Topic: 4130 chrome moly tubing

The surplus depot just got in a bunch of it.  Reading the rules, it doesn't say DON'T use it..
yes it normally is way expensiver, but not at surplus prices..

Re: 4130 chrome moly tubing

I wouldn't.  I'm not a cage builder but I am an engineer and my understanding of the benefits and risks of chrome-moly  is as follows:

- 4130 is stronger than mild steel, which lets you save weight by using less of it.
- Lemons doesn't let you do that, so your 4130 cage will weigh the same as your mild steel cage.
- 4130 is more brittle than mild steel; this is a pretty typical relationship as far as metals go.
- Welding steels of any kind without pre- and post- heat treating can locally make them more brittle.
- Welding is hard.

Anyway, using 4130 instead of mild in the same tube diameters and wall thickness _could_ result in a stronger cage at the same weight, but is likely to result in a cage with more brittle welds, too.

("More brittle" is a terrible phrase, but I will use it instead of the proper but more fancier alternatives.  For clarity.)

It is possible that I am way off base with all of this, and would suggest discussing the pros and cons with John Pagel, but I'd stick with DOM mild steel.

Re: 4130 chrome moly tubing

If it wasn't safe they would not build race cars out of it..it is just like carbon fiber vs fiberglass.
i send pagel email, but replies are usually slow, and this tubing will be gone quickly, like maybe already gone at these prices!   think i will just buy a bunch and use it for my hotrods, trailer, trusses, etc
if not Lemons legal.

Re: 4130 chrome moly tubing

I answered you via email almost immediately..     

And yes, Scott hit all the points that I did.

The race cars that are built out of 4130 are almost all tube frame cars that can be build under controlled conditions and aren't being built into a thin, dirty, mild steel unibody under bad conditions.... 

   If you can set up the correct conditions to build a 4130 cage, OK...      We don't disallow it, just be careful and make sure your techniques and equipment are up to the task.

  -John

Gosh, my business card says 'Tech Tyrant'

Re: 4130 chrome moly tubing

Thanks for the quick reply!

Re: 4130 chrome moly tubing

nimblemotorsports wrote:

If it wasn't safe they would not build race cars out of it..it is just like carbon fiber vs fiberglass.
i send pagel email, but replies are usually slow, and this tubing will be gone quickly, like maybe already gone at these prices!   think i will just buy a bunch and use it for my hotrods, trailer, trusses, etc
if not Lemons legal.


its my understanding that "they" have in fact stopped building cages out of it. FIA has Banned the use of 4130 as well as the US rally organizations.

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Re: 4130 chrome moly tubing

Hey Sexy jesus, got any links on this supposed ban?  I was looking for anything on this and came up with nothing specific to the FIA or US Rally. 

Thanks,

Dave

Re: 4130 chrome moly tubing

bilcoh wrote:

Hey Sexy jesus, got any links on this supposed ban?  I was looking for anything on this and came up with nothing specific to the FIA or US Rally. 

Thanks,

Dave

I think that's because they dont specifically say 4130 is disallowed.    They have wording like only "unalloyed carbon steel" is allowed which rules out chrome moly.  I'm still kinda confused as to why they consider DOM unalloyed but that's above my pay grade.  As John indicated earlier, chrome moly primarily seems to be used in race cars where the tubing is the primary structural component (i.e. sprint cars).  Why it's not allowed elsewhere i would guess is due to the difficulty of making a field determination as to whether it was properly constructed.  I know our sprint cars were heat treated pre and post welding but at times they were also working with pretty thin material like .049.

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Re: 4130 chrome moly tubing

DOM can, and tends to be, straight Mild Carbon Steel.
Usually 1020 or 1026.
1 = Carbon Steel
0 = No Alloying
20 or 26 = 0.20 or 0.26% carbon.

Although it's important to remember that DOM (Drawn Over Mandrel) is a Process not a Material.

But the big thing is an Alloy, Any Alloy, needs a lot more know how to weld properly and with the right filler material.

My guess is a lot of Alloy cages were showing up with mild steel filler and showed cracking and failure issues. Or even worse, MIG welded with cheap HF flux wire.

Mistake By The Lake Racing (MBTL)
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A&D: 2014 Sebrings at Sebring (NSF), 2014 NJMP2 Jurassic Park (SpeedyCop), 2012 Summit Point J30 (PiNuts)
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Re: 4130 chrome moly tubing

Guildenstern wrote:

Although it's important to remember that DOM (Drawn Over Mandrel) is a Process not a Material.

