4130 vs Mild Steel
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- čas přidán 21. 08. 2024
- Tim explains some of the differences between 4130 Chromoly and Mild Steel tubing for use in chassis construction.
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The information contained in this video is based on the opinion of Tim McAmis and his 30+ years in the motorsport and manufacturing industries. Any action you take based upon the content provided shall be done at your own risk. TMRC and its affiliates are not liable for any losses and/or damages in connection with the use of this information.
i can sit for hours watching all your videos on the technical side of things, great work and keep it up mate
If you gas weld the Cromoly like originally intended there's a much lower chance of fracture, cro-moly was engineered for gas welding and free air cooling to the correct temper.
This can be seen by looking at old airplane crashes, piper cubs mostly. It's pretty rare for ~ 100 yr old gas welds to crack.
As a CNC programmer who is tasked with designing and engineering a lot of fixturing in our company and then programming it and machining it, this was a very informative video. Thank you good luck with your cars. That look like a beast you were standing next to
Bc sq can b also or or u can slide rule out just the spec u need while still being light & artistic.
Correction 4130 and 1018 both have the same elastic coefficient, (18 million) 4130 at 0.058 wall vs dom at 0.156 wall will see the dom be much stiffer. The difference is in elastic limits where 4130 is about 130% as high.
Thank you for making it possible for us to have the knowledge to do it right thank you again
Im building my new car out of moly tube but now that i have kids and what not my wife wants super safe as it can be. So i used moly tube but used thickness standards of mild. All the tubing i used was .120 or thicker
When I grow up I want to be like Tim.
king0cans how old are you, 30??
Hello,
I get everything you're saying.. but for safety purposes.. let's say a VW bug, very old and no seatbelts. So of course you'd want to feel safe with a cage.. would the mild steel be better in cases of impact? I mean chromoly is strong but just as strong as mild steel since they require mild steel to be thicker, with that said you pointed out that mild steel will bend rather than snap on impact. Would mild steel be better for safety purposes?
At 1:00 you indicate that mild steel would be more flexible than 4130 but do they not both have the same modulus of elasticity which would mean the "flexibility" would be the same? I realize that the yield strength is very different but up to the yield point of mild steel the deflection for a given load should be the same.
Defender Fabrication Yeah I noticed that too. You're right the stiffness of all steel is about the same. In practice the mild steel tube will need to be thicker wall to achieve the same strength so will actually be a stiffer tube.
Stiffness in the tubing is NOT the same as stiffness in the chassis structure. The 4130 tube chassis when designed correctly, will have higher overall stiffness for a given weight than mild steel. You can't pick out a sectional stiffness of a tube and make a general statement about chassis stiffness. The fact 4130 steel allow a designed to build a light chassis with the required stiffness is why it is used. Another fact is this 4130 steel is certified to mil-std means you know exactly how the 4130 steel behaves. The mechanical property of mild steel is all over the place.
2Phast4Rocket Agree, that's why you have all those triangulation pieces and trusses and gussets and things everywhere. 4130 is always going to be a superior material whenever weight is a factor (and cost less so!)
@@2Phast4Rocket 100 % wrong. Not sure where you got your mechanical engineering degree but where I received mine this makes no sense. Youngs modulus does not change when incorporated into a built up section. The stiffness is for all practical purposes the same for the two. What is not the same is the amount of stress it can take until it has permanent deformation. Also, mechanical properties of low carbon steel are not all over the map. At least not the tube made in the USA. It is also made to standards.
@@lastditch5968 You really need to read my post more carefully before responding. I was not referring to Young's modulus at all. The material Young's modulus is very different to the structural stiffness from structural design where structural stiffness is measured in natural frequencies and structural deflections based on the specific loadings and constraints.
When you say that the same tube out of mild steel is gonna be more “flexible” you’re technically wrong. Both materials have the same Young modulus, they will flex the same under the same bending moment for the same cross section. The chromoly one will withstand a higher maximum load but you can’t say mild steel is more “flexible”, if anything it’s the opposite! With chromoly you’re using thinner sections, lower second moment of area and higher bending
As always, excellent educational video. I definitely learned aspects previously unknown. I am seeking information on various prep and paint/coat methods for CM tubing--can you offer a video or some brief reply how you do it? Also, if you powder coat perhaps you can touch on other methods and how those stack up for effort, cost, quality... Thank you!
Someone told me chrome Molly needs to be heat treated after being welded or else the structural integrity and wells this week. Is that true?
