heat treating moly frame

Discussion in 'Manton Push Rods Top Alcohol Tech Questions' started by nmro2114, Jan 22, 2010.

  1. nmro2114

    nmro2114 Member

    Joined:
    Nov 25, 2005
    Messages:
    269
    Likes Received:
    0
    Is it possible to heat treat a chrome moly frame in a powder coat booth?
    If so what would be the correct procedure? How hot for how long? Thanks
     
    #1
  2. Kenneth S

    Kenneth S Member

    Joined:
    Dec 19, 2006
    Messages:
    245
    Likes Received:
    0
    You can really screw up a chassis trying to heat treat it, on aircraft only small pieces are heat treated, and the engineer of a part has very specific procedure of what temputure plus how long the part has to stay at said temputure, then a specific way plus legnth of time to allow to cool. Don't do it!
    Plus look at the nightmare that McKinney created with heat treating tubing.
     
    #2
  3. rattler

    rattler AA/Fuel Altered

    Joined:
    Feb 22, 2008
    Messages:
    260
    Likes Received:
    0
    I don't think I would put a frame in a powder coating booth to heat treat, However it does not hurt the chassis when you powder coat it and they put it in the oven of 600 degrees for about an hour. I have done it since the 70's on funny car chassis and never had a problem, even the cars that I have crashed never broke a weld or even a tube, just bent up pipe. We did normilize the welds after welding. The late John Shoemaker ( one of the best chassis builders and welders ever ) showed me how to do this.
    Hope this helps
    Ricky
     
    #3
  4. Comax Racing

    Comax Racing Member

    Joined:
    Sep 20, 2006
    Messages:
    669
    Likes Received:
    6
    Heat Treating

    I am of the opinion that chromemoly doesn't need any post heat operations if you using the correct welding rod. The proper rod to use is ER70S2, this is a mild steel rod and thats why you don't heat treat. If you wanted to use a chromemoly filler rod you would have to but nobody does that.

    What you are going to do by putting you chassis in the oven is "stress relieve" not "heat treat". Stress relieving can be done and it probably does help relax the chassis but I don't think its mandatory if you can't do it.

    This is all in my opinion

    Corey
     
    #4
  5. WANNABE

    WANNABE New Member

    Joined:
    Jun 9, 2003
    Messages:
    328
    Likes Received:
    0
    If you are going to heat treat a car, it does help, and has some nice benefits, but it must be done properly. It needs to be fastened down well to a proper jig, and done by people that understand heat treat, and do that for a living. Lots of the bigtime offroad stuff is Normalized 4130 that is heat treated after final welding. But do know this; that after the chassis is heat treated, welding anything on that car, or even fixing welds, etc becomes a real fiasco. Because you can heat treat an already welded car, but post welding on heat treated tubing is fundamentally wrong.
    Now, throwing it in a booth, and crudly tying down the car and heating it up to a few hundred degrees for an hour or so may "Relieve" a few things, but that is not heat treat.
     
    #5
  6. Comax Racing

    Comax Racing Member

    Joined:
    Sep 20, 2006
    Messages:
    669
    Likes Received:
    6
    Heat treating

    I'm some what onboard with what you are saying Wannabe, but are you saying they heat the chassis up to the critical limit and quench the whole thing? Thats how you normally heat treat steel to get your hardness, then you do an anneal to get your ductility back. Or are they just doing an anneal only, this could be done without the quench step. Just heat to about 1500 and oven cool it, I could see that.

    Not trying to be a prick here, I just have seen so many discussions on this subject and nobody has really explained it well. Most people just say "I know these guys that do it" but nobody really explains it. I can't see it being intellectual property or a trademarked secret. :)

    Corey
     
    #6
  7. Fuel Cars

    Fuel Cars AA/AM

    Joined:
    Aug 20, 2003
    Messages:
    283
    Likes Received:
    2
    Why do you want to heat-treat the frame and to what hardness?

    Stress-Relieving, Annealing, Normalizing, Hardening, Aging, basically elevated temperatures, but not hot-working, are all considered a heat-treatment process.

    The temperatures used in powder coating are no wheres near what is needed to properly heat-treat chrome-moly.

    If you are wanting to heat-treat the frame, you will need a jig to hold the frame at critical points or else your going to have spaghetti for a frame, it will become distorted.

    Corey, I somewhat agree with your statement, but, the amount oh heat applied during welding can do significant amount of damage to the joint, with or without the proper filler rod.
     
