
Using sheared strips forces you to wear gloves when welding which is agood thing anyway.
TIGed using same filler rod just as nicely. Very pretty looking welds.
Super X3. 3600rpm. Sheridan 6"x24" Lathe + more. THREE ways to fix things: The RIGHT way, the OTHER way, and maybe YOUR way, which is possibly a FASTER WRONG WAY!
When I worked doing small circle track race car fabrication, all the welds were done with tig and no preheat. They never had failures despite some of the hard crashes the chassis recieved.
Don't know about Mig as back then the owner would't even consider having one in the shop.
Brings back some memories.
Mike
Warning: DIY CNC may cause extreme hair loss due to you pulling your hair out.
ok, hmm. supposedly, brazing when done properly is "as strong or stronger" than arc welding.. since surface adhesion area is far greater than a base and child metals. but i can't afford tig, so my 110v hobart is what i got. it looks like i'll just have to try it and see what happens. 100% co2 causes more spatter? sure makes nice penetration. (tee hee). i cant get co 25% in my alum cylinders.
MoRdAnTlY [Mr. Wolf '91 - '10]
mig on 4130
At my job we use alot of scrap pipe that is 4130 as rolled and heat-treated to 32 to 38 rockwell c or s-135 grade. We build all kinds of things with it using a MIG with ER70S 3/32" wire and a 75% co2 & 25% argon mix. It works great very strong weld and very little spatter with no pre-heat but never cool it with water, just let it cool at room temp at least till It gets below 300 degrees. good luck.
??? what kind of cylinder do you have? What pressure is it when full? My steel cylinders are 2200psi when full, and can be exchanged or filled with any mix or straight argon. Never heard of an aluminum cylinder...?
Yep, straight CO2 is good for penetration, just lots of spatter, but cheaper than using blends. If you going to MIG weld, proper procedure for 4130 thicker than .120" is 300-400*F pre-heat, really only critical if your building a roll cage, no worries on the brewery fab.
And yes, surface area makes all the difference in the world, arc weld will always be stronger. And a properly preformed arc weld under proper procedure will exceed the property values and performance of the PARENT metals. (never heard anyone say child metals? parent filler?)
MC
BTW, arc weld refering to SMAW, GTAW, MIG, SAW and simlar. Brazing and oxy fuel welding is excluded.
i have catalina 2-20# and 2-5# aluminum cylinders all at about 800 psi full.. the vapor point of co2. the tank working pressure is 1800 so who knows. my weld supply said only steel inert gas tanks fill mix. thats too much bother to buy more tanks. its nice to just switch out when im empty.
i would consider a bracket, etc the child. example: a fender of .062" on a triple tree.
thanks for the information.
MoRdAnTlY [Mr. Wolf '91 - '10]
I have been making NHRA certifiable chassis for many years. As for brazing... I couldn't begin to tell you anything, but I have always used ER70S-2 filler with a 100% argon tig setup. They (The guys that ping the chassis to certify it.) would FREAK out if we would weld it with a MIG. They tell us that it thermal shocks it and makes it brittle. If you use a 4130T I believe you have to anniel the joint with a rosebud and a heat crayon.
