The stiffness/elastic modulus is the SAME for both metals while inducing strain in the linear elastic region. The difference is in the YEILD strength and ULTIMATE tensile strength of 1020/1018 vs 4130. But as long as the application of either metal does not exceed the YEILD strength, either the ERE or DOM tube will work fine.
i was just gettin ready to chime in saying the same thing. the chromoly dom remained mostly in its elastic region while the low carbon erw entered its plastic region. erw = much lower yield strength, works perfectly for anything that doesnt exceed that limit. dom obviously much better for high stress applications
@@alexcecil89 So in reality neither is much different for short lengths as in most frame applications, so you must decide if you want more rigidity in the frame thereby placing more stress on the suspension parts or if you want more flex so the frame becomes a suspension component as well. I would like to see some FEAs on this topic with a simple frame.
4130 (chrome molybdenum) is a grade of steel. DOM is a process of forming the tube. DOM =/= 4130. (They are not the same thing!!!) DOM means drawn over mandrel. It can be done to any number of different steel alloys, and DOES NOT garantee or specify 4130 is used. DOM tube is typically a WELDED tube, that is then cold drawn over forming mandrels and through forming dies to give it its final dimensions, which also cold work the steel. The DOM process hides the weld. It does not mean it is (or is not) welded before the DOM process. Here we call DOM tubing CDW. Which means cold drawn welded. You can also get CDS, which means cold drawn seamless. In both cases, made from a un-alloyed low carbon steel. (Not 4130) CDS is proper seamless tubing. It starts as a billet of steal and pierced and drawn over mandrels and dies. Creating a tube truly without seams. 4130 is a whole different thing again. It is a chrome molybdenum alloyed steel. It has stronger material properties. When bought in tubes, it is also drawn seamless in most cases. Although 4130 does not mean, or specify that, it is simply a material grade.
@@BramBiesiekierski thank you for pointing this out, I was going to do the same thing, but you have done a much better job of explaining , cheers, Paul
Hey Groutaone, another great video. I think it would be worth defining the difference between stiffness and strength here and how it relates to this situation. Often the sorts of structures we deal with are stiffness limited. As a result the stresses can remain relatively low when low deflection is required. Always an interesting tradeoff for each situation. Cheers! Looking forward to more progress on the off roader.
I built my ultra light sandrail out of 1 1/2 inch .083 DOM and pounded the beejesus out of it for years on the sand. Good stuff for sure. Nice of you to do a comparison. I was more worried about weight than strength at the time. Not as big of a weight savings on the 1 inch but significant on the 1 1/2. Thanks for making this vid sir
So looking at this video it looks like ERW is stiffer, but its yield strength is lower than DOM. Quite interesting, thanks for the testing! Anyone interested will likely find this video from Ben useful, it explains the difference between stiffness and strength quite well: Intro to heat treatment of steel (hardening and tempering).
Very interesting G1!! I wonder if it would make a difference where the seam was positioned on the ERW tubing? Probably not. Thanks for the great video.
I think seam position would play into this a bit, likely not enough though to make a noticeable change in the results. You are a thinker I can tell, like many others here in the comments, thanks for your comments eveybody
That's a crude version of how we test side loading at school(for mechanics)...Keep in mind that the ERW might be stronger to bending but might be easier to collapse under the influence of end to end loading or be prone to snap when side loaded due to having a weak side. PS: just saw the end and I'm kinda spot on in my mind...thanks
Id say this difference comes down to the strength and stiffness present in the different levels of heat treatment in the steels, the DOM is work hardened a bit, I am sure they are both annealed to relieve stress after manufacture but there still must be a strength/stiffness variation between them. Intro to heat treatment of steel (hardening and tempering) This really put it into perspective for me.
Very interesting video. This is the reason why tubing/cage/construction fabricators use hollow tubing and not massive tubing. (except from weight and cost of course) . A hollow pipe is ALWAYS stronger than massive tubing (vertical load). When the wall of the tubing differs in size, composition or strength along the tube's circumference it loses much of it's properties. The metal of the ER tubing, even wall thickness, length etc etc doesn't matter, only the welding seem makes it weaker. You can see this clearly in a coke can. Put it put straight on a flat floor, stand on it, pick up your wife, it won't give, she'll be impressed and you might get some. Now score a fine line on the side can, poke a small hole,... and repeat wife on can experiment and you'll be sleeping on the couch for a week...
Very interesting experiment. There is one reason why the ERW tube would be winning at the start of the race and then be passed and surpassed by the DOM tube, and that is that the ERW steel has a higher yield strength than the DOM, but that ERW is not made of as tough of a material as the DOM. Meaning that it takes more energy (the weight falling through distance) to continue to permanently bend the DOM than the ERW. .
