chromoly tubing, where to buy?

[Musclerodz]

I have never dealt with 4130"A", always 4130"N" in repairing vintage aircraft structures.

Why is there a need to heat treat 4130"N", when you can remove the embrittlement by pre-heating and post heating the weld when TIG or MIG welding it? I never suggested a huge savings over DOM or even 1020. It is a marginal gain for the cost increase.

I think we are in agreement, just coming at it from different directions. And the day I quit learning will be the day I die.

[chicane]

Yea Mike... I think/know that we are both in agreement.

In my opinion, heat treating any material and in specific terms with this thread and 4130 material... goes beyond the mere attribute of embrittlement. Way beyond. But in a short summation, heat treatment can make metals not only harder, but, stronger and tougher. And depending on the material and the 'how and why' you are heat treating it... you can also make metal softer and more ductile.

If you made a part and spent $1000 on it with the ability to yield a certain value of strength... and then had the ability to make the same part but with a 75% increase in strength and fatigue resistance by simply heat treating it... would you not do it ?? I'll even throw that into the specific respect to airframe materials. I am sure if one were to look at the engineering drawings for any given aircraft part... that it will specify a specific heat treatment.

Really my statement was more to point out that the idea of running 4130x and that one could get away with a thinner wall thickness and have the same strength... isn't necessarily true. When looking at the yield number from my last post, without any heat treatment... all you will end up with is an expensive part with the same, and in most cases, less strength than that of 1018/1020. Now if you were to heat treat it... the numbers would go the other way and yield more favorable results.

I believe that if you don't heat treat 4130x... your wasting valuable time and money. Most of the time it is at your customers expense...

When it comes to putting all of this into a unitized chassis... the 1018/1020 material is better suited for this application... without braking the bank.

[NOT A TA]

So it seems I'll have to meet the specs for at least 4 types of "racing" so to speak. dragstrips, road course, top speed, and open road.

The drag thing isn't a problem because without being a dedicated drag car it won't run quick enough to require more cage than it will have to satisfy the top speed guys.

The road course activities will be limited to HPDE events and there's minimal tech requirements there because it's not door to door racing.

So I really only need to find out what sizes and materials as well as configuration and installation methods will satisfy both the Top speed and open road tech guys while keeping me safe.

I'll order a new tech book from the ECTA and get one from the open road guys.

Thanks for all the info

[NOT A TA]

For those who stumble on this thread one day doing a search for chromoly and wonder what the car looks like here it is.

[Tom.A]

John,

I just went through this same process about 2 months back. I had some telling me do 4130 and others DOM and some shops out there are just using mild steel. When I tried to research rules it seemed like there was no standard. Also it seemed like I read if your floor and firewall are modified or not original that could push into another class. It was all over my head and I think Chicane's advice is good. I am a nobody when it comes to this stuff but his points are things I discovered. The whole post heat treat kinda scared me. When I started my car it was just gonna be a cruiser and by most points still will be just that however the street/track car is appealing more to me. Perhaps in my case starting with a heavier A-Body was not the desired vehicle but it is what is. I also hope to be at the Silver State Classic next fall (Maybe be two years) or Pony Express, Gamblers Run etc. It appears that (I could be wrong) if you show up with a car that has a cage that does not look like a backyard job you will be OK in the lower classes. I believe there are many production cars running in the lower classes. In the SSC the lowest class is 95 MPH avg over the 90 miles you cover. In my case with no driving credentials the max class a rookie can run is 110 MPH avg with a tech speed of 124 MPH.....still sounds like a blast to me. Return trips will with a good staying in the rules record will likely yield an elevated class. I like you don't expect to win anything and in reality my car will only see open track days on road coarse and hopefully some auto x. So in the end I also elected to with 1-3/4" 120 wall DOM. I still have to ad a few things to cage but am happy with the way it came out. You can see pics here http://ls3-chevelle.com/Current_Updates.php , And here is some more reading if you still are pondering 4130. A friend put me in contact with John Parsons and John suggested this link for some reading http://www.netwelding.com/Welding%204130.htm
Good luck on the project and I like the gumballs I got mine in the mail the other day. And if the stars align for SSC maybe will see you out there.

[NOT A TA]

Tom_a, Your car looks like it's coming out nice! Thanks for the welding link, It backs up what Chicane was getting at as well as Mikes experiences on planes. Looks like the 1 3/4 .120 DOM will be the material of choice for the main hoops. No heat treating worries, embrittlement, etc. I'll wait till I get the SCTA/BNI info to compare with the SSCC requirements before final design is determined.