chromoly tubing, where to buy?

[B Schein]

There is an airplane supply place in Pennsylvania where Bought some chromoly tubing when I used to live up in the norther part of Maryland But i can't remember there name I know John Parsons knows who it is because he is the one who told me about them. It the closest thing to New England that I know of.

[chicane]

Any real reason to why you want ChroMo other than to say its made of ChroMo ??

What kind of events are you considering and which sanctioning body are your rules from ??

I only ask because there is no benifit to using ChroMo unless you heat treat the finished product... and in the fashion of a tubular cage... that would mean that you would have to heat treat the entire chassis, which... isnt going to be done. Not to mention that unless you properly preheat the material before weldment and normalize the material after... there is absolutely no benifit to using ChroMo. The extra expense in material cost yields you zero...

A bit of advise ?? I would pick up a copy of Carroll Smith's "Engineer to Win" and then make your determination on what material you should purchase. In fact... if you are going to be doing any kind of motorsport... I would highly recommend that you purchase his whole line of books... trust me, after you read them... you will look at things in a whole 'nother light. >> Click here <<

I believe... that you would be much better off with using 1018 or 1020 DOM. Especially considering inch and five eighths... o-nine five. That is considered to be the absolute bare minimum size/dia in chassis weights under 3000 to 3200 lbs. Not to forget to mention... in the science of safety... the majority of sanc bodies are making the move towards DOM over that of ChroMo in a unitized chassis. Just the mere fact of 4130/N weld embrittlement would make me run the other way.

Im not saying that ChroMo doesnt have its place, because it sure does and I like to use it myself... but definately not in a unitized chassis. If you built the entire chassis out of ChroMo and had the entire chassis heat treated... I would be all over that !! But... the truth of the matter is, that it is not going to happen.

Educate yourself now... before you make a possible mistake.


Aircraft Spruce, Industrial Metal Supply, Metals Depot, All Metals Inc, Online Metals... all of which can ship or source the materials you need and in some instances, even locally to you.

[Tig Man]

aedmotorsports.com

They have the best prices most of the time!

[Musclerodz]

Originally Posted by chicane

Any real reason to why you want ChroMo other than to say its made of ChroMo ??

What kind of events are you considering and which sanctioning body are your rules from ??

I only ask because there is no benifit to using ChroMo unless you heat treat the finished product... and in the fashion of a tubular cage... that would mean that you would have to heat treat the entire chassis, which... isnt going to be done. Not to mention that unless you properly preheat the material before weldment and normalize the material after... there is absolutely no benifit to using ChroMo. The extra expense in material cost yields you zero...

A bit of advise ?? I would pick up a copy of Carroll Smith's "Engineer to Win" and then make your determination on what material you should purchase. In fact... if you are going to be doing any kind of motorsport... I would highly recommend that you purchase his whole line of books... trust me, after you read them... you will look at things in a whole 'nother light. >> Click here <<

I believe... that you would be much better off with using 1018 or 1020 DOM. Especially considering inch and five eighths... o-nine five. That is considered to be the absolute bare minimum size/dia in chassis weights under 3000 to 3200 lbs. Not to forget to mention... in the science of safety... the majority of sanc bodies are making the move towards DOM over that of ChroMo in a unitized chassis. Just the mere fact of 4130/N weld embrittlement would make me run the other way.

Im not saying that ChroMo doesnt have its place, because it sure does and I like to use it myself... but definately not in a unitized chassis. If you built the entire chassis out of ChroMo and had the entire chassis heat treated... I would be all over that !! But... the truth of the matter is, that it is not going to happen.

Educate yourself now... before you make a possible mistake.


Aircraft Spruce, Industrial Metal Supply, Metals Depot, All Metals Inc, Online Metals... all of which can ship or source the materials you need and in some instances, even locally to you.

You don't need to heat treat 4130/N. The problem is people TIG it and don't pre-heat and post heat to normalize the weld. The heat is so concentrated in MIG and TIG, the welded area is heat treated and needs to be normalized to prevent failure right next to the weld. I have been welding 4130/N for years on vintage airplanes and only gas weld it to prevent embrittlement. It becomes much harder to gas weld large tubing and keep the heat in it so TIG works much better. However extra steps in pre and post heat have to be taken to prevent the embrittlement.

The only real gain to using 4130 is weight savings. Due to its higher strength than DOM, you can run lighter wall tubing. If you are just running a 4 point, I don't think it is worth it, but if you are building an entire cage, I would go the extra to use 4130.

[chicane]

Ok... with all the talk about ChroMo being stronger than mild steel... lets clear up the real questions to what is behind it all.

For one to just drop the 4130 tag into a discussion is somewhat futile. To specify which 4130 material to use would be respectable. And to suggest the heat treatment of the stated 4130 would be down right noble. You cant just throw the 4130 tag around like its cool... without explaining the difference to your audience... because they might not know any better. In consideration to what is relevant, this response will only deal with 4130A (the typical 4130 material used; hot worked and annealed, and not recommended), 4130N (what should be specified and used for almost everything you would make any worthy part from), and of course... 1018 and 1020 carbon steel. All materials have an 'ultimate tensile strength' and a coinciding value to which they "yield." So, with this, all of the following numeric values will be in psi.

For cold rolled 1018/1020 the number is 82,000 and yield at 70,000
For 4130A the number is 85,000 and yield at 65,000
For 4130N the number is 97,000 and yield at 85,000

By the numbers, metallurgically... there is not that much of a difference... especially when looking at the yield values, which is where we need to concentrate our focus on, for the individual, material strength.

Since 1018 and 1020 don't respond to heat treat, they will be left out of this. But 4130N on the other hand... when heat treated to a C scale of 25 to 30... the heat treat will increase the yield value to somewhere near 130,000 to 135,000+ psi. THAT... is a considerable difference and increase in strength. It almost doubles that of CR 1018/1020 and it does double that of 4130A.

So basically, if you don't heat treat 4130N... all you end up with is an expensive part with the same strength as 1020... and brittle weld areas.

4130 is often considered to be the ideal material for high strength and stress applications... but it really isn't. I keep hearing... "since 4130 is so much stronger than 1018/1020, you can get away with a thinner wall and save some weight." Well... that just isn't true. Unless you heat treat the 4130N material. With the yield strengths being as close as they are with like material diameters and wall thickness'... if you were to actually listen to those who would say this and go to a thinner wall... you would end up with a roll cage structure that would be measurably weaker than that of using 1018/1020.

If you dont heat treat the entire 4130N component... you will end up with embrittlement issues just outside of the weldment because of the martensite appearent just outside of the pearlitic structure formed by localization and not treating the entire structure. I brought up your same arguement a couple of years ago at work... and it went over the same way. I learned not to question the super genius' from that point on. But, at least I got an education out of it...

[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

[Musclerodz]

Originally Posted by B Schein

There is an airplane supply place in Pennsylvania where Bought some chromoly tubing when I used to live up in the norther part of Maryland But i can't remember there name I know John Parsons knows who it is because he is the one who told me about them. It the closest thing to New England that I know of.

Dillsburg Aeroworks or something like that.

[B Schein]

Originally Posted by Musclerodz

Dillsburg Aeroworks or something like that.

That sound like it.