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Best welding rod (tig) for welding 4130 chromoly tubing

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  • Best welding rod (tig) for welding 4130 chromoly tubing

    Does anyone know the best (strongest) rod for welding 4130 Chromoly tubing. I am building mini sprint chassis.


    Thanks,

    Zeb

  • ArcLight
    replied
    Originally posted by zkoobs1978 View Post
    Does anyone know the best (strongest) rod for welding 4130 Chromoly tubing. I am building mini sprint chassis.


    Thanks,

    Zeb
    I know this is an old thread, but having built more than a few mini sprint chassis out of 4130 I think I can add to the info already presented.

    I always used ER70S-2. Condition N 4130 has a tensile strength of 95ksi and a yield strength of 75ksi. AWS minimum for ER70S-2 rod is 70ksi tensile and 58ksi yield, while typical fillers come in around 70ksi yield and >80ksi tensile. Figure in a strength bump from admixture with the base metal, and maintain a suitable amount of reinforcement in the weld, and it turns out the weld exceeds the strength of the tubing.

    Main cage was 1-1/4" .083" wall, while other structural parts were either 1-1/4" or 1" .065 wall. With the relatively thin wall, and using 70S-2, we found that post-weld stress relief was not necessary. I never had a frame crack anywhere, and no weld ever failed even in the hardest crashes that destroyed the frame. Most importantly, nobody ever got seriously injured in one of our cars. The frames absorbed and dissipated the energy without failure, just as they are supposed to do.

    It's been many years since I built a frame, but I still keep in touch with other frame builders. It seems many, whether sprint car, mini-sprint, midget, etc. have switched to ER80S-D2. They don't stress relieve the welds, and occasionally welds will crack in a hard crash. I have mentioned that we used to use 70S-2 for that very reason, but they insist 80S-D2 is "better", stronger (technically, it is), and recommended by "experts" at companies like Lincoln. I don't bother to debate the issue.

    Anyway, that is my anecdotal evidence for the use of 70S-2. It has the advantage of having been "battle tested", but I'm not an "expert" at a welding equipment manufacturer, so take it for what it is. As usual, YMMV, Void Where Prohibited, No Deposit No Return, etc.

    Leave a comment:


  • JamesM3M5
    replied
    Originally posted by Aerometalworker View Post
    On a personal note, the old 32cms ( now replaced with RG-65 ) makes some beautiful welds if you ever section them or have to machine on the material!
    -Aaron
    I found a couple pounds of RG-65, and I was wondering where on Earth I got it from. I thought Aircraft Spruce, but they only sell a double-vacuum melted 4130 fill rod at $62+ per pound. I rarely weld 4130, but I'm pretty sure I bought it for that purpose.

    Leave a comment:


  • FM117
    replied
    Just quickly looked at those pics, on my screen they look like
    mig welds, can't really tell?
    Gotta agree, I'd be worried about crashing that thing.
    Not enough info to have a conclusion about the why, but
    the bottom line final result is pretty ugly.
    If it was my butt strapped in it I'd be looking at the cage and thinking
    about some gussets. Pictures like that can mess with your confidence.
    Dave P.
    Last edited by FM117; 09-18-2009, 08:42 PM.

    Leave a comment:


  • Aerometalworker
    replied
    Originally posted by Corey74 View Post
    http://web.a-znet.com/~dave1w/maxim_disaster.htm


    This is a little concerning to me since I have a car from the same builder. I don't know this guy nor do I have any connection to him.
    Reading though this thread jogged my memory on this one and it seemed relevant to the topic. What do you guys think? Quality Control failure? Material failure? Wrong filler?

    From the looks of it I would guess it to be a classic embrittlement failure both in the weld fillet and the HAZ. 99% of the time its caused by the welding process, or lack therof. Filler metal has NO INFLUENCE ON THE BASE METAL STRUCTURE IN THE HAZ, despite what the home depot welding book sez. The fillets look small and dainty, too small. Without knowing what filler was used, its only a guess as to if it caused the failures in the weld itself.

