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4130 welding, need advice

4130 welding, need advice

4130 welding, need advice

OK, I'm constructing an ATV frame out of 4130 cromolly.  My question is all I have is a MIG welder, (Solar 2175) and have never done anything like this before with this type of alloy.  I was told for a good weld with 4130, I need to TIG, but I don't have and can't afford a TIG just for this application.  But I was told I could MIG with 100% argon and er70s-6 or es70-s5 wire. (I don't know which one of those I should use)  But is this my only option, or could I oxy-acetelene it using a 4130 rod?  I don't know which one is better, and don't really know the process of how to weld using a oxy-acetelene thorch.  but I need the welds to be strong of course, but all stress points will be gusset.  Any advice is appreciated.

RE: 4130 welding, need advice

Welding is  simply "melting two pieces of metal together".  Welding 41xx TS is not rocket science.  It welds as any other metal of equal size, MIG, TIG, stick, whatever.  Chromoly steels require a post heat treatment in order to prevent the possibility of cracking and failure at the weld interface.  It is the necessity of PHT that makes chromoly TS less than perfect for your stated application.  IMHO, yoiu should use a mild steel DOM TS of suitable wall thickness.  There will be very little loss of strength V weight and it's a bit cheaper.


PS---Brazeing and/or furnace brazing has always been used in tubeframe race car construction before TIG became popular.

RE: 4130 welding, need advice

Yes, you can certainly OxyAc. weld 4130, Use a mild steel rod though ( coat hangers are my preferred rod, but Im sure thats not correct via. the book ) As Rod states, you should draw the weld areas back, and even then, you must accept the inevitability of a crack or two at some point in the future.
You can also MIG it, and the ER70S is a mild steel wire, I am not sure you would have to have 100 percent Argon, however it might help welding thin tubes.
I assume you are building a race frame where weight is paramount? Otherwise, I would also follow Rods suggestion to use mild steel, short of getting goofy on wall thickness, the weight savings shouldnt be more than a couple of Lbs.
As for welding technique with Oxy, think of it as a crude TIG, you are using the flame for the heat source instead of electricity.

RE: 4130 welding, need advice

pwht won't be necessary for wall thickness you would be using for your application. if you gusset, or cluster tubes you might consider it though. gmaw will be tough, but doable with a little practice. i would suggest 80ksi wire[.023 if available] with a 75/25 ArCO2 mix.
Historically, oxyfuel was the method for welding thinwall 4130 because the flame provided the pwht and you had great control of the weldment. that's why gtaw would be a better choice but i think you can do it with "what ya got".  

RE: 4130 welding, need advice

Pat, "coathangers are my preferred rod---" How horrible!!!
I haven't used coat hangers since I found out that PROPER weld rod could be had at the local welding emporium for literally pennies.  Many different sizes including the 1/16" copperclad stuff that I favor.  To be honest, I use the MIG for just about everything these days.  I tend toward CO2 for most everything.  Cheaper.  For the bigger stuff, I switch to FluxCore.


PS to chiph---"Historically, oxyfuel was the method---"
True enough. BTDT but, IMHO, it requires a BIT more than basic skill with a torch to achieve a safely welded frame fapricated from chromoly TS.

RE: 4130 welding, need advice

Wow thanks too all, you all are sure helping me get cleared up on a lot of things.  I may try doing a little research on oxyac, and give it a shot, if I have problems, then I will Mig it and make sure everything is re-enforced well.  But what other metals do I have the option of using.  A lot of after market frames come in 4130, but can someone help me on what maybe I could use that I could weld better with.  A few extra pounds isn't going to hurt anything, plus if it saves me a little $$$ that's always good too.  Thanks to all that respond, this site is very informative, glad I found it!

RE: 4130 welding, need advice

evelrod, i concur with your concern over the integrity of the weld but it "ain't gonna fly" so i think the risk of a failed weld is not nearly as critical as with an airframe.
on the same note, i think it is wise of 400fnSport to consider more forgiving steel alloys.1020 DOM tubing would be a good choice--lots of o.d. and i.d. combinations available and very forgiving to weld.

RE: 4130 welding, need advice

Rod, sorry, that practice was instilled by my father, a Northrup graduate A&E. I am sure there are still many small aircraft flying with his welds. I always use ER70S6 for my TIG work though, just call it old habits. Actually, coat hanger wire is pretty doggone ductile stuff....