Very good video I say the best one out there explaining straight to the point I'm not too happy I bought mild steal car it does low 9 high 8 and I don't think I'm gonna be able to race it anywhere how much to a cage It in Chrome Molly
that's just cool about that knowledge on chromoly very cool
Hello. Share your experience, how do you bend pipes made of 4130 steel?
Thank you!
Some1 try hving 4130 ripped cut & welded full length to sq stock mild steel. So where u need max strength & wt u attach on round side & where u want sq framing like most of construction or u want cheaper & more flex not break connection quality u stay on sq side. Art vs slide rule blended construction. I was on comment showing 49 so 50 really & 813 liked.
I'm building a subwoofer and I need some 3" stock typically mild steel is used but at work they have a bunch of 3" 4140 round bar. There's no structural property's needed it's basically being able to hold a magnetic field Is 4140 as magnetic as mild steel?
are you saying seamless mild steel tubing is not available or doesn't exist? with all due respect, that's not my understanding. if you have time, more info would be greatly appreciated. and just to be clear, i don't mean welded DOM tubing, i mean seamless, DOM mild steel. thanks in advance.
hello, what would a 4130 frame like in the video cost, without wheels, tires, or rear end assem? for a dodge challenger? thx
Hey Tim great videos can you tell me what is the weight difference between the 4130 molly tube and the mild steel tube and also for someone who is a part time racer and not looking at building new cars all the time to compete what is the best out of the 2 to use as I have heard that molly fatigues over time. Thanks Ray
on the question of weight, both materials have nearly identical specific weight, meaning for the same volume of material they would have a negligible weight difference. i.e. a 3' section of 1.5"OD 0.095" wall of both CM and Mild will weigh the same. What is important to look at is the strength density or in other words, a 1' section of 1.5"OD 1.34" wall of Mild Steell (1.993lb/ft) has somewhat equivalent strength as a 1' section of 1.5"OD 0.065" wall CM(0.996lb/ft). So it's not the weight of the material that makes the difference its the strength, since CM is so much stronger than Mild you have to use much less of it.
@@rudyrayaaw5138 The strength only comes into play when the tube is subjected to bending loads or pure tensile loads. In a properly triangulated frame, tubes will buckle under compression long before they would fail in tension. And the buckling strength of mild steel and 4130 is identical, since they have the same modulus of elasticity. But few car frames are properly triangulated frames, unlike aircraft structures.
Whats the normalizing process? Always hear ppl reference it but never saw the process.
What???? 25-1. 25-2. ? Help
When using mild steel for a simple 6 point track day/race car, is it ok to run 1 3/4" ERW tubing with seams. I am unable to find any seamless in my area.
How sure are you that the chromoly tube you are getting is truly seamless, as far as I know, all DOM tube, chromoly or not is hrew that has been drawn over a mandrel to remove the weld and make the wall uniform. Also I dont believe that you can get 4340 in tube, I think its 4130.
How does 4130 do with cold setting?
I'm into vintage dirt bikes, which are all steel frames of one type or another. Typically the European machines and later, serious Japanese used chromoly frames, whereas early or low-performance Japanese bikes were mild steel. The weight difference is amazing. A big Husqvarna MX bike frame is light and easy to handle, while a frame from some toy bike like a 100 Hodaka will threaten to put your back out. In modern dirt bikes, the Japanese use aluminum while KTM/Husky still use chromoly. The steel bikes are lighter than the aluminum! I'm a believer in chromoly. Hell of a material.
The special short takeoff & landing cargo Island dime planes can hve launch done by fly wheels. Doesn't matter if hybrid electric motors drive or 350 chevy, or mini jet like on giant RC plane same fly wheel tech & your great dragster pumpkin*2.
Whats your take on docol r8?
Were do you source you 4130 CM from? i have been using pro moly USA made tubing.
Is there any other companies in the USA or canada
that make the good stuff ?
I used an aircraft metal supplier. They had the cheaper prices for bulk buys
4130 need to be tig welded
506th 👍's up guys thanks for taking the time for us all
Can't agree totally. The yield point of Crome Moly is actually lower than CD1020 (mld steel used for typical chassis tubing). CM being 63,100psi versus 72,000psi for Mild Steel Tubing. This means CM when hit will bend and not return to its original shape at a lower force than ms. Somebody commented that they both have the same Modulas of Elasticity which represents its stiffness and is true. Energy absorption is also a function of the material property called Elongation. CM is 15% and CD1020 MS is only 10%. This shows up in crash simulation. Here's an example: czcams.com/video/tuVqEN1E2W8/video.html to the advantage of CM. It could be Tim uses a higher grade of CM.