I could take the time and explain what's going on here but this video explains it easier than I could. The two different tubes are most likely made of the same type of steel, it's just the difference if manufacturing, resistance welding vs machine rolled and worked. Welding without heat treatment weakens steel.
The chemistry of the the two tubes are signifcantly different. The carbon content of the DOM is twice the carbon content on the ERW. Both tubes have a welded seam that will create a weak place in the tube, the seam in the DOM will be much more difficult to locate, the DOM manufacturing process smooths the seam. If the seam of both tubes were placed perpendicular to the load they would have little effect on the bending, but since the DOM has higher carbon content it will always be stronger than an equally sized ERW tube.
Excellent point. Most DOM is 1026-alloy steel, and has a UTS of ~76 ksi, where as most non-DOM ERW is 1010-alloy steel of only ~ 54 ksi UTS. The 2% Yield Tensile Strength of 2016 DOM is ~54 ksi, where as 1010 non-DOM ERW is only ~38 ksi.
Very kind of you to do the test. It does prove that there is very little difference at the end of the day. With the distances between braces used on most structures, to bend or fail at the ERW seam would mean you have had a very severe impact that probably killed you anyway so if you're building on a budget, go right ahead and use ERW, the total sum of your engineering is far important than the small differences seen here.
Bad premise. When building a safety system, you choose the *best* design, not one that is "just ok." By your logic, we should make automotive seatbelts out of toilet paper, because if you crash you're probably gonna die anyway.
I wouldn't draw conclusions on this and bet your life on it. While interesting to watch, the test isn't showing hard, repetitive impacts. I've seen ERW fail miserably on seemingly well built cages, and some really poorly built cages as well. Usually breaks right at the welds, or the tubing itself just crushes.
With the ERW You have always to consider where the weld is, that's not the case with DOM. Another benefit for the DOM is, You can use a thinner wall, saves weight. ERM is cheaper than DOM
DOM tubing are also welded but they pass through the drawing process after the welding. That is the main reason the material aquires strength. Another important strength improvement is reached by the heat treatment and, of course, the steel alloy used. Drawn Over Mandrel Steel Tubing
My guess is that the DOM is subject to allot more cold working than the ERW in it's manufacture resulting slightly higher work hardening. As hardness increases so does the yield point (the point where the material does not return to it's original shape and deformation takes over) which results in a higher PSI rating. I'd be curious to see a mill cert on both to see if they are the same grade of steel to start out with.
I don't know what kind of force that weight translates to at ten feet, but is the extra strength worth it? And with the short legths you used on your frame, do you think the erw is better? That early flex in the dom caught me by surprise too.
So what I'm seeing is that for chassis based uses with the tube at usable lengths like we would normally do, they are pretty close. The question now is, what is the impact strength of them. Which one would dent or smash from a hard hit the easiest. Thanks for making this video!
I may test both under a press with both the same pressure to give some indication, on a side note the DOM seems to take more effort to bend using my hand powered bender
groutaone nice video. You may want to do an impact test vs. a slow bend test here. Most crashes during racing are high speed impact not a slow continuous impact. Just saying.
I need to build a bash bar for the front of a rig that needs to absorb impact and not transmit all of the energy into the frame. It seems that the ERW might have and advantage for my application?
Fun stuff - however how much a tube will flex before yielding depends on it;s dimensions. Since all steel has pretty much the same modulus of elasticity the two tubes should flex about the same before yielding. How much force it takes to get it to yield depends on it's yield strength. So the higher strength steel will take more force to permanently bend. Softer steel is has better durability, that's why they build bridges and buildings out of A36 or A58 steel and not chrome-moly. Cheers!
+James Valiensi DOM is cold rolled this changes the lattice structure of the steel making it...STIFFER...that's why Tubing rolled DOM has a tensile strengh of 60,000-70,000 vs HREW at about 40,000 ...they will both still dent the same as they are both the same steel and have the same ....hardness... 1.75 hrew gets you the same load carrying ability as 1.5 DOM and both at .120 will dent the same . LOL...can you beleive even steel supply yards think DOM is seamless...lol...there is just so much bad info on tube parroted around 4x4 forums everyone thinks tube bent hrew is junk and DOM is magic shit .
+yerwrng yup! For my bars... I use 2" HREW .120 for the hoop, and 1.90" Sched 40 for the rear legs. If I roll (again...) I WANT some flex... and then to the limit of the rear leg... NO flex! The pipe rear vs tube... dominates in strength.
You are correct sir, steel is steel is steel when it comes to flexing below the yield strength. Even if you were to perform the test with a 301 stainless at 42RC you would get the same amount of elastic deformation assuming the same dimensions of material. Difference would be the plastic deformation, bending, would not happen on the stronger material until much higher loads were encountered. There is no stiffness difference in different steels, but there is plenty of strength differences. The DOM performs better here because of the work hardening of the material during the drawing process.
