DOm vs HREW testing...

[dyogim]

Here's an interesting thread from "BigMike" on MarlinCrawler.com providing some real life results on the misconception that DOM is less dent resistant than HREW. Take it for what it's worth. Just thought it was some reading.

Disclaimer from the author: "Please rest assured I am not attacking your USA DOM steel, in fact the main point is that I am not attacking ANY steel but rather I am attacking the misconception that simply saying "DOM" does not mean it is guaranteed to be more dent resistant than HREW.

Here's a link to the thread: We test Marlin Crawler's HREW vs. Competitor's DOM Bumper Steel

[apimpdad]

I have never really bought into the whole argument on which is stronger and why. There are a plethora of trucks around here that run subframes made out of both DOM and HREW or "poop pipe" or "sprinkler pipe" or "black pipe" or whatever you want to call it. All usually have 44" or larger DOT or tractor tires with gas and diesel engines ranging in power from 300hp to over 1500. All perform flawlessly. The only failure that I have seen was to a DOM subframe during a tug a war. The tube that failed appeared to be too thin but the design was also a big factor supposedly. Its not necessarily the material used its the design that really matters.

If I had a choice on what to build bumpers on, I would probably in fact choose DOM for most of the bumper, but use HREW also. Now for links or axle trusses, I would only use DOM.

[DevinSixtySeven]

Mike, thanks for posting that article. Gotta say I lost an awful lot of respect for Pirate just now. *edit* Somehow I missed the page numbers...am reading the rest, will see where it goes, maybe I'll get that respect back...we'll see. *later edit* Nope. But apparently in the fabrication materials thread. Whatever. I don't care, nothing I read changed any of my opinions or provided any additional knowledge, tho it did reinforce my opinion of countries trying to achieve in ten years through looks what Western nations did in a century through process. There are good sources of foreign goods, but if they don't have a cert, long warranty, excellent customer service, etc., don't buy it until the company is willing to provide those items. Ten bucks sez no certs are available, or ever will be, for that DOM tubing in BigMike's test.

It is critically, critically important to keep in mind that it is the process used to create the tubing...ERW vs ERW which is then cold-drawn over a mandrel...which improves the strength of the ERW tubing in the final "seamless" product.

I'd hate to see the material properties of that crappy tube before it was drawn.

If you are buying import steel, you are likely not buying high quality steel, and BigMike's testing clearly showed the difference. I suspect, if he were to continue the tests, that he'd find a good US-made DOM 1020 would show a significant improvement over the US-made HREW, and would show the import DOM 1035 to be a non-performer.

That wasn't a test of HREW vs DOM, it was a test of US-made HREW vs import DOM. The process does indeed matter...there are a few ways to make seamless tubing (piercing, rolling, hot and cold drawing, etc)...just like the material composition of the tubing affects the tube's mechanical properties...so if the material composition was actually below the standard by which the tube is marked, and the process wasn't what they were expecting when they ordered "seamless" tubing, then (as in this case) a certain vendor may as well have been building parts from seamless poop pipe.

Know what you are buying. If you are buying US-made, cold-DOM ERW 1020, then you are buying good tubing which will be mechanically stronger than its ERW precursor. If you are buying US-made ERW tubing, you can also assume that you are buying good quality, strong tubing.

Bluntly, if you cannot find the screened/dyed/painted mark which clearly states "Made in USA" on the tubing, don't buy it.

There's a signature quote on TTORA that goes about like this..."An Earth made in China is just as good as an Earth made in the USA, but it will be flat and say Made in China on the back."

Pimp, you are correct in that it is the design which is most important. Of three frames which are equally strong, the HREW 1018/1020/1021/etc frame will be heaviest, the frame made from the DOM process of the HREW tubing will be almost twice as light, and the same frame made from 4130 DOM chromoly will be a bit lighter than the DOM carbon steel frame. The choice of material means either lighter weight for the same strength, or greater strength for the same weight, which is why people who can afford it run 4130 DOM links, whether simple tube for the crawlers or massive fabricated links on desert trucks.