    Leave a comment:


  • Corey74
    replied
    http://web.a-znet.com/~dave1w/maxim_disaster.htm


    This is a little concerning to me since I have a car from the same builder. I don't know this guy nor do I have any connection to him.
    Reading though this thread jogged my memory on this one and it seemed relevant to the topic. What do you guys think? Quality Control failure? Material failure? Wrong filler?

    Leave a comment:


  • Aerometalworker
    replied
    Originally posted by WelderMike View Post
    80S-D2 is a recognized alternative to 4130. It is even accepted by the vast majority of sanctioning bodies in the racing community. NASCAR, ARCA, NHRA, IHRA, SCCA ok the use of 80S-D2 as filler metal on ChromeMoly.
    Well,
    With trying to imply no disrespect at all to those groups. I doubt they have ever done testing themselves, and are going off of the recommendation of some frame builder somewhere. Ask them for the test data....I have.

    Leave a comment:


  • WelderMike
    replied
    80S-D2 for ChromeMoly

    80S-D2 is a recognized alternative to 4130. It is even accepted by the vast majority of sanctioning bodies in the racing community. NASCAR, ARCA, NHRA, IHRA, SCCA ok the use of 80S-D2 as filler metal on ChromeMoly.

    Leave a comment:


  • AEROWELDER
    replied
    Proper filler material for AISI/SAE 4130 steel

    Wow! there are a lot of posts for this topic, and not being one to be left out, I will add my opinion here also. Although the question is vague as to what the application is, I will attempt to cover all the bases.

    First, the use filler material that closely matches the base metal is not intirely true, as there are many factors that dictate what filler material to choose. FAA AC43.13-1A, section 5, 4-74 (9), states "Use welding rod and electrodes that are compatible with the materials to be welded. Welding rods and electrodes for various applications have special properties suitable for the application intended". Which means that one must carefully choose the correct filler material for the application, and the intended service of the part/structure.

    According to AWS A5.18, the recommended filler for most applications is ER70-S2. The reason for this is that, 4130 is a fairly brittle alloy. Using a more ductile alloy filler material, will of course be fused and "alloyed" with the parent metal, which inturn will allow the joint to be more ductile and reduce the tendancy for tearing and brittleness at the joint.

    Second, the reason that NASCAR and other sanctioning bodies disallow 4130 in favor of 1020 mild steel, is that 4130 doesn't posses the desired properties for energy absorbtion. It's just too darn tough. The low carbon mild steels absorb impact energy far better as they are more ductile. Ironically, early Piper airframes like the J3 Cub, PA-18, PA-20, etc., were all built from 1020 mild steel. Probably not for energy absorbtion in a crash scenario, but probably because of cost factors.

    I have always used ER70-S2 for all of my GTAW joints in both aircraft and racecars, and I have always had either the airframe, or the chassis heat treated, (normalized), for stress relief. If you can't have the entire structure heat treated in an oven in a controlled enviroment, than pre-heat, and post heats should be employed, as well as maintaining correct inter-pass tempatures for critical joints. Most joints in aircraft, and in racing cars, are small and are of thin walled tubing which will dissapate the heat quickly, and spread the induced stresses away from the joint. Field stress relieving will help reduce this built up joint stress, but for complete structures, an oven is best. AISI/SAE 4130 alloy manufactured to MIL-T-6736, is a normalized and annealed seamless tubing possesing a tensil strength of 90,000 psi. This is the desired alloy for aircraft and most race car rules that require 4130 structures.

    Finally, you must determine what your specific application is and what performance you expect from it, before you can choose the best procedure and filler material for it. Also, Tubing joints, and flat sheet cert tests are not comparable criteria, (MIL-SPEC 1595A), for standard bend tests. Again, each application is different.

    I hope this didn't confuse you any further.
    Last edited by AEROWELDER; 09-09-2009, 10:26 PM.

