Annealing Cage Welds

[jpmachado]

Has anyone ever annealed cage welds to sofen them up and take the stresses out?

[Aerometalworker]

Has anyone ever annealed cage welds to sofen them up and take the stresses out?

annealed? No
Tempered? Yes

Quite a standard and common process in the 4130 and 4140 steels, you didnt mention what you were using though.

[rixtrix1]

I've had in depth conversations with Tom Yancer of Tom Yancer Race Cars on this, and the general consensus is that with the thin wall thicknesses used, it is hard to keep the temps consistant enough to be of great benefit without damaging or changing the tube properties. Also there isn't that much heat used. Maybe if one could put the chassis in an oven it would be worthwhile. I've seen a couple of places that use the Metalax process to relieve stress without heat, but that it usualy takes quite some time for the process. Just what I've heard.
RicG

[Aerometalworker]

Hmmm yes and as I seem to recall, some drag racers chassis builders still havent figured out how to keep welds from failing on a material that has been used for similiar applications for almost 100 years

[SGS Welding]

Aero you love this question. Take em to school, again.

[Miller Swartz]

Realistically you cannot spot anneal or temper material without changing the metallurgy of the surrounding material. There is no way of knowing how far out away from the weld that the metallurgy of the base material was altered during the welding process. It’s possible that you may improve the properties in one area when taking an oxy-fuel torch back over a weld on thin walled chromoly, but with no way of ensuring the amount of heat input (temp vs. time held at that temp), you run a significant risk of adversely affecting the surrounding tube. I have spoken to different metallurgists, as well as many chassis builders who build vehicles for different racing organizations about this topic. Everyone I have spoken to agree with me on this issue. Thankfully these same individuals also question the logic of the drag chassis builder that Aaron is referring to. This particular builder went against the norm by utilizing heat treated chromoly tube in his fabrications rather than standard of normalized 4130. Consequently, this particular chassis being referred to became quite brittle after welding and had a catastrophic failure.

Going back to the original question, yes I do know of one particular sprint car racer who does have his entire chassis annealed in a large heat treat oven. I have seen the difference this made when he cut a tube out of one older chassis that he didn’t have annealed and one that he did. The annealed chassis had almost no stress pent up in the frame as evident by the lack of spring back the tubing had when it was cut out. Conversely, there was a good deal of deflection in the tube of the non-annealed chassis. The reality is that finding an oven that would accommodate a full frame is rare and would normally be quite pricey. Most professional chassis builders make sure to prevent excessive heat build-up while welding in the first place as preventative medicine.

[Aerometalworker]

Aero you love this question. Take em to school, again.

Nah, Im done. The automotive racing community has a different viewpoint and different requirements then what I normally deal with. What works with wheels can be deadly with wings. So im just going to stick with Aviation related issues.....its not worth the hassle trying to educate someone that already has their mind made up ( not specificly this OP or thread ).
-Aaron

P.S. Hey John, Id love to talk to these metallurgists you know. Its always good to draw from a larger pool of knowledge. And I know exactly what you are saying about changing the properties of the base metal, your exactly right. Its a trade off of getting an annealed area while removing a brittle one. Thats exactly why the Av designers use the annealed strength of the material for strength calcs, but use normalized material. Its much easier and safer to calculate for " soft and ductile" rather than predict " hard and brittle ".