400fnSport, SAE1020 DOM tubing is a wise choice, depending on your wall thickness and tubing diameter. I have no direct experience with bikes or ATVs, but as an example, when we use 1020 for the 1-5/8" main roll cage hoop, we typically run .134 wall, but mostly to make sure we satisfy the NHRA .120 min wall mandate. For the 4130, we run 1-5/8" X .083 wall, so that will give you an idea of the difference in wall thickness. I would try and keep the same relative percentage of cross section as a starting point.

RE: 4130 welding, need advice

I must agree.  The SAE 1020 DOM was my choice for ALL the roll bars and roll cages I have fabbed over the years.  A long, long time ago I used  ERW in a pinch but, I do not recommend it(point of fact, it's not allowed in most race organizations).  My vintage mini's  8 point cage is 1020 DOM 1 1/2" 0.095 and the whole shootin match comes in at under 1200 lbs. on track.


RE: 4130 welding, need advice

OK I've decided that I'm going to do a test frame with some cheap metal to make sure I get all the measurements correct, then I will construct a prototype out of 1020DOM.  I will run it for one season to see how well I can build this, then if I feel confident, next year I'll tackle the 4130.  You guys have been an amazing help to me.  I'll be heading to Modern Welding tomorrow morning to pick up everything.  Thanks all for the help

RE: 4130 welding, need advice

Lots of good info here guys!
I build drag cars for a living and tig everything, even the 1020.I use 70s2 wire which is pretty much the industry standard for 4130 and 1020.
Ive been told that if you need to mig 4130 that you can use
70s2 wire with 95% argon 5% c02 and get good results.
All the work i do is to sfi specs. so i dont do to much mig
For 1020 mig i would use 75% argon 25% co2 and 70s2 wire.
Good luck and have fun!

RE: 4130 welding, need advice

Although there are several good filler materials, ER80S-D2, is one you should consider. This filler material is capable of producing welds that approximate the strength of 4130. ER-70S-2 is an acceptable alternative to ER80S-D2, as is ER70S-6, although the weld strength will be slightly lower.

For parts thicker than .120", stress-relieving is recommended and 1,100ºF is the optimum temperature for tubing applications.


RE: 4130 welding, need advice

Boo1 or jeffita
I guess I have always been told the suffix on ERS70 was simply the fluxing action, which seems is incorrect. Do you have any information sites on the web that will explain the exact nomenclature and properties? I did a quick Google search, but came up with more advertising for sale than anything else. Thanks in advance!

RE: 4130 welding, need advice

400Fn sport

4130 is not a standard carbon steel material, nd definately do not use 70s-2. 80 series electrodes and wires are ideal for 4130 material. And PWHT is definately recommended


RE: 4130 welding, need advice


E stands for "Electrode"
R stands for "Rod"
The first two or three numbers are an abbreviation of the weld's strength. To figure out the strength of the weld, take the 2 digits, in this case 80, and multiply by 1000 to get the weld strength in PSI.
S stands for solid electrode or rod.

If there is a letter and number combination next, it relates to the chemical composition of the weld deposit.
D2 stands for 0.25-0.45%Mo 1.25-2%Mn

RE: 4130 welding, need advice


Right or wrong, ALL of the top fuel dragster chassis that you see on the track today were tig welded with 70s2 wire.
The engineers that have worked with the manuf. have concluded that 70s2 is more forgiving as these cars flex an incredible amount.
the main rails from the driver forward are generaly .049 wall, with the main drivers area built of .058 and .065

None of these cars are pre or post heat treated.

In fact the AWS is releasing a new spec. in the near future addressing this.

I spent 16 years in aerospace as a tig weldor and was surprised that none of the builders used a higher tensile wire and didnt do any post annealing of the weld zone.

Its a case of past practice as being accepted as the industry standard.

RE: 4130 welding, need advice

400fnSport is probably getting more input on this question than he really wanted but, this has developed into a discussion/debate that i have been involved with for almost 20 years. My "current opinion" is that if ductility of the weld is important then it is ok to undermatch the filler and use a 70ksi wire. If your weld is single pass on base metal with less than .100 thickness, then the welding process alone seems sufficient to prevent any "hard areas", and pwht is not necessary. Now, if you use 4130 filler, or have welds in close proximity, or you just think it is a "stressed area", pwht is probably a wise choice.
Finally,I must admit, I have never gma welded 4130--just oxy-fuel and gta. i suspect the quick rise and fall of heat associated with gma welding might throw a monkey wrench into my "current opinion".