    Leave a comment:


  • Aerometalworker
    replied
    You know this brings up an interesting point. I think many times recommendations on say filler materials, are transferred too much from one application to another. Even on the very same material! Take for instance filler metals on 4130 tubing. Every company and their uncle has a recommendation. However their recommendation may not mean squat to someone else. I have noticed that Lincoln electric has in their 4130 literature, the mentioned uses of their procedure on race cars, go-karts, and EXPERIMENTAL aircraft, and they make a point to be specific about it. To anyone not in the aviation field that may seem to be no big deal, but it is. The experimental category does not have to follow the same materials and process controls as certified aircraft.....so basicly you can do anything you want within reason. The reason Lincoln had to specify EXPERIMENTAL aircraft on their 4130 literature is twofold, for one in conflicts with the latest recommendations from the FAA on the subject, and 2 Lincoln has no ability to recommend ANYTHING on a certified aircraft. Problem is, many people think that since Lincoln says to do it, it must be right, and transfer that recommendation to any application they want, even ones they shouldnt. Sorry to be long winded, I have just been seeing way too many generalizations of welding lately.

    Leave a comment:


  • Silverback
    replied
    Originally posted by Old Sporty View Post
    Not to detract from some of the other answers, but I would listen to "AskAndy". He deals with this subject on a daily basis with the Nascar Sprint Cup builders and I feel like his knowledge is right on concerning this.
    I was under the impression that NASCAR doesn't allow 4130 at all in their cages, it has to be mild steel if it's around the driver for safety reasons.

    Leave a comment:


  • Aerometalworker
    replied
    Steven,
    What you were testing sounds like guided bend tests on heavy plate, butt welds im guessing? Thats a completely different set of criteria than a welded tubular structure, and has little value. We have fillets, and a much lager weld area to CSA ratio. We also have more relative movement and fatigue issues. SO nothing against your comments, just realize that not everything translates from one application to another.

    Leave a comment:


  • steven_oharra
    replied
    Use Use ER80 rather than ER70 (closer as welded strength)

    When we did our AWS cert in 4130, our first run failed using ER70.
    The as-welded strength of ER70 is 70ksi.
    The normalized state of 4130 is 90-95ksi.
    Our welds had excellent fusion, penetration, and inter-pass cleaning.
    The visuals looked great, then came the 20 ton bend test.
    The 4130 coupons tried to remain straight while all the bending-stretching was being done by the filler on the 2" ram (2" used due to higher ksi of 4130).
    The effect was almost a T-Pee or V bend instead of a U-bend and ultimately, the filler was stretched to the point of breaking into two coupon fragments.

    A second run was made using ER80 (still weaker as-welded than the normalized 4130) and you could see more stretch of the weldment but in the end, the 4130 coupons were forced to follow the 2" ram shape and create a perfect U-bend that passed AWS criteria. Not that you'll be bending your welds into U-bends but as always, you try to make sure your filler is as close a match to the base as possible for a more homogenous weld.
    -Steven L. O'Harra

    Leave a comment:


  • steven_oharra
    replied
    Use Use ER80 rather than ER70 (closer as welded strength)

    When we did our AWS cert in 4130, our first run failed using ER70.
    The as-welded strength of ER70 is 70ksi.
    The normalized state of 4130 is 90-95ksi.
    Our welds had excellent fusion, penetration, and inter-pass cleaning.
    The visuals looked great, then came the 20 ton bend test.
    The 4130 coupons tried to remain straight while all the bending-stretching was being done by the filler on the 2" ram (2" used due to higher ksi of 4130).
    The effect was almost a T-Pee or V bend instead of a U-bend and ultimately, the filler was stretched to the point of breaking into two coupon fragments.

    A second run was made using ER80 (still weaker as-welded than the normalized 4130) and you could see more stretch of the weldment but in the end, the 4130 coupons were forced to follow the 2" ram shape and create a perfect U-bend that passed AWS criteria. Not that you'll be bending your welds into U-bends but as always, you try to make sure your filler is as close a match to the base as possible for a more homogenous weld.
    (closer match of 80ksi/ER80 to normalized 4130's tensile of 90-95ksi)
    -Steven L. O'Harra
    Last edited by steven_oharra; 09-09-2009, 11:40 AM.

    Leave a comment:


  • aametalmaster
    replied
    Hey John nice ride!!!!...Bob

    Leave a comment:

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