Absolutely, DOM is the process of creating the tubing from the steel NOT the type of steel used.

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Re: 4130 chrome moly tubing

Guildenstern wrote:

DOM can, and tends to be, straight Mild Carbon Steel.
Usually 1020 or 1026.
1 = Carbon Steel
0 = No Alloying
20 or 26 = 0.20 or 0.26% carbon.

Although it's important to remember that DOM (Drawn Over Mandrel) is a Process not a Material.

But the big thing is an Alloy, Any Alloy, needs a lot more know how to weld properly and with the right filler material.

My guess is a lot of Alloy cages were showing up with mild steel filler and showed cracking and failure issues. Or even worse, MIG welded with cheap HF flux wire.

Yes, I meant the type of steel typically used in the DOM tubing we build roll cages from.  My point was that my high school education level understanding of material says that the definition of an alloy was that it was a combination of materials to make a 3rd material.  As steel was made by combining iron and carbon that's why I was confused as to why there would be something called unalloyed steel.  To my uneducated mind, something like iron is not an alloy but all steel was alloyed as it  is made from a combination of material.  I'm guessing that in this context the iron/carbon steel combination is considered the base material and if any other metals/materials are mixed into the steel it then becomes alloyed steel.

1990 RX7 "Mazdarita" 
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1964 Sunbeam Imp (IOE 2013 Sears Pointless)
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Re: 4130 chrome moly tubing

cheseroo wrote:

I'm guessing that in this context the iron/carbon steel combination is considered the base material and if any other metals/materials are mixed into the steel it then becomes alloyed steel.


That is largely it. Basic steel is technically an alloy (iron with some carbon), but it's the base alloy that most all else is made from. Alloy steels are any steel that has been added to with other elements to change it in some way. It's generally accepted that saying alloy steel implies a modified steel.

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Re: 4130 chrome moly tubing

cheseroo wrote:

...the definition of an alloy was that it was a combination of materials to make a 3rd material.  As steel was made by combining iron and carbon that's why I was confused as to why there would be something called unalloyed steel.  To my uneducated mind, something like iron is not an alloy but all steel was alloyed as it  is made from a combination of material.  I'm guessing that in this context the iron/carbon steel combination is considered the base material and if any other metals/materials are mixed into the steel it then becomes alloyed steel.

I'll chime in as a mineralogist and/or mineral physicist, since this means I know just enough materials science to get myself in trouble:

An alloy is a combination of a metallic element with one or more other elements. Steel is fundamentally an alloy of iron and a small amount of carbon. Various steels can contain other things as well, but the "starting point" is iron with a small amount of carbon.

For the sake of convenience, then, it is useful to redefine the starting point for the more compositionally complex steels as "iron plus carbon" and treat that as the base material, as you surmised. "Iron alloyed with carbon," therefore, becomes "unalloyed steel" since it's just steel without any additional alloying. Adding something else to it then makes it an "alloyed steel" since it's an alloy of steel plus the other element(s).

To make matters slightly more complicated, the "iron" used in making steel isn't actually pure iron, as it would require some rather expensive processing to separate and remove the last fractions of the associated silicon, sulfur, phosphorus, manganese, and so forth during processing of the iron ore. Usually the presence of these other elements in trace amounts either doesn't matter enough to warrant going to the trouble of removing them or, depending on the application, their presence may even be desirable. This means that even "unalloyed steel" isn't really just iron plus carbon, but again for the sake of convenience that's how it is usuallly described, with the presence of the other trace materials taken as silently understood unless someone actually needs to know the detailed composition of the material. Frequently the amounts and types of those same trace materials may even be deliberately adjusted during the steel-making process and the result is still considered to be unalloyed steel, again just as a matter of convention and convenience.

This is really just the tip of all this, by the way. Iron alone has some rather tricky properties and moving beyond that to steel opens up an entire world of complexities. I've had to nose around in this to a very limited extent for my own mineralogial research but mostly I have come away with an understanding that it is a large field of study in itself. For example, everything I've written above only touches on what elements are present in the material, not their detailed proportions or how they are arranged on various microscopic and submicroscopic scales and how those arrangements change as a function of temperature, time, pressure and other stresses, and so forth. It's either a real mess or a fascinating area of endless wonder, or maybe both.

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Re: 4130 chrome moly tubing

In Metalworking Alloy's are specifically a substitutional mixture of metals only.