RE: 4130 welding, need advice

Thanks Boo1 for the explanation!

RE: 4130 welding, need advice

 Chrome is used as it is  resistant to corrosion and is very strong.
 Molly=  Mollibrium  (SPELLING UNCHECKED) has properties that have great CREEP resistance, resisting  being pulled a part hence ATV FRAMES strong durable and life span many more folds than M/Steel

RE: 4130 welding, need advice

Jeffita, as I indicated above  ER-70S-2 is an acceptable alternative to ER80S-D2, as is ER70S-6, although the weld strength will be slightly lower.  The ductily and stress strain relationships are simular.  Some times products used becouse we have allways use them.  For a full strenght weld the ER80S-D2 is the correct rod selection.

RE: 4130 welding, need advice

Right you are about ER80S-D2.
I brought the filler rod question to a prominent member of the NHRA/SFI chassis committee a while back and brought up that i had read about a new AWS standard that will state just what you had posted.
I was told to continue using ER70s-2.(4130 tig)
So in the drag race world thats what we use.
As a side note, In all my time at Mcdonnell Douglas, Northrop,Boeing, Allied Signal,(yes i made the rounds doing the layoff shuffle)as a tig weldor, we used nothing but 4130 filler wire with a pre and post weld heat operation.

Hopefully we didnt scare 400fn sport away with all of this.

RE: 4130 welding, need advice

Ah,my first post!  First, since you (400fnSport) are a beginning welder, be advised that it is very easy to make good-appearing MIG (GMAW) welds which are only "fused" on one side.  The arc must be directed into BOTH sides.  I would recommend that you weld a 4130 frame using oxy-fuel, AFTER someone shows you how, with emphasis on how to adjust the flame to avoid oxidation or carburization.

The slow cooling of oxy-fuel welds (because you heat up a lot more tubing) should avoid the problem of having a crack-prone heat-affected-zone (HAZ), which is really a base-metal problem rather than a weld metal one.  For a new welder, TIG (GTAW) would be my 2nd choice, but you have ruled that out.  

RE: 4130 welding, need advice

Did someone say they use coathangers for welding rod??  Isn't all that burning plastic and smoke bad for your lunges and eyes??  How could you see what you are doing???

RE: 4130 welding, need advice

Massey, works just fine, the Lacquer coating burns away long before you get much smoke. As I said above, I have never tried using it with GTAW, but it works beautifully for OXY.

RE: 4130 welding, need advice


Please pardon my sick sense of humor--I was referring to the new plastic coat hangars--not the good ol' metal ones.

Hey, if it works for you - more power to you.  I commend your resourcefullness.

RE: 4130 welding, need advice

, I need more coffee in the mornings, sorry, it zoomed right by!

RE: 4130 welding, need advice

I,m building a motorcycle chassis with 4130 and after much consideration,am using oxy/acetylene.Beyond the expense of tig,it is also much more difficult to get into tight spaces,and it requires post heat treatment with the torch anyway.This is the one area that had me worried,I have no gas welding experience.I bought a Meco midget torch,It weighs only 6 ounces,is very precise,and gets into the nooks and crannies easily.My very first joint I got 100% penetration,and what I consider,a nice looking weld.For an atv chassis,as long as your tubing is reasonably thick,you shouldn,t need to worry about things being strong enough.A rule of thumb with motorcycle chassis is,if you can,t cut it with your snips it,s too thick.Another advantage of the torch is that you can go as slowly as you like and really see what,s happening at the weld.For a beginning welder such as myself,perfect.Check out TM technologies for more.

RE: 4130 welding, need advice

I don't know if this thread is dead or not, but I'm going to comment anyhow.  My vantage point is that of a metallurgist and welding engineer, so I'll be more of a purist than apparently any of the other respondents.