Two pieces of steel with different yield strengths will not flex "about the same," the one with the higher yield strength will flex farther before yielding - that's the definition. You can have a 1008 bar of a certain cross section that permanently deforms at a bend of 5 degrees, while a 1030 bar of the same dimensions will spring back if bent 5 degrees. The reason they build bridges out of A36 has nothing to do with this; A36 is cheaper and is "strong enough." Engineers do not overbuild.
I am having a hard time fitting a .750 steel tube into a pillow block bearing. Someone told me that I should use DOM tube since it is more suitable for fitting in. (Better tolerances). Does that sound right to you?
I want to know if the tubes were cut to the same length for this test or not? I know the results will probably be the same and all but I would like to know. In cases were you would be using the same tubing and doing that test it would only take an inch to throw off the test. I wouldn't expect any change in this test because DOM is where it's at.
You got me curious so I went out and measured, I measured the full length around the outside of the bends that were made and they are about 1/8th of an inch difference
Most roll cage builders will tell you to run a .130 wall ERW tube to comply with NHRA rules as if you try to run .120, the consistency with ERW could give you thin spots that fall below the .118 (IIRC) minimum. I’d love to see how a .130 wall ERW vs a .120 wall dom fares. What we may be seeing here is simply those inconsistencies in thickness creating weak points and nothing to do with the material itself being stronger (in terms of the metal’s composition). In the real world building say a roll cage, you could still save a lot of money going ERW .130 wall over dom .120 and I wonder if it would be just as strong, If not stronger? Might gain a little weight but if keeping it light were a priority over cost you’d probably be using cromoly lol
Seen it mentioned a couple times but like it's been said this would be a test of modulus aka stiffness not strength , you can take a piece of totally anealed silly putty steel against the strongest super alloy steel like mar 300 And if you put equal weights they will stretch the same until you exceed the plastic strength of the softer steel at which point it will begin to stretch permanently And strain harden
Since DOM is simply ERW that has been cold drawn to a specific dimension and specification I would bet these test results could be changed by using a different spec DOM tubing... just a guess. I have built plenty of race cars with ERW with good results but my next, and likely last car, will be DOM.
@@j.r.arnolli7494 Both DOM and ERW are made from flat ribbon stock, electrically welded along a seam. DOM tubing is also drawn through a die over a mandrel to flatten the weld seam and improve dimensional accuracy.
I agree with the result that erw is weaker but there is one flaw in this test. the pipe is being bent as it comes out more which scews the results as you go out further. a bend at 3 feet is going to be exaggerated at 6 feet. I am talking the erw. the dom is not actually bending as much due to rebounding from the bend point not disputing your findings at all.
We all know Cold rolled DOM has a higher Tensile strengh than hot rolled I think it's 30-40 for HREW vs Cold rolled DOM at 60-70 , so this owuld be the expected out come . Cold rolling effects the Crystal lattice structure making it stronger and harder to bend ...However in regards to denting they are both still just as HARD so they will dent the same given both were made from the same steel .
hahaha. That's funny. I'd be interested to know how much more resistant DOM is to crushing force like when you roll your vehicle and hit a rock or a tree and get a dent in your rocker or roof tubes. Obviously different parts of a cage see very different types of stresses and impacts.
You can see my video, I bought some at cheapest steel supply in sacramento, 2018, and 1-1/2 .120 ERW 20ft was $40, DOM was $115 for 22ft. So 2-3 times more. If you add gussets to a cage, it is way stronger than any difference in tubing strength.
HREW/ERW and DOM are the same tubing. Tubing and schedule pipe fall into this same category. Only difference are tubing is o.d. and pipe is i.d. The DOM is just the HREW tubing/pipe drawn cold through a die and over a mandrel with a cutter to remove the flash on the inside. Granted the cold draw it experiences realigns the molecules a little and therefore make for a trivial amount of strength difference. DOM is mainly just for operations where the inside needs to be smooth or if pieces are to be inserted into it. DOM does have closer tolerance to true measurement. DOM is NOT seamless pipe/tubing. That is a whole different animal.
There is no cutter used during the drawn over me and draw process. The ID weld flashing is removed on the weld metal during the welding. Drawing over me and roll with the weld flashing there would pull the weld into the tube and make a poor tube. I retired from ArcelorMittal Shelby after 42 years in the tube making business. The company is 131 years old.They average around 200,000 tons of product per year. Size range is 1 inch to 12 1/2 inch with wall thickness is up to .675.
Hey Grouta One! I think that a torsion (twist) test would better serve you because of the short lengths one uses constructing a frame or cage. Yeah you dont want it to bend outright but i would think that tweaking would be more of an everyday problem off-roading than bending during a crash. Don't get me wrong, just try to follow my thought. lol Cool test man!
