Filler material for chrome moly frame

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Hi all,I have been asked to weld on a chrome moly drag bike frame being modified.  My experience with chrome moly is limited to bicycle frames and I usually braze with a torch, this project will be tig welded.  I inspected the frame yesterday to see what the project involved and noticed that it had welds that were chrome looking as if the original builder had used stainless filler to weld some of the joints.  I commented this to the client and he asked me if I could use stainless to weld the modifications he wanted to make.  I told him I would look into it.Is chrome moly usually welded with mild steel rod or does it require a particular filler?  Can stainless filler be used and if so, what type?  I just read an article about this on Miller's site and they recommended er70s-2.  Isn't this mild steel rod?Thanks for any help,TonyLast edited by therrera; 12-05-2013 at 01:07 PM.Reason: for clarity
Reply:70s-2 works well if you don't harden it later. Personally I use er80s-d2 to more closely match the base. Base metal dilution brings the weld up to strength. Post weld stress relieve is recommended to stabilize the HAZ.If you do harden it you would be required to use 4130.Weld like a "WELDOR", not a wel-"DERR" MillerDynasty700DX,Dynasty350DX4ea,Dynasty200DX,Li  ncolnSW200-2ea.,MillerMatic350P,MillerMatic200w/spoolgun,MKCobraMig260,Lincoln SP-170T,PlasmaCam/Hypertherm1250,HFProTig2ea,MigMax1ea.
Reply:If you want to do this right, here you go:1. Find out what kind of "chrome-moly " the base material is. You need the ASTM number- to find out the relative amount of Cr and Mo in the base metal. ( 1.25CR/.5Mo, 2.25Cr/1.25Mo, etc etc.....................2. When you know the answer to number 1, you can then choose the appropriate filler material.3. Stress relieving may or may not be required depending on (1,2) above. With the relatively low thicknesses used for the components you are assembling, it is unlikely PWHT ( post weld heat treatment) will be necessary.
Reply:Use the 70S-2 and call it a day already.......zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:Originally Posted by weldertomIf you want to do this right, here you go:1. Find out what kind of "chrome-moly " the base material is. You need the ASTM number- to find out the relative amount of Cr and Mo in the base metal. ( 1.25CR/.5Mo, 2.25Cr/1.25Mo, etc etc.....................2. When you know the answer to number 1, you can then choose the appropriate filler material.3. Stress relieving may or may not be required depending on (1,2) above. With the relatively low thicknesses used for the components you are assembling, it is unlikely PWHT ( post weld heat treatment) will be necessary.
Reply:Originally Posted by shovelonGood call. I was thinking of it as 4130. I think but I may be wrong, but 1/8" or less does not require stress relief after weld. Er70-s2 should be fine as Flyswatter,,,,,I mean Zapster says.
Reply:Originally Posted by makoman1860I dunno about the 1/8" rule. I have had material down to .032" that required it (4130 of course). It depended on the joint design more so than the material thickness. The only reference to a material thickness cutoff for PWHT on 4130 comes from Wyatt Swain. When pushed for some test data to back up such a broad claim, he had none and admitted it was just an opinion. It may be needed, it may not. Unfortunately there is no way to find out with a manually welded one-of design without destroying it. Doing a PWHT correctly wont do any damage, and at least is good insurance.
Reply:http://www.millerwelds.com/resources...hromoly-tubingApparently there are differing opinions  ...................Here is a discussion regarding 80s-D2 filler. ( The D2 refers to 1/2 Mo..... and the 80,000 psi tensile is more closely related to the properties of 4130.......)I guess I took a more technical approach ( part of my job is to review welding procedures ) rather than a commercial/ shop approach. Good luck!
Reply:If it were my stuff I'd go with er80s-d2. Huge debate regarding this subject.
Reply:80s-D2 is all I use as well I have it in.035, .045 and 1/16th. For a lot that I have seen prep and fit should be the most important, If it is a big snake hole It won't matter what filler you use. And I always warm the joint but then I live in the moldy NW.Syncrowave 180 SDMillermatic 250XSnap On MW 120 Econopac 50Victor O/A with some Smith Attachments 30 X 50 shop with a 400 Amps
Reply:I use er70s-2 for 4130. As has been said, there is a lot of debate over filler choice. For weldments that will not be heat treated (hardened) after welding, Lincoln suggests er80s-d2 as a first choice with er70s-2 and er70s-6 as perfectly suitable second choices. 4130 filler would only be used on weldments that will receive PWHT. I have not seen a definitive rule regarding wall thickness about when to anneal. I have read and heard that anything thicker than 1/8" should be preheated. I'm nowhere near those thicknesses though.