4130 is a heat-treatable medium carbon steel with nominally 0.30% carbon, 1.00% chromium, and 0.20% molybdenum.  The material can be provided with a pretty wide range of properties, all dependent on the heat-treated condition.  Annealed 4130 has a yield strength around 65 ksi and a tensile strength of about 80 ksi.  Mormalized 4130 will run around 65 ksi yield and 100 ksi tensile.  Quenched from 1575 deg F in water and tempered at 900 deg F, the material goes to 160 ksi yield and 170 ksi tensile.

If you are welding such a material and need to match the strength of heat-treated tubing, then you should use a 4130 filler metal and postweld heat treat (i.e. quench and temper) the weldment.

If you want to undermatch the filler metal to the base metal for ductility's sake, then an ER70S-2 or -6 will work, as will ER80S-D2 (or even ER90S-D2) for GMAW.  The ER70S-2 or -6 are carbon steel filler metals.  The -D2 filler metals are alloyed with manganese and molybdenum.

If you are trying to match composition, then an ER80S-B2 is the ticket -- it has a nominal composition of 1.25% chromium and 0.50% modlybdenum.

You have to decide what you are trying to accomplish here.  Just because a bunch of railheads used a cheap carbon steel filler metal for years, doesn't mean it was the right material.  By the way, if you want to use coat hangers, you'll be using the approximate equivalent of ER70S-3.  

Matt Nousak, P.E.
Senior Staff Engineer
Middough Associates Inc.

RE: 4130 welding, need advice

Just for giggles, a few more comments.  It is hard to weld small diameter tubing using GMAW.  The skills required to manipulate the electrode tip properly would usually require some level of automation.  As noted by others, TIG (GTAW) or oxy-acetylene (OFW) would be the choices.  Both require skill, but OFW is more operator dependent than GTAW.  For this application, TIG should be your ticket.

Regarding filler metal designations, you need to go to the American Welding Society web site and start looking up the filler metal specs.  AWS A-5.20 covers carbon steel electrodes for the FCAW process.  The suffix for these wires does indicate the flux type, whether it is gas- or self-shielded, and the arc transfer characteristics (spray versus globular).  AWS A-5.29 covers low-alloy steel electrodes for the FCAW process.  Here the suffix denotes the chemical composition "family" of the wire.  "A" is for carbon - molybdenum wire, "B" is for chromium - molybdenum, "Ni" is for nickel, "D" is for manganese - molybdenum, and "K" is for all others (but mostly nickel - chromium - molybdenum).  The number in the suffix differentiates the amount of alloy within the "family".  There are flux and shielding gas designators also, but they appear before the suffix (and after the "T", which stands for "tubular").

As for using 1020 tubing, there is nothing wrong with it as long as the loads applied don't exceed the material's strength.  1020 comes in various conditions, hot rolled (40 yield & 60 tensile), cold rolled (50 yield & 65 tensile), hot rolled and quenched and tempered (45 yield & 70 tensile), as rolled (50 yield & 70 tensile), normalized ( 50 yield & 70 tensile), and annealed (50 yield & 75 tensile).  The strengths are approximate and given in ksi.  What you should see is that 1020 is considerably weaker than 4130.

Last, but not least, pipeingg needs to brush up a little on his metallurgy.  While chromium is indeed added for corrosion resistance, in low-alloy steels it is intended to improve the strength of the material at elevated temperatures.  Molybdenum is also added to increase corrosion resistance (particularly to pitting) and creep resistance, but creep resistance has nothing to do with this application.  Creep resistance is the ability of a material to resist growth upon prolonged exposure to elevated temperatures, and unless you plan on driving with your frame above 800 deg F (what a hot seat!) for extended periods of time, it doesn't apply.

If you really want to increase the longevity of your frame, then fatigue properties are of interest.  In which case you should be looking at nickel alloyed materials (or even, for your case, nickel-alloyed filler metals).  That's why you see 4340 alloy steel used so much in the aircraft industry.

Lotsa luck.

Matt Nousak, P.E.
Senior Staff Engineer
Middough Associates Inc.

RE: 4130 welding, need advice

The reason 4340 (and the better 300M) steels are used for aircraft are because the parts are so large.  They require deep hardening steels, and that's the main reason all that alloy (Ni, Cr & Mo) are in there.  

An ATV frame isn't anywhere near thick enough to require such deep hardening, unless it's big enough to take a few families out 4-wheelin'!

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