That's all find and dandy but one problem good sir what practical application would you need to span that great of an area, the erw worked fine with the short span better then the other even if your spanning that far you'll have bracing which changes the fulcrum..... just saying haha btw the buggy looks great!!
groutaone It would be cool if you did a strength test with gauges with pieces of metal that are realistic in common use so yo would know where the yield point of each tube
Wait.. LOL @ 5:51-52 The tube is bending and you say... 'may-annnnnn'..... like if you were, a hollywood hipster who is a little drunk and saying 'man' LOL
I knew this before, the dom is more flexible at first, it will alow a little flex and that is also why its strong. If you would build a rollcage from that dom tube then it would not change shape that much in a crash. It wil bend and flex a little, but it wil spring back in to its shape. And that erw tube wil just bend and go flat and snap open. And that was the only surprise for me in this video. I expected the welded tube to split open, but that didnt happen. I have seen it happen when they where bending it on 1 of those cheap chinese benders.
i think another awesome video would be a real tube bender vs princess auto's kinker! i will be sure to show this video to my friends when they wonder why I'm spending the money on DOM for my bug!
i,m more interested in fitment say one inside the other, does the ERW have weld build up on the inside, for instance i can slide a 1" .120 wall DOM inside a 1 1/4" .120 wall DOM with a nice fit can i do that with the ERW ?
Young's modulus represents the stiffness of the material in the ELASTIC deformation region. Yield strength determines at what point the material deforms plastically during loading (e.g., takes a PERMANENT SET when bent). Before the two tubes took a permanent set, they were bending at about the same rate. This is because Young's modulus of all steels is essentially the same (around 30,000 Ksi). Once permanent deformation started to occur, one tube bent a lot more than the other. This tells me that the tubes were made of two different grades of steel (having different Yield strengths). DOM and ERW simply identify the manufacturing process used to form the tubing. Both DOM and ERW tubes are made from flat ribbons of steel, which are electrically welded (ERW = electrical resistance welding). DOM tubing is also drawn through a die over a mandrel. This flattens the weld seam and increases the accuracy of the ID and OD dimensions of the tube, but that weld seam is still there. Regardless, the forming method has nothing to do with Young's modulus, Yield strength, or Ultimate Tensile strength, which are material properties. Bottom line is that for purposes of tests, such as the one in the video, whether the tubing is DOM, ERW, CREW, etc. is not really important, but the grade of the material (1010, 1018, 1020, 1026, 4130, etc.) is.
I would point out that you are adding up the bending in each test. If you go right to the longest test then you won't be testing already bent steel.
The stiffness/elastic modulus is the SAME for both metals while inducing strain in the linear elastic region. The difference is in the YEILD strength and ULTIMATE tensile strength of 1020/1018 vs 4130. But as long as the application of either metal does not exceed the YEILD strength, either the ERE or DOM tube will work fine.
i was just gettin ready to chime in saying the same thing. the chromoly dom remained mostly in its elastic region while the low carbon erw entered its plastic region. erw = much lower yield strength, works perfectly for anything that doesnt exceed that limit. dom obviously much better for high stress applications
@@alexcecil89 So in reality neither is much different for short lengths as in most frame applications, so you must decide if you want more rigidity in the frame thereby placing more stress on the suspension parts or if you want more flex so the frame becomes a suspension component as well.
I would like to see some FEAs on this topic with a simple frame.
4130 (chrome molybdenum) is a grade of steel.
DOM is a process of forming the tube.
DOM =/= 4130. (They are not the same thing!!!)
DOM means drawn over mandrel. It can be done to any number of different steel alloys, and DOES NOT garantee or specify 4130 is used.
DOM tube is typically a WELDED tube, that is then cold drawn over forming mandrels and through forming dies to give it its final dimensions, which also cold work the steel. The DOM process hides the weld. It does not mean it is (or is not) welded before the DOM process.
Here we call DOM tubing CDW. Which means cold drawn welded. You can also get CDS, which means cold drawn seamless. In both cases, made from a un-alloyed low carbon steel. (Not 4130)
CDS is proper seamless tubing. It starts as a billet of steal and pierced and drawn over mandrels and dies. Creating a tube truly without seams.
4130 is a whole different thing again. It is a chrome molybdenum alloyed steel. It has stronger material properties. When bought in tubes, it is also drawn seamless in most cases. Although 4130 does not mean, or specify that, it is simply a material grade.
@@BramBiesiekierski thank you for pointing this out, I was going to do the same thing, but you have done a much better job of explaining , cheers, Paul
@@alexcecil89 the DOM was never specified as 4130.....
Hey Groutaone, another great video.
I think it would be worth defining the difference between stiffness and strength here and how it relates to this situation. Often the sorts of structures we deal with are stiffness limited. As a result the stresses can remain relatively low when low deflection is required. Always an interesting tradeoff for each situation.