    #7
  8. Comax Racing

    Comax Racing Member

    Joined:
    Sep 20, 2006
    Messages:
    669
    Likes Received:
    6
    heat treat

    I was never disputing the fact that overheating the weld area during welding is a bad thing, I totally agree FuelCars. The discussion seems to be what happens after. If you screw up the chassis by welding it way to hot, no amount of post weld heating and cooling will fix it. I am totally on board with that fact.

    I just don't see the need to do anything after the chassis is completely welded, if it is done "properly" and I know that is a loaded word.:)


    Corey
     
    #8
  9. Fuel Cars

    Fuel Cars AA/AM

    Joined:
    Aug 20, 2003
    Messages:
    283
    Likes Received:
    2
    I absolutely agree, I just made my statement because I have heard "well I used the right weld rod, why did my joint fail?" more times than I care to remember.

    A good weld procedure almost always prevents a bad weld joint.
     
    #9
  10. JustinatAce

    JustinatAce Member

    Joined:
    Oct 20, 2008
    Messages:
    599
    Likes Received:
    9
    Heat Treating a chassis just does not seem like a good idea. I know from just clutch lever material experimentation, heat treating overkill makes things brittle and thats the last thing you want on a chassis. And even then, is a powder coating oven even capable of producing the temperatures needed for the proper soak?

    Side story on why temps are critical: A long, long time ago, We used to make the clutch fingers out of normalized 4130, then heat treat them to a 50-55 RC. We would then send them to get a Titanium Carbon Nitride coating for wear resistance in the pin holes, which heated the levers just enough to anneal them back down to a 30 RC. We had some levers in some awfully funny shapes after testing.
     
    #10
  11. Comax Racing

    Comax Racing Member

    Joined:
    Sep 20, 2006
    Messages:
    669
    Likes Received:
    6
    Justin Ace Quote : Heat Treating a chassis just does not seem like a good idea.

    I agree 100%
    Scary part is how many cars are out there just waiting to disintegrate because somebody thought they khew how to "heat treat"

    Corey:)
     
    #11
  12. G. Anderson

    G. Anderson Member

    Joined:
    Oct 2, 2006
    Messages:
    64
    Likes Received:
    0
    NO! NO! NO! NO!
    :mad:
    Did I mention NO!

    Call any heat treat outfit, they will tell you that you must put the whole chassis in a fixture that is roughly three time the mass of the chassis, completely affixed to that fixture/jig. The complete (fixture/chassis) assembly will then be brought to the steels (4130 condition N) plastic temperature for a predetermined amount of time, (determined by a qualified metallurgist) then cooled to room temperature at a fixed rate of speed and temperature (again determined by a qualified metallurgist).

    Can you do this with a rosebud torch by hand in a shop or powder coating oven...in a word..NO!

    Learn to weld without overheating or burning the 4130 with the correct rod (ER70S-2). You will have a strong ,ductile weld joint that if crashed, will not break at the weld itself.
     
    #12
  13. Comax Racing

    Comax Racing Member

    Joined:
    Sep 20, 2006
    Messages:
    669
    Likes Received:
    6
    Well Said.
    As I stated before this is also my opinion of heat treating a chassis.

    Corey
     
    #13
  14. rattler

    rattler AA/Fuel Altered

    Joined:
    Feb 22, 2008
    Messages:
    260
    Likes Received:
    0
    I talked with my powder coater today and he said that his oven temperature is 390 degrees, not 600 as I mentioned in my ealier post. He said that he coats for a certaim BMX racer whom breaks the bike chassis when they don't powder coat them, thinks it is the heating of the oven that makes them stronger. They would break in the welds.
    I too have heard so many pros and cons, especially after Force broke his car in half. I can tell you from experience ( 4 ) nasty crashes in the last 24 years , We never broke a weld or a apiece of tubing, just bent it up pretty bad. Never been hurt in a race car. Build my own chassis, Tutored by the Late, Great John Shoemaker.
    Hope all this helps.
    Ricky Ruiz
    " Nevada Rattler " AA/FA
     
    #14
  15. nmro2114

    nmro2114 Member

    Joined:
    Nov 25, 2005
    Messages:
    269
    Likes Received:
    0
    Thanks for all the replies. The frame was welded with er70s2 as is the other car I have. This one Is new and is going to be powder coated and was curious as to if it is necessary. I hear NO loud and clear just as I had thought but wanted more opinions and info. You always get good info here.
     