Reply:Originally Posted by shovelonI hear ya. The only reason I think 1/8th is a threshold is the parts are fully saturated with heat, and when weld heat is terminated, the heat sinks out very slowly because of that wall thickness. Those are the engineering controls my customers use to design parts. Sheet metal thicknesses bypass PWHT. Except for 4130 used as a filler of which the structure gets hardened. Zank on this forum does a ton of alloy steel, welded and brazed. I would think he has some insight.
Reply:70 S 2 and you are done !!!
Reply:Originally Posted by Vinnie70 S 2 and you are done !!!
Reply:Tony, if you ever want to try some 0.045 or 0.035 filler on the thinner stuff, drop me a private message and I'll send you some. 1/16 is pretty thick for bike frame work. Have fun!
Reply:Originally Posted by zankTony, if you ever want to try some 0.045 or 0.035 filler on the thinner stuff, drop me a private message and I'll send you some. 1/16 is pretty thick for bike frame work. Have fun!
Reply:I'm fairly new on here so you may dismiss my comments but here goes anyway,Theres a company over here Robinson race cars who i consulted a few years back regarding welding chromemoly tube as they build a lot of pro-mod drag cars,They always use A15 filler rod, known as Er70s-2 ?I looked into it and that filler is approx 85% of the strength of the chromemoly base material so its recommended to make the weldpool 10-20% larger to compensate for the weaker filler material.A Robinson race car recently crashed badly at nearly 200mph and the chassis was inspected afterwards and apparently no welds had torn apart, only a few tubes fractured in other areas.
Reply:Originally Posted by therreraHi Zank,I'll pm you shortly on that.  Interesting you mentioned this to me because the reason I braze chrome moly bike frames is because the first time I attempted to tig weld one, it poked a hole in an instant.  Therefore I backed off and began brazing them.  I've done several dozen either repairs or modifications on such frames.  At what amperage would thin bike tubing be tig welded?  Would I need thinner than a 1/16" tungsten to do it?I picked up an .040 (I think that's the size) tungsten one day (gas lens and collet) at the welding supply just to have on hand for the day it becomes needed.  I haven't yet had to use it but maybe that's the size to use for frame tube welding.  What do you think?Thanks,Tony
Reply:I have welded a frame or two, and use a slightly different approach than Zank, though his sounds good too.Using a Dynasty 200dx, I generally set the machine to somewhere between 120-145 amps, with a 1.5 % lanthanated 1/16" tungsten, and a pulse rate of 1.6-2.4 pps.  I use 30% on, and 5% background amps.  Obviously, you need to control final amps with the pedal, but once up and moving, I generally have it floored, or close to it.  I use .045" ER70S-2 filler for most joints, but often use 1/16" rod in joint areas with acute angles, so there is a little less sharp transition between tube members (lower stress).  Using this, I can pretty easily weld down to .6mm (.023") tubing without making holes.  One benefit of doing this is that you get smooth weld toes without burning through.  [IMG][/IMG]Last edited by pbungum; 12-16-2013 at 11:56 PM.Miller Dynasty 200 DXMiller CP-300 with 30A feederHypertherm Powermax 900Oxy-fuel w/Harris torchesScotchman Glide-in bandsawMonarch 10EE latheEmi-Mec Autoturn latheDeckel FP2NC milling machinePro-Tools 105 Bender
Reply:Man, such beautiful stuff. Do you work at Co-Motion? Awesome bikes.
Reply:I am not getting notifications so I wasn't aware there was more activity on this thread.  I didn't end up getting the project on the frame as the client wanted me to miter the tubes, something I am not equipped to do besides trial and error fitting, grinding, filing, fitting again, filing, etc. , etc.  I don't have a lot of experience with tubes beyond welding on them but not fabricating them.  The welds on those bike frames look like a work of art.  Nice work!!!Thanks,Tony