Cheers! Looking forward to more progress on the off roader.
I built my ultra light sandrail out of 1 1/2 inch .083 DOM and pounded the beejesus out of it for years on the sand. Good stuff for sure. Nice of you to do a comparison. I was more worried about weight than strength at the time. Not as big of a weight savings on the 1 inch but significant on the 1 1/2. Thanks for making this vid sir
I always appreciate your comments, thanks for watching, thank you to everybody in these comments
Thanks for doing this, I've always wanted to see a visual comparison.
So looking at this video it looks like ERW is stiffer, but its yield strength is lower than DOM. Quite interesting, thanks for the testing! Anyone interested will likely find this video from Ben useful, it explains the difference between stiffness and strength quite well: Intro to heat treatment of steel (hardening and tempering).
Very interesting G1!! I wonder if it would make a difference where the seam was positioned on the ERW tubing? Probably not. Thanks for the great video.
I think seam position would play into this a bit, likely not enough though to make a noticeable change in the results. You are a thinker I can tell, like many others here in the comments, thanks for your comments eveybody
Thinking the same thing bout the seam and wondering if the heat used to drawl the steel helped to temper it any compared cold roll to weld process
I'm guessing that positioning the seam on the bottom (or top) would have made it stronger...?
That's a crude version of how we test side loading at school(for mechanics)...Keep in mind that the ERW might be stronger to bending but might be easier to collapse under the influence of end to end loading or be prone to snap when side loaded due to having a weak side.
PS: just saw the end and I'm kinda spot on in my mind...thanks
Id say this difference comes down to the strength and stiffness present in the different levels of heat treatment in the steels, the DOM is work hardened a bit, I am sure they are both annealed to relieve stress after manufacture but there still must be a strength/stiffness variation between them.
Intro to heat treatment of steel (hardening and tempering) This really put it into perspective for me.
Very interesting video. This is the reason why tubing/cage/construction fabricators use hollow tubing and not massive tubing. (except from weight and cost of course) .
A hollow pipe is ALWAYS stronger than massive tubing (vertical load). When the wall of the tubing differs in size, composition or strength along the tube's circumference it loses much of it's properties. The metal of the ER tubing, even wall thickness, length etc etc doesn't matter, only the welding seem makes it weaker. You can see this clearly in a coke can. Put it put straight on a flat floor, stand on it, pick up your wife, it won't give, she'll be impressed and you might get some. Now score a fine line on the side can, poke a small hole,... and repeat wife on can experiment and you'll be sleeping on the couch for a week...
Very interesting experiment.
There is one reason why the ERW tube would be winning at the start of the race and then be passed and surpassed by the DOM tube, and that is that the ERW steel has a higher yield strength than the DOM, but that ERW is not made of as tough of a material as the DOM.
Meaning that it takes more energy (the weight falling through distance) to continue to permanently bend the DOM than the ERW.
.
wow this video really helped me out in selecting the right tubing for my wheelie bar.
Damn, this video was useful for the very same question, DOM vs. Rigid pipe. Thanks
i wonder if a line graph of the strengths would looks identical to the tubing at the end of the video?
I wonder if orientation of the weld impacts results? If weld was bottom side it may come out differently.
im thinking weld on top might strengthen seam joint a little better
Kim Sands you can bend a weld but it is harder to stretch one!
Of course it does
I could take the time and explain what's going on here but this video explains it easier than I could. The two different tubes are most likely made of the same type of steel, it's just the difference if manufacturing, resistance welding vs machine rolled and worked. Welding without heat treatment weakens steel.
The chemistry of the the two tubes are signifcantly different. The carbon content of the DOM is twice the carbon content on the ERW. Both tubes have a welded seam that will create a weak place in the tube, the seam in the DOM will be much more difficult to locate, the DOM manufacturing process smooths the seam.
If the seam of both tubes were placed perpendicular to the load they would have little effect on the bending, but since the DOM has higher carbon content it will always be stronger than an equally sized ERW tube.
Excellent point. Most DOM is 1026-alloy steel, and has a UTS of ~76 ksi, where as most non-DOM ERW is 1010-alloy steel of only ~ 54 ksi UTS. The 2% Yield Tensile Strength of 2016 DOM is ~54 ksi, where as 1010 non-DOM ERW is only ~38 ksi.
"...there's your business end right there" 😂😂😂 I LOL'd
Very kind of you to do the test. It does prove that there is very little difference at the end of the day. With the distances between braces used on most structures, to bend or fail at the ERW seam would mean you have had a very severe impact that probably killed you anyway so if you're building on a budget, go right ahead and use ERW, the total sum of your engineering is far important than the small differences seen here.
+Mark Mark concur totally.
