Rock Slider and Roll Cage Tubing Comparison, HREW v DOM v Square all Made in the USA

[traxman25]

Rock Slider and Roll Cage Tubing Comparison and Torture Test
HREW vs. DOM vs. Square Tube all Made In The USA

At 4x Innovations we want our customers to get the most value for their money and we are always checking to ensure that they are. In an effort to ensure this we have tested two of our most popular materials, 1-3/4" Hot Rolled Electrically Welded (HREW) and 1-3/4" Drawn Over Mandrel (DOM) tubing. There are been articles circulating the web that claim HREW tubing is just as strong as DOM tubing and therefore is unnecessary and even a waste to spend premium dollars on DOM for your next cage, sliders, or bumper. Unfortunately, this is information is misleading because of the test parameters and the materials that were tested. The HREW material in those test came from a trusted US steel distributor whereas the competing DOM material is a low quality offshore material. The standards of manufacturing differ greatly resulting in different material properties and a lower quality product. At 4x Innovations we only use high quality Made in the USA steel tubing (melted and rolled), which delivers a much more reliable, consistent, and superior product.

The setup:

For this testing we used laboratory grade equipment located in the University of Wisconsin Platteville's material testing lab. Two tests were performed to determine the strength of each tube sample; a load test and a Rockwell B hardness test.

Since the test cross sectional area is constantly changing during this test it is not possible to create a true
stress-strain curve for a tube in compression loading. Because of this the true testing stress is not able to be calculated for the tube and a load force vs. displacement graph is the only option to display the data. To create these curves a MTS Criterion, figure 1, universal testing machine (UTM) was used to crush the tubes to 0.4" (10mm) of displacement. The 4 inch long sample pieces were tack welded to a plate for safety reasons and two parallels were placed on the top of the sample and on the bottom to distribute the load to the cross head, figure 2.

We wanted to collect the hardness data from the exterior of the tube where it will be exposed to weather, rocks, and any other forms of torment that a real world application would produce. To ensure the part would not deflect under the load of the machine a machined insert was put into the tube being tested, figure 3. This results in a very accurate hardness rating of the outside of the tube by keeping the tube from deflecting. Rockwell B hardness was used for collecting this data and the testing was done on a ROCKY series machine.

The test:

Specimens for the crush test were loaded into the machine all in the same orientation and the test was executed. The load cell collects data on the load vs. the displacement of the crosshead as the test takes place and displays it on the computer display, figure 4.

Needless to say the results were very impressive. The DOM tubing was the clear winner with a maximum sustained load of 6688 pounds-force being applied. This is compared to the HREW material which produced a maximum sustained load of 4239 pounds-force. It was interesting to see that seam placement with the HREW samples made a difference of about 210 lbf.
The max force is not always the most useful comparison unfortunately, instead the point at which permanent deformation starts to occur should be used to compare these samples. In the case of the DOM tubing it occurs at approximately 5000 pounds of force and for the HREW around 3000 pounds, figure 5. This means that the DOM tubing is 66% more resistant to permanent deflection due to a static load than its HREW counterpart. :thumb3:

Similar amounts of spring back were seen in the tested samples regardless of the extreme difference in the forces needed to crush them. As seen in figures 6 (DOM) and 7 (HREW) tubing demonstrated classic tube yielding mechanics.

Figure 6 - DOM Tube deformation.

Figure 7 - HREW Tube deformation.

The hardness test demonstrated a similar trend of results with respect to the crush test. The Rockwell B hardness for the DOM was approximately 84, where the hardness for the HREW samples exhibited an approximate average of about 66,

The verdict:

If you are an explorer checking out fire roads, wooded adventures, driving the typical class 1-3 type trails and run a fairly light truck who needs basic protection from trees, stumps, or the occasional rock HREW might be perfectly suitable for your application. If you are getting into the class 4-5 trails, trails with a lot of rocks and drops, or into expedition and weeklong camping, running a heavier truck you should probably upgrade to the DOM tubing. The added strength of DOM, 66%, will really shine when you "test" your cage or slam your sliders hard on the rocks.