CM is superior in almost all categories except price www.makeitfrom.com/compare/SAE-AISI-1020-S20C-G10200-Carbon-Steel/SAE-AISI-4130-SCM430-G41300-Cr-Mo-Steel
What about Docol?
Blake Matney you tree'd me. I know top fuel is reluctant to change materials as well as NASCAR but I'd love to hear Tims opinion on the future of pro mod and TS regarding construction with docol.
To continue with Docol R8, it has a welded seam instead of being a dom tube. What are your thoughts on that?
Docol R8 is an accepted material in substitution for 4130 in the SFI series of chassis.
@@mikegrady4 Dom has a welded seam its just not as noticeable.
@@Tsalinger, true, the first stages of manufacturing are identical to ones used to make ERW tube except in the finishing stages the entire flash weld is removed and the tube is cold drawn over a mandrel. The cold drawn process essentially makes the tube more symmetrical with regards to its consistency of strength and its resistance to bending. That is a substantial difference.....especially since we typically bend the tubing. This can be a huge deal depending on where the weld is, relative to the bend, when using typical ERW tubing.
Military Spec? Don't you Mean an MTR Material Test Reports with Chemical Composition and Heat#'s
Just about everything made in America has a Mil-spec # and there are thousands of Mil-spec
Lmfao “military grade”
Did I miss something or did he never actually explain how chromoly is better? Yes it’s lighter by comparison but he said himself that chromoly is more prevalent to fracture as opposed to mild steal giving way?...this is not a rhetorical question
chromoly is stronger in a thinner wall thickness, fractures easier than mild steel. Biggest pro for chromoly for me is that it doesn't rust! Especially when you are taking your time fabricating something with mild steel, it starts rusting with just the moisture in my garage
Peter Armour
That’s damn true, I’m a sandblaster by trade but also do Powdercoating and a little fab here and there and I’ll be the first to tell you mild steel rust real quick. I can see where chromoly would have its place. Thanks for the response man I appreciate it
Lighter is gooder, Racing 101,
forget mild steel, what about 4130 vs 4340? every aftermarket guy sells 4340, but if the rules require 4130 obviously they think it is superior... thoughts?
I can give you a good reason I'm using mild steel... I'm a poor broke bastard and do what I can with what I got!!!
Right there with ya, brother..also, CM has to be tigged, while mild steel can be Mig welded..cheaper, easier, and more forgiving welding process..particularly for a weekend warrior building their own junk rather than doing it for a living.
I don't have the skills or the equipment to build a CM chassis, but I can put together a safe mild steel car.
i can understand Mr McAmis insisting on 4130 because he's at the absolute top level of competition with the corresponding budgets, plus the regs require it. however, not to take away anything stated above, every book i've read about road racing chassis design and fab (especially Costin) state mild steel is perfectly fine. i'm not a pro nor do i plan on wheel-to-wheel racing, and i'm certainly not in an elite category so i don't need to have the absolutely lightest chassis. as such, i have about 200 ft of 1.5" OD x 0.093 seamless - yes, seamless - DOM mild steel in the shop now waiting for me to clear the decks and start my build.
plus, i worked a couple years in a high end custom bicycle framebuilding shop, and 4130 does lose some of its temper when TIG welded in the heat affected zone, which renders it the same as mild steel.
What about dom
We have some questions about selection .Will you please guide us ?? Please send your no. Or by any means we want you to guide us . I am preparing for a computation of AVT car . So please kindly reply
AGREE with everything this guy says. If your building for lightness+stiffness i'd suggest no welding whatsoever. Always build on a ground fit slab(accuracy) . Then i'd use Rexroth Bosch Aluminum Framing System("T"-slotted tubing u pick sizes& density). Cover with PrePeg Carbon-Fiber/Zylon TexTreme from www.compositeenvisions.com then vac bag or autoclave.
That blower pulley
I didnt see that untill I read your comment and went back to the vid............ fuck me... thats some serious overdrive and BOOST...... good catch
That looks like a c rotor to me. If not its a d. Most run them 90-120% over
do they back purge 4130?
No need, These aren't open root welds
Another fabricator that doesn’t understand the difference between strength and stiffness😢
Military grade means a giant budget going to the lowest bidder. Who decides that’s the best? Some dick head trying to make money. I question how much better a 4130 chassis is every time the crash. Is it better to have a lighter more brittle chassis? I don’t think so.
Depends. But I do agree that military grade is held to a higher standard than it should.
In the real world everyone uses DOM especially if your welding a cage to a sheet metal chassis. Just check a rule book for the class of car your going to run. Not many require CM.
@@Tsalinger I have a 8.5 cert on my drag car. I could have used DOM but chose CM instead.