Bad premise. When building a safety system, you choose the *best* design, not one that is "just ok." By your logic, we should make automotive seatbelts out of toilet paper, because if you crash you're probably gonna die anyway.
I wouldn't draw conclusions on this and bet your life on it. While interesting to watch, the test isn't showing hard, repetitive impacts. I've seen ERW fail miserably on seemingly well built cages, and some really poorly built cages as well. Usually breaks right at the welds, or the tubing itself just crushes.
With the ERW You have always to consider where the weld is, that's not the case with DOM. Another benefit for the DOM is, You can use a thinner wall, saves weight. ERM is cheaper than DOM
DOM tubing are also welded but they pass through the drawing process after the welding. That is the main reason the material aquires strength. Another important strength improvement is reached by the heat treatment and, of course, the steel alloy used. Drawn Over Mandrel Steel Tubing
My guess is that the DOM is subject to allot more cold working than the ERW in it's manufacture resulting slightly higher work hardening. As hardness increases so does the yield point (the point where the material does not return to it's original shape and deformation takes over) which results in a higher PSI rating. I'd be curious to see a mill cert on both to see if they are the same grade of steel to start out with.
I don't know what kind of force that weight translates to at ten feet, but is the extra strength worth it? And with the short legths you used on your frame, do you think the erw is better? That early flex in the dom caught me by surprise too.
So what I'm seeing is that for chassis based uses with the tube at usable lengths like we would normally do, they are pretty close. The question now is, what is the impact strength of them. Which one would dent or smash from a hard hit the easiest. Thanks for making this video!
I may test both under a press with both the same pressure to give some indication, on a side note the DOM seems to take more effort to bend using my hand powered bender
groutaone nice video. You may want to do an impact test vs. a slow bend test here. Most crashes during racing are high speed impact not a slow continuous impact. Just saying.
I need to build a bash bar for the front of a rig that needs to absorb impact and not transmit all of the energy into the frame. It seems that the ERW might have and advantage for my application?
Fun stuff - however how much a tube will flex before yielding depends on it;s dimensions. Since all steel has pretty much the same modulus of elasticity the two tubes should flex about the same before yielding. How much force it takes to get it to yield depends on it's yield strength. So the higher strength steel will take more force to permanently bend.
Softer steel is has better durability, that's why they build bridges and buildings out of A36 or A58 steel and not chrome-moly.
Cheers!
+James Valiensi DOM is cold rolled this changes the lattice structure of the steel making it...STIFFER...that's why Tubing rolled DOM has a tensile strengh of 60,000-70,000 vs HREW at about 40,000 ...they will both still dent the same as they are both the same steel and have the same ....hardness... 1.75 hrew gets you the same load carrying ability as 1.5 DOM and both at .120 will dent the same . LOL...can you beleive even steel supply yards think DOM is seamless...lol...there is just so much bad info on tube parroted around 4x4 forums everyone thinks tube bent hrew is junk and DOM is magic shit .
+yerwrng yup!
For my bars... I use 2" HREW .120 for the hoop, and 1.90" Sched 40 for the rear legs. If I roll (again...) I WANT some flex... and then to the limit of the rear leg... NO flex!
The pipe rear vs tube... dominates in strength.
You are correct sir, steel is steel is steel when it comes to flexing below the yield strength. Even if you were to perform the test with a 301 stainless at 42RC you would get the same amount of elastic deformation assuming the same dimensions of material. Difference would be the plastic deformation, bending, would not happen on the stronger material until much higher loads were encountered. There is no stiffness difference in different steels, but there is plenty of strength differences. The DOM performs better here because of the work hardening of the material during the drawing process.
Two pieces of steel with different yield strengths will not flex "about the same," the one with the higher yield strength will flex farther before yielding - that's the definition. You can have a 1008 bar of a certain cross section that permanently deforms at a bend of 5 degrees, while a 1030 bar of the same dimensions will spring back if bent 5 degrees. The reason they build bridges out of A36 has nothing to do with this; A36 is cheaper and is "strong enough." Engineers do not overbuild.
I am having a hard time fitting a .750 steel tube into a pillow block bearing. Someone told me that I should use DOM tube since it is more suitable for fitting in. (Better tolerances). Does that sound right to you?
Dom tube tighter tolerances than erw from the mandrel process of dom
I have a very silly question. The flex test is also known as the Bending test right?
was that Matthew Mcconaughey's voice at 5:50?
Bow and flex isn't why we use dom over erw. It's because erw will explode or rip on impact. Dom is forgiving saving our lives.
I want to know if the tubes were cut to the same length for this test or not? I know the results will probably be the same and all but I would like to know. In cases were you would be using the same tubing and doing that test it would only take an inch to throw off the test. I wouldn't expect any change in this test because DOM is where it's at.