Interstitial Non-Metal alloys tend to be considered a Base metal since there's much less compatibility issues than in a substitutional alloy. Especially with Plain Carbon Steel where you're usually taking about less than 1% carbon.

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15 (edited by bilcoh 2019-02-11 04:03 PM)

Re: 4130 chrome moly tubing

Got it. 

So what you're saying is I can braze-weld my cage together if I use 4130?

That's PERFECT because I just got a killer deal on 500lbs of brass brazing rod.

Re: 4130 chrome moly tubing

Here, watch my video on what tubing costs in Sacramento, like,share,subscribe, my views are pathetic.. wink

https://www.youtube.com/watch?v=Cei1MmLkjmE&t=41s

All these tubes are 1.5in .120 wall.

Mild Steel  20ft  $38
DOM         22ft  $120

Surplus 4130   20ft  $62     smile

Re: 4130 chrome moly tubing

bilcoh wrote:

Got it. 

So what you're saying is I can braze-weld my cage together if I use 4130?

That's PERFECT because I just got a killer deal on 500lbs of brass brazing rod.

Are you sure it isn't bronze brazing rod?? LOL

Just a Noob trying to take the long approach to doing it right.

Re: 4130 chrome moly tubing

bilcoh wrote:

Got it. 

So what you're saying is I can braze-weld my cage together if I use 4130?

That's PERFECT because I just got a killer deal on 500lbs of brass brazing rod.

Nope, because brazing like soldering is not welding.

I just know a team must have rolled in with a fully brazed cage at least once.

Mistake By The Lake Racing (MBTL)
88 Thunderbird "THUNDERBIRDS ARE GO!"
A&D: 2014 Sebrings at Sebring (NSF), 2014 NJMP2 Jurassic Park (SpeedyCop), 2012 Summit Point J30 (PiNuts)
2018 Route Sucky-Suck Rally Miata.

Re: 4130 chrome moly tubing

While not the same as welding, brazing is fairly impressive. Done right the braze joint is still stronger than the surrounding metal which blows my mind. I've used silicone bronze braze media on a bunch of home projects, and I tested the strength a few times. Tee joints with 1" square tube? Beat it with a hammer and the tube folds completely over and starts cracking before the braze joint does. It's not what you want for a roll cage, but it's a cool process.

Plus it's pretty. I built a small standing bar for my apartment from 1" square and brazed all the joints. Flap back all the joints and wire wheel it and the joints look awesome with the contrasting colors. I've also done decorative metal work with it. Machine a slot into a piece of steel, then fill with bronze braze, then machine the top surface flat again and you have perfect metal inlay.


Sorry for the tangent, I just like bronze brazing for various things.

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Re: 4130 chrome moly tubing

nimblemotorsports wrote:

Here, watch my video on what tubing costs in Sacramento, like,share,subscribe, my views are pathetic.. wink

https://www.youtube.com/watch?v=Cei1MmLkjmE&t=41s

All these tubes are 1.5in .120 wall.

Mild Steel  20ft  $38
DOM         22ft  $120

Surplus 4130   20ft  $62     smile

Dude, email or call me, I can do so much better  (note, not trying to make money, I can either sell you some(I buy 10,000 feet a year) or guide you...

John

Gosh, my business card says 'Tech Tyrant'

Re: 4130 chrome moly tubing

TheEngineer wrote:

While not the same as welding, brazing is fairly impressive. Done right the braze joint is still stronger than the surrounding metal which blows my mind. I've used silicone bronze braze media on a bunch of home projects, and I tested the strength a few times. Tee joints with 1" square tube? Beat it with a hammer and the tube folds completely over and starts cracking before the braze joint does. It's not what you want for a roll cage, but it's a cool process.

Plus it's pretty. I built a small standing bar for my apartment from 1" square and brazed all the joints. Flap back all the joints and wire wheel it and the joints look awesome with the contrasting colors. I've also done decorative metal work with it. Machine a slot into a piece of steel, then fill with bronze braze, then machine the top surface flat again and you have perfect metal inlay.


Sorry for the tangent, I just like bronze brazing for various things.

Not as pretty as a perfect stack of dimes rainbow tig weld.

Mistake By The Lake Racing (MBTL)
88 Thunderbird "THUNDERBIRDS ARE GO!"
A&D: 2014 Sebrings at Sebring (NSF), 2014 NJMP2 Jurassic Park (SpeedyCop), 2012 Summit Point J30 (PiNuts)
2018 Route Sucky-Suck Rally Miata.