Real world test:

In addition to our egg-head style laboratory tests we conducted some, scientific but, more practical tests on the sliders. We had a 1996 4Runner that we added the three types of rock sliders we offer to; HREW, DOM, and Square Main Tube with DOM outer tube. We then dropped the truck onto a large boulder from varying heights and positions on the rock slider. A video of this test and the results can be found here.

<iframe width="560" height="315" src="https://www.youtube.com/embed/sdQPhzA44ms" frameborder="0" allowfullscreen></iframe>

 

[jwkilgore]

Real world test:

In addition to our egg-head style laboratory tests we conducted some, scientific but, more practical tests on the sliders. We had a 1996 4Runner that we added the three types of rock sliders we offer to; HREW, DOM, and Square Main Tube with DOM outer tube. We then dropped the truck onto a large boulder from varying heights and positions on the rock slider. A video of this test and the results can be found here.

https://www.youtube.com/watch?v=sdQPhzA44ms

[Edit to add:]
Read this first!
This post attracted lots of angst for some reason. If you are an engineer or otherwise have lots of knowledge of material science, then please ignore this post. Get all up in the text and graphs above, and please ignore the rest of this post. If you are a normal driver please continue.[/ETA]

Ignore the rest, the [quoted text] is the important bit. You can run academic studies all day long, but for these type of applications a field break test is the way to get usable data.

If you're a casual off-roader trying to decide whether or not to spend the extra cash for DOM vs. HREW. Or regular vs. extra beefy. Yes, they are stronger... but really, will you be getting into a situation with a 2-ft free-fall drop onto solid rock? The extra-heavy sliders never actually bent... the frame bent first.

And if you only start watching before commenting, they did take the wheels off and re-run the drops later in the video. So they did true free-fall drops.

Excellent information.

 

[traxman25]

Ignore the rest, this above is the important bit. You can run academic studies all day long, but for these type of applications a field break test is the way to get usable data.

If you're a casual off-roader trying to decide whether or not to spend the extra cash for DOM vs. HREW. Or regular vs. extra beefy. Yes, they are stronger... but really, will you be getting into a situation with a 2-ft free-fall drop onto solid rock? The extra-heavy sliders never actually bent... the frame bent first.

And if you only start watching before commenting, they did take the wheels off and re-run the drops later in the video. So they did true free-fall drops.

Excellent information.

I disagree with the lab tests not being useful. They give a clear and exact* strength difference between the HREW and DOM. The practical testing is the easiest to see the difference, but the lab test has great importance. If for no other reason, now when you call and ask how much stronger is it I can give you a definitive answer "66% stronger", not just a "well we dropped this from here and that from there."

The DOM upgrade is still a good choice. That HREW slider has more dents and is bent more from an 18" tires on drop than the DOM slider was at 24" tires on.

On another note, what we really proved here is that you should NEVER weld sliders to the frame without a substantial support plate. I have zero doubt that at 18" even the HREW slider would have pushed a dent in the frame, and that square tube slider gusset would have ripped a hole.

*Nothing in material science is ever truly exact, there is always some variation within certain limits, as shown by the hardness tests.

 

[techno]

Other than the manufacturing process and the HRB, I didn't see any info about the material properties in the different samples. What kind/grade of steel was used? 4140 for example? Were they both the same?

 

[Dorobuta]

I'd also like to see the mill test reports for each of the specific heats for pieces used.

 

[traxman25]

Other than the manufacturing process and the HRB, I didn't see any info about the material properties in the different samples. What kind/grade of steel was used? 4140 for example? Were they both the same?

The HREW samples are from the same batch of material. The DOM samples are from the same batch of material. Both materials are mild steel, and are what we use for all of our production runs. They are not the same grade steels, and DOM is work hardened by nature.

I'd also like to see the mill test reports for each of the specific heats for pieces used.

The HREW samples are from the same batch of material. The DOM samples are from the same batch of material.

 

[KidVermicious]

This is good stuff Adam. Thanks especially for the real world tests.

 

[jwkilgore]

I disagree with the lab tests not being useful. They give a clear and exact* strength difference between the HREW and DOM. The practical testing is the easiest to see the difference, but the lab test has great importance. If for no other reason, now when you call and ask how much stronger is it I can give you a definitive answer "66% stronger", not just a "well we dropped this from here and that from there."