You got me curious so I went out and measured, I measured the full length around the outside of the bends that were made and they are about 1/8th of an inch difference
groutaone
Thanks for letting me know. I was just curious. Also thanks for another great video.
Are they the same steel type?
Thanks for the vid ... now we all know the importance of DOM and why it is the choice for cage builders . next vid chrome moly vs DOM
Good video idea
Most roll cage builders will tell you to run a .130 wall ERW tube to comply with NHRA rules as if you try to run .120, the consistency with ERW could give you thin spots that fall below the .118 (IIRC) minimum. I’d love to see how a .130 wall ERW vs a .120 wall dom fares. What we may be seeing here is simply those inconsistencies in thickness creating weak points and nothing to do with the material itself being stronger (in terms of the metal’s composition). In the real world building say a roll cage, you could still save a lot of money going ERW .130 wall over dom .120 and I wonder if it would be just as strong, If not stronger?
Might gain a little weight but if keeping it light were a priority over cost you’d probably be using cromoly lol
what a great video, thank you so much.
That's the whole point of Dom it flexes it just doesn't snap like pipe
Is there a weight difference between them?
That's a good question but sorry I don't know
No
Looks like you got yourself a new tubing bender to replace that ebay one. lol
Seen it mentioned a couple times but like it's been said this would be a test of modulus aka stiffness not strength , you can take a piece of totally anealed silly putty steel against the strongest super alloy steel like mar 300 And if you put equal weights they will stretch the same until you exceed the plastic strength of the softer steel at which point it will begin to stretch permanently And strain harden
Eric J o
Since DOM is simply ERW that has been cold drawn to a specific dimension and specification I would bet these test results could be changed by using a different spec DOM tubing... just a guess. I have built plenty of race cars with ERW with good results but my next, and likely last car, will be DOM.
Shorty Medlock / no it isn't. W stands for welding, bent sheet and welded, for the DOM they used a mandrel to get the 'hole'
@@j.r.arnolli7494 Both DOM and ERW are made from flat ribbon stock, electrically welded along a seam. DOM tubing is also drawn through a die over a mandrel to flatten the weld seam and improve dimensional accuracy.
Good to know and a great test. I use DOM when build my stuff.
I agree with the result that erw is weaker but there is one flaw in this test.
the pipe is being bent as it comes out more which scews the results as you go out further.
a bend at 3 feet is going to be exaggerated at 6 feet. I am talking the erw. the dom is not actually bending as much due to rebounding from the bend point
not disputing your findings at all.
We all know Cold rolled DOM has a higher Tensile strengh than hot rolled I think it's 30-40 for HREW vs Cold rolled DOM at 60-70 , so this owuld be the expected out come . Cold rolling effects the Crystal lattice structure making it stronger and harder to bend ...However in regards to denting they are both still just as HARD so they will dent the same given both were made from the same steel .
Is that a hit n miss hiding in the background at 6.05
It is, good eye
groutaone
Yea i look in the background alot need to fire it up and get a running video
Logan Adams Never thought about that for a video idea, thanks may have to do that
groutaone cant wait
Thanks for the test. Great information
So... if fishing for a 55 lb fish... use DOM... but for main rollbar hoops... hrew is fine. Got it!
Hilarious
hahaha. That's funny. I'd be interested to know how much more resistant DOM is to crushing force like when you roll your vehicle and hit a rock or a tree and get a dent in your rocker or roof tubes. Obviously different parts of a cage see very different types of stresses and impacts.
Can you do a HREW vs DOM?
Wow, is the cost very different in the two tubing ?
Off hand I don't know how much more, I just know when I buy DOM I can notice the $ ouch a bit more, I should look into the exact cost difference
+krazy45cat I think it is like $4/ft versus $9/ft. You feel it!
You can see my video, I bought some at cheapest steel supply in sacramento, 2018, and 1-1/2 .120 ERW 20ft was $40,
DOM was $115 for 22ft. So 2-3 times more. If you add gussets to a cage, it is way stronger than any difference in tubing strength.
HREW/ERW and DOM are the same tubing. Tubing and schedule pipe fall into this same category. Only difference are tubing is o.d. and pipe is i.d. The DOM is just the HREW tubing/pipe drawn cold through a die and over a mandrel with a cutter to remove the flash on the inside. Granted the cold draw it experiences realigns the molecules a little and therefore make for a trivial amount of strength difference. DOM is mainly just for operations where the inside needs to be smooth or if pieces are to be inserted into it. DOM does have closer tolerance to true measurement. DOM is NOT seamless pipe/tubing. That is a whole different animal.
There is no cutter used during the drawn over me and draw process. The ID weld flashing is removed on the weld metal during the welding. Drawing over me and roll with the weld flashing there would pull the weld into the tube and make a poor tube. I retired from ArcelorMittal Shelby after 42 years in the tube making business. The company is 131 years old.They average around 200,000 tons of product per year. Size range is 1 inch to 12 1/2 inch with wall thickness is up to .675.
