4130 welding, need advice
4130 welding, need advice
(OP)
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
Rod
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
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
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.
Rod
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
RE: 4130 welding, need advice
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
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
Rod
RE: 4130 welding, need advice
RE: 4130 welding, need advice
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!
Jeff
RE: 4130 welding, need advice
For parts thicker than .120", stress-relieving is recommended and 1,100ºF is the optimum temperature for tubing applications.
Cheers
RE: 4130 welding, need advice
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
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
Merzi
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
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
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
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
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
RE: 4130 welding, need advice
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
Thks.
RE: 4130 welding, need advice
RE: 4130 welding, need advice
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.
nousakmj@middough.com
RE: 4130 welding, need advice
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.
nousakmj@middough.com
RE: 4130 welding, need advice
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'!