The DOM upgrade is still a good choice. That HREW slider has more dents and is bent more from an 18" tires on drop than the DOM slider was at 24" tires on.

*Nothing in material science is ever truly exact, there is always some variation within certain limits, as shown by the hardness tests.

The lab tests are technically useful, but not really to the end user. I'm one of those rare structural engineers who doesn't get lost in raw numbers and test results. I look at reality and practicality. I've reviewed plenty of mill reports and other test results, but in the end it's all about meeting a goal.

For sliders, the goals are:
1) Resist bending to transfer rocker panel hits to the frame and allow the vehicle to function after a hit (yield strength)
2) Resist scratching and loss of material through grinding on rocks (hardness)
3) Be tough enough to continue transferring load after multiple hits with localized failures (toughness)

First some :blah::
Yes, the lab testing did confirm that DOM steel (probably ASTM 513 Type 5) is 66% "stronger" than HREW steel (probably ASTM A513 Type 1). For what it's worth, published values put the difference at more like 100% stronger, but that's because the HREW values are somewhat variable. The published design values have to cover the lowest values in the range, which you noted with the * note). It would be quite possible to get HREW close to as strong as DOM; this may be one reason why some other tests show no significant differences between the two. Similar to how ASTM A36 steel is rated at 36ksi but often tests out to 50ksi. But you can't rely on this.

It also confirmed that DOM is more resistant to scratching and abrasion than HREW (hardness).

One thing you didn't lab test is toughness via the Charpy V-notch. In engineering terms, strength is the ability to resist permanent deformation (tube bending long-ways or crushing), while toughness is the ability to resist fracturing after deformation under sudden impact loads. That said, you did approximate the toughness test by dropping the truck on boulders to get localized failures (bending of pipe wall; dents). A tough pipe will bend and deform under impact loads but will remain intact. You don't want a steel that forms small cracks under repeated impacts.
End of :blah:

For your average driver, "66% stronger" is useless information. It doesn't tell you anything practical. It's something a salesman says to impress a customer. What the driver needs to know is if a specific set of sliders will protect their truck under their driving conditions. The video addresses that; "66% stronger" does not.

It's possible that anyone driving off road will accidentally run into the equivalent of your 18" drop, and the HREW sliders functioned perfectly. This would cover the vast majority of drivers. If you drive in locations where you may encounter repeated 18" or more drops, or if you travel long distances off-road with a rig loaded to expedition weights, then you'll want to upgrade to DOM or square.


Honestly, I found that drop test video to be some of the most useful information I've ever seen on slider strength.

 

[Mgyver1]

I'm actually curious about strength to weight, i.e. Is a thinner wall DOM as strong as a thicker walled HREW. I personally don't need the added strength of DOM with the camping that I do, but if I could save some weight by going with a thinner walled DOM that would be appealing. Really what I need is something I can use a Hi-Lift on to jack my truck up if necessary and be able to stand on to reach stuff on my roof rack, I feel confident if it met those requirements if would handle more abuse than my running boards which have served me find so far. I wish I could go aluminum like XO did on their Tacoma but bolt-on sliders just don't seem to be an option for the 3rd gens and aluminum is quite the premium price.

 

[GhostRing]

I'm actually curious about strength to weight, i.e. Is a thinner wall DOM as strong as a thicker walled HREW.

I may be off, but I think that is where you would get into Chromoly tubing -
which is way too nice for sliders (IMO)

That's not to say you couldn't use .095 wall DOM instead of .120 HREW,
but the weight savings are approaching negligible. Using big-ass 3x2" 3/16
tubing for the main tubes on my '94 T4R was overkill for my use, and I could have lightened them up a bit! I use 1.75x.120 HREW for my sliders now.

 

[traxman25]

The lab tests are technically useful, but not really to the end user. I'm one of those rare structural engineers who doesn't get lost in raw numbers and test results......