Hey Grouta One! I think that a torsion (twist) test would better serve you because of the short lengths one uses constructing a frame or cage. Yeah you dont want it to bend outright but i would think that tweaking would be more of an everyday problem off-roading than bending during a crash. Don't get me wrong, just try to follow my thought. lol Cool test man!
I think it's time for another cr500 video:)
Just invented a poor mans tube bender!!
That's all find and dandy but one problem good sir what practical application would you need to span that great of an area, the erw worked fine with the short span better then the other even if your spanning that far you'll have bracing which changes the fulcrum..... just saying haha btw the buggy looks great!!
Yes you are correct about the span bracing used in normal construction as this would make the ERW usable for a lot of applications
groutaone It would be cool if you did a strength test with gauges with pieces of metal that are realistic in common use so yo would know where the yield point of each tube
Thanks for this.
Wait.. LOL @ 5:51-52 The tube is bending and you say... 'may-annnnnn'..... like if you were, a hollywood hipster who is a little drunk and saying 'man' LOL
shhh.. hes Elvis but he might not know it himself yet :)
A big difference for sure.
maybe the is welding then of the tube on the ERW.
I knew this before, the dom is more flexible at first, it will alow a little flex and that is also why its strong. If you would build a rollcage from that dom tube then it would not change shape that much in a crash. It wil bend and flex a little, but it wil spring back in to its shape. And that erw tube wil just bend and go flat and snap open. And that was the only surprise for me in this video. I expected the welded tube to split open, but that didnt happen. I have seen it happen when they where bending it on 1 of those cheap chinese benders.
Construction method counts a bit ... Size differential counts a bit ... Alloy composition counts a whole lot ..
Do you even lift?
Cool video Groutaone.
Thank you for that
Don't accidentally drop one of those on your toe.
This is for aluminium but it's a very interesting process. Drawing Process in Manufacturing / Aluminium tube Production
Canadian as FUCK! I love it.
i think another awesome video would be a real tube bender vs princess auto's kinker! i will be sure to show this video to my friends when they wonder why I'm spending the money on DOM for my bug!
Ah yes the princess auto kinker ha ha, I can relate
Hmm, Very interesting. At 1st I thought they were going to stand firm at side by side throughout the whole process.
Well done, Now we know ! lol
Thanks, yep I think this video will be an eye opener for many
Very interesting experiment/display...I recon your other pipe bender does a better job..lol.
Thanks, yes so far at least I find the bender to work better, sometimes seems like not by much though ha ha
Very interesting. Thanks for sharing
Thanks for watching
i,m more interested in fitment say one inside the other, does the ERW have weld build up on the inside, for instance i can slide a 1" .120 wall DOM inside a 1 1/4" .120 wall DOM with a nice fit can i do that with the ERW ?
DOM is stringer when welded...
The DOM starts as ERW
not quite an official test. Fixture wise etc
Very, very interesting
Good ino bud 👍
interesting....thanks.....
thank you
I think the ERW quality fluctuates a lot more than the DOM, so the DOM is more consistent and reliable.
Very scientific
Thanks
Good
@ 2.55 MY NAME
the erw will snap
Rule of thumb when it comes to metals: you never want to have a brittle fracture.
you are testing Young's modulus, not strength.
Young's modulus represents the stiffness of the material in the ELASTIC deformation region. Yield strength determines at what point the material deforms plastically during loading (e.g., takes a PERMANENT SET when bent). Before the two tubes took a permanent set, they were bending at about the same rate. This is because Young's modulus of all steels is essentially the same (around 30,000 Ksi). Once permanent deformation started to occur, one tube bent a lot more than the other. This tells me that the tubes were made of two different grades of steel (having different Yield strengths). DOM and ERW simply identify the manufacturing process used to form the tubing. Both DOM and ERW tubes are made from flat ribbons of steel, which are electrically welded (ERW = electrical resistance welding). DOM tubing is also drawn through a die over a mandrel. This flattens the weld seam and increases the accuracy of the ID and OD dimensions of the tube, but that weld seam is still there. Regardless, the forming method has nothing to do with Young's modulus, Yield strength, or Ultimate Tensile strength, which are material properties. Bottom line is that for purposes of tests, such as the one in the video, whether the tubing is DOM, ERW, CREW, etc. is not really important, but the grade of the material (1010, 1018, 1020, 1026, 4130, etc.) is.
Number of girls 'mirin=0, DO YOU EVEN LIFT?
Nice.....who said engineering is difficult to understand
karroome Thanks for watching
Ha ha nope Dident see a diffrence ... Lol
Ya it's an eye opener for sure
groutaone seems like his eyes were closed