-Sean

[Corban_White]

Originally Posted by DevinSixtySeven

Mike, thanks for posting that article. Gotta say I lost an awful lot of respect for Pirate just now. *edit* Somehow I missed the page numbers...am reading the rest, will see where it goes, maybe I'll get that respect back...we'll see. *later edit* Nope. But apparently in the fabrication materials thread. Whatever. I don't care, nothing I read changed any of my opinions or provided any additional knowledge, tho it did reinforce my opinion of countries trying to achieve in ten years through looks what Western nations did in a century through process. There are good sources of foreign goods, but if they don't have a cert, long warranty, excellent customer service, etc., don't buy it until the company is willing to provide those items. Ten bucks sez no certs are available, or ever will be, for that DOM tubing in BigMike's test.

It is critically, critically important to keep in mind that it is the process used to create the tubing...ERW vs ERW which is then cold-drawn over a mandrel...which improves the strength of the ERW tubing in the final "seamless" product.

I'd hate to see the material properties of that crappy tube before it was drawn.

If you are buying import steel, you are likely not buying high quality steel, and BigMike's testing clearly showed the difference. I suspect, if he were to continue the tests, that he'd find a good US-made DOM 1020 would show a significant improvement over the US-made HREW, and would show the import DOM 1035 to be a non-performer.

That wasn't a test of HREW vs DOM, it was a test of US-made HREW vs import DOM. The process does indeed matter...there are a few ways to make seamless tubing (piercing, rolling, hot and cold drawing, etc)...just like the material composition of the tubing affects the tube's mechanical properties...so if the material composition was actually below the standard by which the tube is marked, and the process wasn't what they were expecting when they ordered "seamless" tubing, then (as in this case) a certain vendor may as well have been building parts from seamless poop pipe.

Know what you are buying. If you are buying US-made, cold-DOM ERW 1020, then you are buying good tubing which will be mechanically stronger than its ERW precursor. If you are buying US-made ERW tubing, you can also assume that you are buying good quality, strong tubing.

Bluntly, if you cannot find the screened/dyed/painted mark which clearly states "Made in USA" on the tubing, don't buy it.

There's a signature quote on TTORA that goes about like this..."An Earth made in China is just as good as an Earth made in the USA, but it will be flat and say Made in China on the back."

Pimp, you are correct in that it is the design which is most important. Of three frames which are equally strong, the HREW 1018/1020/1021/etc frame will be heaviest, the frame made from the DOM process of the HREW tubing will be almost twice as light, and the same frame made from 4130 DOM chromoly will be a bit lighter than the DOM carbon steel frame. The choice of material means either lighter weight for the same strength, or greater strength for the same weight, which is why people who can afford it run 4130 DOM links, whether simple tube for the crawlers or massive fabricated links on desert trucks.

-Sean

Just to clarify a few things; DOM does have a seam, and the last paragraph is only true because the wall thickness can be decreased on the stronger material-yielding the same strength and lighter weight. (This was implied but it took me reading it a few times to get it straight. )

[DevinSixtySeven]

I probably should've been more explicit ...

FWIW, I mentioned 1020 DOM...but it comes in more flavors than that...they're all plenty good, as long as it's seamed tubing which has been cold-worked over a mandrel to final dimensions (the seam is effectively hidden by the drawing process). I dunno anything about pierced & drawn seamless tubing, which is literally seamless & not something normally ordered by anyone in this scene...

[trfytoy]

Doesnt a lower Rockwell number indicate a harder surface? Thats what I have been taught anyway.

[Corban_White]

There are several different rockwell scales (B, C, etc.) as well as many other scales with different names. However, all the ones I am familiar with get harder as the numbers go up.

[trfytoy]

Ahh, thank you.