I have my engineering degree too. :thumb3:

I'm actually curious about strength to weight, i.e. Is a thinner wall DOM as strong as a thicker walled HREW. I personally don't need the added strength of DOM with the camping that I do, but if I could save some weight by going with a thinner walled DOM that would be appealing. Really what I need is something I can use a Hi-Lift on to jack my truck up if necessary and be able to stand on to reach stuff on my roof rack, I feel confident if it met those requirements if would handle more abuse than my running boards which have served me find so far. I wish I could go aluminum like XO did on their Tacoma but bolt-on sliders just don't seem to be an option for the 3rd gens and aluminum is quite the premium price.

For our tubing we use 0.120 wall tube for both types of tube. You wouldn't want to go any thinner as your resilience to denting would drop significantly for what is a negligible weight savings. A full set of sliders is under 70 pounds anyway.

 

[MTD]

Ignore the rest, this above is the important bit. You can run academic studies all day long, but for these type of applications a field break test is the way to get usable data.

If you're a casual off-roader trying to decide whether or not to spend the extra cash for DOM vs. HREW. Or regular vs. extra beefy. Yes, they are stronger... but really, will you be getting into a situation with a 2-ft free-fall drop onto solid rock? The extra-heavy sliders never actually bent... the frame bent first.

And if you only start watching before commenting, they did take the wheels off and re-run the drops later in the video. So they did true free-fall drops.

Excellent information.

Um I don't know about most people, but I like concrete data to back up what I see. The combination of the test data and the video with the drop test is great. For the data it explains it pretty well in layman's terms what each thing represents and definitively shows that the DOM is stronger. Be it a rock slider, or a roll cage it offers more strength and by extension more safety.

The lab tests are technically useful, but not really to the end user. I'm one of those rare structural engineers who doesn't get lost in raw numbers and test results. I look at reality and practicality. I've reviewed plenty of mill reports and other test results, but in the end it's all about meeting a goal.

For sliders, the goals are:
1) Resist bending to transfer rocker panel hits to the frame and allow the vehicle to function after a hit (yield strength) Modulus of Elasticity
2) Resist scratching and loss of material through grinding on rocks (hardness)
3) Be tough enough to continue transferring load after multiple hits with localized failures (toughness) Resilience and Fatigue resistance

First some :blah::
Yes, the lab testing did confirm that DOM steel (probably ASTM 513 Type 5) is 66% "stronger" than HREW steel (probably ASTM A513 Type 1). For what it's worth, published values put the difference at more like 100% stronger, but that's because the HREW values are somewhat variable. The published design values have to cover the lowest values in the range, which you noted with the * note). fftopic: It would be quite possible to get HREW close to as strong as DOM; this may be one reason why some other tests show no significant differences between the two. You cannot compare 2 different wall thicknesses of tubing, which is the only way you will ever get US DOM to the same strength as US HREWSimilar to how ASTM A36 steel is rated at 36ksi but often tests out to 50ksi. But you can't rely on this.

It also confirmed that DOM is more resistant to scratching and abrasion than HREW (hardness).

One thing you didn't lab test is toughness via the Charpy V-notch. In engineering terms, strength is the ability to resist permanent deformation NOPE (tube bending long-ways or crushing), while toughness is the ability to resist fracturing after deformation under sudden impact loads. That said, you did approximate the toughness test by dropping the truck on boulders to get localized failures (bending of pipe wall; dents). A tough pipe will bend and deform under impact loads but will remain intact. You don't want a steel that forms small cracks under repeated impacts.
End of :blah:

For your average driver, "66% stronger" is useless information. It doesn't tell you anything practical. It's something a salesman says to impress a customer. What the driver needs to know is if a specific set of sliders will protect their truck under their driving conditions. The video addresses that; "66% stronger" does not.

It's possible that anyone driving off road will accidentally run into the equivalent of your 18" drop, and the HREW sliders functioned perfectly. This would cover the vast majority of drivers. If you drive in locations where you may encounter repeated 18" or more drops, or if you travel long distances off-road with a rig loaded to expedition weights, then you'll want to upgrade to DOM or square.


Honestly, I found that drop test video to be some of the most useful information I've ever seen on slider strength.

