Chromoly Welding?

[TrxR]

I am looking at putting a 12 point cage into my street/strip Dakota project and was wondering what was the deal with stress relieving chromoly? Is it needed for cage work? Would I be better off sticking with DOM instead? I am looking to to have the truck legal to 8.50's

Thanks

[Aerometalworker]

I am looking at putting a 12 point cage into my street/strip Dakota project and was wondering what was the deal with stress relieving chromoly? Is it needed for cage work? Would I be better off sticking with DOM instead? I am looking to to have the truck legal to 8.50's

Thanks

I think thats a pretty open question with a lot of variables. It is true that if you Tig 4130 your going to have areas next to the weld with low fatigue life, and its true that post weld treatments are used to aleviate this. However how much stress and fatigue cycles are put into a roll cage? Is it a structural member of the vehicle that will flex much with the chassis under normal driving? Typically when I design a part like that, I will look at the fatigue loading of the part, and if its so over-built that the low fatigue life of an un-treated tig weld wont be an issue, then the part is too heavy to start with. Basicly you can do one of two things, throw brains at the problem, or throw metal at it. Usually using the brains results in a lighter, faster vehicle. If it was me, and every ounce counted, I would use 4130, Tig and post treat, or Gas weld it. Or if weight wasnt so much of an issue I would use DOM and beef up the design accordingly. Your call on what the situation demands.
-Aaron

[lewray]

4130 is nice, kinda braggin rights in some ways. My crawler has a custom built DOM cage and its been tested several times on several rollovers and barrel rolls. Never ever had problems with the welds or structural damage.

All Mig welded using the best practices

Try the 4130 and as mentioned earlier, add a bit more structure, plenty of gussets too

[Badd00SS]

4130 is nice, kinda braggin rights in some ways. My crawler has a custom built DOM cage and its been tested several times on several rollovers and barrel rolls. Never ever had problems with the welds or structural damage.

All Mig welded using the best practices

Try the 4130 and as mentioned earlier, add a bit more structure, plenty of gussets too

Well, they use min .083 wall 4130, or min .120 wall dom, thats why usually 4130 is used, to save weight. I would try to locate a local chassis builder if I were you and ask him some ?'s Ive only done 6pts to 9.99

[Craig in Denver]

What does the local sanctioning call for? NHRA wants chromoly, NASCAR uses mild steel. Both specify weld process also (I think).