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Control arm metal selection


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Im starting the process of building the front control arm s for my 76. They will end up looking a lot like the Arizona z arms and I was wondering what type of steel all you think would be best. I was thinking chromemoly would be neat. My memory isn’t that great but I think that’s sae 4130 and 4140. and any of you who know anything about heat treatment tell me what you think the best treatment for a given steel in this application would be.

Thanks

Jon…

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In the tubing wall thicknesses typically used for control arms (less then .125" wall) heat treatment is not necessary. Post weld stress relieving (normalizing) is of some benefits if the interpass temperatures get too high.

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I used 4130 for my control arms. 4140 has more carbon content and is therefore less weldable and more prone to crack if not subjected to PWHT. Johnc is much more knowledgable than I on this subject, and I hope that he will correct me if I'm wrong.

 

Arm4.JPG

 

 

PICT0005.JPG

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Again, in the thicknesses we are talking about ASTM and AWS do not recommend PWHT. Proper technique and a lower carbon filler (ER70 as opposed to ER80) helps reduce carbon buildup in the heat affected zone.

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One of the issues we face welding stuff in the automotive/motorsports world is that there are no real standards applicable to us. There are some pipe welding standards developed from the oil and gas industries but they fall short with pipe diameters under 6" and pressure vessel standards are beyond comprehension for what we are doing.

 

In the welding world, standards are developed by the application industry and then administered by the American Welding Society. Lincoln Electric has been working with NASCAR to develop welding standards for roll cage and tubular structures but nothing formal has been released to AWS that I know of. I was involved in welding coupons for a 4130 CroMo tube standard but I haven't heard of it being released.

 

I've got a little certificate on my wall stating the yes, I have made a successful 4130 tube weld. I only got that (FWIW) because I kept bugging the guys at Lincoln for something so I think they sent me the certificate to shut me up.

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  • 2 weeks later...
I used 4130 for my control arms. 4140 has more carbon content and is therefore less weldable and more prone to crack if not subjected to PWHT. Johnc is much more knowledgable than I on this subject' date=' and I hope that he will correct me if I'm wrong.

[/quote']

 

do you sell your control arms? if not, do you have specifications for them!?

 

they look quite strong

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I have made one other set for someone else, and I have a fixture for making more. I am a little shy of making them for others to to the possible legal ramifications (I am not an LLC). The other issue is price. It costs me ~$400.00 to make these ($300.00 in materials and $100.00 to have them welded).

 

In this thread, I discussed the control arms at length:

 

http://forums.hybridz.org/showthread.php?t=91888&highlight=control+arms

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