Sweet I am an engineer as well :bigok: Graduate in 2 weeks and will be going to work for Chrysler! Luckily for the end user it really isn't raw data its been collected into a few easy to read graphs with explanations for each. You gotta give your fellow man/woman some credit lol

That being said I am fairly well studied on this stuff coming out of school and I believe you are confusing what you describe as yield strength with the modulus of elasticity of the material or young's modulus. Granted yield strength is the pinnacle or top value before reaching the plastic region, the region where the material stays deformed instead of springing back for anyone who doesn't know, the general idea of the slider or cage not deforming after a hit is related to the elasticity (young's modulus) and not necessarily the yield strength solely. Obviously if the yield strength is surpassed there will be some deformation, but most hits on sliders and cages will not be that hard, at least globally.

The same for toughness, what you are describing is actually a combination of resilience, because plastic deformation is to be avoided, and fatigue resistance, because of multiple hits stipulation. In this case low cycle fatigue is the most relevant fatigue since that is the point where fatigue incorporates stress cycles that go over the modulus of elasticity or yield strength. Toughness is actually a value that can be found by taking the integral of the entire stress-strain curve, simply finding the area under the curve for anyone who might not be brushed up on their calculus, and that value will be the toughness of the material, which gives insight on how the sample will fail. Modulus of Resilience is the integral of the stress strain curve again but this time on from 0 to the yield strain. This is a value of resilience is the amount of energy that can be absorbed with only reversible deformation of material.

In regard to your claim that a Charpy impact energy or Izod impact test would be needed to determine the toughness you could get that from the stress-strain curve by way of a super simple integration. Unfortunately in this case it is not possible to find the true stress strain curve as stated in the OP, so toughness as a value is completely out of the window for this test unless a sample is subjected to a tensile test somehow. As for approximating toughness using the deformation of the slider I don't have any idea how you would go about that, if you find out though I am sure you will be able to name the test after yourself :first: :wink2:

With respect to your claim about strength, in engineering terms you are wrong... Resilience is the ability of the material to absorb energy and resist permanent deformation, not a strength value, and there are several specific values of strength. Your definition of toughness is correct here though which is strange.

You are correct in saying small cracks are not desireable, but with low cycle fatigue there will be dislocations in the crystalline structure of the steel that actually harden the material which is not a bad thing in most cases. If the slider isn't already touching the body by this point it will actually increase the yield strength of the slider (legs mainly, denting is irrelevant).

I recommend looking over your material science references from school, I used Materials Science and Engineering: An Introduction 8th Edition by W.D. Callister Jr. as a reference for what I pointed out above, but even an internet search would be a good start if you want to talk in depth about material sciences. Just a tip for the future. :yo:

At the end of the day the 66% increase in yield strength is not irrelevant or useless it is a big deal. Especially for anyone who knows what they want to do with their rig. Me for example, I will probably opt for the HREW sliders because my rig will never see the rocks, I want sliders to protect from that sand berm that I may take a funny angle or that tree that is just out to get me. People who get out and actually begin to wheel their rig before going all out mall crawler on their build, so they know their limits and where they want to take their adventures. I personally think reading over the OP and watching the video makes for a much more informed buyer and not just another sheep IMHO.

 

[jwkilgore]

[Off topic rant in response to MTD's insults deleted for civility. [MENTION=76968]traxman25[/MENTION]: I apologize for the tangent.]

For the third time, for the average driver without an engineering degree who has no clue how much force is put on sliders in normal use, the lab test numbers are useless. Watch the video. Do you plan on intentionally taking your rig where you'll get the equivalent of repeated 18" drops? Then upgrade. Otherwise, HREW is all you need. If you have an engineering degree then you aren't the average driver. Just for giggles, go ahead and read the lab analysis, ask for the mill test reports, and run load calculations based on sideswiping a 36" white oak tree at 15mph, then determine a value that is 66% stronger than that.

@MTD: There is nothing "strange" about the fact that my definition for toughness is correct. Everything I said related to engineering and material properties is correct. Your "corrections" are not, at least not with regard to what I was trying to say. Your terms apply to elastic stresses and behavior. My terms apply to plastic stresses and behavior; i.e., what happens when the elastic strength of the material (yield strength) is exceeded. Instead of insulting others, maybe you should take your own advice.

 

[traxman25]

Ok kids, let's take a break here. JW, you said your opinion, we get it, that's fine.

 

[Engineer]

I figured this thread could use one more engineer :fencing:

:yield: Just kidding