    #15
  16. Comax Racing

    Comax Racing Member

    Joined:
    Sep 20, 2006
    Messages:
    669
    Likes Received:
    6
    Heat treating

    I should probably just let this go, but 390Deg f is so little heat it would not do anything to the metal. If the bike guy thinks its doing something, great, but its a false sence of security. The paint is doing more to hold the joints together than the 390f.:)


    Corey
     
    #16
  17. TOL

    TOL Active Member

    Joined:
    May 18, 2005
    Messages:
    1,118
    Likes Received:
    5
    I would like to ask a somewhat related question.........

    Let's say that a person has a properly built/welded moly chassis, non heat treated, initially built on a jig. Then down the road it is crashed and repaired on a jig, or taken to a new chassis cert level with lots of significant new bars and stuff, or maybe even both due to the opportunity at the time.

    In that circumstance, would people then recommend putting the repaired/finished chassis into an industrial oven to stress releive or normalize the reworked chassis? If so, any idea of what temp or for how long, or what sort of cool down process? Or, can the same effect be accomplished by a good chassis builder with a torch and some controlled heating/cooling?

    Thanks.
     
    #17
  18. Fuel Cars

    Fuel Cars AA/AM

    Joined:
    Aug 20, 2003
    Messages:
    283
    Likes Received:
    2
    I will quote a previous answer:
    Any chassis shop that does that type of work should know the proper method of repairing and/or upgrading a chassis.

    And putting a torch to use for any purpose of changing mechanical/physical properties on chrome-moly is a big NO NO!

    Just remember that a proper weld will have a controlled amount of Heat Affected Zone (HAZ) and in that HAZ is where the chem/phys properties change from the base of the weld joint to the normal material properties.

    On a proper weld, the HAZ is where the base material, in this case the N-Condition chrome-moly tubing, changes from the N-Condition to something different.

    If the weld is left to cool at room temperature at a normal rate, no additional cooling, most of the weld joint including the HAZ will return to the N-Condition.

    An alternative to using heat for stress-relieving is grit blasting. It should be done lightly as to not move the base material. It will not have as much as an impact in the relieving of stress as using heat but it will remove a large amount of captured stress.

    Also remember that whenever you use any method to stress relieve, if the chassis is not secured at critical points, the chassis will "move" and alignments will be off.
     
    #18
  19. Comax Racing

    Comax Racing Member

    Joined:
    Sep 20, 2006
    Messages:
    669
    Likes Received:
    6
    Heat treating

    As far as doing repairs/upgrades, why is that any different from the process of building the chassis new. IT IS NOT. Adding bars to a chassis on a jig is no different than putting them in, in the first place, the welding process is the same.:)

    Corey
     
    #19
  20. Bob Meyer

    Bob Meyer Comp Eliminator

    Joined:
    May 13, 2003
    Messages:
    712
    Likes Received:
    11
    I probably should stay out of this, because some 5 yr. experienced person will correct me, and after SFI "invalidated" Don Long, Dave Uyehara, and myself for not understanding heat treated 4130, maybe our 40+ years each of experience proved to be factual.
    I would like to add that G. Anderson and Paul (Fuel Cars) are on the right track. There is more to it though, and if I could type faster, I'd explain it. Within the term "HAZ", "heat draw/weld size/temp." is more critical. Meaning a very tiny goldish weld with a 1/16" blue ring behind it is more apt to break next to the weld because it "quenched" too fast. A proper weld will have more width and a heat draw ring closer to 3-4 times the weld width, cooling slower as it draws out, which achieves a sort of self stress relieve.
    Two points:
    1. because 90% of todays ER70-S2 being mfg to the spec of "single deoxified" and not "triple" like the old Oxweld #65 (now owned by ESAB and hard to find), I now use ER80-D2 with a spec stating "triple deoxified" (meaning far cleaner).
    2. Hot Rods and lawn chairs are good candidates for powder coating, not thin wall race car chassis. Why ? Because we love the hard surface, but is soft underneath which is why it dosn't chip, but that means it just stretches over developing cracks. It will hide the problem area until it breaks severly. I ask my customers to please use anything but that, if they want paint.


    Bob Meyer
    Meyer Race Cars / San Diego
    2010 Our 45th Anniversary
     
    #20

Share This Page