http://www.lincolnelectric.com...y.asp

- 1996 Honda Civic Ex - B20, SC60 @ 20psi, Tuned on E85

No one said that.

"I am Ironman" said to use mild steel filler if not heat treating.

- 1996 Honda Civic Ex - B20, SC60 @ 20psi, Tuned on E85

racecar parts/streetcar parts FORSALE

I don't know how you could do that to a whole chassis, but I have heard of people heating up the weld joints post welding with a torch blood red, then letting them air cool. (Most notably small aircraft builders). But the only result of that would be to partially anneal the weld joint, which I can't imagine would be beneficial in a mechanical structure.

Imagine a chassis is being built from popsicle sticks. To hold the sticks together with super-glue is comparable to using 4130 filler, because it is super strong, but also super stiff and BRITTLE. To hold the sticks together with elmer's glue is comparable to using 80s2, because it is softer, and will flex at the joint.

When loaded, the super-glue stick chassis is the most rigid and is the strongest, but apply a rapid blunt force, it will crack and break typically at the joints, which was held together with super glue (4130).

When loaded, the elmer's glue chassis is not the strongest or most rigid, however when the same rapid blunt force is applied, it has a higher chance of surviving because of the flexibility of the joint. This is comparable to using the 80s2.

This is assuming that the chassis will not be heat treated, but at any rate, the chassis welded with 4130 rod still has a much higher chance of cracking and tearing.

The analogy isn't perfect, but it gets the point across.

and nobody here is going to ht their cage.
and normalizing is what youd be doing if you wanted to, but that should only be done by a specialized place that does it frequently, in and oven, and not with Oxy torch or anything of that nature due to it not being consistent anywhere.
and i think normalize temp is about 1200 for a few hours, and no quench. quench is pretty much a bad idea IMO. unless youre a metallurgist and know what youre doing.

VT MSME/SAE baja

lesser tensile strength than 80s-d2... SLIGHT difference in Elasticity....favoring the 70s-d2. I do 70s-d2. d2 flows better than d6 IMO.

VT MSME/SAE baja

They do pull tests and have learned that even in ideal conditions it is easy for cracking to occur under the bead where you can't even see it, and those cracks will only make themselves known at the worst possible time.

i took it as him meaning to use mild steel tubing if not heat treating. chromoly cages that aren't heat treated break, not bend like mild steel will.

And how many cages have you welded? I doubt 95% are ht anything.

http://www.RCautoworks.com

This is the procedure the small aircraft guys do around here. We pre bend their air frame pieces in 4130 then they tig them all together and torch em.

"Post heat is a correct way to refer to this operation. Torch normalizing is correct as well. Stress relieving is NOT a correct term.

Post heat: apply heat after joint welded.

Torch normalize: warm the 4130 to dull red, remove heat and let cool slowly in very still air to return the metal to Cond N status. This can be done to increase the strength of 4130 cond A to make it cond N as well as bring cond N 4130 that has been welded and hardened back down to cond N 95,000PSI.

Stress Relieve: To do this, the entire part needs to be heated to a dull red all at one time in a large enough oven to hold the part and then let cool in still air. The part should be jigged in a very substantial fixture that is not affected by heat such that the part does not change shape if the part has fitting holes etc in it. Typically, if a part is to be stress relieved in manufacturing, it is built but has not had attach points final machined and drilled, then stress relieved, cooled and then jigged in a final fixture for spot facing and drilling of the attach holes, fittings etc.

Annealing 4130 can be done with a torch as well. This will take 4130 cond N 95,000PSI and reduce it to cond A of around 45-55,000PSI. This is useful for forming of parts. After forming, normalize to cond N. The reason I bring this up is that applying the heat wrong can result in a weaker structure.

Torch normalizing locally heats the part and in many cases, affects the alignment. Spiral welding minimizes the stress introduced during the welding process. Heating the structure at one joint can result in all stresses in the frame to be concentrated at that joint resulting in a bulge in the tube at that point. This will affect the frame dimensions and as you know, a bulge must be patched. If you patch it, you weld it again, etc.

All factory built Pitts and Husky airframes have been TIG welded since the 1960s. Maule frames are MIG welded. Most factory welded parts use arc welding of one form or another to assemble weldments. In the case of Maule and Pitts, there is not stress reliving or torch normalizing done. Basically, it is a "bird in the hand....." sort of thing (no pun intended in ref. to Finch) KK"

Modified by CRMB at 6:57 PM 5/14/2008

That's it! Let's ban chromoly because Brian Slames says so (OMG just saying his name makes me wet!), no clue who he is, but whatever.

I can show you a bunch of pictures of mild steel cages tearing in the HAZ. So what?

- 1996 Honda Civic Ex - B20, SC60 @ 20psi, Tuned on E85

mike

i'm not saying "dont do a chromoly cage," i'm just implying if you do, then do it right and get it heat treated.